WorldWideScience

Sample records for hexavalent chromium crvi

  1. Simultaneously photocatalytic treatment of hexavalent chromium (Cr(VI)) and endocrine disrupting compounds (EDCs) using rotating reactor under solar irradiation

    International Nuclear Information System (INIS)

    Kim, Youngji; Joo, Hyunku; Her, Namguk; Yoon, Yeomin; Sohn, Jinsik; Kim, Sungpyo; Yoon, Jaekyung

    2015-01-01

    Highlights: • Self-rotating reactor including TiO 2 NTs is applied under solar irradiation. • Simultaneously photocatalysis of Cr(VI) and EDCs is observed to be up to 95%. • Photocatalytic reactions of Cr(VI) and EDCs are favorable under acidic pH. • Charge interaction and hole scavenge between TiO 2 and pollutants are synergy factors. - Abstract: In this study, simultaneous treatments, reduction of hexavalent chromium (Cr(VI)) and oxidation of endocrine disrupting compounds (EDCs), such as bisphenol A (BPA), 17α-ethinyl estradiol (EE2) and 17β-estradiol (E2), were investigated with a rotating photocatalytic reactor including TiO 2 nanotubes formed on titanium mesh substrates under solar UV irradiation. In the laboratory tests with a rotating type I reactor, synergy effects of the simultaneous photocatalytic reduction and oxidation of inorganic (Cr(VI)) and organic (BPA) pollutants were achieved. Particularly, the concurrent photocatalytic reduction of Cr(VI) and oxidation of BPA was higher under acidic conditions. The enhanced reaction efficiency of both pollutants was attributed to a stronger charge interaction between TiO 2 nanotubes (positive charge) and the anionic form of Cr(VI) (negative charge), which are prevented recombination (electron–hole pair) by the hole scavenging effect of BPA. In the extended outdoor tests with a rotating type II reactor under solar irradiation, the experiment was extended to examine the simultaneous reduction of Cr(VI) in the presence of additional EDCs, such as EE2 and E2 as well as BPA. The findings showed that synergic effect of both photocatalytic reduction and oxidation was confirmed with single-component (Cr(VI) only), two-components (Cr(VI)/BPA, Cr(VI)/EE2, and Cr(VI)/E2), and four-components (Cr(VI)/BPA/EE2/E2) under various solar irradiation conditions

  2. Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Peng, E-mail: yuanpeng@gig.ac.cn [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Liu Dong; Fan Mingde; Yang Dan [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhu Runliang; Ge Fei [College of Chemical Engineering, Xiangtan University, Xiangtan 411105 (China); Zhu Jianxi; He Hongping [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2010-01-15

    Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.

  3. Removal of hexavalent chromium [Cr(VI)] from aqueous solutions by the diatomite-supported/unsupported magnetite nanoparticles.

    Science.gov (United States)

    Yuan, Peng; Liu, Dong; Fan, Mingde; Yang, Dan; Zhu, Runliang; Ge, Fei; Zhu, JianXi; He, Hongping

    2010-01-15

    Diatomite-supported/unsupported magnetite nanoparticles were prepared by co-precipitation and hydrosol methods, and characterized by X-ray diffraction, nitrogen adsorption, elemental analysis, differential scanning calorimetry, transmission electron microscopy and X-ray photoelectron spectroscopy. The average sizes of the unsupported and supported magnetite nanoparticles are around 25 and 15 nm, respectively. The supported magnetite nanoparticles exist on the surface or inside the pores of diatom shells, with better dispersing and less coaggregation than the unsupported ones. The uptake of hexavalent chromium [Cr(VI)] on the synthesized magnetite nanoparticles was mainly governed by a physico-chemical process, which included an electrostatic attraction followed by a redox process in which Cr(VI) was reduced into trivalent chromium [Cr(III)]. The adsorption of Cr(VI) was highly pH-dependent and the kinetics of the adsorption followed a pseudo-second-order model. The adsorption data of diatomite-supported/unsupported magnetite fit well with the Langmuir isotherm equation. The supported magnetite showed a better adsorption capacity per unit mass of magnetite than unsupported magnetite, and was more thermally stable than their unsupported counterparts. These results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.

  4. Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

    Science.gov (United States)

    Pranoto; Masykur, A.; Nugroho, Y. A.

    2018-03-01

    Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

  5. A plan for study of hexavalent chromium, CR(VI) in groundwater near a mapped plume, Hinkley, California, 2016

    Science.gov (United States)

    Izbicki, John A.; Groover, Krishangi D.

    2016-01-22

    The Pacific Gas and Electric Company (PG&E) Hinkley compressor station, in the Mojave Desert 80 miles northeast of Los Angeles, is used to compress natural gas as it is transported through a pipeline from Texas to California. Between 1952 and 1964, cooling water used at the compressor station was treated with a compound containing chromium to prevent corrosion. After cooling, the wastewater was discharged to unlined ponds, resulting in contamination of soil and groundwater in the underlying alluvial aquifer (Lahontan Regional Water Quality Control Board, 2013). Since 1964, cooling-water management practices have been used that do not contribute chromium to groundwater.In 2007, a PG&E study of the natural background concentrations of hexavalent chromium, Cr(VI), in groundwater estimated average concentrations in the Hinkley area to be 1.2 micrograms per liter (μg/L), with a 95-percent upper-confidence limit of 3.1 μg/L (CH2M-Hill, 2007). The 3.1 μg/L upper-confidence limit was adopted by the Lahontan Regional Water Quality Control Board (RWQCB) as the maximum background concentration used to map the plume extent. In response to criticism of the study’s methodology, and an increase in the mapped extent of the plume between 2008 and 2011, the Lahontan RWQCB (Lahontan Regional Water Quality Control Board, 2012) agreed that the 2007 PG&E background-concentration study be updated.The purpose of the updated background study is to evaluate the presence of natural and man-made Cr(VI) near Hinkley, Calif. The study also is to estimate natural background Cr(VI) concentrations in the aquifer upgradient and downgradient from the mapped Cr(VI) contamination plume, as well as in the plume and near its margins. The study was developed by the U.S. Geological Survey (USGS) in collaboration with a technical working group (TWG) composed of community members, the Independent Review Panel (IRP) Manager (Project Navigator, Ltd.), the Lahontan RWQCB, PG&E, and consultants for PG&E.&E.

  6. Hexavalent Chromium reduction by Trichoderma inhamatum

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Battera, L.; Cristiani-Urbina, E.

    2009-07-01

    Reduction of hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] is a useful and attractive process for remediation of ecosystems and industrial effluents contaminated with Cr(VI). Cr(VI) reduction to Cr(II) can be achieved by both chemical and biological methods; however, the biological reduction is more convenient than the chemical one since costs are lower, and sludge is generated in smaller amounts. (Author)

  7. Hexavalent Chromium Minimization Strategy

    Science.gov (United States)

    2011-05-01

    Logistics 4 Initiative - DoD Hexavalent Chromium Minimization Non- Chrome Primer IIEXAVAJ ENT CHRO:M I~UMI CHROMIUM (VII Oil CrfVli.J CANCEfl HAnRD CD...Management Office of the Secretary of Defense Hexavalent Chromium Minimization Strategy Report Documentation Page Form ApprovedOMB No. 0704-0188...00-2011 4. TITLE AND SUBTITLE Hexavalent Chromium Minimization Strategy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

  8. Natural and man-made hexavalent chromium, Cr(VI), in groundwater near a mapped plume, Hinkley, California—study progress as of May 2017, and a summative-scale approach to estimate background Cr(VI) concentrations

    Science.gov (United States)

    Izbicki, John A.; Groover, Krishangi D.

    2018-03-22

    This report describes (1) work done between January 2015 and May 2017 as part of the U.S. Geological Survey (USGS) hexavalent chromium, Cr(VI), background study and (2) the summative-scale approach to be used to estimate the extent of anthropogenic (man-made) Cr(VI) and background Cr(VI) concentrations near the Pacific Gas and Electric Company (PG&E) natural gas compressor station in Hinkley, California. Most of the field work for the study was completed by May 2017. The summative-scale approach and calculation of Cr(VI) background were not well-defined at the time the USGS proposal for the background Cr(VI) study was prepared but have since been refined as a result of data collected as part of this study. The proposed summative scale consists of multiple items, formulated as questions to be answered at each sampled well. Questions that compose the summative scale were developed to address geologic, hydrologic, and geochemical constraints on Cr(VI) within the study area. Each question requires a binary (yes or no) answer. A score of 1 will be assigned for an answer that represents data consistent with anthropogenic Cr(VI); a score of –1 will be assigned for an answer that represents data inconsistent with anthropogenic Cr(VI). The areal extent of anthropogenic Cr(VI) estimated from the summative-scale analyses will be compared with the areal extent of anthropogenic Cr(VI) estimated on the basis of numerical groundwater flow model results, along with particle-tracking analyses. On the basis of these combined results, background Cr(VI) values will be estimated for “Mojave-type” deposits, and other deposits, in different parts of the study area outside the summative-scale mapped extent of anthropogenic Cr(VI).

  9. Hexavalent Chromium Compounds

    Science.gov (United States)

    Learn about chromium, exposure to which can increase your risk of lung cancer and cancer of the paranasal sinuses and nasal cavity. Hexavalent chromium compounds have been used as corrosion inhibitors in a wide variety of products and processes.

  10. Hexavalent Chromium (Cr(VI Down-Regulates Acetylation of Histone H4 at Lysine 16 through Induction of Stressor Protein Nupr1.

    Directory of Open Access Journals (Sweden)

    Danqi Chen

    Full Text Available The environmental and occupational carcinogen Hexavalent Chromium (Cr(VI has been shown to cause lung cancer in humans when inhaled. In spite of a considerable research effort, the mechanisms of Cr(VI-induced carcinogenesis remain largely unknown. Nupr1 (nuclear protein 1 is a small, highly basic, and unfolded protein with molecular weight of 8,800 daltons and is induced by a variety of stressors. Studies in animal models have suggested that Nupr1 is a key factor in the development of lung and pancreatic cancers, with little known about the underlying molecular mechanisms. Here we report that the level of Nupr1 is significantly increased in human bronchial epithelial BEAS2B cells following exposure to Cr(VI through epigenetic mechanisms. Interestingly, Cr(VI exposure also results in the loss of acetylation at histone H4K16, which is considered a 'hallmark' of human cancer. Cr(VI-induced reduction of H4K16 acetylation appears to be caused by the induction of Nupr1, since (a overexpression of Nupr1 decreased the levels of both H4K16 acetylation and the histone acetyltransferase MOF (male absent on the first; also known as Kat8, Myst 1, which specifically acetylates H4K16; (b the loss of acetylation of H4K16 upon Cr(VI exposure is greatly compromised by knockdown of Nupr1. Moreover, Nupr1-induced reduction of H4K16 acetylation correlates with the transcriptional down-regulation at several genomic loci. Notably, overexpression of Nupr1 induces anchorage-independent cell growth and knockdown of Nupr1 expression prevents Cr(VI-induced cell transformation. We propose that Cr(VI induces Nupr1 and rapidly perturbs gene expression by downregulating H4K16 acetylation, thereby contributing to Cr(VI-induced carcinogenesis.

  11. Hexavalent Chromium Substitution Projects

    Science.gov (United States)

    2011-05-12

    Hexavalent Chromium Substitution Projects Date (12 May 2011) Gene McKinley ASC/WNV (937) 255-3596 Gene.McKinley@wpafb.af.mil Aeronautical Systems...valid OMB control number. 1. REPORT DATE 12 MAY 2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Hexavalent ...A-10) – AETC (T-6, T-38 and T1A) • Both Cr Primers & Non-Cr primers as well as Cr Surface Treatment – F-22 8 Non- Chrome Tie-coat & touch-up

  12. Evaluation of the genetic alterations in direct and indirect exposures of hexavalent chromium [Cr(VI)] in leather tanning industry workers North Arcot District, South India.

    Science.gov (United States)

    Balachandar, Vellingiri; Arun, Meyyazhagan; Mohana Devi, Subramaniam; Velmurugan, Palanivel; Manikantan, Pappusamy; Karthick Kumar, Alagamuthu; Sasikala, Keshavarao; Venkatesan, Chinnakulandai

    2010-10-01

    The focal aim of the present study was to identify the genetic alterations occurring in the tannery workers and surrounding inhabitants chronically exposed to hexavalent chromium [Cr(VI)]. A total of 108 samples which includes 72 exposed subjects [36 directly exposed (DE) subjects and 36 indirectly exposed (IE) subjects] and 36 controls were recruited for this study. The exposed subjects and controls were selected based on the Cr level present in air and their urine. Directly exposed subjects were categorized based on their work duration in the tannery industries, whereas the indirectly exposed subjects were categorized based on their year of residence in the place adjacent to tannery industries for more than 3 decades. Controls were normal and healthy. Age was matched for the exposed subjects and controls. The exposed subjects as well as the controls were categorized based on their age (group I, 41 years). Cell cultures were established from blood samples (5 ml from each subject) collected from the subjects (exposed subjects and controls) after obtaining informed consent. G-banding (Giemsa staining) of the cultures, micronucleus (MN) assay and comet assay were used to identify the genetic alterations of individuals exposed to Cr(VI) in comparison with the controls. A higher degree of total CA [12 ± 8.49 (21-25 years)] and MN [18.69 ± 7.39 (11-15 years)] was found in DE subjects compared to other groups. In IE subjects, elevated levels of CA [5.67 ± 1.15 (51-60 years)] and MN [25 ± 9.89 (71-80 years)] were observed. As expected, controls exhibited minimal number of alterations. The overall CA frequency due to Cr exposure was significantly different from that of the controls for both chromatid and chromosome type aberrations (P < 0.05 by ANOVA). The MN/1,000 binucleated cells were significantly increased (P < 0.05) in the peripheral lymphocytes of DE and IE subjects in comparison with controls. The mean tail length of comet assay for DE, IE and controls were

  13. Removal and transformation of hexavalent chromium in sequencing ...

    African Journals Online (AJOL)

    The objectives of this study are to evaluate the efficiency of removal of hexavalent chromium (Cr(VI)) in a sequencing batch reactor (SBR) and to ascertain the fate of Cr(VI) in the treatment process. An SBR was operated with the FILL, REACT, SETTLE, DRAW and IDLE periods in the time ratio of 2:12:2:1.5:6.5 for a cycle ...

  14. Adsorption of hexavalent chromium by graphite–chitosan binary ...

    Indian Academy of Sciences (India)

    Hexavalent chromium; graphite–chitosan composite; adsorption kinetics. 1. Introduction ... [2], while Cr(III) is less toxicity and relatively innocuous. Cr(VI) generates in ..... Human Environments (New York: Wiley Inter-Science) p 3. [4] U.S. EPA ...

  15. Hexavalent chromium reduction by a hypocrea tawa fungal strain

    International Nuclear Information System (INIS)

    Morales-Battera, L.; Guillen-Jimenez, F. M.; Cristiani-Urbina, E.

    2009-01-01

    Microbial transformation of the highly toxic, water-soluble and mobile hexavalent chromium [Cr(VI)], to the less toxic, insoluble and immobile trivalent chromium [Cr(III)], is an economically feasible alternative for the treatment of wastewaters contaminated with Cr(VI). The main purpose of this work was to isolate, identify and characterize a microbial strain water by batch enrichment culture techniques, and further identified as Hypocrea tawa by its D1/D2 domain sequence of the 26S rRNA gene with 99,44% similarity. (Author)

  16. Hexavalent chromium induces chromosome instability in human urothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Wise, Sandra S. [Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Holmes, Amie L. [Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Department of Radiation Oncology, Dana Farber Cancer Institute, 450 Brookline Ave., Boston, MA 02215 (United States); Liou, Louis [Department of Pathology, Boston University School of Medicine, 670 Albany St., Boston, MA 02118 (United States); Adam, Rosalyn M. [Department of Surgery, Harvard Medical School, Boston, MA 02115 (United States); Wise, John Pierce Sr., E-mail: john.wise@louisville.edu [Wise Laboratory of Environmental and Genetic Toxicology, Maine Center for Toxicology and Environmental Health, Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States)

    2016-04-01

    Numerous metals are well-known human bladder carcinogens. Despite the significant occupational and public health concern of metals and bladder cancer, the carcinogenic mechanisms remain largely unknown. Chromium, in particular, is a metal of concern as incidences of bladder cancer have been found elevated in chromate workers, and there is an increasing concern for patients with metal hip implants. However, the impact of hexavalent chromium (Cr(VI)) on bladder cells has not been studied. We compared chromate toxicity in two bladder cell lines; primary human urothelial cells and hTERT-immortalized human urothelial cells. Cr(VI) induced a concentration- and time-dependent increase in chromosome damage in both cell lines, with the hTERT-immortalized cells exhibiting more chromosome damage than the primary cells. Chronic exposure to Cr(VI) also induced a concentration-dependent increase in aneuploid metaphases in both cell lines which was not observed after a 24 h exposure. Aneuploidy induction was higher in the hTERT-immortalized cells. When we correct for uptake, Cr(VI) induces a similar amount of chromosome damage and aneuploidy suggesting that the differences in Cr(VI) sensitivity between the two cells lines were due to differences in uptake. The increase in chromosome instability after chronic chromate treatment suggests this may be a mechanism for chromate-induced bladder cancer, specifically, and may be a mechanism for metal-induced bladder cancer, in general. - Highlights: • Hexavalent chromium is genotoxic to human urothelial cells. • Hexavalent chromium induces aneuploidy in human urothelial cells. • hTERT-immortalized human urothelial cells model the effects seen in primary urothelial cells. • Hexavalent chromium has a strong likelihood of being carcinogenic for bladder tissue.

  17. Reduction of Hexavalent Chromium Using Sorbaria sorbifolia Aqueous Leaf Extract

    Directory of Open Access Journals (Sweden)

    Shashi Prabha Dubey

    2017-07-01

    Full Text Available Aqueous plant leaves extract (PLE of an abundant shrub, Sorbaria sorbifolia, was explored for the reduction of hexavalent chromium, Cr(VI, to trivalent chromium, Cr(III. The effect of contact time, pH, PLE quantity, ionic strength, hardness, temperature and effective initial Cr(VI ion concentration were tested; Cr(VI reduction followed the pseudo-first order rate kinetics and maximum reduction was observed at pH 2. Significantly, Cr(VI reduction efficacies varied from 97 to 66% over the pH range of 2 to 10, which bodes well for PLE to be used for the reduction of Cr(VI also at a higher pH. PLE-mediated Cr(VI reduction displays considerable efficiency at various ionic strengths; however, hardness strongly affects the reduction ability. Higher temperature significantly enhances the Cr(VI reduction. This study reveals the potential use of PLE as a green reducing agent in aqueous extract for the efficient reduction of Cr(VI to Cr(III.

  18. Reduction of hexavalent chromium in water samples acidified for preservation

    Science.gov (United States)

    Stollenwerk, K.G.; Grove, D.B.

    1985-01-01

    Reduction of hexavalent chromium, Cr(VI), in water samples, preserved by standard techniques, was investigated. The standard preservation technique for water samples that are to be analyzed for Cr(VI) consists of filtration through a 0.45-??m membrane, acidification to a pH plastic bottles. Batch experiments were conducted to evaluate the effect of H+ concentration, NO2, temperature, and dissolved organic carbon (DOC) on the reduction of Cr(VI) to Cr(III). The rate of reduction of Cr(VI) to Cr(III) increased with increasing NO2, DOC, H+, and temperature. Reduction of Cr(VI) by organic matter occurred in some samples even though the samples were unacidified. Reduction of Cr(VI) is inhibited to an extent by storing the sample at 4??C. Stability of Cr(VI) in water is variable and depends on the other constituents present in the sample. Water samples collected for the determination of Cr(VI) should be filtered (0.45-??m membrane), refrigerated, and analyzed as quickly as possible. Water samples should not be acidified. Measurement of total Cr in addition to Cr(VI) can serve as a check for Cr(VI) reduction. If total Cr is greater than Cr(VI), the possibility that Cr(VI) reduction has occurred needs to be considered.The rate of reduction of Cr(VI) to Cr(III) increased with increasing NO//2, DOC, H** plus , and temperature. Reduction of Cr(VI) by organic matter occurred in some samples even though the samples were unacidified. Reduction of Cr(VI) is inhibited to an extent by storing the sample at 4 degree C. Stability of Cr(VI) in water is variable and depends on the other constituents present in the sample. Water samples collected for the determination of Cr(VI) should be filtered (0. 45- mu m membrane), refrigerated, and analyzed as quickly as possible. Water samples should not be acidified. Measurement of total Cr in addition to Cr(VI) can serve as a check for Cr(VI) reduction. If total Cr is greater than Cr(VI), the possibility that Cr(VI) reduction has occurred needs

  19. Hexavalent Chromium Is Cytotoxic and Genotoxic to American Alligator Cells

    OpenAIRE

    Wise, Sandra S.; Wise, Catherine; Xie, Hong; Guillette, Louis J.; Zhu, Cairong; Wise, John Pierce; Wise, John Pierce

    2015-01-01

    Metals are a common pollutant in the aquatic ecosystem. With global climate change, these levels are anticipated to rise as lower pH levels allow sediment bound metals to be released. The American alligator (Alligator mississippiensis) is an apex predator in the aquatic ecosystem and is considered a keystone species; as such it serves as a suitable monitor for localized pollution. One metal of increasing concern is hexavalent chromium (Cr(VI)). It is present in the aquatic environment and is ...

  20. [Occupational exposure to hexavalent chromium during aircraft painting].

    Science.gov (United States)

    Gherardi, M; Gatto, M P; Gordiani, A; Paci, E; Proietto, A

    2007-01-01

    Hygienists are interested in hexavalent chromium due to its genotoxic and carcinogenic effect on humans. The use of products containing hexavalent chromium is decreasing in many industrial fields because of the substitution with less-toxic compounds. In the aeronautical industry, however, the chromate are added to primer paint as a corrosion inhibitor of aircrafts surfaces: so hexavalent chromium compounds are available in many primers with a composition ranging from 10% to 13%. The application of these primers by using electrostatic guns potentially exposes painting and coating workers at high concentrations of aerosols containing Cr(VI). The aim of the present study is the evaluation of professional exposure to hexavalent chromium during aircraft painting, by adopting both environmental personal sampling and biological monitoring. To valuate workers exposure levels the personal measurements results have been compared with the exposure limit values (TLV-TWA) and the urinary chromium contents with the biological exposure indices (IBE). Moreover the strategy of coupling environmental sampling with biological monitoring seems to be a useful instrument to measure the validity of the individual protection devices.

  1. Soil humic acids may favour the persistence of hexavalent chromium in soil

    International Nuclear Information System (INIS)

    Leita, Liviana; Margon, Alja; Pastrello, Arnold; Arcon, Iztok; Contin, Marco; Mosetti, Davide

    2009-01-01

    The interaction between hexavalent chromium Cr(VI), as K 2 CrO 4 , and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils. - Humic acids (HAs) did not induce reduction of Cr(VI) to its trivalent chemical form, as the interaction between Cr(VI) and HAs rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes.

  2. Mechanisms of hexavalent chromium resistance and removal by microorganisms.

    Science.gov (United States)

    Joutey, Nezha Tahri; Sayel, Hanane; Bahafid, Wifak; El Ghachtouli, Naïma

    2015-01-01

    Chromium has been and is extensively used worldwide in multiple industrial processes and is routinely discharged to the environment from such processes. Therefore, this heavy metal is a potential threat to the environment and to public health, primarily because it is non-biodegradable and environmentally persistent. Chromium exists in several oxidation states, the most stable of which are trivalent Cr(Ill) and hexavalent Cr(VI) species. Each species possesses its own individual chemical characteristics and produces its own biological effects. For example, Cr (Ill) is an essential oligoelement for humans, whereas Cr(VI) is carcinogenic and mutagenic. Several chemical methods are used to remove Cr(VI) from contaminated sites. Each of these methods has advantages and disadvantages. Currently, bioremediation is often the preferred method to deal with Cr contaminated sites, because it is eco-friendly, cost-effective and is a "natural" technology. Many yeast, bacterial and fungal species have been assessed for their suitability to reduce or remove Cr(VI) contamination. The mechanisms by which these microorganisms resist and reduce Cr(VI) are variable and are species dependent. There are several Cr-resistance mechanisms that are displayed by microorganisms. These include active efflux of Cr compounds, metabolic reduction of Cr(VI) to Cr (ill), and either intercellular or extracellular prec1p1tation. Microbial Cr (VI) removal typically involves three stages: binding of chromium to the cell surface, translocation of chromium into the cell, and reduction of Cr(VI) to Cr (ill). Cr(VI) reduction by microorganisms may proceed on the cell surface, outside the cell, or intracellularly, either directly via chromate reductase enzymes, or indirectly via metabolite reduction of Cr(VI). The uptake of chromium ions is a biphasic process. The primary step is known as biosorption, a metabolic energyindependent process. Thereafter, bioaccumulation occurs, but is much slower, and is

  3. Photocatalytic Reduction of Hexavalent Chromium Induced by Photolysis of Ferric/tartrate Complex

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xianghua; Ding, Shimin; Zhang, Lixian [Yangtze Normal Univ., Fuling (China)

    2012-11-15

    Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations results in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly.

  4. Photocatalytic Reduction of Hexavalent Chromium Induced by Photolysis of Ferric/tartrate Complex

    International Nuclear Information System (INIS)

    Feng, Xianghua; Ding, Shimin; Zhang, Lixian

    2012-01-01

    Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations results in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly

  5. An assessment of the environmental toxicity of hexavalent chromium in fish

    NARCIS (Netherlands)

    Putte, van der I.

    1981-01-01

    At present chromium is a common contaminant in surface waters in many countries. In water the metal may be present in the trivalent form (CrIII) or in the hexavalent form (CrVI), the latter of which is more toxic to aquatic organisms.
    The investigations presented in this thesis

  6. REMOVAL OF HEXAVALENT CHROMIUM FROM AQUEOUS ...

    African Journals Online (AJOL)

    a

    be used again to adsorb heavy metal ions. ... Among these heavy metals are chromium, copper and ... poisoning can result from high exposure to hexavalent chromium [2]. Most of the ..... At low pH, the sorbent is positively charged because of.

  7. Use of Cork Waste as Biosorbent for Hexavalent Chromium

    International Nuclear Information System (INIS)

    Sfaksi, Z.; Azzouz, N.; Abdelwahab, A.

    2011-01-01

    The biosorption by cork powder is considered as a new method for heavy metal removal from industrial waste waters such as chromium tanning factories. The aim of this study is to evaluate the efficiency extent of this method using a cork powder as biosorbent for hexavalent chromium Cr(VI). The Fourier Transform Infrared spectroscopy (FTIR) analysis permits to distinguish the type of functional groups likely to participate in metal binding. A linear form of BET isotherms for all the three used temperatures (25, 35 and 45 0 C) and a pseudo-second-order Lagergren equation of adsorption kinetics are obtained. Other experimental results highlight the meaningful influence of parameters such as contact time, pH and concentrations of the solution, on chromium adsorption rate that reach a 97% value under definite conditions particularly a pH of 2-3 values. (author)

  8. Hexavalent Chromium Free Coatings Projects for Aerospace Applications

    Science.gov (United States)

    2012-08-01

    laboratory qualification of a total hexavalent chrome free coating systems for use on magnesium transmission housings. This project will leverage... hexavalent chrome free coating system by utilizing a hexavalent chrome free topcoat, primer, and pretreatment for magnesium parts used on Army...of the hexavalent chrome free conversion coatings. Hexavalent Chromium Free Coating System for Magnesium Housings on Aviation Systems Desert

  9. Reduction of hexavalent chromium collected on PVC filters.

    Science.gov (United States)

    Shin, Y C; Paik, N W

    2000-01-01

    Chromium exists at various valences, including elemental, trivalent, and hexavalent chromium, and undergoes reduction-oxidation reactions in the environment. Since hexavalent chromium is known as a human carcinogen, it is most important to evaluate the oxidation-reduction characteristics of the hexavalent chromium species. Although hexavalent chromium can be reduced to trivalent state, the detailed information on this in workplace environments is limited. The purpose of this study was to investigate hexavalent chromium reduction in time in various conditions. A pilot chrome plating operation was prepared and operated in a laboratory for this study. There was evidence that the hexavalent chromium was reduced by time after mist generation. The percentage ratio (with 95% confidence intervals in parentheses) of hexavalent chromium to total chromium was almost 100% (99.1 approximately 102.3) immediately after mist generation, and was reduced to 87.4% (84.8 approximately 89.9) at 1 hour and 81.0% (78.3 approximately 83.5) at 2 hours, respectively. Another test indicated that hexavalent chromium collected on PVC filters was also reduced by time after sampling. Hexavalent chromium was reduced to 90.8% (88.2 approximately 93.3) at 2 hours after sampling. It also was found that hexavalent chromium was reduced during storage in air. It is recommended that air samples of hexavalent chromium be protected against reduction during storage.

  10. Hexavalent Chromium IV-Free Primer Development

    Science.gov (United States)

    Alldredge, Michael J.; Buck, Amy L.

    2015-01-01

    Primer materials provide corrosion protection for metal parts as well as an increased adhesion between metallic substrates and thermal protection systems (TPSs). Current primers for use in cryogenic applications contain hexavalent chromium. This hexavalent chromium provides excellent corrosion protection even in a cryogenic environment, but it is a carcinogen that requires special equipment and waste control procedures to use. The hazardous nature of hexavalent chromium makes it an obsolescence risk in the future. This study included two phases of evaluation. Thirteen primers were initially identified as candidates and twelve of those primers were tested in phase 1. Four of the best performing candidates from phase 1 continued into phase 2 testing. Phase 1 testing consisted mostly of liquid constituent and physical property testing. Cryoflex and salt fog testing were included in phase 1 because of their importance to the overall success of a candidate material. Phase 2 consisted of physical, thermal, and mechanical properties for nominally processed and fabricated specimens.

  11. Hexavalent chromium is cytotoxic and genotoxic to American alligator cells.

    Science.gov (United States)

    Wise, Sandra S; Wise, Catherine; Xie, Hong; Guillette, Louis J; Zhu, Cairong; Wise, John Pierce; Wise, John Pierce

    2016-02-01

    Metals are a common pollutant in the aquatic ecosystem. With global climate change, these levels are anticipated to rise as lower pH levels allow sediment bound metals to be released. The American alligator (Alligator mississippiensis) is an apex predator in the aquatic ecosystem and is considered a keystone species; as such it serves as a suitable monitor for localized pollution. One metal of increasing concern is hexavalent chromium (Cr(VI)). It is present in the aquatic environment and is a known human carcinogen and reproductive toxicant. We measured the cytotoxicity and genotoxicity of Cr(VI) in American alligator cells derived from scute tissue. We found that particulate and soluble Cr(VI) are both cytotoxic and genotoxic to alligator cells in a concentration-dependent manner. These data suggest that alligators may be used as a model for assessing the effects of environmental Cr(VI) contamination as well as for other metals of concern. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Genotoxicity of Tri- and Hexavalent Chromium Compounds In Vivo and Their Modes of Action on DNA Damage In Vitro

    Science.gov (United States)

    Fang, Zhijia; Zhao, Min; Zhen, Hong; Chen, Lifeng; Shi, Ping; Huang, Zhiwei

    2014-01-01

    Chromium occurs mostly in tri- and hexavalent states in the environment. Hexavalent chromium [Cr(VI)] compounds are extensively used in diverse industries, and trivalent chromium [Cr(III)] salts are used as micronutrients and dietary supplements. In the present work, we report that they both induce genetic mutations in yeast cells. They both also cause DNA damage in both yeast and Jurkat cells and the effect of Cr(III) is greater than that of Cr(VI). We further show that Cr(III) and Cr(VI) cause DNA damage through different mechanisms. Cr(VI) intercalates DNA and Cr(III) interferes base pair stacking. Based on our results, we conclude that Cr(III) can directly cause genotoxicity in vivo. PMID:25111056

  13. REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

    Directory of Open Access Journals (Sweden)

    A. R. Asgari ، F. Vaezi ، S. Nasseri ، O. Dördelmann ، A. H. Mahvi ، E. Dehghani Fard

    2008-10-01

    Full Text Available Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide. It was found that granular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from water at pH≤7 and in 90 min contact time. Maximum adsorption capacity was determined to be 0.788 mg Cr+6/g granular ferric hydroxide. Although relatively good adsorption of sulfate and chloride had been specified in this study, the interfering effects of these two anions had not been detected in concentrations of 200 and 400 mg/L. The absorbability of hexavalent chromium by granular ferric hydroxide could be expressed by Freundlich isotherm with R2>0.968. However, the disadvantage was that the iron concentration in water was increased by the granular ferric hydroxide. Nevertheless, granular ferric hydroxide is a promising adsorbent for chromium removal, even in the presence of other interfering compounds, because granular ferric hydroxide treatment can easily be accomplished and removal of excess iron is a simple practice for conventional water treatment plants. Thus, this method could be regarded as a safe and convenient solution to the problem of chromium-polluted water resources.

  14. Origin of hexavalent chromium in groundwater

    DEFF Research Database (Denmark)

    Kazakis, N.; Kantiranis, N.; Kalaitzidou, K.

    2017-01-01

    Hexavalent chromium constitutes a serious deterioration factor for the groundwater quality of several regions around the world. High concentrations of this contaminant have been also reported in the groundwater of the Sarigkiol hydrological basin (near Kozani city, NW Greece). Specific interest w...

  15. The cytotoxicity and genotoxicity of particulate and soluble hexavalent chromium in leatherback sea turtle lung cells.

    Science.gov (United States)

    Speer, Rachel M; Wise, Catherine F; Young, Jamie L; Aboueissa, AbouEl-Makarim; Martin Bras, Mark; Barandiaran, Mike; Bermúdez, Erick; Márquez-D'Acunti, Lirio; Wise, John Pierce

    2018-05-01

    Hexavalent chromium [Cr(VI)] is a marine pollution of concern as recent studies show it has a global distribution, with some regions showing high Cr concentrations in marine animal tissue, and it is extensively used. Leatherback sea turtles (Dermochelys coriacea) are an endangered marine species that may experience prolonged exposures to environmental contaminants including Cr(VI). Human activities have led to global Cr(VI) contamination of the marine environment. While Cr(VI) has been identified as a known human carcinogen, the health effects in marine species are poorly understood. In this study, we assessed the cytotoxic and genotoxic effects of particulate and soluble Cr(VI) in leatherback sea turtle lung cells. Both particulate and soluble Cr(VI) induced a concentration-dependent increase in cytotoxicity. Next, using a chromosome aberration assay, we assessed the genotoxic effects of Cr(VI) in leatherback sea turtle lung cells. Particulate and soluble Cr(VI) induced a concentration-dependent increase in clastogenicity in leatherback sea turtle lung cells. These data indicate that Cr(VI) may be a health concern for leatherback sea turtles and other long-lived marine species. Additionally, these data provide foundational support to use leatherback sea turtles as a valuable model species for monitoring the health effects of Cr(VI) in the environment and possibly as an indicator species to assess environmental human exposures and effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Hexavalent chromium reduction by bacterial consortia and pure strains from an alkaline industrial effluent.

    Science.gov (United States)

    Piñón-Castillo, H A; Brito, E M S; Goñi-Urriza, M; Guyoneaud, R; Duran, R; Nevarez-Moorillon, G V; Gutiérrez-Corona, J F; Caretta, C A; Reyna-López, G E

    2010-12-01

    To characterize the bacterial consortia and isolates selected for their role in hexavalent chromium removal by adsorption and reduction. Bacterial consortia from industrial wastes revealed significant Cr(VI) removal after 15 days when incubated in medium M9 at pH 6·5 and 8·0. The results suggested chromium reduction. The bacterial consortia diversity (T-RFLP based on 16S rRNA gene) indicated a highest number of operational taxonomic units in an alkaline carbonate medium mimicking in situ conditions. However, incubations under such conditions revealed low Cr(VI) removal. Genomic libraries were obtained for the consortia exhibiting optimal Cr(VI) removal (M9 medium at pH 6·5 and 8·0). They revealed the dominance of 16S rRNA gene sequences related to the genera Pseudomonas/Stenotrophomonas or Enterobacter/Halomonas, respectively. Isolates related to Pseudomonas fluorescens and Enterobacter aerogenes were efficient in Cr(VI) reduction and adsorption to the biomass. Cr(VI) reduction was better at neutral pH rather than under in situ conditions (alkaline pH with carbonate). Isolated strains exhibited significant capacity for Cr(VI) reduction and adsorption. Bacterial communities from chromium-contaminated industrial wastes as well as isolates were able to remove Cr(VI). The results suggest a good potential for bioremediation of industrial wastes when optimal conditions are applied. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology. No claim to Mexican Government works.

  17. [New perspectives in biomonitoring of metallic elements: the example of hexavalent chromium].

    Science.gov (United States)

    Mutti, A; De Palma, G; Goldoni, M

    2012-01-01

    Plating industry is an important productive sector in all the national territory, because of its contribution to a high number of industrial products and crafts. In the chrome plating sector there is a specific chemical risk due to the exposure to compounds containing hexavalent Chromium [Cr(VI)]. Exhaled breath condensate (EBC) has been used to study both acute and long term exposure to Cr(VI) in chrome plating workers. Cr-EBC correlates with specific oxidative stress biomarkers. Moreover, both total Cr and its hexavalent fraction can be measured in EBC, which therefore is a promising biological fluid to assess the absorbed dose at the target organ level, the pulmonary reduction kinetics of Cr(VI) and in general its local pneumotoxic effects. EBC collection and analysis could give additional information to the traditional measures performed during biomonitoring.

  18. Removal of hexavalent chromium upon interaction with biochar under acidic conditions: mechanistic insights and application.

    Science.gov (United States)

    Choudhary, Bharat; Paul, Debajyoti; Singh, Abhas; Gupta, Tarun

    2017-07-01

    Chromium pollution of soil and water is a serious environmental concern due to potential carcinogenicity of hexavalent chromium [Cr(VI)] when ingested. Eucalyptus bark biochar (EBB), a carbonaceous black porous material obtained by pyrolysis of biomass at 500 °C under oxygen-free atmosphere, was used to investigate the removal of aqueous Cr(VI) upon interaction with the EBB, the dominant Cr(VI) removal mechanism(s), and the applicability to treat Cr(VI)-contaminated wastewater. Batch experiments showed complete removal of aqueous Cr(VI) at pH 1-2; sorption was negligible at pH 1, but ~55% of total Cr was sorbed onto the EBB surface at pH 2. Detailed investigations on unreacted and reacted EBB through Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry (XPS) indicate that the carboxylic groups in biochar played a dominant role in Cr(VI) sorption, whereas the phenolic groups were responsible for Cr(VI) reduction. The predominance of sorption-reduction mechanism was confirmed by XPS studies that indicated ~82% as Cr(III) and ~18% as Cr(VI) sorbed on the EBB surface. Significantly, Cr(VI) reduction was also facilitated by dissolved organic matter (DOM) extracted from biochar. This reduction was enhanced by the presence of biochar. Overall, the removal of Cr(VI) in the presence of biochar was affected by sorption due to electrostatic attraction, sorption-reduction mediated by surface organic complexes, and aqueous reduction by DOM. Relative dominance of the aqueous reduction mechanism depended on a critical biochar dosage for a given electrolyte pH and initial Cr(VI) concentration. The low-cost EBB developed here successfully removed all Cr(VI) in chrome tanning acidic wastewater and Cr(VI)-contaminated groundwater after pH adjustment, highlighting its potential applicability in effective Cr(VI) remediation.

  19. Reduction of hexavalent chromium by Rhizopus Oryzae

    African Journals Online (AJOL)

    EJIRO

    reduction data and the specific growth rate constant value was calculated as 0.082 and the ... Key words: Hexavalent chromium, Rhizopus Oryzae, leather tanning, Monod and Haldane models. ... composition; Glucose 1 g; K2HPO4 0.5 g; NaCl 0.5 g; MgCl2 1.0 g; ... ficantly, because of the inhibitor role of high concentration.

  20. Chromium Stable Isotope Fractionation - An Indicator of Hexavalent Chromium Reduction.

    Science.gov (United States)

    Ellis, A.; Johnson, T. M.; Bullen, T. D.

    2001-12-01

    Chromium is a common anthropogenic contaminant in surface water and ground water, and is also of interest in oceanography. It is redox-active; the two common valences in natural waters are Cr(VI), which is highly soluble and toxic, and Cr(III), which is relatively insoluble. Redox reactions thus control Cr mobility in aqueous solutions, and reduction of Cr(VI) to Cr(III) is the most important reaction controlling attenuation of Cr in groundwater. Our results show that Cr(VI) reduction favors the lighter isotopes and leads to enrichment of heavier isotopes in the remaining Cr(VI). Cr isotope measurements thus show great promise as indicators of Cr(VI) reduction. We report here the first measurements of the magnitude of Cr isotope fractionation during Cr(VI) reduction and variations in δ 53Cr values obtained from three contaminated sites. Experiments were conducted to measure Cr isotope fractionation during Cr(VI) reduction by suspensions of magnetite and unamended sediments from a local pond, Urbana, IL and San Francisco Estuary near Martinez, CA. Suspensions were incubated anaerobically with constant shaking, and complete Cr(VI) reduction occurred within a few days. Cr(VI) from intermediate time points in the experiments was purified via ion exchange and 53Cr/52Cr ratios were measured via TIMS with a double isotope spike. The instantaneous per mil fractionation, ɛ , was calculated assuming a Rayleigh fractionation model. The ɛ for Cr(VI) reduction on magnetite surfaces yielded a fractionation of -3.5 ‰ . The ɛ values for the pond and estuary sediments were -3.5 ‰ and -3.3 ‰ respectively. The size of this Cr isotope fractionation is encouraging, as current precision is 0.2 \\permil. δ 53Cr values in dissolved Cr(VI) from three contaminated sites range from 1.1 ‰ to 5.8 ‰ , suggesting that Cr(VI) reduction has occurred and has induced isotopic fractionation in these settings. δ 53Cr values measured from Cr(VI) in plating baths show little or no

  1. Reduction of Hexavalent Chromium and Detection of Chromate Reductase (ChrR in Stenotrophomonas maltophilia

    Directory of Open Access Journals (Sweden)

    Rosa Baldiris

    2018-02-01

    Full Text Available An Gram negative strain of S. maltophilia, indigenous to environments contaminated by Cr(VI and identified by biochemical methods and 16S rRNA gene analysis, reduced chromate by 100%, 98–99% and 92% at concentrations in the 10–70, 80–300, and 500 mg/L range, respectively at pH 7 and temperature 37 °C. Increasing concentrations of Cr(VI in the medium lowered the growth rate but could not be directly correlated with the amount of Cr(VI reduced. The strain also exhibited multiple resistance to antibiotics and tolerance and resistance to various heavy metals (Ni, Zn and Cu, with the exception of Hg. Hexavalent chromium reduction was mainly associated with the soluble fraction of the cell evaluated with crude cell-free extracts. A protein of molecular weight around 25 kDa was detected on SDS-PAGE gel depending on the concentration of hexavalent chromium in the medium (0, 100 and 500 mg/L. In silico analysis in this contribution, revealed the presence of the chromate reductase gene ChrR in S. maltophilia, evidenced through a fragment of around 468 bp obtained experimentally. High Cr(VI concentration resistance and high Cr(VI reducing ability of the strain make it a suitable candidate for bioremediation.

  2. Hexavalent and trivalent chromium in leather: What should be done?

    Science.gov (United States)

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Sampling and analysis considerations for the determination of hexavalent chromium in workplace air; Reflexions sur le prelevement et l'analyse du chrome hexavalent dans l'air des lieux de travail

    Energy Technology Data Exchange (ETDEWEB)

    Ashley, K.E. [CDC/NIOSH, Cincinnati, Ohio (United States); Howe, A.M. [HSL, Sheffield (United Kingdom); Demange, M. [INRS - Centre de Lorraine, Departement Metrologie des polluants, 54 - Vandoeuvre-les-Nancy (France); Nygren, O. [NIWL, Umea (Sweden)

    2004-07-01

    Airborne hexavalent chromium Cr(VI) is a known human respiratory carcinogen and allergen. Workers in a variety of industries may be exposed to airborne hexavalent chromium, with exposures frequently occurring via inhalation and/or dermal contact. Analytical methods for the measurement of Cr(VI) compounds in workplace samples, rather than for the determination of total elemental chromium in workplace air, are often desired because exposure limit values for Cr(VI) compounds are much lower than for total Cr. For years, sampling and analytical test methods for airborne Cr(VI) have been investigated so as to provide means for occupational exposure assessment to this highly toxic species. Inter-conversion of trivalent chromium Cr(III) and Cr(VI) can sometimes occur during sampling and sample preparation, and efforts to minimize unwanted redox reactions involving these chromium valences have been sought. Because of differences in toxicity, there is also interest in the ability to differentiate between water soluble and insoluble forms of Cr(VI), and procedures that provide solubility information concerning Cr(VI) compounds have been developed. This paper reviews the state of the art concerning the measurement of airborne Cr(VI) compounds in workplace aerosols and related samples. (authors)

  4. Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers.

    Science.gov (United States)

    Zhang, Xu-Hui; Zhang, Xuan; Wang, Xu-Chu; Jin, Li-Fen; Yang, Zhang-Ping; Jiang, Cai-Xia; Chen, Qing; Ren, Xiao-Bin; Cao, Jian-Zhong; Wang, Qiang; Zhu, Yi-Min

    2011-04-12

    Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI)) exposure can cause DNA damage in electroplating workers. 157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%). Urinary 8-OHdG levels were measured by ELISA. Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 μg/L) than that in control subjects (1.54 μg/L, P electroplating workers. Low-level occupational chromium exposure induced DNA damage.

  5. Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaolei; Dong, Hailiang; Yang, Xuewei; Kovarik, Libor; Chen, Yu; Zeng, Qiang

    2018-02-01

    Iron-bearing clay minerals and organic matter are two important components in natural environments that influence hexavalent chromium (Cr(VI)) reduction. Previous studies have shown that organic ligands could influence Cr(VI) reduction by aqueous Fe2+ and pyrite. However, the effects of organic ligands on Cr(VI) reduction by structural Fe(II) in clays are not well understood. In this study, the effects of citrate on Cr(VI) reduction by nontronite (NAu-2) were investigated under near neutral pH condition (pH=6). Our results showed that the presence of citrate decreased the rate but increased the amount of Cr(VI) reduction by structural Fe(II) in NAu-2. The decreased reaction rate was likely due to competitive sorption of citrate and polyanionic dichromate (Cr2O7- ), because sorption of dichromate appeared to be the first step for subsequent Cr(VI) reduction. The increased amount of Cr(VI) reduction in the presence of citrate was likely because citrate provided additional reducing power through ligand-metal electron transfer in the presence of soluble Fe 3+ derived from dissolution of reduced NAu-2. Soluble Cr(III)-citrate complex was the possible form of reduced chromium when citrate was present. In contrast, nanometer-sized Cr2O3 particles were the product of Cr(VI) reduction by reduced NAu-2 without citrate. Our study highlights the importance of organic ligands on Cr(VI) reduction and immobilization when iron-bearing clay minerals are applied to treat Cr(VI) contaminant in organic matter rich environments.

  6. Detoxification of hexavalent chromium by Leucobacter sp. uses a reductase with specificity for dihydrolipoamide.

    Science.gov (United States)

    Sarangi, Abhipsa; Krishnan, Chandraraj

    2016-02-01

    Leucobacter sp. belongs to the metal stressed community and possesses higher tolerance to metals including chromium and can detoxify toxic hexavalent chromium by reduction to less toxic trivalent chromium. But, the mechanism of reduction of hexavalent chromium by Leucobacter sp. has not been studied. Understanding the enzyme catalyzing reduction of chromium is important to improve the species for application in bioremediation. Hence, a soluble reductase catalyzing the reduction of hexavalent chromium was purified from a Leucobacter sp. and characterized. The pure chromate reductase was obtained from the cell-free extract through hydrophobic interaction and gel filtration column chromatographic methods. It was a monomeric enzyme and showed similar molecular weights in both gel filtration (∼68 KDa) and SDS-PAGE (64 KDa). It reduced Cr(VI) using both NADH and NADPH as the electron donor, but exhibited higher activity with NADH. The optimal activity was found at pH 5.5 and 30 °C. The K(m) and V(max) for Cr(VI) reduction with NADH were 46.57 μM and 0.37 μmol min(-1) (mg protein) (-1), respectively. The activity was inhibited by p-hydroxy mercury benzoate, Ag(2+) and Hg(2+) indicating the role of thiol groups in the catalysis. The spectrophotometric analysis of the purified enzyme showed the absence of bound flavin in the enzyme. The N-terminal amino acid sequence and LC/MS analysis of trypsin digested purified enzyme showed similarity to dihydrolipoyl dehydrogenase. The purified enzyme had dihydrolipoyl dehydrogenase activity with dihydrolipoamide as the substrate, which suggested that Leucobacter sp. uses reductase with multiple substrate specificity for reduction of Cr(VI) detoxification. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 76 FR 71926 - Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium Policy to...

    Science.gov (United States)

    2011-11-21

    ... 0750-AH39 Defense Federal Acquisition Regulation Supplement: Applicability of Hexavalent Chromium... the use of materials containing hexavalent chromium. DATES: Comment Date: Comments on the proposed... human health and environmental risks related to the use of hexavalent chromium. Hexavalent chromium is a...

  8. Recovery of hexavalent chromium from water using photoactive TiO2-montmorillonite under sunlight

    Directory of Open Access Journals (Sweden)

    Ridha Djellabi

    2016-04-01

    Full Text Available Hexavalent chromium was removed from water under sunlight using a synthesized TiO2-montmorillonite (TiO2-M employing tartaric acid as a hole scavenger. Cr(VI species was then reduced to Cr(III species by electrons arising from TiO2 particles. After that, the produced Cr(III species  was transferred to montmorillonite  due to electrostatic attractions leading to  set free TiO2 particles for a further Cr(VI species reduction. Furthermore, produced Cr(III, after Cr(VI reduction, does not  penetrate into the solution. The results indicate that no dark adsorption of Cr(VI species on TiO2-M is present, however, the reduction of Cr(VI species under sunlight increased strongly as a function of tartaric acid concentration up to 60 ppm, for which the extent of reduction is maximum within 3 h. On the other hand, the reduction extent of Cr(VI species is maximum with an initial concentration of Cr(VI species lower than 30 ppm by the use of 0.2 g/L of TiO2-M. Nevertheless, the increase of the Cr(VI initial concentration led to increase the amount of Cr(VI species reduced (capacity of reduction until a Cr(VI concentration of 75 and 100 ppm, for which  it remained constant at around 221 mg/g. For comparison, the increase of Cr(VI species concentration in the case of the commercial TiO2 P25 under the same conditions exhibited its deactivation when the reduced amount decreased from 198.1 to 157.6 mg/g as the concentration increased from 75 to 100 ppm.

  9. Quaternized wood as sorbent for hexavalent chromium.

    Science.gov (United States)

    Low, K S; Lee, C K; Lee, C Y

    2001-01-01

    The potential of quaternized wood (QW) chips in removing hexavalent chromium from synthetic solution and chrome waste under both batch and continuous-flow conditions was investigated. Sorption was found to be dependent on pH, metal concentration, and temperature. QW chips provide higher sorption capacity and wider pH range compared with untreated wood chips. The equilibrium data could be fitted into the Langmuir isotherm model, and maximum sorption capacities were calculated to be 27.03 and 25.77 mg/g in synthetic chromate solution and chrome waste, respectively. The presence of sulfate in high concentration appeared to suppress the uptake of chromium by QW chips. Column studies showed that bed depth influenced the breakthrough time greatly whereas flow rate of influent had little effect on its sorption on the column.

  10. Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions

    Science.gov (United States)

    Kwak, Hyo Won; Shin, Munju; Yun, Haesung; Lee, Ki Hoon

    2016-01-01

    In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. A 1 M lithium chloride (LiCl)/dimethyl sulfoxide (DMSO) solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI) adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI) occurred on the heterogeneous surface. Cr(VI) adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI) ions were recovered from the Cr(VI) adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI) ions in industrial wastewater. PMID:27598142

  11. Investigation of Hexavalent Chromium Flux to Groundwater at the 100-C-7:1 Excavation Site

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J.; Vermeul, Vincent R.; Fritz, Brad G.; Mackley, Rob D.; Horner, Jacob A.; Johnson, Christian D.; Newcomer, Darrell R.

    2012-11-16

    Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.

  12. Preparation of Silk Sericin/Lignin Blend Beads for the Removal of Hexavalent Chromium Ions

    Directory of Open Access Journals (Sweden)

    Hyo Won Kwak

    2016-09-01

    Full Text Available In the present study, novel adsorbents having high adsorption capability and reusability were prepared using agricultural by-products: silk sericin and lignin. Silk sericin and lignin blend beads were successfully prepared using simple coagulation methods for the removal of hexavalent chromium (Cr(VI from aqueous solution. A 1 M lithium chloride (LiCl/dimethyl sulfoxide (DMSO solvent system successfully dissolved both sericin and lignin and had sufficient viscosity for bead preparation. Compared to the conventional sericin bead adsorbent, sericin/lignin blend beads showed higher Cr(VI adsorption capacity. The amount of lignin added to the adsorbent greatly affected the adsorption capacity of the beads, and a 50:50 sericin/lignin blend ratio was optimal. Adsorption behavior followed the Freundlich isotherm, which means the adsorption of Cr(VI occurred on the heterogeneous surface. Cr(VI adsorption capability increased with temperature because of thermodynamic-kinetic effects. In addition, over 90% of Cr(VI ions were recovered from the Cr(VI adsorbed sericin/lignin beads in a 1 M NaOH solution. The adsorption-desorption recycling process was stable for more than seven cycles, and the recycling efficiency was 82%. It is expected that the sericin/lignin beads could be successfully applied in wastewater remediation especially for hazardous Cr(VI ions in industrial wastewater.

  13. Reduction of Hexavalent Chromium Using L-Cysteine Capped Nickel Nanocatalysts

    Directory of Open Access Journals (Sweden)

    Razium Ali Soomro

    2013-06-01

    Full Text Available The aim of this study was to reduce the highly toxic hexavalent chromium Cr(VI into less toxic chromium Cr(III species by using nickel nanoparticles (Ni NPs as catalysts in order to provide safety to the aqueous environment. In the first phase Ni NPs were synthesized in ethylene glycol and capped with l-cysteine by a modified microwave irradiation method using NaOH as the accelerator. The formed Ni NPs were characterized by various techniques such as UV-Visible spectroscopy, Fourier Transform Infra-red (FTIR spectroscopy and Scanning Electron Microscopy (SEM. In the second phase the formed Ni NPs were immobilized on glass surfaces and employed as catalyst for the reduction of Cr(VI ions. According to observations, 99% reduction of Cr(VI ions was achieved in the presence of 0.5 mg of Ni NPs catalyst in just five minutes as compared to nickel powder that showed only 16% reduction in 15 minutes. The study has a great impact on the aqueous pollution control of Cr(VI especially caused by the discharge of waste water from several industries utilizing Cr(VI containing salt as one of the essential gradients.

  14. Punica granatum L. protects mice against hexavalent chromium-induced genotoxicity

    Directory of Open Access Journals (Sweden)

    Renato Ivan de Ávila

    2013-12-01

    Full Text Available This study investigated the chemoprotective effects of Punica granatum L. (Punicaceae fruits alcoholic extract (PGE on mice exposed to hexavalent chromium [Cr(VI]. Animals were pretreated with PGE (25, 50 or 75 mg/kg/day for 10 days and subsequently exposed to a sub-lethal dose of Cr(VI (30 mg/kg. The frequency of micronucleated polychromatic erythrocytes in the bone marrow was investigated and the Cr(VI levels were measured in the kidneys, liver and plasm. For the survival analysis, mice were previously treated with PGE for 10 days and exposed to a single lethal dose of Cr(VI (50 mg/kg. Exposure to a sub-lethal dose of Cr(VI induced a significant increase in the frequency of micronucleated cells. However, the prophylactic treatment with PGE led to a reduction of 44.5% (25 mg/kg, 86.3% (50 mg/kg and 64.2% (75 mg/kg in the incidence of micronuclei. In addition, the 50 mg/kg dose of PGE produced a higher chemoprotective effect, since the survival rate was 90%, when compared to that of the non-treated group. In these animals, reduced amounts of chromium were detected in the biological materials, in comparison with the other groups. Taken together, the results demonstrated that PGE exerts a protective effect against Cr(VI-induced genotoxicity.

  15. IRIS Toxicological Review of Hexavalent Chromium (Peer Review Plan)

    Science.gov (United States)

    EPA is conducting a peer review of the scientific basis supporting the human health hazard and dose-response assessment of hexavalent chromium that will appear on the Integrated Risk Information System (IRIS) database.

  16. Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

    Science.gov (United States)

    Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

    2017-01-01

    Al(OH)3 and Ca(OH)2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. Ca-Al precursor (C3A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO4 LDH product. Ca-Al-CrO4 LDH phase occurred preferentially to Ca-Al-MCl2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist.

  17. The Growth of Gypsum in the Presence of Hexavalent Chromium: A Multiscale Study

    Directory of Open Access Journals (Sweden)

    Juan Morales

    2016-03-01

    Full Text Available The sorption of dissolved inorganic pollutants into the structure of minerals is an important process that controls the mobility and fate of these pollutants in the Earth’s crust. It also modifies the surface structure and composition of the host mineral, affecting its crystallization kinetics. Here, we investigate the effect of hexavalent chromium, Cr(VI, on the nucleation and growth of gypsum by conducting two types of experiments: (i in situ atomic force microscopy (AFM observations of the growth of gypsum {010} surfaces in the presence of Cr(VI and (ii gypsum precipitation experiments by mixing aqueous solutions containing variable amounts of Cr(VI. Gypsum precipitation is progressively delayed when occurring from solutions bearing increasing Cr(VI concentrations. Chemical analyses of gypsum precipitates show that gypsum incorporates small Cr(VI amounts that correlate with the content of this ion in the aqueous solution. Gypsum cell parameters variation reflects this incorporation. At the molecular scale, Cr(VI induces a slowdown of step advance rates on gypsum {010} surfaces accompanied by the roughening of nanostep edges and the so-called “template effect”. This effect involves the reproduction of the original nanotopography after the completion of individual advancing monolayers and appears as a general nanoscale phenomenon occurring during growth of solid solutions from aqueous solutions even in the case of compositionally-restricted solid solutions.

  18. RDT&E Progress and Plansfor Hexavalent Chromium (Cr6+)

    Science.gov (United States)

    2011-05-12

    RDT&E Progress and Plans for Hexavalent Chromium (Cr6+) Bruce Sartwell Weapons Systems and Platforms Program Manager E2S2 Conference May 12, 2011...2011 2. REPORT TYPE 3. DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE RDT&E Progress and Plansfor Hexavalent Chromium (Cr6+) 5a...Development of Accelerated Corrosion Test Protocols Alternatives to Hex Chrome and Cadmium Plating Alternatives to Hex Chrome Pretreatments

  19. Remediation of hexavalent chromium spiked soil by using synthesized iron sulfide particles.

    Science.gov (United States)

    Li, Yujie; Wang, Wanyu; Zhou, Liqiang; Liu, Yuanyuan; Mirza, Zakaria A; Lin, Xiang

    2017-02-01

    Carboxymethyl cellulose (CMC) stabilized microscale iron sulfide (FeS) particles were synthesized and applied to remediate hexavalent chromium (Cr(VI)) spiked soil. The effects of parameters including dosage of FeS particles, soil moisture, and natural organic matter (NOM) in soil were investigated with comparison to iron sulfate (FeSO 4 ). The results show that the stabilized FeS particles can reduce Cr(VI) and immobilize Cr in soil quickly and efficiently. The soil moisture ranging from 40% to 70% and NOM in soil had no significant effects on Cr(VI) remediation by FeS particles. When molar ratio of FeS to Cr(VI) was 1.5:1, about 98% of Cr(VI) in soil was reduced by FeS particles in 3 d and Cr(VI) concentration decreased from 1407 mg kg -1 to 16 mg kg -1 . The total Cr and Cr(VI) in Toxicity Characteristic Leaching Procedure (TCLP) leachate were reduced by 98.4% and 99.4%, respectively. In FeS particles-treated soil, the exchangeable Cr fraction was mainly converted to Fe-Mn oxides bound fraction because of the precipitation of Cr(III)-Fe(III) hydroxides. The physiologically based extraction test (PBET) bioaccessibility of Cr was decreased from 58.67% to 6.98%. Compared to FeSO 4 , the high Cr(VI) removal and Cr immobilization efficiency makes prepared FeS particles a great potential in field application of Cr(VI) contaminated soil remediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Electrodeposited tungsten-nickel-boron: A replacement for hexavalent chromium

    International Nuclear Information System (INIS)

    Steffani, C.; Meltzer, M.

    1995-04-01

    Chromium, deposited from acidic solutions of its hexavalent ion, has been the rule for wear resistant, corrosion resistant coatings for many years. Although chromium coatings are durable, the plating process generates air emissions, effluent rinse waters, and process solutions that are toxic, suspected carcinogens, and a risk to human health and the environment. Tungsten-nickel-boron (W-Ni-B) alloy deposition is a potential substitute for hexavalent chrome. It has excellent wear, corrosion, and mechanical properties and also may be less of an environmental risk. This study examines the electroplating process and deposit properties of W-Ni-B and compares them with those of hexavalent chrome

  1. Cr(VI) reduction from contaminated soils by Aspergillus sp. N2 and Penicillium sp. N3 isolated from chromium deposits.

    Science.gov (United States)

    Fukuda, Tsubasa; Ishino, Yasuhiro; Ogawa, Akane; Tsutsumi, Kadzuyo; Morita, Hiroshi

    2008-10-01

    Aspergillus sp. N2 and Penicillium sp. N3 are chromate-resistant filamentous fungi that were isolated from Cr(VI) contaminated soil based on their ability to decrease hexavalent chromium levels in the growth medium. After 120 h of growth in a medium containing 50 ppm Cr(VI) at near neutral pH, Aspergillus sp. N2 reduced the Cr(VI) concentration by about 75%. Penicillium sp. N3 was able to reduce the Cr(VI) concentration by only 35%. However, Penicillium sp. N3 reduced the Cr(VI) concentration in the medium by 93% under acidic conditions. Interestingly, the presence of Cu(II) enhanced the Cr(VI) reducing ability of Aspergillus sp. N2 and Penicillium sp. N3 at near neutral pH. Aspergillus sp. N2 and Penicillium sp. N3 reduced the Cr(VI) concentration in the growth medium to a virtually undetectable level within 120 h. For both Aspergillus sp. N2 and Penicillium sp. N3, mycelial seed cultures were more efficient at Cr(VI) reduction than conidium seed cultures. The mechanisms of Cr(VI) reduction in Aspergillus sp. N2 and Penicillium sp. N3 were enzymatic reduction and sorption to mycelia. Enzymatic activity contributed significantly to Cr(VI) reduction. Aspergillus sp. N2 and Penicillium sp. N3 reduced the levels of Cr(VI) in polluted soil samples, suggesting that these strains might be useful for cleaning up chromium-contaminated sites.

  2. On the removal of hexavalent chromium from a Class F fly ash.

    Science.gov (United States)

    Huggins, F E; Rezaee, M; Honaker, R Q; Hower, J C

    2016-05-01

    Coarse and fine samples of a Class F fly ash obtained from commercial combustion of Illinois bituminous coal have been exposed to two long-term leaching tests designed to simulate conditions in waste impoundments. ICP-AES analysis indicated that the coarse and fine fly ash samples contained 135 and 171mg/kg Cr, respectively. Measurements by XAFS spectroscopy showed that the ash samples originally contained 5 and 8% of the chromium, respectively, in the hexavalent oxidation state, Cr(VI). After exposure to water for more than four months, the percentage of chromium as Cr(VI) in the fly-ash decreased significantly for the coarse and fine fly-ash in both tests. Combining the XAFS data with ICP-AES data on the concentration of chromium in the leachates indicated that, after the nineteen-week-long, more aggressive, kinetic test on the coarse fly ash, approximately 60% of the Cr(VI) had been leached, 20% had been reduced to Cr(III) and retained in the ash, and 20% remained as Cr(VI) in the ash. In contrast, during the six-month-long baseline test, very little Cr was actually leached from either the coarse or the fine fly-ash (ash was retained in the ash in that form, while the remainder, 34% and 80%, respectively, was reduced and retained in the ash as Cr(III). The results are interpreted as indicating that Cr(VI) present in Class F fly-ash can be reduced to Cr(III) when in contact with water and that such chemical reduction can compete with physical removal of Cr(VI) from the ash by aqueous leaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Biomarkers of oxidative stress in electroplating workers exposed to hexavalent chromium.

    Science.gov (United States)

    Pan, Chih-Hong; Jeng, Hueiwang Anna; Lai, Ching-Huang

    2018-01-01

    This study evaluates levels of biomarkers of oxidative DNA damage and lipid peroxidation in 105 male workers at 16 electroplating companies who had been exposed to hexavalent chromium (Cr(VI)). The study participants were 230 non-smoking male workers, comprising 105 electroplating workers who had been exposed to chromium and 125 control subjects who performed office tasks. Personal air samples, spot urine samples, hair samples, fingernail samples and questionnaires were used to quantify exposure to Cr(VI), oxidative DNA damage, lipid peroxidation, and environmental pollutants. Both the geometric mean personal concentrations of Cr(VI) of the Cr-exposed workers and the total Cr concentrations in the air to which they were exposed significantly exceeded those for the control subjects. The geometric mean concentrations of Cr in urine, hair and fingernails, and the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), and malondialdehyde (MDA) levels in the Cr(VI) exposed workers exceeded those in the control subjects. Daily cumulative Cr(VI) exposure and urinary Cr were significantly correlated with urinary 8-OHdG levels following adjustments for covariates. A ten-fold increase in urinary Cr level was associated with a 1.73-fold increase in urinary 8-OHdG level. Daily cumulative Cr(VI) exposure and urinary Cr level were significantly correlated with urinary MDA level following adjustments for covariates. A ten-fold increase in urinary Cr was associated with a 1.45-fold increase in urinary MDA. Exposure to Cr(VI) increased oxidative DNA injury and the oxidative deterioration of lipids in electroplating workers.

  4. AN IN SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUNDWATER:VOLUME 2 PERFORMANCE MONITORING

    Science.gov (United States)

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  5. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUND WATER: VOLUME 1 DESIGN AND INSTALLATION

    Science.gov (United States)

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  6. Hexavalent chromium reduction under fermentative conditions with lactate stimulated native microbial communities.

    Science.gov (United States)

    Somenahally, Anil C; Mosher, Jennifer J; Yuan, Tong; Podar, Mircea; Phelps, Tommy J; Brown, Steven D; Yang, Zamin K; Hazen, Terry C; Arkin, Adam P; Palumbo, Anthony V; Van Nostrand, Joy D; Zhou, Jizhong; Elias, Dwayne A

    2013-01-01

    Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM) and continuously amended with Cr(VI) at 0.0 (No-Cr), 0.1 (Low-Cr) and 3.0 (High-Cr) mg/L. Microbial growth, metabolites, Cr(VI), 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%), Methanosarcina (17%) and others, to mostly Methanosarcina spp. (95%). Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result 3.0 mg/L Cr(VI) did not impact the overall bacterial community structure.

  7. Hexavalent chromium reduction under fermentative conditions with lactate stimulated native microbial communities.

    Directory of Open Access Journals (Sweden)

    Anil C Somenahally

    Full Text Available Microbial reduction of toxic hexavalent chromium (Cr(VI in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI concentrations on community structure and on the Cr(VI-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM and continuously amended with Cr(VI at 0.0 (No-Cr, 0.1 (Low-Cr and 3.0 (High-Cr mg/L. Microbial growth, metabolites, Cr(VI, 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%, Methanosarcina (17% and others, to mostly Methanosarcina spp. (95%. Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI reduction, and as a result 3.0 mg/L Cr(VI did not impact the overall bacterial community structure.

  8. Prolonged Particulate Hexavalent Chromium Exposure Suppresses Homologous Recombination Repair in Human Lung Cells.

    Science.gov (United States)

    Browning, Cynthia L; Qin, Qin; Kelly, Deborah F; Prakash, Rohit; Vanoli, Fabio; Jasin, Maria; Wise, John Pierce

    2016-09-01

    Genomic instability is one of the primary models of carcinogenesis and a feature of almost all cancers. Homologous recombination (HR) repair protects against genomic instability by maintaining high genomic fidelity during the repair of DNA double strand breaks. The defining step of HR repair is the formation of the Rad51 nucleofilament, which facilitates the search for a homologous sequence and invasion of the template DNA strand. Particulate hexavalent chromium (Cr(VI)), a human lung carcinogen, induces DNA double strand breaks and chromosome instability. Since the loss of HR repair increases Cr(VI)-induced chromosome instability, we investigated the effect of extended Cr(VI) exposure on HR repair. We show acute (24 h) Cr(VI) exposure induces a normal HR repair response. In contrast, prolonged (120 h) exposure to particulate Cr(VI) inhibited HR repair and Rad51 nucleofilament formation. Prolonged Cr(VI) exposure had a profound effect on Rad51, evidenced by reduced protein levels and Rad51 mislocalization to the cytoplasm. The response of proteins involved in Rad51 nuclear import and nucleofilament formation displayed varying responses to prolonged Cr(VI) exposure. BRCA2 formed nuclear foci after prolonged Cr(VI) exposure, while Rad51C foci formation was suppressed. These results suggest that particulate Cr(VI), a major chemical carcinogen, inhibits HR repair by targeting Rad51, causing DNA double strand breaks to be repaired by a low fidelity, Rad51-independent repair pathway. These results further enhance our understanding of the underlying mechanism of Cr(VI)-induced chromosome instability and thus, carcinogenesis. © The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Hexavalent Chromium Reduction under Fermentative Conditions with Lactate Stimulated Native Microbial Communities

    Energy Technology Data Exchange (ETDEWEB)

    Somenahally, Anil C [ORNL; Mosher, Jennifer J [ORNL; Yuan, Tong [University of Oklahoma; Phelps, Tommy Joe [ORNL; Brown, Steven D [ORNL; Yang, Zamin Koo [ORNL; Hazen, Terry C [ORNL; Arkin, Adam [Lawrence Berkeley National Laboratory (LBNL); Palumbo, Anthony Vito [ORNL; Van Nostrand, Dr. Joy D. [Oklahoma University; Zhou, Jizhong [University of Oklahoma; Elias, Dwayne A [ORNL

    2013-01-01

    Microbial reduction of toxic hexavalent chromium (Cr(VI)) in-situ is a plausible bioremediation strategy in electron-acceptor limited environments. However, higher [Cr(VI)] may impose stress on syntrophic communities and impact community structure and function. The study objectives were to understand the impacts of Cr(VI) concentrations on community structure and on the Cr(VI)-reduction potential of groundwater communities at Hanford, WA. Steady state continuous flow bioreactors were used to grow native communities enriched with lactate (30 mM) and continuously amended with Cr(VI) at 0.0 (No-Cr), 0.1 (Low-Cr) and 3.0 (High-Cr) mg/L. Microbial growth, metabolites, Cr(VI), 16S rRNA gene sequences and GeoChip based functional gene composition were monitored for 15 weeks. Temporal trends and differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) levels were below detection from week 1 until week 15. With lactate enrichment, native bacterial diversity substantially decreased as Pelosinus spp., and Sporotalea spp., became the dominant groups, but did not significantly differ between Cr concentrations. The Archaea diversity also substantially decreased after lactate enrichment from Methanosaeta (35%), Methanosarcina (17%) and others, to mostly Methanosarcina spp. (95%). Methane production was lower in High-Cr reactors suggesting some inhibition of methanogens. Several key functional genes were distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant microbes, Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result 3.0 mg/L Cr(VI) did not impact the overall bacterial community structure.

  10. Removal of hexavalent chromium by using red mud activated with cetyltrimethylammonium bromide.

    Science.gov (United States)

    Li, Deliang; Ding, Ying; Li, Lingling; Chang, Zhixian; Rao, Zhengyong; Lu, Ling

    2015-01-01

    The removal of hexavalent chromium [Cr(VI)] from aqueous solution by using red mud activated with cetyltrimethylammonium bromide (CTAB) was studied. The optimum operation parameters, such as CTAB concentration, pH values, contact time, and initial Cr(VI) concentration, were investigated. The best concentration of CTAB for modifying red mud was found to be 0.50% (mCTAB/VHCl,0.6 mol/L). The lower pH (mud activated with CTAB can greatly improve the removal ratio of Cr(VI) as high as four times than that of original red mud. Adsorption equilibrium was reached within 30 min under the initial Cr(VI) concentration of 100 mg L(-1). The isotherm data were analysed using Langmuir and Freundlich models. The adsorption of Cr(VI) on activated red mud fitted well to the Langmuir isotherm model, and the maximum adsorption capacity was estimated as 22.20 mg g(-1) (Cr/red mud). The adsorption process could be well described using the pseudo-second-order model. The result shows that activated red mud is a promising agent for low-cost water treatment.

  11. Comparative Cytotoxicity and Genotoxicity of Particulate and Soluble Hexavalent Chromium in Human and Sperm Whale (Physeter macrocephalus) Skin Cells

    Science.gov (United States)

    Li Chen, Tânia; LaCerte, Carolyne; Wise, Sandra S.; Holmes, Amie; Martino, Julieta; Wise, John Pierce; Thompson, W. Douglas; Wise, John Pierce

    2014-01-01

    Chromium (Cr) is a global marine pollutant, present in marine mammal tissues. Hexavalent chromium [Cr(VI)] is a known human carcinogen. In this study we compare the cytotoxic and clastogenic effects of Cr(VI) in human (Homo sapiens) and sperm whale (Physeter macrocephalus) skin fibroblasts. Our data show that increasing concentrations of both particulate and soluble Cr(VI) induce increasing amounts of cytotoxicity and clastogenicity in human and sperm whale skin cells. Furthermore, the data show that sperm whale cells are resistant to these effects exhibiting less cytotoxicity and genotoxicity than the human cells. Differences in Cr uptake accounted for some but not all of the differences in particulate and soluble Cr(VI) genotoxicity, although it did explain the differences in particulate Cr(VI) cytotoxicity. Altogether the data indicate that Cr(VI) is a genotoxic threat to whales, but also suggest that whales have evolved cellular mechanisms to protect them against the genotoxicity of environmental agents such as Cr(VI). PMID:21466859

  12. Assessment of Hexavalent Chromium Natural Attenuation for the Hanford Site 100 Area

    Energy Technology Data Exchange (ETDEWEB)

    Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szecsody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Qafoku, Nikolla P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sahajpal, Rahul [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhong, Lirong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawter, Amanda R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lee, Brady D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-01

    Hexavalent chromium (Cr(VI)) plumes are present in the 100 Area at the Hanford Site. Remediation efforts are under way with objectives of restoring the groundwater to meet the drinking-water standard (48 µg/L) and protecting the Columbia River by ensuring that discharge of groundwater to the river is below the surface-water quality standard (10 µg/L). Current remedies include application of Pump-and-Treat (P&T) at the 100-D, 100-H, and 100-K Areas and Monitored Natural Attenuation (MNA) at the 100-F/IU Area. Remedy selection is still under way at the other 100 Areas. Additional information about the natural attenuation processes for Cr(VI) is important in all of these cases. In this study, laboratory experiments were conducted to demonstrate and quantify natural attenuation mechanisms using 100 Area sediments and groundwater conditions.

  13. 75 FR 18041 - Defense Federal Acquisition Regulation Supplement; Minimizing Use of Hexavalent Chromium (DFARS...

    Science.gov (United States)

    2010-04-08

    ...-AG35 Defense Federal Acquisition Regulation Supplement; Minimizing Use of Hexavalent Chromium (DFARS... Regulation Supplement (DFARS) to address requirements for minimizing the use of hexavalent chromium in... of items containing hexavalent chromium under DoD contracts unless an exception applies. DATES...

  14. Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology

    International Nuclear Information System (INIS)

    Schneider, Brent C.; Constant, Stephanie L.; Patierno, Steven R.; Jurjus, Rosalyn A.; Ceryak, Susan M.

    2012-01-01

    Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels. -- Highlights: ► Allergic asthma correlated with exposure to certain inhaled particulate chromates. ► Direct causal association between Cr(VI) and allergic asthma not established. ► Cr exacerbated pathology and airway hyperresponsiveness in an OVA-challenged mouse. ► Particulate Cr(VI

  15. Exposure to particulate hexavalent chromium exacerbates allergic asthma pathology

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Brent C. [Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC 20037 (United States); Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037 (United States); Constant, Stephanie L. [Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC 20037 (United States); Patierno, Steven R. [Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037 (United States); GW Cancer Institute, The George Washington University, Washington, DC 20037 (United States); Jurjus, Rosalyn A. [Department of Anatomy and Regenerative Biology, The George Washington University, Washington, DC 20037 (United States); Ceryak, Susan M., E-mail: phmsmc@gwumc.edu [Department of Pharmacology and Physiology, The George Washington University, Washington, DC 20037 (United States)

    2012-02-15

    Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels. -- Highlights: ► Allergic asthma correlated with exposure to certain inhaled particulate chromates. ► Direct causal association between Cr(VI) and allergic asthma not established. ► Cr exacerbated pathology and airway hyperresponsiveness in an OVA-challenged mouse. ► Particulate Cr(VI

  16. Utility of Ochrobactrum anthropi YC152 in a Microbial Fuel Cell as an Early Warning Device for Hexavalent Chromium Determination

    Directory of Open Access Journals (Sweden)

    Guey-Horng Wang

    2016-08-01

    Full Text Available Fast hexavalent chromium (Cr(VI determination is important for environmental risk and health-related considerations. We used a microbial fuel cell-based biosensor inoculated with a facultatively anaerobic, Cr(VI-reducing, and exoelectrogenic Ochrobactrum anthropi YC152 to determine the Cr(VI concentration in water. The results indicated that O. anthropi YC152 exhibited high adaptability to pH, temperature, salinity, and water quality under anaerobic conditions. The stable performance of the microbial fuel cell (MFC-based biosensor indicated its potential as a reliable biosensor system. The MFC voltage decreased as the Cr(VI concentration in the MFC increased. Two satisfactory linear relationships were observed between the Cr(VI concentration and voltage output for various Cr(VI concentration ranges (0.0125–0.3 mg/L and 0.3–5 mg/L. The MFC biosensor is a simple device that can accurately measure Cr(VI concentrations in drinking water, groundwater, and electroplating wastewater in 45 min with low deviations (<10%. The use of the biosensor can help in preventing the violation of effluent regulations and the maximum allowable concentration of Cr(VI in water. Thus, the developed MFC biosensor has potential as an early warning detection device for Cr(VI determination even if O. anthropi YC152 is a possible opportunistic pathogen.

  17. Genesis and transport of hexavalent chromium in the system ophiolitic rocks - groundwater

    Science.gov (United States)

    Shchegolikhina, Anastasia; Guadagnini, Laura; Guadagnini, Alberto

    2015-04-01

    ., Brozzo, G., Canepa, M., Cipolli, F., Marini, L., Ottonello, G., Zuccolini, M., 2002. Natural hexavalent chromium in groundwaters interacting with ophiolitic rocks. Environmental Geology 42, 871-882. Lelli, M., Grassi, S., Amadori, M., Franceschini, F., 2013. Natural Cr(VI) contamination of groundwater in the Cecina coastal area and its inner sectors (Tuscany, Italy). Environmental Earth Sciences 71, 3907-3919. Oze, C., Fendorf, S., Bird, D.K., Coleman, R.G., 2004. Chromium geochemistry of serpentine soils. International Geology Review 46, 97-126. Stephen, M.T., James, A.J., 2004. Overview of chromium (VI) in the environment. Chromium (VI) Handbook. CRC Press, pp. 21.

  18. Hexavalent chromium is cytotoxic and genotoxic to hawksbill sea turtle cells

    Energy Technology Data Exchange (ETDEWEB)

    Wise, Sandra S., E-mail: sandra.wise@maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Maine Center for Toxicology and Environmental Health, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Xie, Hong, E-mail: hongxie@usm.maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Maine Center for Toxicology and Environmental Health, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Fukuda, Tomokazu, E-mail: tomofukuda009@gmail.com [Graduate School of Agricultural Sciences, Tohoku University, Laboratory of Animal Breeding and Genetics, Second Research Building, Rm 112, 1-1 Amamiyamachi, Aoba-ku, Sendai 981-8555 (Japan); Douglas Thompson, W., E-mail: dougt@usm.maine.edu [Maine Center for Toxicology and Environmental Health, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); Department of Applied Medical Science, University of Southern Maine, Science Building, 96 Falmouth Street, Portland, ME 04103 (United States); and others

    2014-09-01

    Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, we evaluated the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 μg/cm{sup 2} lead chromate induced 108, 79, 54, and 7% relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 μg/cm{sup 2} lead chromate induced damage in 4, 10, 15, 26, and 36% of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate induced 84, 69, 46, 25, and 3% relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29% of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general. - Highlights: • Particulate Cr(VI) is cytotoxic and clastogenic to hawksbill sea turtle cells. • Soluble Cr(VI) is cytotoxic and clastogenic to hawksbill sea turtle cells. • Cr(VI) may be a risk factor for hawksbill sea turtle health.

  19. Hexavalent chromium is cytotoxic and genotoxic to hawksbill sea turtle cells

    International Nuclear Information System (INIS)

    Wise, Sandra S.; Xie, Hong; Fukuda, Tomokazu; Douglas Thompson, W.

    2014-01-01

    Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, we evaluated the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 μg/cm 2 lead chromate induced 108, 79, 54, and 7% relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 μg/cm 2 lead chromate induced damage in 4, 10, 15, 26, and 36% of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate induced 84, 69, 46, 25, and 3% relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29% of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general. - Highlights: • Particulate Cr(VI) is cytotoxic and clastogenic to hawksbill sea turtle cells. • Soluble Cr(VI) is cytotoxic and clastogenic to hawksbill sea turtle cells. • Cr(VI) may be a risk factor for hawksbill sea turtle health

  20. Hexavalent chromium adsorption from aqueous solution using carbon nano-onions (CNOs).

    Science.gov (United States)

    Sakulthaew, Chainarong; Chokejaroenrat, Chanat; Poapolathep, Amnart; Satapanajaru, Tunlawit; Poapolathep, Saranya

    2017-10-01

    The capacity of carbon nano-onions (CNOs) to remove hexavalent chromium (Cr(VI)) from aqueous solution was investigated. Batch experiments were performed to quantify the effects of the dosage rate, pH, counter ions, and temperature. The adsorption of Cr(VI) onto CNOs was best described by a pseudo-second order rate expression. The adsorption efficiency increased with increasing adsorbent dosage and contact time and reached equilibrium in 24 h. The equilibrium data showed better compliance with a Langmuir isotherm than a Freundlich isotherm. Effective removal of Cr(VI) was demonstrated at pH values ranging from 2 to 10. The adsorption capacity of Cr(VI) was found to be highest (82%) at pH 3.4 and greatly depended on the solution pH. We found that Cr(VI) adsorption decreased with increasing pH over the pH range of 3.4-10. The adsorption capacity increased dramatically when the temperature increased from 10 °C to 50 °C regardless of the amount of CNOs used. Cr(VI) removal decreased by ∼13% when Zn(II), Cu(II), and Pb(II) were present, while there were no significant changes observed when NO 3 - or SO 4 2- was present. The overall results support that CNOs can be used as an alternative adsorbent material to remove Cr(VI) in the water treatment industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Low temperature reduction of hexavalent chromium by a microbial enrichment consortium and a novel strain of Arthrobacter aurescens

    Directory of Open Access Journals (Sweden)

    Thompson Vicki S

    2006-01-01

    Full Text Available Abstract Background Chromium is a transition metal most commonly found in the environment in its trivalent [Cr(III] and hexavalent [Cr(VI] forms. The EPA maximum total chromium contaminant level for drinking water is 0.1 mg/l (0.1 ppm. Many water sources, especially underground sources, are at low temperatures (less than or equal to 15 Centigrade year round. It is important to evaluate the possibility of microbial remediation of Cr(VI contamination using microorganisms adapted to these low temperatures (psychrophiles. Results Core samples obtained from a Cr(VI contaminated aquifer at the Hanford facility in Washington were enriched in Vogel Bonner medium at 10 Centigrade with 0, 25, 50, 100, 200, 400 and 1000 mg/l Cr(VI. The extent of Cr(VI reduction was evaluated using the diphenyl carbazide assay. Resistance to Cr(VI up to and including 1000 mg/l Cr(VI was observed in the consortium experiments. Reduction was slow or not observed at and above 100 mg/l Cr(VI using the enrichment consortium. Average time to complete reduction of Cr(VI in the 30 and 60 mg/l Cr(VI cultures of the consortium was 8 and 17 days, respectively at 10 Centigrade. Lyophilized consortium cells did not demonstrate adsorption of Cr(VI over a 24 hour period. Successful isolation of a Cr(VI reducing organism (designated P4 from the consortium was confirmed by 16S rDNA amplification and sequencing. Average time to complete reduction of Cr(VI at 10 Centigrade in the 25 and 50 mg/l Cr(VI cultures of the isolate P4 was 3 and 5 days, respectively. The 16S rDNA sequence from isolate P4 identified this organism as a strain of Arthrobacter aurescens, a species that has not previously been shown to be capable of low temperature Cr(VI reduction. Conclusion A. aurescens, indigenous to the subsurface, has the potential to be a predominant metal reducer in enhanced, in situ subsurface bioremediation efforts involving Cr(VI and possibly other heavy metals and radionuclides.

  2. Chronic occupational exposure to hexavalent chromium causes DNA damage in electroplating workers

    Directory of Open Access Journals (Sweden)

    Ren Xiao-Bin

    2011-04-01

    Full Text Available Abstract Background Occupational exposure to chromium compounds may result in adverse health effects. This study aims to investigate whether low-level hexavalent chromium (Cr(VI exposure can cause DNA damage in electroplating workers. Methods 157 electroplating workers and 93 control subjects with no history of occupational exposure to chromium were recruited in Hangzhou, China. Chromium levels in erythrocytes were determined by graphite furnace atomic absorption spectrophotometer. DNA damage in peripheral lymphocytes was evaluated with the alkaline comet assay by three parameters: Olive tail moment, tail length and percent of DNA in the comet tail (tail DNA%. Urinary 8-OHdG levels were measured by ELISA. Results Chromium concentration in erythrocytes was about two times higher in electroplating workers (median: 4.41 μg/L than that in control subjects (1.54 μg/L, P P P P Conclusion The findings in this study indicated that there was detectable chromium exposure in electroplating workers. Low-level occupational chromium exposure induced DNA damage.

  3. Review article. Adverse hematological effects of hexavalent chromium: an overview

    Directory of Open Access Journals (Sweden)

    Ray Rina Rani

    2016-06-01

    Full Text Available Workers of tanneries, welding industries, factories manufacturing chromate containing paints are exposed to hexavalent chromium that increas¬es the risk of developing serious adverse health effects. This review elucidates the mode of action of hexavalent chromium on blood and its adverse effects. Both leukocyte and erythrocyte counts of blood sharply decreased in Swiss mice after two weeks of intraperitoneal treatment with Cr (VI, with the erythrocytes transforming into echinocytes. The hexavalent chromium in the blood is readily reduced to trivalent form and the reductive capacity of erythrocytes is much greater than that of plasma. Excess Cr (VI, not reduced in plasma, may enter erythrocytes and lymphocytes and in rodents it induces microcytic anemia. The toxic effects of chromium (VI include mitochondrial injury and DNA damage of blood cells that leads to carcinogenicity. Excess Cr (VI increases cytosolic Ca2+ activity and ATP depletion thereby inducing eryptosis. Se, vitamin C, and quercetin are assumed to have some protective effect against hexavalent chromium induced hematological disorders.

  4. The influence of Chromium supplied by tanning and wet finishing processes on the formation of cr(vi in leather

    Directory of Open Access Journals (Sweden)

    W. F. Fuck

    2011-06-01

    Full Text Available Chromium used in leather manufacturing can be oxidized from the trivalent to the hexavalent state, causing environmental concerns. In this study, the influence of Cr(III from tanning, deacidification pH, fatliquors, chrome retanning and vegetable retanning on the formation of Cr(VI in leather was analyzed by comparing natural and aged samples. In wet-blue leather, even after aging and in fatliquored leathers that did not suffer the aging process, the presence of Cr(VI was always below the detection limit of 3 mg/kg. Considering the presence of Cr(VI, the supply of chromium during the retanning step had a more significant effect than during the tanning. In the fatliquoring process with sulfites, fish and synthetic fatliquor leather samples contained Cr(VI when aged, and the highest concentration detected was 26.7 mg/kg. The evaluation of Cr(VI formation led to recommendations for regulation in the leather industry.

  5. Exposure to Particulate Hexavalent Chromium Exacerbates Allergic Asthma Pathology

    Science.gov (United States)

    Schneider, Brent C.; Constant, Stephanie L.; Patierno, Steven R.; Jurjus, Rosalyn A.; Ceryak, Susan M.

    2011-01-01

    Airborne hexavalent chromate, Cr(VI), has been identified by the Environmental Protection Agency as a possible health threat in urban areas, due to the carcinogenic potential of some of its forms. Particulate chromates are produced in many different industrial settings, with high levels of aerosolized forms historically documented. Along with an increased risk of lung cancer, a high incidence of allergic asthma has been reported in workers exposed to certain inhaled particulate Cr(VI) compounds. However, a direct causal association between Cr(VI) and allergic asthma has not been established. We recently showed that inhaled particulate Cr(VI) induces an innate neutrophilic inflammatory response in BALB/c mice. In the current studies we investigated how the inflammation induced by inhaled particulate Cr(VI) might alter the pathology of an allergic asthmatic response. We used a well-established mouse model of allergic asthma. Groups of ovalbumin protein (OVA)-primed mice were challenged either with OVA alone, or with a combination of OVA and particulate zinc chromate, and various parameters associated with asthmatic responses were measured. Co-exposure to particulate Cr(VI) and OVA mediated a mixed form of asthma in which both eosinophils and neutrophils are present in airways, tissue pathology is markedly exacerbated, and airway hyperresponsiveness is significantly increased. Taken together these findings suggest that inhalation of particulate forms of Cr(VI) may augment the severity of ongoing allergic asthma, as well as alter its phenotype. Such findings may have implications for asthmatics in settings in which airborne particulate Cr(VI) compounds are present at high levels. PMID:22178736

  6. Evaluation of extraction methods for hexavalent chromium determination in dusts, ashes, and soils

    Science.gov (United States)

    Wolf, Ruth E.; Wilson, Stephen A.

    2010-01-01

    One of the difficulties in performing speciation analyses on solid samples is finding a suitable extraction method. Traditional methods for extraction of hexavalent chromium, Cr(VI), in soils, such as SW846 Method 3060A, can be tedious and are not always compatible with some determination methods. For example, the phosphate and high levels of carbonate and magnesium present in the U.S. Environmental Protection Agency (USEPA) Method 3060A digestion for Cr(VI) were found to be incompatible with the High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICP-MS) detection method used by our laboratory. Modification of Method 3060A by eliminating the use of the phosphate buffer provided improved performance with the detection method, however dilutions are still necessary to achieve good chromatographic separation and detection of Cr(VI). An ultrasonic extraction method using a 1 mM Na2CO3 - 9 mM NaHCO3 buffer solution, adapted from Occupational Safety and Health Administration (OSHA) Method ID215, has been used with good results for the determination of Cr(VI) in air filters. The average recovery obtained for BCR-545 - Welding Dust Loaded on Filter (IRMM, Belgium) using this method was 99 percent (1.2 percent relative standard deviation) with no conversion of Cr(VI) to Cr(III) during the extraction process. This ultrasonic method has the potential for use with other sample matrices, such as ashes and soils. Preliminary investigations using NIST 2701 (Hexavalent Chromium in Contaminated Soil) loaded onto quartz filters showed promising results with approximately 90 percent recovery of the certified Cr(VI) value. Additional testing has been done using NIST 2701 and NIST 2700 using different presentation methods. Extraction efficiency of bulk presentation, where small portions of the sample are added to the bottom of the extraction vessel, will be compared with supported presentation, where small portions of the sample are loaded onto a

  7. Adsorption of hexavalent chromium by graphite–chitosan binary

    Indian Academy of Sciences (India)

    Graphite chitosan binary (GCB) composite was prepared for hexavalent chromium adsorption from studied water. GCB was characterized by TGA, FTIR, SEM and X-ray diffraction techniques.Wide porous sorptive surface of 3.89 m 2 g − 1 and absorptive functionalities of GCB was due to 20% (w/w) graphite support on ...

  8. Removal of Hexavalent Chromium from Aqueous Solutions using ...

    African Journals Online (AJOL)

    The hexavalent chromium exists in aquatic media as water soluble complex anions and persist. These are concentrated in industrial waste water especially from the tannery industries and release of effluents from industries adversely affects the environment. The removal of heavy metals from aqueous solutions is carried ...

  9. Assessment of the mode of action for hexavalent chromium-induced lung cancer following inhalation exposures

    International Nuclear Information System (INIS)

    Proctor, Deborah M.; Suh, Mina; Campleman, Sharan L.; Thompson, Chad M.

    2014-01-01

    Highlights: • No published or well recognized MOA for Cr(VI)-induced lung tumors exists. • MOA analysis for Cr(VI)-induced lung cancer was conducted to inform risk assessment. • Cr(VI) epidemiologic, toxicokinetic, toxicological, mechanistic data were evaluated. • Weight of evidence does not support a mutagenic MOA for Cr(VI)-induced lung cancer. • Non-linear approaches should be considered for evaluating Cr(VI) lung cancer risk. - Abstract: Inhalation of hexavalent chromium [Cr(VI)] is associated with increased lung cancer risk among workers in several industries, most notably chromate production workers exposed to high concentrations of Cr(VI) (≥100 μg/m 3 ), for which clear exposure–response relationships and respiratory irritation and tissue damage have been reported. Data from this industry are used to assess lung cancer risk associated with environmental and current occupational exposures, occurring at concentrations that are significantly lower. There is considerable uncertainty in the low dose extrapolation of historical occupational epidemiology data to assess risk at current exposures because no published or well recognized mode of action (MOA) for Cr(VI)-induced lung tumors exists. We conducted a MOA analysis for Cr(VI)-induced lung cancer evaluating toxicokinetic and toxicological data in humans and rodents and mechanistic data to assess plausibility, dose–response, and temporal concordance for potential MOAs. Toxicokinetic data support that extracellular reduction of Cr(VI), which limits intracellular absorption of Cr(VI) and Cr(VI)-induced toxicity, can be overwhelmed at high exposure levels. In vivo genotoxicity and mutagenicity data are mostly negative and do not support a mutagenic MOA. Further, both chronic bioassays and the epidemiologic literature support that lung cancer occurs at exposures that cause tissue damage. Based on this MOA analysis, the overall weight of evidence supports a MOA involving deposition and accumulation

  10. Investigations on the nephrotoxicity and hepatotoxicity of trivalent and hexavalent chromium compounds.

    Science.gov (United States)

    Dartsch, P C; Hildenbrand, S; Kimmel, R; Schmahl, F W

    1998-09-01

    In contrast to trivalent chromium (Cr(III)) compounds, hexavalent chromium ((Cr(VI)) compounds are oxidizing agents capable of directly inducing tissue damage and possessing carcinogenic, mutagenic and teratogenic potency. After oral or dermal absorption of Cr(VI), the kidney is the main target organ for chromium accumulation, which might result in acute tubular necrosis in humans. In contrast, an acute toxic effect of Cr(VI) on the liver has not yet been described. Therefore, we used two established epithelial cell lines from the kidney (Opossum kidney cells) and the liver (Hep G2 cells) to design an in vitro-assay which is able to examine acute toxic effects of chromium compounds. Cells of both cell lines were treated with various concentrations of Cr(III) and Cr(VI) ranging from 0.01 micromol/l to 1 mmol/l for 24 h. Thereafter, cell morphology, organization of the intracellular cytoskeleton, number of viable cells and mean cell volume were examined. The results show that Cr(VI), but not Cr(III), has an acute cytotoxic effect and causes a dose-dependent loss in cell viability. The effective dose that caused 50% of cell death was 5 micromol/l for kidney epithelial cells and 50 micromol/l for liver epithelial cells. This means that kidney epithelial cells are 10 times more sensitive towards Cr(VI) treatment than liver epithelial cells and this might explain the known nephrotoxicity in vivo. The loss in cell viability was accompanied by a rounding and detachment of the cells and a marked reduction of intracellular F-actin-containing stress fibers. Microtubules and intermediate-sized filaments were observed to be unaffected. Only in the case of kidney epithelial cells, a dose-dependent cell volume increase was observed after Cr(VI) treatment at concentrations up to 50 micromol/l. At higher concentrations, the cell volume decreased due to the high number of cells undergoing lysis and the appearance of cellular fragments. Various chloride channel blockers with

  11. Molecular and cellular mechanisms of hexavalent chromium-induced lung cancer: an updated perspective.

    Science.gov (United States)

    Urbano, A M; Ferreira, L M R; Alpoim, M C

    2012-03-01

    For over a century, chromium (Cr) has found widespread industrial and commercial use, namely as a pigment, in the production of stainless steel and in chrome plating. The adverse health effects to the skin and respiratory tract of prolonged exposure to Cr have been known or suspected for a long time, but it was much more recently that the toxicity of this element was unequivocally attributed to its hexavalent state. Based on the combined results of extensive epidemiological studies, animal carcinogenicity studies and several types of other relevant data, authoritative regulatory agencies have found sufficient evidence to classify hexavalent chromium [Cr(VI)] compounds as encountered in the chromate production, chromate pigment production and chromium plating industries as carcinogenic to humans. Crucial for the development of novel strategies to prevent, detect and/or treat Cr(VI)-induced cancers is a detailed knowledge of the molecular and cellular mechanisms underlying these pathologies. Unfortunately, in spite of a considerable research effort, crucial facets of these mechanisms remain essentially unknown. This review is intended to provide a concise, integrated and critical perspective of the current state of knowledge concerning multiple aspects of Cr(VI) carcinogenesis. It will present recent theories of Cr(VI)-induced carcinogenesis and will include aspects not traditionally covered in other reviews, such as the possible involvement of the energy metabolism in this process. A brief discussion on the models that have been used in the studies of Cr(VI)-induced carcinogenicity will also be included, due to the impact of this parameter on the relevance of the results obtained.

  12. The effects of water rock interaction and the human activities on the occurrence of hexavalent chromium in waters. The case study of the Psachna basin, Central Euboea, Greece.

    Science.gov (United States)

    Vasileiou, Eleni; Perraki, Maria; Stamatis, George; Gartzos, Efthimios

    2014-05-01

    High concentrations of heavy metals, particularly of the toxic hexavalent chromium, are recorded in surface and ground waters in many areas, and constitute one of the most severe environmental problems nowadays. The natural genesis of chromium is associated with the geological environment (peridotites and serpentintites). Chromium is structured in many minerals, mainly in spinel (e.g. chromite), in silicate minerals such as phyllosilicate serpentine minerals, chlorite, talc and chain-silicate minerals of pyroxene and amphibole group. Chromium is found in two forms in soils, waters and rocks, the hexavalent and the trivalent one. The relation between Cr(III) and Cr(VI) strongly depends on pH and oxidative properties of the area; however, in most cases, Cr(III) is the dominating variant. The natural oxidation of trivalent to hexavalent chromium can be achieved by manganese oxides, H2O2, O2 gas and oxy-hydroxides of trivalent iron. Anthropogenic factors may also cause the process of chromium's oxidation. In the Psachna basin, Central Euboea, Greece, high concentrations of hexavalent chromium were recently measured in spring- and drill- waters. In this work, we study the effect of the geological environment and of the anthropogenic activities on the water quality with emphasis on chromium. A detailed geochemical, petrological and mineralogical study of rocks and soils was carried out by means of optical microscopy, XRF, XRD and SEM/EDS. Ground and surface water samples were physically characterized and hydrochemically studied by means of ICP and AAF. Combined result evaluation indicates a natural source for the trivalent chromium in waters, attributed to the alteration of Cr-bearing minerals of the ultramafic rocks. However the oxidation of trivalent to hexavalent chromium results from anthropogenic activities, mainly from intensive agricultural activities and the extensive use of fertilizers and pesticides causing nitrate pollution in groundwater. It has been shown

  13. Ecotoxicology of Hexavalent Chromium in Freshwater Fish: A Critical Review

    Science.gov (United States)

    Velma, Venkatramreddy; Vutukuru, S.S.; Tchounwou, Paul B.

    2010-01-01

    Chromium (Cr) is a naturally occurring element found in rocks, animals, plants, and soil, predominantly in its insoluble trivalent form [Cr(III)]. Intense industrialization and other anthropogenic activities have led to the global occurrence of soluble Cr(VI), which is readily leached from soil to groundwater or surface water, in concentrations above permissible levels. The ecotoxicology of Cr(VI) is linked to its environmental persistence and the ability to induce a variety of adverse effects in biologic systems, including fish. In aquatic ecosystems, Cr(VI) exposure poses a significant threat to aquatic life. This paper reviews the fate and transport of Cr(VI) in the environment and its acute and chronic effects on fish. We also discuss Cr(VI) toxicity at the cellular, biochemical, and genetic levels. An attempt is made in this review to comprehend the staggered data on the toxic effects of Cr(VI) to various species of fish. Such data are extremely useful to the scientific community and public officials involved in health risk assessment and management of environmental contaminants as a guide to the best course of action to restore ecosystems and, in turn, to preserve human health. PMID:19658319

  14. Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Panda, L. [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India); Das, B., E-mail: bdas@immt.res.in [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India); Rao, D.S.; Mishra, B.K. [Council of Scientific and Industrial Research, Institute of Minerals and Materials Technology, Bhubaneswar 751013 (India)

    2011-08-30

    Graphical abstract: Dolochar - a waste material from sponge iron industry, is put to test as an adsorbent for removal of cadmium and hexavalent chromium ions from aqueous solutions. The sample consists of lots of voids and pores. Batch adsorption experiments have indicated that, higher pH and temperature enhances sorption for cadmium ions. The adsorption for chromium is found better at acidic pH in comparison to alkaline pH. The adsorption is well fitted to Langmuir isotherm model compared to the Freundlich model indicating monolayer adsorption. The kinetics of adsorption better fit to pseudo second order model.. Display Omitted Highlights: {yields} Dolochar, a waste material is generated during the production of sponge iron. {yields} Dolochar consists of metallic iron, carbon, and lime bearing phases along with lots of voids and pores. {yields} It was found to be an good adsorbent for the removal of cadmium and hexavalent chromium ions from aqueous solutions. {yields} The adsorption follows Langmuir isotherm and kinetics of adsorption better fit of pseudo second order model. - Abstract: Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6 m{sup 2}/g and micropore area of 34.1 m{sup 2}/g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast

  15. Application of dolochar in the removal of cadmium and hexavalent chromium ions from aqueous solutions

    International Nuclear Information System (INIS)

    Panda, L.; Das, B.; Rao, D.S.; Mishra, B.K.

    2011-01-01

    Graphical abstract: Dolochar - a waste material from sponge iron industry, is put to test as an adsorbent for removal of cadmium and hexavalent chromium ions from aqueous solutions. The sample consists of lots of voids and pores. Batch adsorption experiments have indicated that, higher pH and temperature enhances sorption for cadmium ions. The adsorption for chromium is found better at acidic pH in comparison to alkaline pH. The adsorption is well fitted to Langmuir isotherm model compared to the Freundlich model indicating monolayer adsorption. The kinetics of adsorption better fit to pseudo second order model.. Display Omitted Highlights: → Dolochar, a waste material is generated during the production of sponge iron. → Dolochar consists of metallic iron, carbon, and lime bearing phases along with lots of voids and pores. → It was found to be an good adsorbent for the removal of cadmium and hexavalent chromium ions from aqueous solutions. → The adsorption follows Langmuir isotherm and kinetics of adsorption better fit of pseudo second order model. - Abstract: Dolochar, a waste material generated in sponge iron industry, is processed and put to test as an adsorbent for removal of Cd(II) and Cr(VI) ions from aqueous solutions. The dolochar samples were characterised to determine the different phases and their distribution by reflection microscopy. The analysis indicated that the sample consists of metallic iron, fused carbon, and Ca-Mg bearing phases (Ca-Mg-silicate-oxide) along with lots of voids and pores. The fixed carbon (FC) content of the material is 13.8% with a Langmuir surface area of 81.6 m 2 /g and micropore area of 34.1 m 2 /g. Batch adsorption experiments have been conducted to study the sorption behaviour of Cd(II) and Cr(VI) ions on dolochar as a function of particle size, contact time, adsorbent dosages, pH and temperature. It is observed that higher pH and temperature enhances sorption of Cd(II) ions. In contrast, the adsorption for Cr(VI

  16. Origin of hexavalent chromium in groundwater: The example of Sarigkiol Basin, Northern Greece.

    Science.gov (United States)

    Kazakis, N; Kantiranis, N; Kalaitzidou, K; Kaprara, E; Mitrakas, M; Frei, R; Vargemezis, G; Tsourlos, P; Zouboulis, A; Filippidis, A

    2017-09-01

    Hexavalent chromium constitutes a serious deterioration factor for the groundwater quality of several regions around the world. High concentrations of this contaminant have been also reported in the groundwater of the Sarigkiol hydrological basin (near Kozani city, NW Greece). Specific interest was paid to this particular study area due to the co-existence here of two important factors both expected to contribute to Cr(VI) presence and groundwater pollution; namely the area's exposed ophiolitic rocks and its substantial fly ash deposits originating from the local lignite burning power plant. Accordingly, detailed geochemical, mineralogical, hydro-chemical, geophysical and hydrogeological studies were performed on the rocks, soils, sediments and water resources of this basin. Cr(VI) concentrations varied in the different aquifers, with the highest concentration (up to 120μgL -1 ) recorded in the groundwater of the unconfined porous aquifer situated near the temporary fly ash disposal site. Recharge of the porous aquifer is related mainly to precipitation infiltration and occasional surface run-off. Nevertheless, a hydraulic connection between the porous and neighboring karst aquifers could not be delineated. Therefore, the presence of Cr(VI) in the groundwater of this area is thought to originate from both the ophiolitic rock weathering products in the soils, and the local leaching of Cr(VI) from the diffused fly ash located in the area surrounding the lignite power plant. This conclusion was corroborated by factor analysis, and the strongly positively fractionated Cr isotopes (δ 53 Cr up to 0.83‰) recorded in groundwater, an ash leachate, and the bulk fly ash. An anthropogenic source of Cr(VI) that possibly influences groundwater quality is especially apparent in the eastern part of the Sarigkiol basin. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Equilibrium and kinetics study on hexavalent chromium adsorption onto diethylene triamine grafted glycidyl methacrylate based copolymers

    International Nuclear Information System (INIS)

    Maksin, Danijela D.; Nastasović, Aleksandra B.; Milutinović-Nikolić, Aleksandra D.; Suručić, Ljiljana T.; Sandić, Zvjezdana P.; Hercigonja, Radmila V.; Onjia, Antonije E.

    2012-01-01

    Highlights: ► Methacrylate based copolymers grafted with diethylene triamine as Cr(VI) sorbents. ► Chemisorption and pore diffusion are characteristics of this sorption system. ► Langmuir isotherm provided best fit and maximum adsorption capacity was 143 mg g −1 . ► Cr(VI) sorption onto amino-functionalized copolymer was endothermic and spontaneous. ► A simple, efficient and cost-effective hexavalent chromium removal method. - Abstract: Two porous and one non-porous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) [abbreviated PGME] were prepared by suspension copolymerization and functionalized with diethylene triamine [abbreviated PGME-deta]. Samples were characterized by elemental analysis, mercury porosimetry, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and transmission electron microscopy. Kinetics of Cr(VI) sorption by PGME-deta were investigated in batch static experiments, in the temperature range 25–70 °C. Sorption was rapid, with the uptake capacity higher than 80% after 30 min. Sorption behavior and rate-controlling mechanisms were analyzed using five kinetic models (pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Bangham model). Kinetic studies showed that Cr(VI) adsorption adhered to the pseudo-second-order model, with definite influence of pore diffusion. Equilibrium data was tested with Langmuir, Freundlich and Tempkin adsorption isotherm models. Langmuir model was the most suitable indicating homogeneous distribution of active sites on PGME-deta and monolayer sorption. The maximum adsorption capacity from the Langmuir model, Q max , at pH 1.8 and 25 °C was 143 mg g −1 for PGME2-deta (sample with the highest amino group concentration) while at 70 °C Q max reached the high value of 198 mg g −1 . Thermodynamic parameters revealed spontaneous and endothermic nature of Cr(VI) adsorption onto PGME-deta.

  18. Lung injury, inflammation and Akt signaling following inhalation of particulate hexavalent chromium

    International Nuclear Information System (INIS)

    Beaver, Laura M.; Stemmy, Erik J.; Constant, Stephanie L.; Schwartz, Arnold; Little, Laura G.; Gigley, Jason P.; Chun, Gina; Sugden, Kent D.

    2009-01-01

    Certain particulate hexavalent chromium [Cr(VI)] compounds are human respiratory carcinogens that release genotoxic soluble chromate, and are associated with fibrosis, fibrosarcomas, adenocarcinomas and squamous cell carcinomas of the lung. We postulate that inflammatory processes and mediators may contribute to the etiology of Cr(VI) carcinogenesis, however the immediate (0-24 h) pathologic injury and immune responses after exposure to particulate chromates have not been adequately investigated. Our aim was to determine the nature of the lung injury, inflammatory response, and survival signaling responses following intranasal exposure of BALB/c mice to particulate basic zinc chromate. Factors associated with lung injury, inflammation and survival signaling were measured in airway lavage fluid and in lung tissue. A single chromate exposure induced an acute immune response in the lung, characterized by a rapid and significant increase in IL-6 and GRO-α levels, an influx of neutrophils, and a decline in macrophages in lung airways. Histological examination of lung tissue in animals challenged with a single chromate exposure revealed an increase in bronchiolar cell apoptosis and mucosal injury. Furthermore, chromate exposure induced injury and inflammation that progressed to alveolar and interstitial pneumonitis. Finally, a single Cr(VI) challenge resulted in a rapid and persistent increase in the number of airways immunoreactive for phosphorylation of the survival signaling protein Akt, on serine 473. These data illustrate that chromate induces both survival signaling and an inflammatory response in the lung, which we postulate may contribute to early oncogenesis

  19. [Hexavalent chromium pollution and exposure level in electroplating workplace].

    Science.gov (United States)

    Zhang, Xu-hui; Zhang, Xuan; Yang, Zhang-ping; Jiang, Cai-xia; Ren, Xiao-bin; Wang, Qiang; Zhu, Yi-min

    2012-08-01

    To investigate the pollution of hexavalent chromium in the electroplating workplace and screen the biomarkers of chromium exposure. Field occupational health investigation was conducted in 25 electroplating workplaces. 157 electroplating workers and 93 healthy unexposed controls were recruited. The epidemiological information was collected with face to face interview. Chromium in erythrocytes was determined by graphite furnace atomic absorption spectrophotometer. The median of short-term exposure concentration of chromium in the air at electroplating workplace was 0.06 mg/m(3) (median) and ranging from 0.01 (detect limit) to 0.53 mg/m(3)). The median concentration of Cr (VI) in erythrocytes in electroplating workers was 4.41 (2.50 ∼ 5.29) µg/L, which was significantly higher than that in control subjects [1.54 (0.61 ∼ 2.98) µg/L, P electroplating workers and control subjects, except for the subjects of age less than 30 years old (P = 0.11). There was hexavalent chromium pollution in electroplating workplace. Occupational hazards prevention measures should be taken to control the chromium pollution hazards.

  20. Hexavalent chromium causes the oxidation of thioredoxin in human bronchial epithelial cells

    International Nuclear Information System (INIS)

    Myers, Judith M.; Antholine, William E.; Myers, Charles R.

    2008-01-01

    Hexavalent chromium [Cr(VI)] species such as chromates are cytotoxic. Inhalational exposure is a primary concern in many Cr-related industries and their immediate environments, and bronchial epithelial cells are directly exposed to inhaled Cr(VI). Chromates are readily taken up by cells and are reduced to reactive Cr species which may also result in the generation of reactive oxygen species (ROS). The thioredoxin (Trx) system has a key role in the maintenance of cellular thiol redox balance and is essential for cell survival. Cells normally maintain the cytosolic (Trx1) and mitochondrial (Trx2) thioredoxins largely in the reduced state. Redox Western blots were used to assess the redox status of the thioredoxins in normal human bronchial epithelial cells (BEAS-2B) incubated with soluble Na 2 CrO 4 or insoluble ZnCrO 4 for different periods of time. Both chromates caused a dose- and time-dependent oxidation of Trx2 and Trx1. Trx2 was more susceptible in that it could all be converted to the oxidized form, whereas a small amount of reduced Trx1 remained even after prolonged treatment with higher Cr concentrations. Only one of the dithiols, presumably the active site, of Trx1 was oxidized by Cr(VI). Cr(VI) did not cause significant GSH depletion or oxidation indicating that Trx oxidation does not result from a general oxidation of cellular thiols. With purified Trx and thioredoxin reductase (TrxR) in vitro, Cr(VI) also resulted in Trx oxidation. It was determined that purified TrxR has pronounced Cr(VI) reducing activity, so competition for electron flow from TrxR might impair its ability to reduce Trx. The in vitro data also suggested some direct redox interaction between Cr(VI) and Trx. The ability of Cr(VI) to cause Trx oxidation in cells could contribute to its cytotoxic effects, and could have important implications for cell survival, redox-sensitive cell signaling, and the cells' tolerance of other oxidant insults

  1. Adsorption characteristics of hexavalent chromium on HCB/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li; Zhang, Yonggang, E-mail: 13502182420@163.com

    2014-10-15

    Graphical abstract: - Highlights: • Sol–gel method was adopted to prepare HCB/TiO{sub 2}. • Its adsorption performance of Cr(VI) was investigated. • The maximum adsorption capacity for Cr(VI) was at 27.33 mg g{sup −1} in an acidic medium. • The value is worth comparable with other low-cost adsorbents. - Abstract: Sol–gel method was adopted to prepare HCB/TiO{sub 2} and its adsorption ability of hexavalent chromium, Cr(VI), and removal from aqueous solution were investigated. The samples were characterized by Power X-ray diffraction (XRD) and a transmission electron microscope (TEM) which showed that the TiO{sub 2} was deposited on the surface of HCB. FTIR was used to identify the changes of the surface functional groups before and after adsorption. Potentiometric titration method was used to characterize the zero charge (pH{sub pzc}) characteristics of the surface of HCB/TiO{sub 2} which showed more acidic functional groups containing. Batch experiments showed that initial pH, absorbent dosage, contact time and initial concentration of Cr(VI) were important parameters for the Cr(VI) adsorption studies. The Freundlich isotherm model better reflected the experimental data better. Cr(VI) adsorption process followed the pseudo-second order kinetic model, which illustrated chemical adsorption. The thermodynamic parameters, such as Gibbs free energy (ΔG), changes in enthalpy change (ΔH) and changes in entropy change (ΔS) were also evaluated. Negative value of free energy occurred at temperature range of 25–45 °C, so Cr(VI) adsorption by HCB/TiO{sub 2} is spontaneous. Desorption results showed that the adsorption capacity could maintain 80% after five cycles. The maximum adsorption capacity for Cr(VI) was at 27.33 mg g{sup −1} in an acidic medium, of which the value is worth comparable with other low-cost adsorbents.

  2. Two fold modified chitosan for enhanced adsorption of hexavalent chromium from simulated wastewater and industrial effluents.

    Science.gov (United States)

    Kahu, S S; Shekhawat, A; Saravanan, D; Jugade, R M

    2016-08-01

    Ionic solid (Ethylhexadecyldimethylammoniumbromide) impregnated phosphated chitosan (ISPC) was synthesized and applied for enhanced adsorption of hexavalent chromium from industrial effluent. The compound obtained was extensively characterized using instrumental techniques like FT-IR, TGA-DTA, XRD, SEM, BET and EDX. ISPC showed high adsorption capacity of 266.67mg/g in accordance with Langmuir isotherm model at pH 3.0 due to the presence of multiple sites which contribute for ion pair and electrostatic interactions with Cr(VI) species. The sorption kinetics and thermodynamic studies revealed that adsorption of Cr(VI) followed pseudo-second-order kinetics with exothermic and spontaneous behaviour. Applicability of ISPC for higher sample volumes was discerned through column studies. The real chrome plating industry effluent was effectively treated with total chromium recovery of 94%. The used ISPC was regenerated simply by dilute ammonium hydroxide treatment and tested for ten adsorption-desorption cycles with marginal decrease in adsorption efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Hexavalent Chromium: Analysis of the Mechanism of Groundwater Contamination in a Former Industrial Site in the Province of Vicenza (Northern Italy)

    OpenAIRE

    Valentina Accoto; Pierluigi Bullo; Ruben Faccio; Leonardo Mason; Andrea Sottani

    2017-01-01

    The study consisted in the analysis of the mobilization mechanisms of hexavalent chromium (Cr(VI)) into groundwater from a decommissioned contaminated factory. The site is located in the Province of Vicenza and formerly was a chrome-plating plant. The subsoil consists predominantly of gravelly deposits with a thickness of at least one hundred meters. An unconfined aquifer is present with water table at about 23 m depth bgl. During the seven years of monitoring (2008-2014), the fluctuation of ...

  4. Regeneration of pilot-scale ion exchange columns for hexavalent chromium removal.

    Science.gov (United States)

    Korak, Julie A; Huggins, Richard; Arias-Paic, Miguel

    2017-07-01

    Due to stricter regulations, some drinking water utilities must implement additional treatment processes to meet potable water standards for hexavalent chromium (Cr(VI)), such as the California limit of 10 μg/L. Strong base anion exchange is effective for Cr(VI) removal, but efficient resin regeneration and waste minimization are important for operational, economic and environmental considerations. This study compared multiple regeneration methods on pilot-scale columns on the basis of regeneration efficiency, waste production and salt usage. A conventional 1-Stage regeneration using 2 N sodium chloride (NaCl) was compared to 1) a 2-Stage process with 0.2 N NaCl followed by 2 N NaCl and 2) a mixed regenerant solution with 2 N NaCl and 0.2 N sodium bicarbonate. All methods eluted similar cumulative amounts of chromium with 2 N NaCl. The 2-Stage process eluted an additional 20-30% of chromium in the 0.2 N fraction, but total resin capacity is unaffected if this fraction is recycled to the ion exchange headworks. The 2-Stage approach selectively eluted bicarbonate and sulfate with 0.2 N NaCl before regeneration using 2 N NaCl. Regeneration approach impacted the elution efficiency of both uranium and vanadium. Regeneration without co-eluting sulfate and bicarbonate led to incomplete uranium elution and potential formation of insoluble uranium hydroxides that could lead to long-term resin fouling, decreased capacity and render the resin a low-level radioactive solid waste. Partial vanadium elution occurred during regeneration due to co-eluting sulfate suppressing vanadium release. Waste production and salt usage were comparable for the 1- and 2-Stage regeneration processes with similar operational setpoints with respect to chromium or nitrate elution. Published by Elsevier Ltd.

  5. Lactational exposure to hexavalent chromium delays puberty by impairing ovarian development, steroidogenesis and pituitary hormone synthesis in developing Wistar rats

    International Nuclear Information System (INIS)

    Banu, Sakhila K.; Samuel, Jawahar B.; Arosh, Joe A.; Burghardt, Robert C.; Aruldhas, Michael M.

    2008-01-01

    Hexavalent chromium (Cr-VI) is used in a wide range of industries. Cr-VI from chromate industries and atmospheric emissions contribute to the Cr contamination in the environment. Cr is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects including ovotoxicity. Therefore, the goal of this study was to investigate the basic mechanisms involved in Cr(VI)-induced ovotoxicity, and the protective role of vitamin C on ovarian follicular development and function in Cr(VI)-induced reproductive toxicity using both in vivo and in vitro approaches. Lactating rats received potassium dichromate (200 mg/L) with or without vitamin C (500 mg/L), through drinking water from postpartum days 1-21. During postnatal days (PND) 1-21 the pups received Cr(VI) via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards, and euthanized on PND-21, -45 and -65. Cr(VI) decreased steroidogenesis, GH and PRL, increased FSH and did not alter LH. Cr(VI) delayed puberty, decreased follicle number, and extended estrous cycle. Spontaneously immortalized rat granulosa cells were treated with 12.5 μM (IC 50 ) potassium dichromate for 12 and 24 h, with or without vitamin C pre-treatment. Cr(VI) decreased the mRNA expressions of StAR, SF-1, 17β-HSD-1, 17β-HSD-2, FSHR, LHR, ERα and ERβ. Vitamin C pre-treatment protected ovary and granulosa cells from the deleterious effects of Cr(VI) toxicity, both in vivo and in vitro. Therefore, Cr(VI) toxicity could be a potential risk to the reproductive system in developing females, and vitamin C plays a protective role against Cr(VI)-induced ovotoxicity

  6. Antidotal impact of extra virgin olive oil against genotoxicity, cytotoxicity and immunotoxicity induced by hexavalent chromium in rat

    Directory of Open Access Journals (Sweden)

    Samah Khalil

    2013-12-01

    Full Text Available An in vivo study was carried out to verify whether extra-virgin olive oil (EVOO has the potential to modulate alterations resulted from exposure to hexavalent chromium (CrVI as potassium dichromate in rats. For this purpose, CrVI was injected intraperitoneally (i.p. at a dose of 0.4 mg/kg bw/day, EVOO was given orally at a dose of 300 μl daily either a lone or co-treated with CrVI at the same doses, routes and duration (26 days. At the end of the experiment, blood and spleen samples were collected. Genotoxicity, cytotoxicity and immunotoxicity biomarkers induced by CrVI were evaluated. Also, histopathological and immunohistochemical investigations of spleen tissue were conducted. A significant increase in genotoxicity and cytotoxicity biomarkers (micronucleus frequency, 8-hydroxy-2-deoxyguanosine level and lactate dehydrogenase activity were recorded in CrVI treated rats. In addition, the immunotoxicity biomarkers showed a significant decrease in phagocytic%, stimulated nitric oxide production and decrease in the serum lysozyme activity. Histopathological and immunohistochemical studies support the cytotoxicity study. Oral administration of EVOO can ameliorate those effects but not restored to control level. Thus, authors recommend that regular consumption of this oil in the diet provides a constant supply of potential antioxidants that could reduce these alterations.

  7. Hexavalent Chromium Is Cytotoxic and Genotoxic to Hawksbill Sea Turtle Cells

    Science.gov (United States)

    Wise, Sandra S.; Xie, Hong; Fukuda, Tomokazu; Thompson, W. Douglas; Wise, John Pierce

    2014-01-01

    Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, we evaluated the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 μg/cm2 lead chromate induced 108, 79, 54, and 7 percent relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 μg/cm2 lead chromate induced damage in 4, 10, 15, 26, and 36 percent of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate induced 84, 69, 46, 25, and 3 percent relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29 percent of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5 μM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general. PMID:24952338

  8. Lipid peroxidation in workers exposed to hexavalent chromium.

    Science.gov (United States)

    Huang, Y L; Chen, C Y; Sheu, J Y; Chuang, I C; Pan, J H; Lin, T H

    1999-02-26

    The aim of this study was to investigate whether exposure to hexavalent chromium induces lipid peroxidation in human. This study involved 25 chrome-plating factory workers and a reference group of 28 control subjects. The whole-blood and urinary chromium concentrations were determined by graphite furnace atomic absorption spectrophotometry. Malondialdehyde (MDA), the product of lipid peroxidation, was determined by high-performance liquid chromatography, and the activities of protective enzymes were measured by ultraviolet-visible spectrophotometry. In the chrome-plating workers, the mean concentrations of chromium in blood and urine were 5.98 microg/L and 5.25 microg/g creatinine, respectively; the mean concentrations of MDA in blood and urine were 1.7 micromol/L and 2.24 micromol/g creatinine. The concentrations of both chromium and MDA in blood and urine were significantly higher in the chromium-exposed workers. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) were not markedly different between control and exposed workers. Data suggest that MDA may be used as a biomarker for occupational chromium exposure. Antioxidant enzymic activities are not a suitable marker for chromium exposure.

  9. Fixed-bed column study for hexavalent chromium removal and recovery by short-chain polyaniline synthesized on jute fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Potsangbam Albino [Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039 (India); Chakraborty, Saswati [Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039 (India)], E-mail: saswati@iitg.ernet.in

    2009-03-15

    Fixed-bed column studies were conducted to evaluate performance of a short-chain polymer, polyaniline, synthesized on the surface of jute fiber (PANI-jute) for the removal of hexavalent chromium [Cr(VI)] in aqueous environment. Influent pH, column bed depth, influent Cr(VI) concentrations and influent flow rate were variable parameters for the present study. Optimum pH for total chromium removal was observed as 3 by electrostatic attraction of acid chromate ion (HCrO{sub 4}{sup -}) with protonated amine group (NH{sub 3}{sup +}) of PANI-jute. With increase in column bed depth from 40 to 60 cm, total chromium uptake by PANI-jute increased from 4.14 to 4.66 mg/g with subsequent increase in throughput volume from 9.84 to 12.6 L at exhaustion point. The data obtained for total chromium removal were well described by BDST equation till 10% breakthrough. Adsorption rate constant and dynamic bed capacity at 10% breakthrough were observed as 0.01 L/mg h and 1069.46 mg/L, respectively. Adsorbed total chromium was recovered back from PANI-jute as non-toxic Cr(III) after ignition with more than 97% reduction in weight, minimizing the problem of solid waste disposal.

  10. Reduction of hexavalent chromium by fasted and fed human gastric fluid. I. Chemical reduction and mitigation of mutagenicity

    Energy Technology Data Exchange (ETDEWEB)

    De Flora, Silvio, E-mail: sdf@unige.it [Department of Health Sciences, University of Genoa, 16132 Genoa (Italy); Camoirano, Anna, E-mail: Anna.Fiorenza.Camoirano@unige.it [Department of Health Sciences, University of Genoa, 16132 Genoa (Italy); Micale, Rosanna T., E-mail: rosannamicale@yahoo.it [Department of Health Sciences, University of Genoa, 16132 Genoa (Italy); La Maestra, Sebastiano, E-mail: lamaestra78@yahoo.it [Department of Health Sciences, University of Genoa, 16132 Genoa (Italy); Savarino, Vincenzo, E-mail: vsavarin@unige.it [Gastroenterology Unit, Department of Internal Medicine, University of Genoa, 16132 Genoa (Italy); Zentilin, Patrizia, E-mail: Patrizia.Zentilin@unige.it [Gastroenterology Unit, Department of Internal Medicine, University of Genoa, 16132 Genoa (Italy); Marabotto, Elisa, E-mail: emarabotto@libero.it [Gastroenterology Unit, Department of Internal Medicine, University of Genoa, 16132 Genoa (Italy); Suh, Mina, E-mail: msuh@toxstrategies.com [ToxStrategies, Mission Viejo, CA 92692 (United States); Proctor, Deborah M., E-mail: dproctor@toxstrategies.com [ToxStrategies, Mission Viejo, CA 92692 (United States)

    2016-09-01

    Evaluation of the reducing capacity of human gastric fluid from healthy individuals, under fasted and fed conditions, is critical for assessing the cancer hazard posed by ingested hexavalent chromium [Cr(VI)] and for developing quantitative physiologically-based pharmacokinetic models used in risk assessment. In the present study, the patterns of Cr(VI) reduction were evaluated in 16 paired pre- and post-meal gastric fluid samples collected from 8 healthy volunteers. Human gastric fluid was effective both in reducing Cr(VI), as measured by using the s-diphenylcarbazide colorimetric method, and in attenuating mutagenicity in the Ames test. The mean (± SE) Cr(VI)-reducing ability of post-meal samples (20.4 ± 2.6 μg Cr(VI)/mL gastric fluid) was significantly higher than that of pre-meal samples (10.2 ± 2.3 μg Cr(VI)/mL gastric fluid). When using the mutagenicity assay, the decrease of mutagenicity produced by pre-meal and post-meal samples corresponded to reduction of 13.3 ± 1.9 and 25.6 ± 2.8 μg Cr(VI)/mL gastric fluid, respectively. These data are comparable to parallel results conducted by using speciated isotope dilution mass spectrometry. Cr(VI) reduction was rapid, with > 70% of total reduction occurring within 1 min and 98% of reduction is achieved within 30 min with post-meal gastric fluid at pH 2.0. pH dependence was observed with decreasing Cr(VI) reducing capacity at higher pH. Attenuation of the mutagenic response is consistent with the lack of DNA damage observed in the gastrointestinal tract of rodents following administration of ≤ 180 ppm Cr(VI) for up to 90 days in drinking water. Quantifying Cr(VI) reduction kinetics in the human gastrointestinal tract is necessary for assessing the potential hazards posed by Cr(VI) in drinking water. - Highlights: • Cr(VI) reduction capacity was greater in post-meal than paired pre-meal samples. • Cr(VI) reduction was rapid, pH dependent, and due to heat stable components. • Gastric fluid attenuates

  11. Epithelial–mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanism in lung epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Song-Ze, E-mail: dingsongze@hotmail.com [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States); Yang, Yu-Xiu; Li, Xiu-Ling [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Michelli-Rivera, Audrey [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States); Han, Shuang-Yin [Department of Internal Medicine, Henan Provincial People’s Hospital, Zhengzhou University, Wei-Wu Road, Zhengzhou, Henan 450000 (China); Wang, Lei; Pratheeshkumar, Poyil; Wang, Xin; Lu, Jian; Yin, Yuan-Qin; Budhraja, Amit; Hitron, Andrew J. [Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536 (United States)

    2013-05-15

    Hexavalent chromium [Cr(VI)] is an important human carcinogen associated with pulmonary diseases and lung cancer. Exposure to Cr(VI) induces DNA damage, cell morphological change and malignant transformation in human lung epithelial cells. Despite extensive studies, the molecular mechanisms remain elusive, it is also not known if Cr(VI)-induced transformation might accompany with invasive properties to facilitate metastasis. We aimed to study Cr(VI)-induced epithelial–mesenchymal transition (EMT) and invasion during oncogenic transformation in lung epithelial cells. The results showed that Cr(VI) at low doses represses E-cadherin mRNA and protein expression, enhances mesenchymal marker vimentin expression and transforms the epithelial cell into fibroblastoid morphology. Cr(VI) also increases cell invasion and promotes colony formation. Further studies indicated that Cr(VI) uses multiple mechanisms to repress E-cadherin expression, including activation of E-cadherin repressors such as Slug, ZEB1, KLF8 and enhancement the binding of HDAC1 in E-cadherin gene promoter, but DNA methylation is not responsible for the loss of E-cadherin. Catalase reduces Cr(VI)-induced E-cadherin and vimentin protein expression, attenuates cell invasion in matrigel and colony formation on soft agar. These results demonstrate that exposure to a common human carcinogen, Cr(VI), induces EMT and invasion during oncogenic transformation in lung epithelial cells and implicate in cancer metastasis and prevention. - Graphical abstract: Epithelial–mesenchymal transition during oncogenic transformation induced by hexavalent chromium involves reactive oxygen species-dependent mechanisms in lung epithelial cells. - Highlights: • We study if Cr(VI) might induce EMT and invasion in epithelial cells. • Cr(VI) induces EMT by altering E-cadherin and vimentin expression. • It also increases cell invasion and promotes oncogenic transformation. • Catalase reduces Cr(VI)-induced EMT, invasion and

  12. Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

    International Nuclear Information System (INIS)

    Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu; Liu, Xinzhong

    2017-01-01

    Al(OH) 3 and Ca(OH) 2 powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C 3 A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C 3 A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO 4 LDH product. Ca-Al-CrO 4 LDH phase occurred preferentially to Ca-Al-MCl 2 LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl 2 LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.

  13. Precursor preparation for Ca-Al layered double hydroxide to remove hexavalent chromium coexisting with calcium and magnesium chlorides

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Lihua; He, Xiaoman; Qu, Jun; Li, Xuewei; Lei, Zhiwu; Zhang, Qiwu [School of Resources and Environment Engineering, Wuhan University of Technology, Wuhan 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 (China)

    2017-01-15

    Al(OH){sub 3} and Ca(OH){sub 2} powders are co-ground to prepare a precursor which hydrates into a layered double hydroxide (LDH) phase by agitation in aqueous solution with target hexavalent chromium (Cr(VI)) at room temperature, to achieve an obvious improvement in removal efficiency of Cr(VI) through an easy incorporation into the structure. Although the prepared precursor transforms into LDH phases also when agitated in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. The adsorption isotherm and kinetic studies show that the phenomena occurring on the Al-Ca precursor fit a pseudo-second-order kinetics with a Langmuir adsorption capacity of 59.45 mg/g. Besides, characterizations of the prepared precursor and the samples after adsorption are also performed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Transmission electron microscope (TEM) to understand the reason of the preferential incorporation of Cr(VI) to the coexisting chloride salts during the LDH phase formation. - Graphical abstract: Activated Ca-Al hydroxides (C{sub 3}A) transformed into Ca-Al-OH compound when agitated in water. Ca-Al precursor (C{sub 3}A) was agitated in a hexavalent chromium (Cr(VI)) solution to form Al-Ca-CrO{sub 4} LDH product. Ca-Al-CrO{sub 4} LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases in the solutions of calcium and magnesium chlorides, it incorporates Cr(VI) preferentially to the chloride salts when they coexist. - Highlights: • Activated Ca-Al hydroxides transformed into LDH when agitated in water with some inorganic substances. • Hexavalent Cr was incorporated in the LDH structure at high adsorption capacity. • Ca-Al-Cr LDH phase occurred preferentially to Ca-Al-MCl{sub 2} LDH phases with coexistence. • The prepared Ca-Al hydroxides had high performance as adsorbent even with high salinity of the solution.

  14. Hexavalent chromium exposures and exposure-control technologies in American enterprise: results of a NIOSH field research study.

    Science.gov (United States)

    Blade, L M; Yencken, M Story; Wallace, M E; Catalano, J D; Khan, A; Topmiller, J L; Shulman, S A; Martinez, A; Crouch, K G; Bennett, J S

    2007-08-01

    The National Institute for Occupational Safety and Health (NIOSH) conducted 21 field surveys in selected industries to characterize workers' exposures to hexavalent chromium-containing airborne particulate and to evaluate existing technologies for controlling these exposures. Hexavalent chromium Cr(VI) is a respiratory irritant and chronic inhalation may cause lung cancer. Primary evaluation methods included collection of full work shift, personal breathing-zone (PBZ) air samples for Cr(VI), measurement of ventilation system parameters, and documentation of processes and work practices. This study emphasized evaluation of engineering exposure control measures, so PBZ exposures were measured on the outside of personal protective equipment, for example, respirators. Field surveys were conducted in two chromium electroplating facilities, including one where full-shift PBZ exposures to Cr(VI) ranged from 3.0 to 16 times the 1 micro g/m(3)NIOSH recommended exposure limit (REL) despite several engineering controls on the plating tanks. At a painting and coating facility that used Cr(VI)-containing products, full-shift exposures of painters and helpers (2.4 to 55 micro g/m(3)) exceeded the REL, but LEV effectiveness was limited. Other operations evaluated included welding in construction; metal cutting operations on chromium-containing materials in ship breaking; chromate-paint removal with abrasive blasting; atomized alloy-spray coating; foundry operations; printing; and the manufacture of refractory brick, colored glass, prefabricated concrete products, and treated wood products. NIOSH researchers concluded that, in many of the evaluated processes, Cr(VI) exposures at or below the current NIOSH REL are achievable. However, for some processes, it is unclear whether controlling exposures to this range is consistently achievable without respirator use. Some operations involving the application of coatings and finishes may be among those most difficult to control to this

  15. A study of the process of desorption of hexavalent chromium

    Directory of Open Access Journals (Sweden)

    W.B. Amorim

    2003-09-01

    Full Text Available In this work the process of desorption of hexavalent chromium, a toxic metal ion, from the marine algae Sargassum sp, following biosorption experiments 2³ factorial design was studied. A technique was applied to three eluents: HCl, H2SO4 and EDTA. Three factors of importance were evaluated: concentration of eluent, the ratio between mass of biosorbent and volume of eluent (S/L and process time. A statistical analysis of the experimental results showed that the three variables evaluated are significant for all three eluents. The models for chromium desorption were validated, as the results agreed well with the observed values. Through use of the response surface methodology, a factorial design based optimization technique; it was possible to identify the most suitable eluent and the interval of values for the process variables that resulted in the most significant desorption of chromium, which is relevant information for work aiming at process optimization.

  16. Laboratory Validation and Demonstrations of Non-Hexavalent Chromium Conversion Coatings for Steel Substrates (Briefing Charts)

    Science.gov (United States)

    2011-02-01

    UNCLASSIFIED: Approved for public release; distribution unlimited. Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion...00-00-2011 4. TITLE AND SUBTITLE Laboratory Validation and Demonstrations of Non- Hexavalent Chromium Conversion Coatings for Steel Substrates 5a...to MRAP II Acquisition Pretreatment /conversion coatings omitted: • Hex- chrome pretreatments prohibited for new ground vehicles • Hydrogen

  17. A Novel Early Warning System Based on a Sediment Microbial Fuel Cell for In Situ and Real Time Hexavalent Chromium Detection in Industrial Wastewater.

    Science.gov (United States)

    Zhao, Shuai; Liu, Pu; Niu, Yongyan; Chen, Zhengjun; Khan, Aman; Zhang, Pengyun; Li, Xiangkai

    2018-02-22

    Hexavalent chromium (Cr(VI)) is a well-known toxic heavy metal in industrial wastewater, but in situ and real time monitoring cannot be achieved by current methods used during industrial wastewater treatment processes. In this study, a Sediment Microbial Fuel Cell (SMFC) was used as a biosensor for in situ real-time monitoring of Cr(VI), which was the organic substrate is oxidized in the anode and Cr(VI) is reduced at the cathode simultaneously. The pH 6.4 and temperature 25 °C were optimal conditions for the operation. Under the optimal conditions, linearity (R² = 0.9935) of the generated voltage was observed in the Cr(VI) concentration range from 0.2 to 0.7 mg/L. The system showed high specificity for Cr(VI), as other co-existing ions such as Cu 2+ , Zn 2+ , and Pb 2+ did not interfere with Cr(VI) detection. In addition, when the sediment MFC-based biosensor was applied for measuring Cr(VI) in actual wastewater samples, a low deviation (real time in situ detection of Cr(VI) in industrial wastewaters.

  18. Study on anaerobic treatment of wastewater containing hexavalent chromium.

    Science.gov (United States)

    Xu, Yan-bin; Xiao, Hua-hua; Sun, Shui-yu

    2005-06-01

    A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and COD(Cr) of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr6+ removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms.

  19. Study on anaerobic treatment of wastewater containing hexavalent chromium*

    Science.gov (United States)

    Xu, Yan-bin; Xiao, Hua-hua; Sun, Shui-yu

    2005-01-01

    A self-made anaerobic bio-filter bed which was inoculated with special sludge showed high efficiency in removing hexavalent chromium. When pump flow was 47 ml/min and CODCr of wastewater was about 140 mg/L, it took 4 h to decrease the Cr6+ concentrations from about 60 mg/L to under 0.5 mg/L, compared with 14 h without carbon source addition. Cr6+ concentrations ranged from 64.66 mg/L to 75.53 mg/L, the system efficiency was excellent. When Cr6+ concentration reached 95.47 mg/L, the treatment time was prolonged to 7.5 h. Compared with the contrast system, the system with trace metals showed clear superiority in that the Cr6+ removal rate increased by 21.26%. Some analyses also showed that hexavalent chromium could probably be bio-reduced to trivalent chromium, and that as a result, the chrome hydroxide sediment was formed on the surface of microorganisms. PMID:15909347

  20. Advances In Hexavalent Chromium Removal At Hanford

    International Nuclear Information System (INIS)

    Neshem, D.O.; Riddelle, J.

    2012-01-01

    At the Hanford Site, chromium was used as a corrosion inhibitor in the reactor cooling water and was introduced into the groundwater as a result of planned and unplanned discharges from reactors during plutonium production since 1944. Beginning in 1995, groundwater treatment methods were evaluated leading to the use of pump and treat facilities with ion exchange using Dowex 21 K, a regenerable strong base anion exchange resin. This required regeneration of the resin, which is currently performed offsite. Resin was installed in a 4 vessel train, with resin removal required from the lead vessel approximately once a month. In 2007, there were 8 trains (32 vessels) in operation. In 2008, DOE recognized that regulatory agreements would require significant expansion in the groundwater chromium treatment capacity. Previous experience from one of the DOE project managers led to identification of a possible alternative resin, and the contractor was requested to evaluate alternative resins for both cost and programmatic risk reductions. Testing was performed onsite in 2009 and 2010, using a variety of potential resins in two separate facilities with groundwater from specific remediation sites to demonstrate resin performance in the specific groundwater chemistry at each site. The testing demonstrated that a weak base anion single-use resin, ResinTech SIR-700, was effective at removing chromium, had a significantly higher capacity, could be disposed of efficiently on site, and would eliminate the complexities and programmatic risks from sampling, packaging, transportation and return of resin for regeneration. This resin was installed in Hanford's newest groundwater treatment facility, called 100-DX, which began operations in November, 2010, and used in a sister facility, 100-HX, which started up in September of 2011. This increased chromium treatment capacity to 25 trains (100 vessels). The resin is also being tested in existing facilities that utilize Dowex 21 K for

  1. Hexavalent Chromium: Analysis of the Mechanism of Groundwater Contamination in a Former Industrial Site in the Province of Vicenza (Northern Italy

    Directory of Open Access Journals (Sweden)

    Valentina Accoto

    2017-01-01

    Full Text Available The study consisted in the analysis of the mobilization mechanisms of hexavalent chromium (Cr(VI into groundwater from a decommissioned contaminated factory. The site is located in the Province of Vicenza and formerly was a chrome-plating plant. The subsoil consists predominantly of gravelly deposits with a thickness of at least one hundred meters. An unconfined aquifer is present with water table at about 23 m depth bgl. During the seven years of monitoring (2008-2014, the fluctuation of groundwater level was more than 6 m; hydraulic conductivity is about 1.0E-03 m/s and groundwater seepage velocity about 12 m/day. At the area of the source of contamination, the unsaturated soil is contaminated by hexavalent chromium throughout the thickness: concentrations range from 200 to 500 mg/kg. At the bottom of zone of groundwater level fluctuation, the hexavalent chromium concentration decreases to below the detection limit. The available data (e.g. hexavalent chromium concentrations in groundwater, groundwater level, local rainfall give the opportunity to assess the effects, on the magnitude of groundwater contamination, of the effective infiltration versus the fluctuation of groundwater level. The main analysis was performed on a statistical basis, in order to find out which of the two factors was most likely related to the periodic peaks of hexavalent chromium concentration in groundwater. Statistical analysis results were verified by a mass balance. Data show that at the site both the effective infiltration through the unsaturated zone and the leaching of soil contaminated by groundwater, when it exceeds a certain piezometric level, lead to peak concentrations of hexavalent chromium, even if with characteristics and effects different.

  2. Reduction of hexavalent chromium by fasted and fed human gastric fluid. II. Ex vivo gastric reduction modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kirman, Christopher R., E-mail: ckirman@summittoxicology.com [Summit Toxicology, Orange Village, OH, 44022 (United States); Suh, Mina, E-mail: msuh@toxstrategies.com [ToxStrategies, Inc., Mission Viejo, CA, 92692 (United States); Hays, Sean M., E-mail: shays@summittoxicology.com [Summit Toxicology, Allenspark, CO, 8040 (United States); Gürleyük, Hakan, E-mail: hakan@brooksrand.com [Brooks Applied Labs, Bothell, WA, 98011 (United States); Gerads, Russ, E-mail: russ@brooksrand.com [Brooks Applied Labs, Bothell, WA, 98011 (United States); De Flora, Silvio, E-mail: sdf@unige.it [Department of Health Sciences, University of Genoa, 16132 Genoa (Italy); Parker, William, E-mail: william.parker@duke.edu [Duke University Medical Center, Department of Surgery, Durham, NC, 27710 (United States); Lin, Shu, E-mail: shu.lin@duke.edu [Duke University Medical Center, Department of Surgery, Durham, NC, 27710 (United States); Haws, Laurie C., E-mail: lhaws@toxstrategies.com [ToxStrategies, Inc., Katy, TX, 77494 (United States); Harris, Mark A., E-mail: mharris@toxstrategies.com [ToxStrategies, Inc., Austin, TX, 78751 (United States); Proctor, Deborah M., E-mail: dproctor@toxstrategies.com [ToxStrategies, Inc., Mission Viejo, CA, 92692 (United States)

    2016-09-01

    To extend previous models of hexavalent chromium [Cr(VI)] reduction by gastric fluid (GF), ex vivo experiments were conducted to address data gaps and limitations identified with respect to (1) GF dilution in the model; (2) reduction of Cr(VI) in fed human GF samples; (3) the number of Cr(VI) reduction pools present in human GF under fed, fasted, and proton pump inhibitor (PPI)-use conditions; and (4) an appropriate form for the pH-dependence of Cr(VI) reduction rate constants. Rates and capacities of Cr(VI) reduction were characterized in gastric contents from fed and fasted volunteers, and from fasted pre-operative patients treated with PPIs. Reduction capacities were first estimated over a 4-h reduction period. Once reduction capacity was established, a dual-spike approach was used in speciated isotope dilution mass spectrometry analyses to characterize the concentration-dependence of the 2nd order reduction rate constants. These data, when combined with previously collected data, were well described by a three-pool model (pool 1 = fast reaction with low capacity; pool 2 = slow reaction with higher capacity; pool 3 = very slow reaction with higher capacity) using pH-dependent rate constants characterized by a piecewise, log-linear relationship. These data indicate that human gastric samples, like those collected from rats and mice, contain multiple pools of reducing agents, and low concentrations of Cr(VI) (< 0.7 mg/L) are reduced more rapidly than high concentrations. The data and revised modeling results herein provide improved characterization of Cr(VI) gastric reduction kinetics, critical for Cr(VI) pharmacokinetic modeling and human health risk assessment. - Highlights: • SIDMS allows for measurement of Cr(VI) reduction rate in gastric fluid ex vivo • Human gastric fluid has three reducing pools • Cr(VI) in drinking water at < 0.7 mg/L is rapidly reduced in human gastric fluid • Reduction rate is concentration- and pH-dependent • A refined PK

  3. Hexavalent and total chromium at low reporting concentrations in source-water aquifers and surface waters used for public supply in Illinois, 2013

    Science.gov (United States)

    Mills, Patrick C.; Cobb, Richard P.

    2015-01-01

    On the basis of their recent review of the human health effects of hexavalent chromium [Cr(VI)] in public drinking water, the U.S. Environmental Protection Agency is considering the need for Federal regulation of Cr(VI). Presently, only total chromium is regulated, at a Maximum Contaminant Level (MCL) of 100 micrograms per liter (µg/L). The occurrence of Cr(VI) in groundwater and surface waters generally is attributed to industrial sources, but can be of natural origin. California’s recently established MCL for Cr(VI) of 10 µg/L illustrates the drinking-water concerns associated with Cr(VI). To improve understanding of the possible impact of a Cr(VI)-specific standard that approximates the California level on the management of Illinois’ public drinking water, the U.S. Geological Survey, in cooperation with the Illinois Environmental Protection Agency, assessed the occurrence and distribution of Cr(VI) in the State’s public-water supplies.

  4. Groundwater remediation of hexavalent chromium along the Columbia River at the Hanford site in Washington state, USA - 59030

    International Nuclear Information System (INIS)

    Foss, Dyan L.; Charboneau, Briant L.

    2012-01-01

    The U.S. Department of Energy Hanford Site, formerly used for nuclear weapons production, encompasses 1500 square kilometers in southeast Washington State along the Columbia River. A principle threat to the river are the groundwater plumes of hexavalent chromium (Cr(VI)), which affect approximately 9.8 square kilometers, and 4.1 kilometers of shoreline. Cleanup goals are to stop Cr(VI) from entering the river by the end of 2012 and remediate the groundwater plumes to the drinking water standards by the end of 2020. Five groundwater pump-and-treat systems are currently in operation for the remediation of Cr(VI). Since the 1990's, over 13.6 billion L of groundwater have been treated; over 1, 435 kg of Cr(VI) have been removed. This paper describes the unique aspects of the site, its environmental setting, hydrogeology, groundwater-river interface, riverine hydraulic effects, remediation activities completed to date, a summary of the current and proposed pump-and-treat operations, the in situ redox manipulation barrier, and the effectiveness of passive barriers, resins, and treatability testing results of calcium polysulfide, bio-stimulation, and electrocoagulation, currently under evaluation. (authors)

  5. Modulation of histone methylation and MLH1 gene silencing by hexavalent chromium

    International Nuclear Information System (INIS)

    Sun Hong; Zhou Xue; Chen Haobin; Li Qin; Costa, Max

    2009-01-01

    Hexavalent chromium [Cr(VI)] is a mutagen and carcinogen, and occupational exposure can lead to lung cancers and other adverse health effects. Genetic changes resulting from DNA damage have been proposed as an important mechanism that mediates chromate's carcinogenicity. Here we show that chromate exposure of human lung A549 cells increased global levels of di- and tri-methylated histone H3 lysine 9 (H3K9) and lysine 4 (H3K4) but decreased the levels of tri-methylated histone H3 lysine 27 (H3K27) and di-methylated histone H3 arginine 2 (H3R2). Most interestingly, H3K9 dimethylation was enriched in the human MLH1 gene promoter following chromate exposure and this was correlated with decreased MLH1 mRNA expression. Chromate exposure increased the protein as well as mRNA levels of G9a a histone methyltransferase that specifically methylates H3K9. This Cr(VI)-induced increase in G9a may account for the global elevation of H3K9 dimethylation. Furthermore, supplementation with ascorbate, the primary reductant of Cr(VI) and also an essential cofactor for the histone demethylase activity, partially reversed the H3K9 dimethylation induced by chromate. Thus our studies suggest that Cr(VI) may target histone methyltransferases and demethylases, which in turn affect both global and gene promoter specific histone methylation, leading to the silencing of specific tumor suppressor genes such as MLH1.

  6. Isolation of Electrogenic Microorganisms with Potential to Reduce Hexavalent Chromium

    Directory of Open Access Journals (Sweden)

    Alexander Mora Collazos

    2017-01-01

    Full Text Available Isolation of cultivable microorganisms was made from the biofilm formed on the anode of a microbial fuel cell put into operation for 30 days; isolated microorganisms were evaluated for their ability to produce energy and reduce the hexavalent chromium Cr (VI. Five microorganisms were isolated, which were characterized by analysis of 16S rRNA gene, placing them in four bacterial genera: Exiguobacterium (CrMFC1, Acinetobacter (CrMFC2, Aeromonas (CrMFC3 and CrMFC5 and Serratia (CrMFC4. All isolates showed electrogenic activity and ability to reduce hexavalent chromium; the Acinetobacter CrMFC1 strain showed the best electrochemical performance registering a maximum power density of 18.61 mW/m2; the other strains showed values of maximum power density between 4.6 mW/m2and 7.1 mW/m2. Strains Aeromonas CrMFC5 and Exiguobacterium CrMFC1 showed the best rates of chromium reduction being able to reduce 100 % of the Cr (VI in less than 24 hours, the Aeromonas CrMFC5 strain was the most efficient, reducing 100 % of Cr (VI in 10 hours; the other strains reduced 100% of the contaminant after 28 to 30 hours. The microorganisms isolated in this study are hardly known for their electrogenic capacity and for reducing Cr (VI; however, show promise for their use in combined systems involving energy production system coupled to bioremediation of chromium contaminated water.

  7. Removal of hexavalent chromium from wastewater using a new composite chitosan biosorbent.

    Science.gov (United States)

    Boddu, Veera M; Abburi, Krishnaiah; Talbott, Jonathan L; Smith, Edgar D

    2003-10-01

    A new composite chitosan biosorbent was prepared by coating chitosan, a glucosamine biopolymer, onto ceramic alumina. The composite bioadsorbent was characterized by high-temperature pyrolysis, porosimetry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Batch isothermal equilibrium and continuous column adsorption experiments were conducted at 25 degrees C to evaluate the biosorbent for the removal of hexavalent chromium from synthetic as well as field samples obtained from chrome plating facilities. The effect of pH, sulfate, and chloride ion on adsorption was also investigated. The biosorbent loaded with Cr(VI) was regenerated using 0.1 M sodium hydroxide solution. A comparison of the results of the present investigation with those reported in the literature showed that chitosan coated on alumina exhibits greater adsorption capacity for chromium(VI). Further, experimental equilibrium data were fitted to Langmuir and Freundlich adsorption isotherms, and values of the parameters of the isotherms are reported. The ultimate capacity obtained from the Langmuir model is 153.85 mg/g chitosan.

  8. Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells

    International Nuclear Information System (INIS)

    Hayashi, Yoko; Kondo, Takashi; Zhao Qingli; Ogawa Ryohei; Cui Zhengguo; Feril, Loreto B.; Teranishi, Hidetoyo; Kasuya, Minoru

    2004-01-01

    It has been reported that the hexavalent chromium compound (Cr(VI)) can induce both p53-dependent and p53-independent apoptosis. While a considerable amount of information is available on the p53-dependent pathway, only little is known about the p53-independent pathway. To elucidate the p53-independent mechanism, the roles of the Ca 2+ -calpain- and mitochondria-caspase-dependent pathways in apoptosis induced by Cr(VI) were investigated. When human lymphoma U937 cells, p53 mutated cells, were treated with 20 μM Cr(VI) for 24 h, nuclear morphological changes and DNA fragmentation were observed. Production of hydroxyl radicals revealed by electron paramagnetic resonance (EPR)-spin trapping, and increase of intracellular calcium ion concentration monitored by digital imaging were also observed in Cr(VI)-treated cells. An intracellular Ca 2+ chelator, BAPTA-AM, and calpain inhibitors suppressed the Cr(VI)-induced DNA fragmentation. The number of cells showing low mitochondrial membrane potential (MMP), high level of superoxide anion radicals (O 2 - ), and high activity of caspase-3, which are indicators of mitochondria-caspase-dependent pathway, increased significantly in Cr(VI)-treated cells. An antioxidant, N-acetyl-L-cysteine (NAC), decreased DNA fragmentation and inhibited the changes in MMP, O 2 - formation, and activation of caspase-3 induced by Cr(VI). No increase of the expressions of Fas and phosphorylated JNK was observed after Cr(VI) treatment. Cell cycle analysis revealed that the fraction of G2/M phase tended to increase after 24 h of treatment, suggesting that Cr(VI)-induced apoptosis is related to the G2 block. These results indicate that Ca 2+ -calpain- and mitochondria-caspase-dependent pathways play significant roles in the Cr(VI)-induced apoptosis via the G2 block, which are independent of JNK and Fas activation. The inhibition of apoptosis and all its signal transductions by NAC suggests that intracellular reactive oxygen species (ROS) are

  9. Evaluating the Impact of the U.S. National Toxicology Program: A Case Study on Hexavalent Chromium.

    Science.gov (United States)

    Xie, Yun; Holmgren, Stephanie; Andrews, Danica M K; Wolfe, Mary S

    2017-02-01

    Evaluating the impact of federally funded research with a broad, methodical, and objective approach is important to ensure that public funds advance the mission of federal agencies. We aimed to develop a methodical approach that would yield a broad assessment of National Toxicology Program's (NTP's) effectiveness across multiple sectors and demonstrate the utility of the approach through a case study. A conceptual model was developed with defined activities, outputs (products), and outcomes (proximal, intermediate, distal) and applied retrospectively to NTP's research on hexavalent chromium (CrVI). Proximal outcomes were measured by counting views of and requests for NTP's products by external stakeholders. Intermediate outcomes were measured by bibliometric analysis. Distal outcomes were assessed through Web and LexisNexis searches for documents related to legislation or regulation changes. The approach identified awareness of NTP's work on CrVI by external stakeholders (proximal outcome) and citations of NTP's research in scientific publications, reports, congressional testimonies, and legal and policy documents (intermediate outcome). NTP's research was key to the nation's first-ever drinking water standard for CrVI adopted by California in 2014 (distal outcome). By applying this approach to a case study, the utility and limitations of the approach were identified, including challenges to evaluating the outcomes of a research program. This study identified a broad and objective approach for assessing NTP's effectiveness, including methodological needs for more thorough and efficient impact assessments in the future. Citation: Xie Y, Holmgren S, Andrews DMK, Wolfe MS. 2017. Evaluating the impact of the U.S. National Toxicology Program: a case study on hexavalent chromium. Environ Health Perspect 125:181-188; http://dx.doi.org/10.1289/EHP21.

  10. Oxidation of Cr(III)-Fe(III) Mixed-phase Hydroxides by Chlorine: Implications on the Control of Hexavalent Chromium in Drinking Water.

    Science.gov (United States)

    Chebeir, Michelle; Liu, Haizhou

    2018-05-17

    The occurrence of chromium (Cr) as an inorganic contaminant in drinking water is widely reported. One source of Cr is its accumulation in iron-containing corrosion scales of drinking water distribution systems as Cr(III)-Fe(III) hydroxide, i.e., FexCr(1-x)(OH)3(s), where x represents the Fe(III) molar content and typically varies between 0.25 and 0.75. This study investigated the kinetics of inadvertent hexavalent chromium Cr(VI) formation via the oxidation of FexCr(1-x)(OH)3(s) by chlorine as a residual disinfectant in drinking water, and examined the impacts of Fe(III) content and drinking water chemical parameters including pH, bromide and bicarbonate on the rate of Cr(VI) formation. Data showed that an increase in Fe(III) molar content resulted in a significant decrease in the stoichiometric Cr(VI) yield and the rate of Cr(VI) formation, mainly due to chlorine decay induced by Fe(III) surface sites. An increase in bicarbonate enhanced the rate of Cr(VI) formation, likely due to the formation of Fe(III)-carbonato surface complexes that slowed down the scavenging reaction with chlorine. The presence of bromide significantly accelerated the oxidation of FexCr(1-x)(OH)3(s) by chlorine, resulting from the catalytic effect of bromide acting as an electron shuttle. A higher solution pH between 6 and 8.5 slowed down the oxidation of Cr(III) by chlorine. These findings suggested that the oxidative conversion of chromium-containing iron corrosion products in drinking water distribution systems can lead to the occurrence of Cr(VI) at the tap, and the abundance of iron, and a careful control of pH, bicarbonate and bromide levels can assist the control of Cr(VI) formation.

  11. Selected science: an industry campaign to undermine an OSHA hexavalent chromium standard

    Directory of Open Access Journals (Sweden)

    Lurie Peter

    2006-02-01

    Full Text Available Abstract While exposure to hexavalent chromium (Cr(VI has been associated with increased lung cancer risk for more than 50 years, the chemical is not currently regulated by the U.S. Occupational Safety and Health Administration (OSHA on the basis of its carcinogenicity. The agency was petitioned in 1993 and sued in 1997 and 2002 to lower the workplace Cr(VI exposure limit, resulting in a court order to issue a final standard by February 2006. Faced with the threat of stronger regulation, the chromium industry initiated an effort to challenge the scientific evidence supporting a more protective standard. This effort included the use of "product defense" consultants to conduct post hoc analyses of a publicly-funded study to challenge results viewed unfavorably by the industry. The industry also commissioned a study of the mortality experience of workers at four low-exposure chromium plants, but did not make the results available to OSHA in a timely manner, despite multiple agency requests for precisely these sorts of data. The commissioned study found a statistically significant elevation in lung cancer risk among Cr(VI-exposed workers at levels far below the current standard. This finding changed when the multi-plant cohort was divided into two statistically underpowered components and then published separately. The findings of the first paper published have been used by the chromium industry to attempt to slow OSHA's standard setting process. The second paper was withheld from OSHA until it was accepted for publication in a scientific journal, after the rulemaking record had closed. Studies funded by private sponsors that seek to influence public regulatory proceedings should be subject to the same access and reporting provisions as those applied to publicly funded science. Parties in regulatory proceedings should be required to disclose whether the studies were performed by researchers who had the right to present their findings without the

  12. Laboratory and field evaluations of a methodology for determining hexavalent-chromium emissions from stationary sources. Final report

    International Nuclear Information System (INIS)

    Carver, A.C.

    1991-10-01

    The study was initiated to determine whether chromium emissions should be regulated under Section 112 of the Clean Air Act National Emissions Standards for Hazardous Air Pollutants (NESHAP). To support stationary source regulations, it is important that (1) the sampling procedure not change the chromium valence state during sampling and (2) an analytical technique for measuring low concentration levels of chromium be available. These goals are achieved with the current EPA 'Draft Method for Sampling and Analysis of Hexavalent Chromium at Stationary Sources.' The draft method utilizes a recirculating system to flush impinger reagent into the sampling nozzle during sample collection. Immediate contact of the stack gas with impinger reagent 'fixes' the chromium valence state. Ion chromatography coupled with post column derivatization and ultraviolet visible detector is used to analyze Cr(VI) in the parts per trillion range. Field tests were conducted at metal plating facilities, industrial cooling towers, municipal waste incinerators, sewage sludge incinerators, and hazardous waste incinerators. It was at the hazardous waste facility that the new method was proven to have acceptable precision and essentially no conversion in the sample train

  13. Electrochemical reduction of hexavalent chromium in ground water

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, S. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    Electrochemical reduction of hexavalent chromium (Cr{sup +6}) to its trivalent state (Cr{sup +3}) is showing promising results in treating ground water at Lawrence Livermore National Laboratory`s (LLNL`s) Main Site. An electrolytic cell using stainless-steel and brass electrodes has been found to offer the most efficient reduction while yielding the least amount of precipitate. Trials have successfully lowered concentrations of Cr{sup +6} to below 11 parts per billion (micrograms/liter), the California state standard. We ran several trials to determine optimal voltage for running the cell; each trial consisted of applying a voltage between 6V and 48V for ten minutes through samples obtained at Treatment Facility C(TFC). No conclusive data has been obtained yet.

  14. Homologous Recombination Repair Signaling in Chemical Carcinogenesis: Prolonged Particulate Hexavalent Chromium Exposure Suppresses the Rad51 Response in Human Lung Cells

    Science.gov (United States)

    Qin, Qin; Xie, Hong; Wise, Sandra S.; Browning, Cynthia L.; Thompson, Kelsey N.; Holmes, Amie L.; Wise, John Pierce

    2014-01-01

    The aim of this study was to focus on hexavalent chromium, [Cr(VI)], a chemical carcinogen and major public health concern, and consider its ability to impact DNA double strand break repair. We further focused on particulate Cr(VI), because it is the more potent carcinogenic form of Cr(VI). DNA double strand break repair serves to protect cells against the detrimental effects of DNA double strand breaks. For particulate Cr(VI), data show DNA double strand break repair must be overcome for neoplastic transformation to occur. Acute Cr(VI) exposures reveal a robust DNA double strand break repair response, however, longer exposures have not been considered. Using the comet assay, we found longer exposures to particulate zinc chromate induced concentration-dependent increases in DNA double strand breaks indicating breaks were occurring throughout the exposure time. Acute (24 h) exposure induced DNA double strand break repair signaling by inducing Mre11 foci formation, ATM phosphorylation and phosphorylated ATM foci formation, Rad51 protein levels and Rad51 foci formation. However, longer exposures reduced the Rad51 response. These data indicate a major chemical carcinogen can simultaneously induce DNA double strand breaks and alter their repair and describe a new and important aspect of the carcinogenic mechanism for Cr(VI). PMID:25173789

  15. Hexavalent chromium, a lung carcinogen, confers resistance to thermal stress and interferes with heat shock protein expression in human bronchial epithelial cells.

    Science.gov (United States)

    Abreu, Patrícia L; Cunha-Oliveira, Teresa; Ferreira, Leonardo M R; Urbano, Ana M

    2018-03-16

    Exposure to hexavalent chromium [Cr(VI)], a lung carcinogen, triggers several types of cellular stresses, namely oxidative, genotoxic and proteotoxic stresses. Given the evolutionary character of carcinogenesis, it is tempting to speculate that cells that survive the stresses produced by this carcinogen become more resistant to subsequent stresses, namely those encountered during neoplastic transformation. To test this hypothesis, we determined whether pre-incubation with Cr(VI) increased the resistance of human bronchial epithelial cells (BEAS-2B cells) to the antiproliferative action of acute thermal shock, used here as a model for stress. In line with the proposed hypothesis, it was observed that, at mildly cytotoxic concentrations, Cr(VI) attenuated the antiproliferative effects of both cold and heat shock. Mechanistically, Cr(VI) interfered with the expression of two components of the stress response pathway: heat shock proteins Hsp72 and Hsp90α. Specifically, Cr(VI) significantly depleted the mRNA levels of the former and the protein levels of the latter. Significantly, these two proteins are members of heat shock protein (Hsp) families (Hsp70 and Hsp90, respectively) that have been implicated in carcinogenesis. Thus, our results confirm and extend previous studies showing the capacity of Cr(VI) to interfere with the expression of stress response components.

  16. Fleet Readiness Center - Southeast Technology Development Program (Cadmium & Hexavalent Chromium Reduction)

    Science.gov (United States)

    2014-11-01

    Fleet Readiness Center - Southeast TECHNOLOGY DEVELOPMENT PROGRAM (Cadmium & Hexavalent Chromium Reduction) Jack Benfer Senior Materials...Development Program (Cadmium & Hexavalent Chromium Reduction) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...Rinse Black Oxide Rinse CRES Passivation Chrome Plating Cadmium Plating Cadmium Brush Plating Class N (TRL 9) Class N (TRL 7) Class N (TRL 6

  17. Hexavalent chromium-induced apoptosis of granulosa cells involves selective sub-cellular translocation of Bcl-2 members, ERK1/2 and p53

    International Nuclear Information System (INIS)

    Banu, Sakhila K.; Stanley, Jone A.; Lee, JeHoon; Stephen, Sam D.; Arosh, Joe A.; Hoyer, Patricia B.; Burghardt, Robert C.

    2011-01-01

    Hexavalent chromium (CrVI) has been widely used in industries throughout the world. Increased usage of CrVI and atmospheric emission of CrVI from catalytic converters of automobiles, and its improper disposal causes various health hazards including female infertility. Recently we have reported that lactational exposure to CrVI induced a delay/arrest in follicular development at the secondary follicular stage. In order to investigate the underlying mechanism, primary cultures of rat granulosa cells were treated with 10 μM potassium dichromate (CrVI) for 12 and 24 h, with or without vitamin C pre-treatment for 24 h. The effects of CrVI on intrinsic apoptotic pathway(s) were investigated. Our data indicated that CrVI: (i) induced DNA fragmentation and increased apoptosis, (ii) increased cytochrome c release from the mitochondria to cytosol, (iii) downregulated anti-apoptotic Bcl-2, Bcl-XL, HSP70 and HSP90; upregulated pro-apoptotic BAX and BAD, (iv) altered translocation of Bcl-2, Bcl-XL, BAX, BAD, HSP70 and HSP90 to the mitochondria, (v) upregulated p-ERK and p-JNK, and selectively translocated p-ERK to the mitochondria and nucleus, (vi) activated caspase-3 and PARP, and (vii) increased phosphorylation of p53 at ser-6, ser-9, ser-15, ser-20, ser-37, ser-46 and ser-392, increased p53 transcriptional activation, and downregulated MDM-2. Vitamin C pre-treatment mitigated CrVI effects on apoptosis and related pathways. Our study, for the first time provides a clear insight into the effect of CrVI on multiple pathways that lead to apoptosis of granulosa cells which could be mitigated by vitamin C.

  18. Determination of hexavalent chromium concentration in industrial waste incinerator stack gas by using a modified ion chromatography with post-column derivatization method.

    Science.gov (United States)

    Miyake, Yuichi; Tokumura, Masahiro; Iwazaki, Yuta; Wang, Qi; Amagai, Takashi; Horii, Yuichi; Otsuka, Hideyuki; Tanikawa, Noboru; Kobayashi, Takeshi; Oguchi, Masahiro

    2017-06-16

    An ion chromatography with post-column derivatization with 1,5-diphenylcarbazide (IC-DPC) analytical method was modified to enable measurement of trace-level hexavalent chromium (Cr(VI)) in air. One of the difficulties in determining trace levels of Cr(VI) in air with conventional IC-DPC methods is co-elution of the solvent and ion peaks due to high concentrations of ionic compounds in the extract. However, by using gradient elution rather than isocratic elution we were able to fully resolve the Cr(VI) ion peak from the solvent peak without the need for diluting the extract, which would have reduced the minimum quantifiable level of the method. With this method, we were able to detect Cr(VI) in air at concentrations of 5.3ng/m 3 (assuming a sampling volume of 1m 3 and a final solution volume of 10mL). Recovery tests at three different concentrations of Cr(VI) (50, 250, 1000ng) were performed with or without fly ash; recovery rates at all the concentrations of Cr(VI), with or without fly ash, ranged from 68% to 110% (mean±relative standard deviation, 96%±11%), and there were no differences in recovery rates with respect to the presence or absence of fly ash. Finally, we used the developed method to determine the concentration of Cr(VI) in stack gases collected from eight industrial waste incinerators located in Japan. The concentration of Cr(VI) in the stack gases ranged from below the method quantification limit to 3100ng/m 3 . The highest concentrations of Cr(VI) detected in the stack gases were two to three orders of magnitude higher than that in ambient air in Japan. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. The intracellular redox stress caused by hexavalent chromium is selective for proteins that have key roles in cell survival and thiol redox control

    International Nuclear Information System (INIS)

    Myers, Judith M.; Antholine, William E.; Myers, Charles R.

    2011-01-01

    Hexavalent chromium [Cr(VI)] compounds (e.g. chromates) are strong oxidants that readily enter cells where they are reduced to reactive Cr intermediates that can directly oxidize some cell components and can promote the generation of reactive oxygen and nitrogen species. Inhalation is a major route of exposure which directly exposes the bronchial epithelium. Previous studies with non-cancerous human bronchial epithelial cells (BEAS-2B) demonstrated that Cr(VI) treatment results in the irreversible inhibition of thioredoxin reductase (TrxR) and the oxidation of thioredoxins (Trx) and peroxiredoxins (Prx). The mitochondrial Trx/Prx system is somewhat more sensitive to Cr(VI) than the cytosolic Trx/Prx system, and other redox-sensitive mitochondrial functions are subsequently affected including electron transport complexes I and II. Studies reported here show that Cr(VI) does not cause indiscriminant thiol oxidation, and that the Trx/Prx system is among the most sensitive of cellular protein thiols. Trx/Prx oxidation is not unique to BEAS-2B cells, as it was also observed in primary human bronchial epithelial cells. Increasing the intracellular levels of ascorbate, an endogenous Cr(VI) reductant, did not alter the effects on TrxR, Trx, or Prx. The peroxynitrite scavenger MnTBAP did not protect TrxR, Trx, Prx, or the electron transport chain from the effects of Cr(VI), implying that peroxynitrite is not required for these effects. Nitration of tyrosine residues of TrxR was not observed following Cr(VI) treatment, further ruling out peroxynitrite as a significant contributor to the irreversible inhibition of TrxR. Cr(VI) treatments that disrupt the TrxR/Trx/Prx system did not cause detectable mitochondrial DNA damage. Overall, the redox stress that results from Cr(VI) exposure shows selectivity for key proteins which are known to be important for redox signaling, antioxidant defense, and cell survival.

  20. Hexavalent Chromium Removal from Model Water and Car Shock Absorber Factory Effluent by Nanofiltration and Reverse Osmosis Membrane

    Directory of Open Access Journals (Sweden)

    Amine Mnif

    2017-01-01

    Full Text Available Nanofiltration and reverse osmosis are investigated as a possible alternative to the conventional methods of Cr(VI removal from model water and industrial effluent. The influences of feed concentration, water recovery, pH, and the coexisting anions were studied. The results have shown that retention rates of hexavalent chromium can reach 99.7% using nanofiltration membrane (NF-HL and vary from 85 to 99.9% using reverse osmosis membrane (RO-SG depending upon the composition of the solution and operating conditions. This work was also extended to investigate the separation of Cr(VI from car shock absorber factory effluent. The use of these membranes is very promising for Cr(VI water treatment and desalting industry effluent. Spiegler-Kedem model was applied to experimental results in the aim to determine phenomenological parameters, the reflection coefficient of the membrane (σ, and the solute permeability coefficient (Ps. The convective and diffusive parts of the mass transfer were quantified with predominance of the diffusive contribution.

  1. Effect of NaX zeolite-modified graphite felts on hexavalent chromium removal in biocathode microbial fuel cells.

    Science.gov (United States)

    Wu, Xiayuan; Tong, Fei; Yong, Xiaoyu; Zhou, Jun; Zhang, Lixiong; Jia, Honghua; Wei, Ping

    2016-05-05

    Two kinds of NaX zeolite-modified graphite felts were used as biocathode electrodes in hexavalent chromium (Cr(VI))-reducing microbial fuel cells (MFCs). The one was fabricated through direct modification, and the other one processed by HNO3 pretreatment of graphite felt before modification. The results showed that two NaX zeolite-modified graphite felts are excellent bio-electrode materials for MFCs, and that a large NaX loading mass, obtained by HNO3 pretreatment (the HNO3-NaX electrode), leads to a superior performance. The HNO3-NaX electrode significantly improved the electricity generation and Cr(VI) removal of the MFC. The maximum Cr(VI) removal rate increased to 10.39±0.28 mg/L h, which was 8.2 times higher than that of the unmodified control. The improvement was ascribed to the strong affinity that NaX zeolite particles, present in large number on the graphite felt, have for microorganisms and Cr(VI) ions. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Strategies to reduce mass and photons transfer limitations in heterogeneous photocatalytic processes: Hexavalent chromium reduction studies.

    Science.gov (United States)

    Marinho, Belisa A; Cristóvão, Raquel O; Djellabi, Ridha; Caseiro, Ana; Miranda, Sandra M; Loureiro, José M; Boaventura, Rui A R; Dias, Madalena M; Lopes, José Carlos B; Vilar, Vítor J P

    2018-07-01

    The current work presents different approaches to overcome mass and photon transfer limitations in heterogeneous photocatalytic processes applied to the reduction of hexavalent chromium to its trivalent form in the presence of a sacrificial agent. Two reactor designs were tested, a monolithic tubular photoreactor (MTP) and a micro-meso-structured photoreactor (NETmix), both presenting a high catalyst surface area per reaction liquid volume. In order to reduce photon transfer limitations, the tubular photoreactor was packed with transparent cellulose acetate monolithic structures (CAM) coated with the catalyst by a dip-coating method. For the NETmix reactor, a thin film of photocatalyst was uniformly deposited on the front glass slab (GS) or on the network of channels and chambers imprinted in the back stainless steel slab (SSS) using a spray system. The reaction rate for the NETmix photoreactor was evaluated for two illumination sources, solar light or UVA-LEDs, using the NETmix with the front glass slab or/and back stainless steel slab coated with TiO 2 -P25. The reusability of the photocatalytic films on the NETmix walls was also evaluated for three consecutive cycles using fresh Cr(VI) solutions. The catalyst reactivity in combination with the NETmix-SSS photoreactor is almost 70 times superior to one obtained with the MTP. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Treatment of hexavalent chromium Cr (VI) in tanning effluent

    International Nuclear Information System (INIS)

    Ahmed, I.; Ali, S.

    1999-01-01

    Most common chemical used in chrome tanning is basic chromium sulphate (BCS). Manufacturing of BCS involves many steps producing liquid waste. Waste generated at every stage contains Cr (VI), which must be reduced to Cr (III) before being disposed to the environment. Different methods were studied for the reduction of toxic Cr (III). Pickle liquor (waste of electroplating industry) can also be used for the reduction of hexavalent chromium Cr (vi) along with other reducing materials / chemicals. In an electroplating process metal is treated with HCl or H/sub 2/SO/sub 4/ to remove scales and rust, the pickled items are then washed with water, washing contains FeCl/sub 2/ or fees/sub 4/ respectively called pickle liquor. During waste treatment pH adjustment to 6.0 - 9.0 and settling the sludge, is discharged to the lagoon. The sludge obtained is dried and disposed off in landfills. Other reducing agents like sodium bisulphite and sulfur dioxide were also studied, but pickle liquor was found to be more effective and economical. (author)

  4. Assessment of the mutagenic potential of hexavalent chromium in the duodenum of big blue® rats.

    Science.gov (United States)

    Thompson, Chad M; Young, Robert R; Dinesdurage, Harshini; Suh, Mina; Harris, Mark A; Rohr, Annette C; Proctor, Deborah M

    2017-09-01

    A cancer bioassay on hexavalent chromium Cr(VI) in drinking water reported increased incidences of duodenal tumors in B6C3F1 mice at exposures of 30-180ppm, and oral cavity tumors in F344 rats at 180ppm. A subsequent transgenic rodent (TGR) in vivo mutation assay in Big Blue® TgF344 rats found that exposure to 180ppm Cr(VI) in drinking water for 28days did not increase cII transgene mutant frequency (MF) in the oral cavity (Thompson et al., 2015). Herein, we extend our analysis to the duodenum of these same TgF344 rats. At study termination, duodenum chromium levels were below either the limit of detection or quantification in control rats, but were 24.6±3.8μg/g in Cr(VI)-treated rats. The MF in control (23.2×10 -6 ) and Cr(VI)-treated rats (22.7×10 -6 ) were nearly identical. In contrast, the MF in the duodenum of rats exposed to 1-ethyl-1-nitrosourea for six days (study days 1, 2, 3, 12, 19, 26) increased 24-fold to 557×10 -6 . These findings indicate that mutagenicity is unlikely an early initiating event in Cr(VI)-induced intestinal carcinogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Removal of Hexavalent Chromium from Aqueous Solution by Modified Holly Sawdust: A Study of Equilibrium and Kinetics

    Directory of Open Access Journals (Sweden)

    S. Azizian

    2010-01-01

    Full Text Available Introduction & Objective: Industrial wastewaters including heavy metals, are among the important sources of environmental pollution. Heavy metals such as chromium are found in plating wastewater and is harmful for human health and environment. The purpose of the present study was to investigate the absorption of heavy metals such as chromium onto modified holly sawdust as an cheaper absorbent. Materials & Methods: This study was a fundamental- application study done in Hamadan University of Medical Sciences, hygiene faculty water and wastewater chemistry laboratory. This study investigated the removal of hexavalent chromium by using modified holly sawdust with pH changes ,contact time ,absorbent dose and Cr(VI concentrations in batch system. Then the result was analyzed by Excel software.Results: The results showed that the removal efficiency decrease is accompanied by the increase of pH and initial chromium concentration. pH increase from 2 to 12(equilibrium time= 180 min, adsorbent dose= 0.6g/100CC, Cr(VI concentrations= 60 mg/L,leaded to the removal efficiency decrease from 99.67 % to 29.78 %. Also removal efficiency decreased from 99.37 % to 40.24 % after increasing the initial chromium concentrations from 20 mg/L to 100 mg/L. Moreover the results showed the removal efficiency increased after increasing the adsorbent dose and contact time. By increasing adsorbent dose from 0.2 g/100CC to 1 g/100CC, the removal efficiency increased from 34.65 % to 99.76 %.Additionally, the removal efficiency increased from 48.53%to 99.76% by increasing contact time from 5 mins to 180 mins. Experimental isotherms and kinetics models were assessed by Langmuir and Freundlich isotherms and pseudo-first-order and pseudo-second-order kinetics models. The results showed that the data were acceptably explained acceptably by Langmuir isotherms and pseudo-second-order kinetics models respectively.Conclusion: The results showed that the removal of hexavalent chromium

  6. Escherichia coli NemA is an efficient chromate reductase that can be biologically immobilized to provide a cell free system for remediation of hexavalent chromium.

    Directory of Open Access Journals (Sweden)

    Katherine J Robins

    Full Text Available Hexavalent chromium is a serious and widespread environmental pollutant. Although many bacteria have been identified that can transform highly water-soluble and toxic Cr(VI to insoluble and relatively non-toxic Cr(III, bacterial bioremediation of Cr(VI pollution is limited by a number of issues, in particular chromium toxicity to the remediating cells. To address this we sought to develop an immobilized enzymatic system for Cr(VI remediation. To identify novel Cr(VI reductase enzymes we first screened cell extracts from an Escherichia coli library of soluble oxidoreductases derived from a range of bacteria, but found that a number of these enzymes can reduce Cr(VI indirectly, via redox intermediates present in the crude extracts. Instead, activity assays for 15 candidate enzymes purified as His6-tagged proteins identified E. coli NemA as a highly efficient Cr(VI reductase (k(cat/K(M= 1.1×10(5 M(-1 s(-1 with NADH as cofactor. Fusion of nemA to the polyhydroxyalkanoate synthase gene phaC from Ralstonia eutropha enabled high-level biosynthesis of functionalized polyhydroxyalkanoate granules displaying stable and active NemA on their surface. When these granules were combined with either Bacillus subtilis glucose dehydrogenase or Candida boidinii formate dehydrogenase as a cofactor regenerating partner, high levels of chromate transformation were observed with only low initial concentrations of expensive NADH cofactor being required, the overall reaction being powered by consumption of the cheap sacrificial substrates glucose or formic acid, respectively. This system therefore offers promise as an economic solution for ex situ Cr(VI remediation.

  7. Aberration of mitosis by hexavalent chromium in some Fabaceae members is mediated by species-specific microtubule disruption.

    Science.gov (United States)

    Eleftheriou, Eleftherios P; Michalopoulou, Vasiliki A; Adamakis, Ioannis-Dimosthenis S

    2015-05-01

    Because the detrimental effects of chromium (Cr) to higher plants have been poorly investigated, the present study was undertaken to verify the toxic attributes of hexavalent chromium [Cr(VI)] to plant mitotic microtubules (MTs), to determine any differential disruption of MTs during mitosis of taxonomically related species and to clarify the relationship between the visualized chromosomal aberrations and the Cr(VI)-induced MT disturbance. For this purpose, 5-day-old uniform seedlings of Vicia faba, Pisum sativum, Vigna sinensis and Vigna angularis, all belonging to the Fabaceae family, were exposed to 250 μM Cr(VI) supplied as potassium dichromate (K₂Cr₂O₇) for 24, 72 and 120 h and others in distilled water serving as controls. Root tip samples were processed for tubulin immunolabelling (for MT visualization) and DNA fluorescent staining (for chromosomal visualization). Microscopic preparations of cell squashes were then examined and photographed by confocal laser scanning microscopy (CLSM). Cr(VI) halted seedling growth turning roots brown and necrotic. Severe chromosomal abnormalities and differential disturbance of the corresponding MT arrays were found in all mitotic phases. In particular, in V. faba MTs were primarily depolymerized and replaced by atypical tubulin conformations, whereas in P. sativum, V. sinensis and V. angularis they became bundled in a time-dependent manner. In P. sativum, the effects were milder compared to those of the other species, but in all cases MT disturbance adversely affected the proper aggregation of chromosomes on the metaphase plate, their segregation at anaphase and organization of the new nuclei at telophase. Cr(VI) is very toxic to seedling growth. The particular effect depends on the exact stage the cell is found at the time of Cr(VI) entrance and is species-specific. Mitotic MT arrays are differentially deranged by Cr(VI) in the different species examined, even if they are taxonomically related, while their

  8. Transient gestational exposure to drinking water containing excess hexavalent chromium modifies insulin signaling in liver and skeletal muscle of rat progeny.

    Science.gov (United States)

    Shobana, Navaneethabalakrishnan; Aruldhas, Mariajoseph Michael; Tochhawng, Lalmuankimi; Loganathan, Ayyalu; Balaji, Sadhasivam; Kumar, Mani Kathiresh; Banu, Liaquat Alikhan Sheerin; Navin, Ajit Kumar; Mayilvanan, Chinnaiyan; Ilangovan, Ramachandran; Balasubramanian, Karundevi

    2017-11-01

    Chromium (Cr), an essential micronutrient potentiates insulin action, whereas excess hexavalent Cr (CrVI) acts as an endocrine disruptor. Pregnant mothers living in areas abutting industries using the metal and chromite ore dumps are exposed to ground water contaminated with Cr. Nevertheless, the impact of prenatal exposure to excess CrVI on insulin signaling in the progeny remains obscure. We tested the hypothesis "transient gestational exposure to drinking water containing excess CrVI may modify insulin signaling during postnatal life". Pregnant Wistar rats were given drinking water containing 50, 100 and 200 ppm CrVI (K 2 Cr 2 O 7 ) from gestational day 9-14 encompassing the period of organogenesis; the male progenies were tested at postnatal day 60. Neither fasting blood glucose nor oral glucose tolerance was altered in CrVI treated progeny. Nevertheless, western blot detection pointed out attenuated expression level of insulin receptor (IR), its downstream signaling molecules (IRS-1, pIRS-1 Tyr632 , Akt and pAkt Ser473 ) and organ specific glucose transporters (GLUT2 in liver and GLUT4 in gastrocnemius muscle), along with a significant increase in serum insulin level in male progenies exposed to CrVI. While 14 C-2-deoxy glucose uptake increased in the liver, the same decreased in the skeletal muscle whereas, 14 C-glucose oxidation recorded a consistent decrease in both tissues of CrVI exposed rats. These findings support our hypothesis and suggest that transient gestational exposure to excess CrVI may affect insulin signaling and glucose oxidation in the progeny, predictably rendering them vulnerable to insulin resistance. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

    Energy Technology Data Exchange (ETDEWEB)

    Zazoua, A. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Zougar, S. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Kherrat, R. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Samar, M.H. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Jaffrezic-Renault, N. [CEGELY-UMR 5005 CNRS, Ecole centrale de Lyon, 69134 Ecully cedex (France)]. E-mail: Nicole.Jaffrezic@ec-lyon.fr; Errachid, A. [Center of Reference for Bioengineering in Catalonia (CREBEC), Laboratory of Nanobioengineering, Parc Cientific de Barcelona, Universidad de Barcelona C/ Josep Samitier 1-5, 08028 Barcelona (Spain); Abbaci, A. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria)

    2006-03-15

    This paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/loga {sub Cr{sup 6+}} in the range of 10{sup -4} to 10{sup -2} M. The detection limit was found to be 10{sup -5} M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium.

  10. Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

    International Nuclear Information System (INIS)

    Zazoua, A.; Zougar, S.; Kherrat, R.; Samar, M.H.; Jaffrezic-Renault, N.; Errachid, A.; Abbaci, A.

    2006-01-01

    This paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/loga Cr 6+ in the range of 10 -4 to 10 -2 M. The detection limit was found to be 10 -5 M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium

  11. Assessment of the mode of action underlying development of rodent small intestinal tumors following oral exposure to hexavalent chromium and relevance to humans

    Science.gov (United States)

    Proctor, Deborah M.; Suh, Mina; Haws, Laurie C.; Kirman, Christopher R.; Harris, Mark A.

    2013-01-01

    Chronic exposure to high concentrations of hexavalent chromium (Cr(VI)) in drinking water causes intestinal adenomas and carcinomas in mice, but not in rats. Cr(VI) causes damage to intestinal villi and crypt hyperplasia in mice after only one week of exposure. After two years of exposure, intestinal damage and crypt hyperplasia are evident in mice (but not rats), as are intestinal tumors. Although Cr(VI) has genotoxic properties, these findings suggest that intestinal tumors in mice arise as a result of chronic mucosal injury. To better understand the mode of action (MOA) of Cr(VI) in the intestine, a 90-day drinking water study was conducted to collect histological, biochemical, toxicogenomic and pharmacokinetic data in intestinal tissues. Using MOA analyses and human relevance frameworks proposed by national and international regulatory agencies, the weight of evidence supports a cytotoxic MOA with the following key events: (a) absorption of Cr(VI) from the intestinal lumen, (b) toxicity to intestinal villi, (c) crypt regenerative hyperplasia and (d) clonal expansion of mutations within the crypt stem cells, resulting in late onset tumorigenesis. This article summarizes the data supporting each key event in the MOA, as well as data that argue against a mutagenic MOA for Cr(VI)-induced intestinal tumors. PMID:23445218

  12. Large scale groundwater flow and hexavalent chromium transport modeling under current and future climatic conditions: the case of Asopos River Basin.

    Science.gov (United States)

    Dokou, Zoi; Karagiorgi, Vasiliki; Karatzas, George P; Nikolaidis, Nikolaos P; Kalogerakis, Nicolas

    2016-03-01

    In recent years, high concentrations of hexavalent chromium, Cr(VI), have been observed in the groundwater system of the Asopos River Basin, raising public concern regarding the quality of drinking and irrigation water. The work described herein focuses on the development of a groundwater flow and Cr(VI) transport model using hydrologic, geologic, and water quality data collected from various sources. An important dataset for this goal comprised an extensive time series of Cr(VI) concentrations at various locations that provided an indication of areas of high concentration and also served as model calibration locations. Two main sources of Cr(VI) contamination were considered in the area: anthropogenic contamination originating from Cr-rich industrial wastes buried or injected into the aquifer and geogenic contamination from the leaching process of ophiolitic rocks. The aquifer's response under climatic change scenario A2 was also investigated for the next two decades. Under this scenario, it is expected that rainfall, and thus infiltration, will decrease by 7.7 % during the winter and 15 % during the summer periods. The results for two sub-scenarios (linear and variable precipitation reduction) that were implemented based on A2 show that the impact on the study aquifer is moderate, resulting in a mean level decrease less than 1 m in both cases. The drier climatic conditions resulted in higher Cr(VI) concentrations, especially around the industrial areas.

  13. Biotransformation of hexavalent chromium into extracellular chromium(III) oxide nanoparticles using Schwanniomyces occidentalis.

    Science.gov (United States)

    Mohite, Pallavi T; Kumar, Ameeta Ravi; Zinjarde, Smita S

    2016-03-01

    To demonstrate biotransformation of toxic Cr(VI) ions into Cr2O3 nanoparticles by the yeast Schwanniomyces occidentalis. Reaction mixtures containing S. occidentalis NCIM 3459 and Cr(VI) ions that were initially yellow turned green after 48 h incubation. The coloration was due to the synthesis of chromium (III) oxide nanoparticles (Cr2O3NPs). UV-Visible spectra of the reaction mixtures showed peaks at 445 and 600 nm indicating (4)A2g → (4)T1g and (4)A2g → (4)T2g transitions in Cr2O3, respectively. FTIR profiles suggested the involvement of carboxyl and amide groups in nanoparticle synthesis and stabilization. The Cr2O3NPs ranged between 10 and 60 nm. Their crystalline nature was evident from the selective area electron diffraction and X-ray diffraction patterns. Energy dispersive spectra confirmed the chemical composition of the nanoparticles. These biogenic nanoparticles could find applications in different fields. S. occidentalis mediated biotransformation of toxic Cr(VI) ions into crystalline extracellular Cr2O3NPs under benign conditions.

  14. Hexavalent chromium reduction in a sulfur reducing packed-bed bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Sahinkaya, Erkan, E-mail: erkansahinkaya@yahoo.com [Department of Bioengineering, Istanbul Medeniyet University, Goeztepe, Istanbul (Turkey); Kilic, Adem [Department of Environmental Engineering, Harran University, Osmanbey Campus, 63000 Sanliurfa (Turkey); Altun, Muslum [Department of Chemistry, Hacettepe University, Beytepe, Ankara (Turkey); Komnitsas, Kostas [Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania (Greece); Lens, Piet N.L. [Unesco-IHE Institute for Water Education, Westvest 7, Delft 2611 AX (Netherlands)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Elemental sulfur can be used as electron acceptor for sulfide production. Black-Right-Pointing-Pointer Biogenically produced sulfide reduces Cr(VI) to the much less toxic and immobile form of Cr(III). Black-Right-Pointing-Pointer Sulfur packed bioreactor is efficient for Cr(VI) containing wastewater treatment. Black-Right-Pointing-Pointer Reduced form of chromium precipitates in the bioreactor. - Abstract: The most commonly used approach for the detoxification of hazardous industrial effluents and wastewaters containing Cr(VI) is its reduction to the much less toxic and immobile form of Cr(III). This study investigates the cleanup of Cr(VI) containing wastewaters using elemental sulfur as electron acceptor, for the production of hydrogen sulfide that induces Cr(VI) reduction. An elemental sulfur reducing packed-bed bioreactor was operated at 28-30 Degree-Sign C for more than 250 days under varying influent Cr(VI) concentrations (5.0-50.0 mg/L) and hydraulic retention times (HRTs, 0.36-1.0 day). Ethanol or acetate (1000 mg/L COD) was used as carbon source and electron donor. The degree of COD oxidation varied between 30% and 85%, depending on the operating conditions and the type of organic carbon source. The oxidation of organic matter was coupled with the production of hydrogen sulfide, which reached a maximum concentration of 750 mg/L. The biologically produced hydrogen sulfide reduced Cr(VI) chemically to Cr(III) that precipitated in the reactor. Reduction of Cr(VI) and removal efficiency of total chromium always exceeded 97% and 85%, respectively, implying that the reduced chromium was retained in the bioreactor. This study showed that sulfur can be used as an electron acceptor to produce hydrogen sulfide that induces efficient reduction and immobilization of Cr(VI), thus enabling decontamination of Cr(VI) polluted wastewaters.

  15. Nano-sized Fe2O3/Fe3O4 facilitate anaerobic transformation of hexavalent chromium in soil-water systems.

    Science.gov (United States)

    Zhang, Yaxian; Li, Hua; Gong, Libo; Dong, Guowen; Shen, Liang; Wang, Yuanpeng; Li, Qingbiao

    2017-07-01

    The purpose of this study is to investigate the effects of nano-sized or submicro Fe 2 O 3 /Fe 3 O 4 on the bioreduction of hexavalent chromium (Cr(VI)) and to evaluate the effects of nano-sized Fe 2 O 3 /Fe 3 O 4 on the microbial communities from the anaerobic flooding soil. The results indicated that the net decreases upon Cr(VI) concentration from biotic soil samples amended with nano-sized Fe 2 O 3 (317.1±2.1mg/L) and Fe 3 O 4 (324.0±22.2mg/L) within 21days, which were approximately 2-fold of Cr(VI) concentration released from blank control assays (117.1±5.6mg/L). Furthermore, the results of denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing indicated a greater variety of microbes within the microbial community in amendments with nano-sized Fe 2 O 3 /Fe 3 O 4 than the control assays. Especially, Proteobacteria occupied a predominant status on the phylum level within the indigenous microbial communities from chromium-contaminated soils. Besides, some partial decrease of soluble Cr(VI) in abiotic nano-sized Fe 2 O 3 /Fe 3 O 4 amendments was responsible for the adsorption of nano-sized Fe 2 O 3 /Fe 3 O 4 to soluble Cr(VI). Hence, the presence of nano-sized Fe 2 O 3 /Fe 3 O 4 could largely facilitate the mobilization and biotransformation of Cr(VI) from flooding soils by adsorption and bio-mediated processes. Copyright © 2017. Published by Elsevier B.V.

  16. Reduction of hexavalent chromium by the thermophilic methanogen Methanothermobacter thermautotrophicus

    Science.gov (United States)

    Singh, Rajesh; Dong, Hailiang; Liu, Deng; Zhao, Linduo; Marts, Amy R.; Farquhar, Erik; Tierney, David L.; Almquist, Catherine B.; Briggs, Brandon R.

    2015-01-01

    Despite significant progress on iron reduction by thermophilic microorganisms, studies on their ability to reduce toxic metals are still limited, despite their common co-existence in high temperature environments (up to 70 °C). In this study, Methanothermobacter thermautotrophicus, an obligate thermophilic methanogen, was used to reduce hexavalent chromium. Experiments were conducted in a growth medium with H2/CO2 as substrate with various Cr6+ concentrations (0.2, 0.4, 1, 3, and 5 mM) in the form of potassium dichromate (K2Cr2O7). Time-course measurements of aqueous Cr6+ concentrations using 1,5-diphenylcarbazide colorimetric method showed complete reduction of the 0.2 and 0.4 mM Cr6+ solutions by this methanogen. However, much lower reduction extents of 43.6%, 13.0%, and 3.7% were observed at higher Cr6+ concentrations of 1, 3 and 5 mM, respectively. These lower extents of bioreduction suggest a toxic effect of aqueous Cr6+ to cells at this concentration range. At these higher Cr6+ concentrations, methanogenesis was inhibited and cell growth was impaired as evidenced by decreased total cellular protein production and live/dead cell ratio. Likewise, Cr6+ bioreduction rates decreased with increased initial concentrations of Cr6+ from 13.3 to 1.9 μM h-1. X-ray absorption near-edge structure (XANES) spectroscopy revealed a progressive reduction of soluble Cr6+ to insoluble Cr3+ precipitates, which was confirmed as amorphous chromium hydroxide by selected area electron diffraction pattern. However, a small fraction of reduced Cr occurred as aqueous Cr3+. Scanning and transmission electron microscope observations of M. thermautotrophicus cells after Cr6+ exposure suggest both extra- and intracellular chromium reduction mechanisms. Results of this study demonstrate the ability of M. thermautotrophicus cells to reduce toxic Cr6+ to less toxic Cr3+ and its potential application in metal bioremediation, especially at high temperature subsurface radioactive waste disposal

  17. Self-assembly modified-mushroom nanocomposite for rapid removal of hexavalent chromium from aqueous solution with bubbling fluidized bed.

    Science.gov (United States)

    Xu, Fei; Liu, Xu; Chen, Yijiao; Zhang, Ke; Xu, Heng

    2016-05-18

    A self-assembled modified Pleurotus Cornucopiae material (SMPM) combined with improved Intermittent Bubbling Fluidized Bed (IBFB) was investigated to remove the hexavalent chromium ions in aqueous solution. After the modification, the powder-like raw material gradually self-assembled together to SMPM, which had crinkly porous structure, improved the Cr-accommodation ability in a sound manner. Optimized by Taguchi method, Cr(VI) removal efficiency was up to 75.91% and 48.01% for 100 mg/L and 500 mg/L initial concentration of Cr(VI), respectively. Results indicated that the metal removal was dependent on dosage of adsorbent, particle diameter and treatment time. The experimental data obtained from the biosorption process was successfully correlated with Freundlich isotherm model. Thermodynamic study indicated the endothermic nature of the process. The results confirmed that self-assembly modified Pleurotus Cornucopiae material could be applied for the removal of heavy metal from wastewater in continuous fluidized bed process.

  18. In situ remediation of hexavalent chromium with pyrite fines : bench scale demonstration

    International Nuclear Information System (INIS)

    Cathum, S.; Wong, W.P.; Brown, C.E.

    2002-01-01

    An in situ remediation technique for chromium contaminated soil with pyrite fines was presented. Past industrial activities and lack of disposal facilities have contributed to a serious problem dealing with chromium, which cannot be eliminated from the environment because it is an element. Both bench-scale and laboratory testing was conducted to confirm the efficiency of the proposed process which successfully converted Cr(VI) into Cr(III) in soil and water. Cr(III) is less toxic and immobile in the environment compared to Cr(VI) which moves freely in the soil matrix, posing a risk to the groundwater quality. pH in the range of 2.0 to 7.6 has no effect on the reactivity of pyrite towards Cr(VI). The optimization of the bench-scale treatment resulted in a large volume of chromium waste, mostly from the control experiments and column hydrology testing. These waste streams were treated according to municipal guidelines before disposal to the environment. Samples of chromium waste before and after treatment were analyzed. Cr (VI) was completely mineralized to below guideline levels. It was determined that several conditions, including contact time between pyrite and Cr(VI), are crucial for complete mineralization of Cr(VI). 13 refs., 8 tabs., 9 figs

  19. Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers.

    Science.gov (United States)

    Goldoni, Matteo; Caglieri, Andrea; Poli, Diana; Vettori, Maria Vittoria; Corradi, Massimo; Apostoli, Pietro; Mutti, Antonio

    2006-03-15

    Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers.Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively.The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC.Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI).

  20. Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers

    International Nuclear Information System (INIS)

    Goldoni, Matteo; Caglieri, Andrea; Poli, Diana; Vettori, Maria Vittoria; Corradi, Massimo; Apostoli, Pietro; Mutti, Antonio

    2006-01-01

    Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers. Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively. The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC. Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI)

  1. Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers

    Energy Technology Data Exchange (ETDEWEB)

    Goldoni, Matteo [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy); National Institute of Occupational Safety and Prevention, Research Centre at University of Parma, Parma (Italy); Caglieri, Andrea [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy); Poli, Diana [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy); National Institute of Occupational Safety and Prevention, Research Centre at University of Parma, Parma (Italy); Vettori, Maria Vittoria [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy); National Institute of Occupational Safety and Prevention, Research Centre at University of Parma, Parma (Italy); Corradi, Massimo [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy); National Institute of Occupational Safety and Prevention, Research Centre at University of Parma, Parma (Italy); Apostoli, Pietro [Laboratory of Industrial Hygiene, Department of Experimental and Applied Medicine, University of Brescia (Italy); Mutti, Antonio [Laboratory of Industrial Toxicology, Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Via Gramsci 14, 43100 Parma (Italy)]. E-mail: antonio.mutti@unipr.it

    2006-03-15

    Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers. Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively. The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC. Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI)

  2. The survey of biological absorption of hexavalent chromium from aqueous solutions by Wastewater stabilization pond algae

    Directory of Open Access Journals (Sweden)

    Mohammad Nourisepehr

    2016-06-01

    Full Text Available Background: Contamination of aquatic habitats due to toxicity and accumulation of heavy metals leading to serious damage to organisms and their advance to the food chain. Chrome is one of these heavy metals for the three and six-valence oxides used in industry. Health risks such as carcinogenic hexavalent chromium have been For this reason, removal and reduction of environment is essential. Target of this study hexavalent chromium biosorption by waste stabilization pond algae is of the aquatic environment. Methods: This study was a fundamental applied; In this batch reactor, variables Was investigated pH(3,5,7,9,11, Contact time(30,60,120,180,240,300min, The concentration of hexavalent chromium(0.5,1,5mg And the concentration of algae(0.25, 0.5, 1, 3g. Liquid mixed municipal wastewater treatment stabilization pond was used for insemination. For the investigate the effects of variables pH, contact time, the concentration of hexavalent chromium values in a 250 ml Erlenmeyer flask prepared and various amounts of dried algae (0.25-0.5-1- 3 g were added to it. Then became the shakers. After mixing, the filter paper was passed. The lab temperature was centrifuged for min10-5 rpm 2700 rpm. Then it was read at a wavelength absorbed by 540 nm. . Then collected was data to Excel and SPSS software. Finally was used for hexavalent chromium adsorption isotherm model equation of Langmuir and Freundlich. Results: This study shows that PH, contact time, the concentration of hexavalent chromium and chromium concentrations of algae optimal absorption by algae concentrations, respectively, in5 mg / l, min 120, 0.5 mg / l and is 1gr. Average maximum absorption of chromium Wastewater stabilization ponds by algae 97/2%, respectively. Correlation coefficients absorption curves of these models showed that Cr (VI adsorption isotherm on wastewater stabilization pond algae follows (= R.  Conclusion: The results showed that wastewater stabilization pond algae as a

  3. Application of ICP-MS and HPLC-ICP-MS for diagnosis and therapy of a severe intoxication with hexavalent chromium and inorganic arsenic.

    Science.gov (United States)

    Heitland, Peter; Blohm, Martin; Breuer, Christian; Brinkert, Florian; Achilles, Eike Gert; Pukite, Ieva; Köster, Helmut Dietrich

    2017-05-01

    ICP-MS and HPLC-ICP-MS were applied for diagnosis and therapeutic monitoring in a severe intoxication with a liquid containing hexavalent chromium (Cr(VI)) and inorganic arsenic (iAs). In this rare case a liver transplantation of was considered as the only chance of survival. We developed and applied methods for the determination of Cr(VI) in erythrocytes and total chromium (Cr) and arsenic (As) in blood, plasma, urine and liver tissue by ICP-MS. Exposure to iAs was diagnosed by determination of iAs species and their metabolites in urine by anion exchange HPLC-ICP-MS. Three days after ingestion of the liquid the total Cr concentrations were 2180 and 1070μg/L in whole blood and plasma, respectively, and 4540μg/L Cr(VI) in erythrocytes. The arsenic concentration in blood was 206μg/L. The urinary As species concentrations were <0.5, 109, 115, 154 and 126μg/L for arsenobetaine, As(III), As(V), methylarsonate (V) and dimethylarsinate (V), respectively. Total Cr and As concentrations in the explanted liver were 11.7 and 0.9mg/kg, respectively. Further analytical results of this case study are tabulated and provide valuable data for physicians and toxicologists. Copyright © 2017. Published by Elsevier GmbH.

  4. A new method in estimation of total hexavalent chromium in Portland pozzolan cement

    International Nuclear Information System (INIS)

    Sharma, R.; Sharma, D.

    2017-01-01

    Variamine blue was used first time for the detection of hexavalent chromium from cement samples. In present method, cement was treated sequentially with water, sulphate and carbonate buffer to extract soluble, sparingly soluble and insoluble hexavalent chromium respectively. Extracted Cr (VI) was determined using variamine blue as chromogenic reagent. The determination is based on the reaction of hexavalent chromium with potassium iodide in an acid medium to liberate iodine. This oxidizes variamine blue to form a violet coloured species having an absorption to maximum at 556 nm. Energy-dispersive X-ray spectroscopy (EDX) and Infrared Spectroscopy (IR) confirmed the complete extraction of hexavalent chromium by sequential extraction process. SRM 2701 (Reference material from NIST, USA) was used for revalidating the results. The percentage of recovery for proposed and reference method (diphelycarbazide method) varied from 98.5 to 101 and 97.5 to 100.5. Whereas, their relative error percentage varied from -1.5 to 0.33 and -2.5 to 0.5. [es

  5. On-line dynamic extraction and automated determination of readily bioavailable hexavalent chromium in solid substrates using micro-sequential injection bead-injection lab-on-valve hyphenated with electrothermal atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Long, Xiangbao; Miró, Manuel; Hansen, Elo Harald

    2006-01-01

    A novel and miniaturized micro-sequential injection bead injection lab-on-valve (μSI-BI-LOV) fractionation system was developed for in-line microcolumn soil extraction under simulated environmental scenarios and accurate monitoring of the content of easily mobilisable hexavalent chromium in soil...... environments at the sub-low parts-per-million level. The flow system integrates dynamic leaching of hexavalent chromium using deionized water as recommended by the German Standard DIN 38414-S4 method; on-line pH adjustment of the extract by a 0.01 mol L-1 Tris-HNO3 buffer solution; isolation of the chromate...... polluted agricultural soil material (San Joaquin Soil-Baseline Trace Element Concentrations) with water-soluble Cr(VI) salts at different concentration levels. The potential of the μSI-BI-LOV set-up with renewable surfaces for flame-AAS determination of high levels of readily bioavailable chromate...

  6. Coals as sorbents for the removal and reduction of hexavalent chromium from aqueous waste streams

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, J.; Brown, S.D.; Snape, C.E. [University of Miskolc, Miskolc (Hungary). Dept. of Analytical Chemistry

    2002-03-01

    The aim of this study is to demonstrate the potential of coals as a low-cost reactive barrier material for environmental protection applications, with the ability to prevent leaching of toxic Cr(VI) and other transition metals. Depending upon the type of ion and the surface functionalities, the uptake can involve ion sorption, ion exchange, chelation and redox mechanisms with the surface functionalities being considered as partners in electron transfer processes. The capacity for Cr(VI) uptake of low rank coals and oxidized bituminous coals has been found to lie within the range 02-0.6 mM g{sup -1}. Air oxidation of bituminous coals can increase their Cr(VI) removal capacities. The effect of air oxidation of coals on uptake capacity was more pronounced for Cr(VI) than Cr(III) but less than for Hg(II) and the other ions (Ca{sup 2+}, Ba{sup 2+}, Zn{sup 2+}, Cd{sup 2}) investigated. As previously found for Hg(II), redox mechanisms plays an important role in Cr(VI) uptake, with resultant Cr(III) is exchanged back into solution by hydrogen ions, but some of the sorbed chromium is irreversibly bound to the coal. The reduction of Cr(VI) alone is often considered a satisfactory solution in view of Cr(III) being essentially nontoxic. 56 refs., 11 figs., 1 tab.

  7. Hexavalent chromium removal using aerobic activated sludge batch ...

    African Journals Online (AJOL)

    The following Cr(VI) removal systems were tested: activated sludge alone; activated sludge with an external electron donor (5 g/. of lactose); activated sludge with PAC addition (4 g/.); activated sludge with both PAC and lactose; and PAC alone. The results reported here showed that activated sludges are capable of ...

  8. The determination of hexavalent chromium (Cr6+) in electronic and electrical components and products to comply with RoHS regulations

    International Nuclear Information System (INIS)

    Hua, L.; Chan, Y.C.; Wu, Y.P.; Wu, B.Y.

    2009-01-01

    Toxicity of hexavalent chromium (Cr 6+ ) was focused on with a publication of EU RoHS directive, a novel method to determine hexavalent chromium is developed. It is a combination of energy dispersion X-ray fluorescence spectrometry (EDXRF), spot test, alkali digestion and UV-vis spectrophotometric analysis. First, by EDXRF screening, the presence or absence of element Cr was established. Spot test was followed to identify the valent state of chromium because Cr 6+ and Cr 3+ normally coexist. After alkali digestion, Cr(VI) was separated without an undersired Cr(VI)-Cr(III) interconversions. With a color reagent (DPC) to chelated with Cr(VI), the solution was finally detected by a UV-vis spectrophotometer at a wavelength of 540 nm which is the basis of analyzing Cr(VI) quantitatively. Some parameters affecting analyses were studied. It was found that when pH in the final solution was 2.0, the extraction time was 60 min, the extraction temperature was 90 deg. C, pH during the extraction process was 7.5-8.5, and a mixed buffer solution (0.5 M K 2 HPO 4 /0.5 M KH 2 PO 4 ) was added up to 1 ml, colorimetric reagent was added to 2 ml, it is optimal for extraction. Under this condition, interferences from Fe 3+ , Pb 2+ , Ag + , etc., were overcome. It was also found that the curves are rectilinear in the range of 0-500 μg l -1 , the correlation coefficient is up to 0.999924, and the recovery rates are more than 85%, the Cr(III)-DPCO complex can be kept stable for 24 h with a relative humidity (RH) range of 60-90%, and a temperature range of 5-40 deg. C. So it can be concluded that the proposed method has a good sensitivity and high precision. It is a more convincing and reliable method due to its relative standard deviation (R.S.D.) <1% after six replicate determinations of Cr(VI) in an Fe-Ni alloy sample

  9. Investigation of alternative phosphating treatments for nickel and hexavalent chromium elimination

    International Nuclear Information System (INIS)

    Jazbinsek, Luiz Antonio Rossi

    2014-01-01

    The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate

  10. Polyacrylonitrile/polypyrrole core/shell nanofiber mat for the removal of hexavalent chromium from aqueous solution

    International Nuclear Information System (INIS)

    Wang, Jianqiang; Pan, Kai; He, Qiwei; Cao, Bing

    2013-01-01

    Highlights: ► PAN nanofibers obtained by electrospinning. ► PAN/PPy core/shell nanofiber membrane was prepared. ► PAN/PPy core/shell nanofiber membrane used for Cr(VI) removal. ► Adsorption capacity remained up to 80% within 5 times cycles. -- Abstract: Polyacrylonitrile/polypyrrole (PAN/PPy) core–shell structure nanofibers were prepared via electrospinning followed by in situ polymerization of pyrrole monomer for the removal of hexavalent chromium (Cr(VI)) from aqueous solution. Attenuated total reflections Fourier transform infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) results confirmed the presence of the polypyrrole (PPy) layer on the surface of PAN nanofibers. The morphology and structure of the core–shell PAN/PPy nanofibers were studied by scanning electron microscopy (SEM) and transmission electron microscope (TEM), and the core–shell structure can be clearly proved from the SEM and TEM images. Adsorption results indicated that the adsorption capacity increased with the initial solution pH decreased. The adsorption equilibrium reached within 30 and 90 min as the initial solution concentration increased from 100 to 200 mg/L, and the process can be described using the pseudo-second-order model. Isotherm data fitted well to the Langmuir isotherm model. Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature. Desorption results showed that the adsorption capacity can remain up to 80% after 5 times usage. The adsorption mechanism was also studied by XPS

  11. PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

    OpenAIRE

    Puangrat Kajitvichyanukul; Chulaluck Changul

    2017-01-01

    A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums) from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.6...

  12. Pilot Scale Production of Activated Carbon Spheres Using Fluidized Bed Reactor and Its Evaluation for the Removal of Hexavalent Chromium from Aqueous Solutions

    Science.gov (United States)

    Tripathi, Nagesh Kumar; Sathe, Manisha

    2017-12-01

    Large scale production of activated carbon is need of ongoing research due to its excellent adsorption capacity for removal of heavy metals from contaminated solutions. In the present study, polymeric precursor polystyrene beads [Brunauer Emmett Teller (BET) surface area, 46 m2/g; carbon content, 40.64%; crushing strength, 0.32 kg/sphere] were used to produce a new variant of activated carbon, Activated Carbon Spheres (ACS) in a pilot scale fluidized bed reactor. ACS were prepared by carbonization of polymeric precursor at 850 °C followed by activation of resultant material with steam. Prepared ACS were characterized using scanning electron microscope, CHNS analyzer, thermogravimetric analyzer, surface area analyzer and crushing strength tester. The produced ACS have 1009 m2/g BET surface area, 0.89 cm3/g total pore volume, 92.32% carbon content and 1.1 kg/sphere crushing strength with less than 1% of moisture and ash content. The ACS were also evaluated for its potential to remove hexavalent chromium [Cr(VI)] from contaminated solutions. The chromium removal is observed to be 99.1% at initial concentration 50 mg/l, pH 2, ACS dose 1 g/l, contact time 2 h, agitation 120 rpm and temperature 30 °C. Thus ACS can be used as an adsorbent material for the removal of Cr(VI) from contaminated solutions.

  13. Hexavalent chromium removal by chitosan modified-bioreduced nontronite

    Science.gov (United States)

    Singh, Rajesh; Dong, Hailiang; Zeng, Qiang; Zhang, Li; Rengasamy, Karthikeyan

    2017-08-01

    Recent efforts have focused on structural Fe(II) in chemically or biologically reduced clay minerals to immobilize Cr(VI) from aqueous solution, but the coulombic repulsion between the negatively charged clay surface and the polyanionic form of Cr(VI), e.g., dichromate, can hinder the effectiveness of this process. The purpose of this study was to investigate the efficiency and mechanism of Cr(VI) removal by a charge-reversed nontronite (NAu-2), an Fe-rich smectite. Chitosan, a linear polysaccharide derived from chitin found in soil and groundwater, was used to reverse the charge of NAu-2. Intercalation of chitosan into NAu-2 interlayer increased the basal d-spacing of NAu-2 from 1.23 nm to 1.83 nm and zeta potential from -27.17 to +34.13 mV, with the amount of increase depending on chitosan/NAu-2 ratio. Structural Fe(III) in chitosan-exchanged NAu-2 was then biologically reduced by an iron-reducing bacterium Shewanella putrefaciens CN32 in bicarbonate buffer with lactate as the sole electron donor, with and without electron shuttle, AQDS. Without AQDS, the extent of Fe(III) reduction increased from the lowest (∼9%) for the chitosan-free NAu-2 to the highest (∼12%) for the highest chitosan loaded NAu-2 (3:1 ratio). This enhancement of Fe(III) reduction was likely due to the attachment of negatively charged bacterial cells to charge-reversed (e.g., positively charged) NAu-2 surfaces, facilitating the electron transfer between cells and structural Fe(III). With AQDS, Fe(III) reduction extent doubled relative to those without AQDS, but the enhancement effect was similar across all chitosan loadings, suggesting that AQDS was more important than chitosan in enhancing Fe(III) bioreduction. Chitosan-exchanged, biologically reduced NAu-2 was then utilized for removing Cr(VI) in batch experiments with three consecutive spikes of 50 μM Cr. With the first Cr spike, the rate of Cr(VI) removal by charged-reversed NAu-2 that was bioreduced without and with AQDS was ∼1

  14. The electrochemical aspect of the corrosion of austenitic stainless steels, in nitric acid and in the presence of hexavalent chromium (1961)

    International Nuclear Information System (INIS)

    Coriou, H.; Hure, J.; Plante, G.

    1961-01-01

    The corrosion of austenitic stainless steels in boiling nitric acid markedly increases when the medium contains hexavalent chromium ions. Because of several redox phenomena, the potential of the steel generally changes in course of time. Measurements show a relation between the weight loss and the potential of specimens. Additions of Mn(VII) and Ce(IV) are compared with that of Cr(VI), and show that the relation is a general one. The attack cf the metal in oxidizing media is largely intergranular, leading to exfoliation of the grains, although the steel studied is not sensitive to the classical Huey and Strauss tests. Also even in the absence of any other oxidizing reaction, the current density observed when the steel is anodically polarized under potentiostatic conditions does not correspond to the actual weight loss of the metal. (authors) [fr

  15. DNA-protein crosslinks in peripheral lymphocytes of individuals exposed to hexavalent chromium compounds.

    Science.gov (United States)

    Zhitkovich, A; Lukanova, A; Popov, T; Taioli, E; Cohen, H; Costa, M; Toniolo, P

    1996-01-01

    Abstract DNA-protein crosslinks were measured in peripheral blood lymphocytes of chrome-platers and controls from Bulgaria in order to evaluate a genotoxic effect of human exposure to carcinogenic Cr(VI) compounds. Chrome-platers and most of the unexposed controls were from the industrial city of Jambol; some additional controls were recruited from the seaside town of Burgas. The chrome-platers had significantly elevated levels of chromium in pre- and post-shift urine, erythrocytes and lymphocytes compared with the control subjects. The largest differences between the two groups were found in erythrocyte chromium concentrations which are considered to be indicative of Cr(VI) exposure. Despite the significant differences in internal chromium doses, levels of DNA-protein crosslinks were not significantly different between the combined controls and exposed workers. Individual DNA-protein crosslinks, however, correlated strongly with chromium in erythrocytes at low and moderate doses but at high exposures, such as among the majority of chrome-platers, these DNA adducts were saturated at maximum levels. The saturation of DNA-protein crosslinks seems to occur at 7-8 μg I-(1) chromium in erythrocytes whereas a mean erythrocyte chromium among the chrome platers was as high as 22.8 μg l(-1). Occupationally unexposed subjects exhibited a significant variability with respect to the erythrocyte chromium concentration, however erythrocyte chromium levels correlated closely with DNA-protein crosslinks in lymphocytes. The controls from Jambol had higher chromium concentrations in erythrocytes and elevated levels of DNA-protein crosslinks compared with Burgas controls. Occupational exposure to formaldehyde among furniture factory workers did not change levels of DNA-protein crosslinks in peripheral lymphocytes. DNA-protein crosslink measurements showed a low intraindividual variability and their levels among both controls and exposed indivduals were not affected by smoking, age

  16. PHOTOCATALYTIC REMOVAL OF TR I- AND HEXA-VALENT CHROMIUM IONS FROM CHROME-ELECTROPL ATING WASTEWATER

    Directory of Open Access Journals (Sweden)

    Puangrat Kajitvichyanukul

    2017-11-01

    Full Text Available A novel technique based on photocatalysis was applied to eliminate chromium ions, a toxic hazardous environmental pollutant. The photoreduction of each species of chromium (total, hexavalent, and trivalent chromiums from chrome-electroplating wastewater was investigated using a titanium dioxide suspension under irradiation by a low-pressure mercury lamp. The initial concentration of total chromium was 300 mg/l. The applied conditions were the direct photocatalytic reduction process at pH 3.65 and the indirect photocatalytic reduction with added hole scavengers at the same solution pH. Results from both processes were comparatively discussed. Result show that chromium was not efficiently removed by direct photoreduction. In contrast, with the adding of hole scavengers, which were formate ions, the photoreduction of chromium was very favorable. Both hexavalent and trivalent chromiums were efficiently removed. The photocatalytic mechanism is purposed in this study.

  17. Removal of chromium hexavalent of residual water from tannery using hydrotalcite

    International Nuclear Information System (INIS)

    Martinez G, S.; Martinez, V.; Bulbulian, S.

    2000-01-01

    One of the main problems of leather tanned is the treatment that must be give to the waste water polluted with chrome which stays in trivalent form, but it is easily oxidated at chromium hexavalent. This work pretends to find an elimination media for chromium (VI) from water using the original synthetic hydrotalcite and calcined as sorbent by its anion exchange and memory effect properties. The tannery water was characterized by X-ray diffraction, thermal gravimetric analysis, specific surface and infrared spectroscopy. (Author)

  18. Hexavalent chromium at low concentration alters Sertoli cell barrier and connexin 43 gap junction but not claudin-11 and N-cadherin in the rat seminiferous tubule culture model

    Energy Technology Data Exchange (ETDEWEB)

    Carette, Diane [INSERM U 1065, Team 5 “Physiopathology of Germ Cell Control: Genomic and Non Genomic Mechanisms” C3M, University of Nice Sophia Antipolis, Nice (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Perrard, Marie-Hélène, E-mail: marie-helene.durand@ens-lyon.fr [Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon I, CNRS, INRA, Ecole Normale Supérieure de Lyon, Lyon (France); Prisant, Nadia [University of Versailles/St Quentin-en-Yvelines (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Gilleron, Jérome; Pointis, Georges [INSERM U 1065, Team 5 “Physiopathology of Germ Cell Control: Genomic and Non Genomic Mechanisms” C3M, University of Nice Sophia Antipolis, Nice (France); Segretain, Dominique [University of Versailles/St Quentin-en-Yvelines (France); UMR S775, University Paris Descartes, 45 rue des Saints Pères, 75006, Paris (France); Durand, Philippe [Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, Université Lyon I, CNRS, INRA, Ecole Normale Supérieure de Lyon, Lyon (France); Kallistem SAS Ecole Normale Supérieure de Lyon, Lyon (France)

    2013-04-01

    Exposure to toxic metals, specifically those belonging to the nonessential group leads to human health defects and among them reprotoxic effects. The mechanisms by which these metals produce their negative effects on spermatogenesis have not been fully elucidated. By using the Durand's validated seminiferous tubule culture model, which mimics the in vivo situation, we recently reported that concentrations of hexavalent chromium, reported in the literature to be closed to that found in the blood circulation of men, increase the number of germ cell cytogenetic abnormalities. Since this metal is also known to affect cellular junctions, we investigated, in the present study, its potential influence on the Sertoli cell barrier and on junctional proteins present at this level such as connexin 43, claudin-11 and N-cadherin. Cultured seminiferous tubules in bicameral chambers expressed the three junctional proteins and ZO-1 for at least 12 days. Exposure to low concentrations of chromium (10 μg/l) increased the trans-epithelial resistance without major changes of claudin-11 and N-cadherin expressions but strongly delocalized the gap junction protein connexin 43 from the membrane to the cytoplasm of Sertoli cells. The possibility that the hexavalent chromium-induced alteration of connexin 43 indirectly mediates the effect of the toxic metal on the blood–testis barrier dynamic is postulated. - Highlights: ► Influence of Cr(VI) on the Sertoli cell barrier and on junctional proteins ► Use of cultured seminiferous tubules in bicameral chambers ► Low concentrations of Cr(VI) (10 μg/l) altered the trans-epithelial resistance. ► Cr(VI) did not alter claudin-11 and N-cadherin. ► Cr(VI) delocalized connexin 43 from the membrane to the cytoplasm of Sertoli cells.

  19. Characterization and recovery of hexavalent chromium salts of an environmental liability

    International Nuclear Information System (INIS)

    Rangel C, A. A.; Isarain C, E.; Maldonado V, M.

    2015-01-01

    The purpose of this study was to examine a diverse group of washing solutions for its use in the recovery of the industrial waste hexavalent chromium, in compliance with the Mexican regulation NOM-147-SEMARNAT/SSA1-2004. The recovery process consisted of a simple random sampling and a physical-chemical characterization with consideration to the high solubility of hexavalent chromium compounds. A test was performed which implemented five different washing solutions (water, sulfuric acid, citric acid, sodium hydroxide, calcium and hydroxide). This was followed by a factorial experimental design to optimize resources with a removal efficiency of 80% and hence a recovery of 33 g/kg as CaCrO 4 (calcium chromate). Chromium hexavalent concentration in the leachate was quantified using UV-Vis spectrometry at a wavelength λ = 540 nm, while the salts recovered by evaporation were characterized using X-ray fluorescence analysis, leading to the conclusion that precipitate can be used as raw material, the main elements are Cr, Ca, Fe and Mg, and their concentration depends on the washing solution. (Author)

  20. Development of a site-specific water quality criterion for hexavalent chromium

    International Nuclear Information System (INIS)

    McIntyre, D.O.; Sticko, J.P.; Reash, R.J.

    1995-01-01

    The effluent of treated fly ash from a coal-fired power plant located on the Ohio River periodically exceeds its NPDES acute permit limit for hexavalent chromium of 15 microg/L. The increased levels of hexavalent chromium in the effluent are a recent occurrence which are likely due to changes in coal blends burned in the generating units. Ohio EPA determined the use designation of the receiving stream (Limited Resource Water) was being attained and a one-year biomonitoring program of the effluent detected no acute toxicity to Ceriodaphnia dubia or Daphnia magna. The water-effect ratio (WER) procedure was selected to develop a site-specific criterion maximum concentration for hexavalent chromium for the effluent's receiving stream. WER procedures followed those described in EPA's ''Interim Guidance on Determination and Use of Water-Effect Ratios for Metals'' (1994). Site water used in the WER determinations was undiluted effluent since the receiving stream originates at the discharge point of the outfall. 48-hour acute D. magna and 96-hour acute fathead minnow toxicity tests were selected as the primary and secondary tests, respectively for use in three seasonal WER determinations. The results of the three WER determinations and the status of the regulatory process will be presented

  1. Biodegradation of hexavalent chromium (Cr+6) in wastewater using Pseudomonas sp. and Bacillus sp. bacterial strains

    Energy Technology Data Exchange (ETDEWEB)

    Qasim, Muhammad [Department of Chemical Engineering, American University of Sharjah (United Arab Emirates)

    2013-07-01

    The recovery of toxic metal compounds is a deep concern in all industries. Hexavalent chromium is particularly worrying because of its toxic influence on human health. In this paper, biodegradation of hexavalent chromium (Cr+6) present in wastewater has been studied using two different bacterial strains; Pseudomonas sp. and Bacillus sp. A chemostat (with and without recycle of cells) with 10 L liquid culture volume was used to study the substrate and the biomass cell concentrations with time. Also, the degree of substrate conversion was studied by the varying the dilution rate as an independent parameter. The dilution rate (ratio of feed flow rate to the culture volume) was varied by varying the feed volumetric rate from 110-170 mL/h for inlet hexavalent chromium concentrations of 70 mg/dm3. The results show that a chemostat with recycle gives a better performance in terms of substrate conversion than a chemostat without a recycle. Moreover, the degree of substrate conversion decreases as the dilution rate is increased. Also, Bacillus sp. was found to give higher conversions compared to pseudomonas sp.

  2. Comparative Study of Portland Cement-based and Zeolite-based Concretes in Terms of Hexavalent Chromium Leaching

    Directory of Open Access Journals (Sweden)

    Oravec Jozef

    2016-12-01

    Full Text Available The paper presents the results of the leaching study of Portland cement-based and zeolite-based concretes regarding water soluble hexavalent chromium. Three leaching water media (distilled water, rain water, and Britton-Robinson buffer of various pH values were under investigation. The correlation between pH and leached-out concentrations of chromium was not confirmed. The content of hexavalent water-soluble chromium in leachates of zeolite-based concretes was found to be higher than that in leachates of Portland cement-based samples.

  3. Hexavalent chromium-induced differential disruption of cortical microtubules in some Fabaceae species is correlated with acetylation of α-tubulin.

    Science.gov (United States)

    Eleftheriou, Eleftherios P; Adamakis, Ioannis-Dimosthenis S; Michalopoulou, Vasiliki A

    2016-03-01

    The effects of hexavalent chromium [Cr(VI)] on the cortical microtubules (MTs) of five species of the Fabaceae family (Vicia faba, Pisum sativum, Vigna sinensis, Vigna angularis, and Medicago sativa) were investigated by confocal laser scanning microscopy after immunolocalization of total tubulin with conventional immunofluorescence techniques and of acetylated α-tubulin with the specific 6-11B-1 monoclonal antibody. Moreover, total α-tubulin and acetylated α-tubulin were quantified by Western immunoblotting and scanning densitometry. Results showed the universality of Cr(VI) detrimental effects to cortical MTs, which proved to be a sensitive and reliable subcellular marker for monitoring Cr(VI) toxicity in plant cells. However, a species-specific response was recorded, and a correlation of MT disturbance with the acetylation status of α-tubulin was demonstrated. In V. faba, MTs were depolymerized at the gain of cytoplasmic tubulin background and displayed low α-tubulin acetylation, while in P. sativum, V. sinensis, V. angularis, and M. sativa, MTs became bundled and changed orientation from perpendicular to oblique or longitudinal. Bundled MTs were highly acetylated as determined by both immunofluorescence and Western immunoblotting. Tubulin acetylation in P. sativum and M. sativa preceded MT bundling; in V. sinensis it followed MT derangement, while in V. angularis the two phenomena coincided. Total α-tubulin remained constant in all treatments. Should acetylation be an indicator of MT stabilization, it is deduced that bundled MTs became stabilized, lost their dynamic properties, and were rendered inactive. Results of this report allow the conclusion that Cr(VI) toxicity disrupts MTs and deranges the MT-mediated functions either by depolymerizing or stabilizing them.

  4. Hexavalent chromium reduction potential of Cellulosimicrobium sp. isolated from common effluent treatment plant of tannery industries.

    Science.gov (United States)

    Bharagava, Ram Naresh; Mishra, Sandhya

    2018-01-01

    Present study deals with the isolation and characterization of a bacterium capable for the effective reduction of Cr(VI) from tannery wastewater. Based on the 16S rRNA gene sequence analysis, this bacterium was identified as Cellulosimicrobium sp. (KX710177). During the Cr(VI) reduction experiment performed at 50, 100, 200,and 300mg/L of Cr(VI) concentrations, the bacterium showed 99.33% and 96.98% reduction at 50 and 100mg/L at 24 and 96h, respectively. However, at 200 and 300mg/L concentration of Cr(VI), only 84.62% and 62.28% reduction was achieved after 96h, respectively. The SEM analysis revealed that bacterial cells exposed to Cr(VI) showed increased cell size in comparison to unexposed cells, which might be due to either the precipitation or adsorption of reduced Cr(III) on bacterial cells. Further, the Energy Dispersive X-ray (EDX) analysis showed some chromium peaks for cells exposed to Cr(VI), which might be either due to the presence of precipitated reduced Cr(III) on cells or complexation of Cr(III) with cell surface molecules. The bacterium also showed resistance and sensitivity against the tested antibiotics with a wide range of MIC values ranging from 250 to 800mg/L for different heavy metals. Thus, this multi-drug and multi-metal resistant bacterium can be used as a potential agent for the effective bioremediation of metal contaminated sites. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Bioreduction of hexavalent chromium by live and active phanerochaete chrysosporium: kinetics and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Murugavelh, Somasundaram; Mohanty, Kaustubha [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam (India)

    2012-07-15

    In this work the potential of live and active Phanerochaete chrysosporium, a white rot fungi, to remove lower Cr(VI) concentration from aqueous solutions was reported for the first time. A medium pH had significant effect on the growth of the fungus and bioremoval of Cr(VI). Substrate inhibition on the growth of Phanerochaete chrysosporium was evident beyond 20 g L{sup -1} of dextrose concentration. A maximum biomass concentration of 15.64 g L{sup -1} was obtained for an initial dextrose concentration of 20 g L{sup -1} in metal free medium at pH 6.0. An increase in Cr(VI) concentration beyond 10 mg L{sup -1} inhibited the growth of the fungi, thereby, reducing the chromium bioremoval efficiency. A maximum reduction efficiency of 98.92% was reported for an initial metal concentration of 10 mg L{sup -1}. A mathematical expression for the bioreduction of Cr(VI) considering the organic compounds in the cells was proposed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Bioreduction of hexavalent chromium by live and active phanerochaete chrysosporium: kinetics and modeling

    International Nuclear Information System (INIS)

    Murugavelh, Somasundaram; Mohanty, Kaustubha

    2012-01-01

    In this work the potential of live and active Phanerochaete chrysosporium, a white rot fungi, to remove lower Cr(VI) concentration from aqueous solutions was reported for the first time. A medium pH had significant effect on the growth of the fungus and bioremoval of Cr(VI). Substrate inhibition on the growth of Phanerochaete chrysosporium was evident beyond 20 g L -1 of dextrose concentration. A maximum biomass concentration of 15.64 g L -1 was obtained for an initial dextrose concentration of 20 g L -1 in metal free medium at pH 6.0. An increase in Cr(VI) concentration beyond 10 mg L -1 inhibited the growth of the fungi, thereby, reducing the chromium bioremoval efficiency. A maximum reduction efficiency of 98.92% was reported for an initial metal concentration of 10 mg L -1 . A mathematical expression for the bioreduction of Cr(VI) considering the organic compounds in the cells was proposed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Reduction of hexavalent chromium by Rhizopus Oryzae | Sukumar ...

    African Journals Online (AJOL)

    The ability of Rhizopus oryzae to reduce Cr6+ was evaluated in batch microcosms. The optimum pH of R. oryzae growth was between 6.0 and 7.0. The maximum chromium reduction efficiency of 91.15% and biomass growth was achieved at a pH of 7, temperature of 37°C, with an initial Cr6+ concentration of 400 ppm and ...

  8. Titanium dioxide–gold nanocomposite materials embedded in silicate sol–gel film catalyst for simultaneous photodegradation of hexavalent chromium and methylene blue

    International Nuclear Information System (INIS)

    Pandikumar, Alagarsamy; Ramaraj, Ramasamy

    2012-01-01

    Graphical abstract: Aminosilicate sol–gel supported TiO 2 –Au nanocomposite material photocatalyst was prepared by deposition–precipitation method and used for the simultaneous oxidation and reduction of methyelene blue dye and Cr(VI) ions. Highlights: ► The EDAS/(TiO 2 –Au) nps is used to design the solid-phase thin film photocatalyst. ► Au promotes the interfacial electron transfer from TiO 2 to Cr(VI) to form Cr(III). ► The holes produced at the TiO 2 oxidize the MB dye. ► The EDAS/(TiO 2 –Au) nps film was used for the simultaneous oxidation and reduction of toxic molecules. ► The photoinduced simultaneous redox process provides dual benefit for the environment remediation. - Abstract: Aminosilicate sol–gel supported titanium dioxide–gold (EDAS/(TiO 2 –Au) nps ) nanocomposite materials were synthesized by simple deposition–precipitation method and characterized. The photocatalytic oxidation and reduction activity of the EDAS/(TiO 2 –Au) nps film was evaluated using hexavalent chromium (Cr(VI)) and methylene blue (MB) dye under irradiation. The photocatalytic reduction of Cr(VI) to Cr(III) was studied in the presence of hole scavengers such as oxalic acid (OA) and methylene blue (MB). The photocatalytic degradation of MB was investigated in the presence and absence of Cr(VI). Presence of Au nps on the (TiO 2 ) nps surface and its dispersion in the silicate sol-gel film (EDAS/(TiO 2 –Au) nps ) improved the photocatalytic reduction of Cr(VI) and oxidation of MB due to the effective interfacial electron transfer from the conduction band of the TiO 2 to Au nps by minimizing the charge recombination process when compared to the TiO 2 and (TiO 2 –Au) nps in the absence of EDAS. The EDAS/(TiO 2 –Au) nps nanocomposite materials provided beneficial role in the environmental remediation and purification process through synergistic photocatalytic activity by an advanced oxidation–reduction processes.

  9. Electrogenerated Chemiluminescence Behavior of Au nanoparticles-hybridized Pb (II) metal-organic framework and its application in selective sensing hexavalent chromium.

    Science.gov (United States)

    Ma, Hongmin; Li, Xiaojian; Yan, Tao; Li, Yan; Liu, Haiyang; Zhang, Yong; Wu, Dan; Du, Bin; Wei, Qin

    2016-02-23

    In this work, a novel electrochemiluminescence (ECL) sensor based on Au nanoparticles-hybridized Pb (II)-β-cyclodextrin (Pb-β-CD) metal-organic framework for detecting hexavalent chromium (Cr(VI)) was developed. Pb-β-CD shows excellent ECL behavior and unexpected reducing ability towards Au ions. Au nanoparticles could massively form on the surface of Pb-β-CD (Au@Pb-β-CD) without use of any additional reducing agent. In the presence of coreactant K2S2O8, the ECL emission of Pb-β-CD was enhanced by the formation of Au nanoparticles. Cr(VI) can collisionally quench the ECL behavior of Au@Pb-β-CD/S2O8(2-) system and the detection mechanism was investigated. This ECL sensor is found to have a linear response in the range of 0.01-100 μM and a low detection limit of 3.43 nM (S/N = 3) under the optimal conditions. These results suggest that metal-organic framework Au@Pb-β-CD has great potential in extending the application in the ECL field as an efficient luminophore.

  10. Study on Leaching of Hexavalent Chromium from Hardened Concretes Using Tank Leaching Test

    OpenAIRE

    Takahashi, Shigeru; Sakai, Etsuo; Sugiyama, Takafumi

    2007-01-01

    Tank leaching tests were carried out to investigate the behavior of leaching trace elements from monolith samples. This study consists of two series, and the trace element used was hexavalent chromium. In Series I, the influence of the leachant/surface area of the specimen (L/S ratio) on the leaching amount was investigated. The leaching amount was found to increase with the amount of worked water. This shows that any L/S ratio can be selected in the tank leaching test. In Series II, th...

  11. Ferrous sulphate mono and heptahydrate reduction of hexavalent chromium in cement: effectiveness and storability

    Directory of Open Access Journals (Sweden)

    Valverde, J. L.

    2005-09-01

    Full Text Available In Community legislation, substances containing hexavalent chromium are classified as carcinogenic, mutagenic and sensitizing. In cement, hexavalent chromium intensifies sensitization and may set off severe allergic reactions in workers in routine contact with the product, whether in the factory or on construction sites. The allergic or contact dermatitis causes is a very painful disease that may lead to permanent worker disability. According to Directive 2003/53/EC of the European Parliament and the Council, Governments of all member countries will be required to prohibit the marketing and use, as of 17 January 2005, of any cement or cement preparation containing more than 2 ppm of chromium (VI. Hexavalent chromium can be reduced with ferrous sulphate to trivalent chromium, which is water-insoluble and therefore innocuous to the skin. The present paper reports the effects of adding ferrous sulphate mono- or heptahydrate to a commercial cement and the storage time of the mix on the concentration of hexavalent chromium. The salts studied were found to effectively reduce hexavalent chromium in cement for at least three months.

    Las sustancias que contienen cromo hexavalente están clasificadas en la legislación comunitaria como sustancias carcinogénicas, mutagénicas y sensibilizantes. El cromo hexavalente del cemento potencia la sensibilización y provoca graves reacciones alérgicas que sufren bastante a menudo los trabajadores que lo manipulan habitualmente, ya sea en fábrica o en el sector de la construcción. La dermatitis alérgica o de contacto que produce es muy dolorosa y puede dejar a los trabajadores en estado de discapacidad. La Directiva 2003/53/CE del Parlamento Europeo y del Consejo, exige a los Gobiernos de los países miembros, que a partir del 17 de enero de 2005, prohiban el uso y la comercialización de todos aquellos cementos y preparados que contengan cemento, cuyo contenido en cromo (VI soluble, una vez hidratados

  12. THE ATM-SMC1 PATHWAY IS ESSENTIAL FOR ACTIVATION OF THE CHROMIUM[VI]-INDUCED S-PHASE CHECKPOINT

    Science.gov (United States)

    Hexavalent chromium (Cr[VI] is a common industrial waste product, an environmental pollutant, and a recognized human carcinogen. Following cellular uptake, Cr[VI] can cause DNA damage, however, the mechanisims by which mammalian cells respond to Cr-induced DNA damage remain to b...

  13. Chemical and microbial remediation of hexavalent chromium from contaminated soil and mining/metallurgical solid waste: a review.

    Science.gov (United States)

    Dhal, B; Thatoi, H N; Das, N N; Pandey, B D

    2013-04-15

    Chromium is a highly toxic non-essential metal for microorganisms and plants, and its occurrence is rare in nature. Lower to higher chromium containing effluents and solid wastes released by activities such as mining, metal plating, wood preservation, ink manufacture, dyes, pigments, glass and ceramics, tanning and textile industries, and corrosion inhibitors in cooling water, induce pollution and may cause major health hazards. Besides, natural processes (weathering and biochemical) also contribute to the mobility of chromium which enters in to the soil affecting the plant growth and metabolic functions of the living species. Generally, chemical processes are used for Cr- remediation. However, with the inference derived from the diverse Cr-resistance mechanism displayed by microorganisms and the plants including biosorption, diminished accumulation, precipitation, reduction of Cr(VI) to Cr(III), and chromate efflux, bioremediation is emerging as a potential tool to address the problem of Cr(VI) pollution. This review focuses on the chemistry of chromium, its use, and toxicity and mobility in soil, while assessing its concentration in effluents/wastes which becomes the source of pollution. In order to conserve the environment and resources, the chemical/biological remediation processes for Cr(VI) and their efficiency have been summarised in some detail. The interaction of chromium with various microbial/bacterial strains isolated and their reduction capacity towards Cr(VI) are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Investigation of the Mode of Action Underlying the Tumorigenic Response Induced in B6C3F1 Mice Exposed Orally to Hexavalent Chromium

    Science.gov (United States)

    Thompson, Chad M.; Proctor, Deborah M.; Haws, Laurie C.; Hébert, Charles D.; Grimes, Sheila D.; Shertzer, Howard G.; Kopec, Anna K.; Hixon, J.Gregory; Zacharewski, Timothy R.; Harris, Mark A.

    2011-01-01

    Chronic ingestion of high concentrations of hexavalent chromium [Cr(VI)] in drinking water induces intestinal tumors in mice. To investigate the mode of action (MOA) underlying these tumors, a 90-day drinking water study was conducted using similar exposure conditions as in a previous cancer bioassay, as well as lower (heretofore unexamined) drinking water concentrations. Tissue samples were collected in mice exposed for 7 or 90 days and subjected to histopathological, biochemical, toxicogenomic, and toxicokinetic analyses. Described herein are the results of toxicokinetic, biochemical, and pathological findings. Following 90 days of exposure to 0.3–520 mg/l of sodium dichromate dihydrate (SDD), total chromium concentrations in the duodenum were significantly elevated at ≥ 14 mg/l. At these concentrations, significant decreases in the reduced-to-oxidized glutathione ratio (GSH/GSSG) were observed. Beginning at 60 mg/l, intestinal lesions were observed including villous cytoplasmic vacuolization. Atrophy, apoptosis, and crypt hyperplasia were evident at ≥ 170 mg/l. Protein carbonyls were elevated at concentrations ≥ 4 mg/l SDD, whereas oxidative DNA damage, as assessed by 8-hydroxydeoxyguanosine, was not increased in any treatment group. Significant decreases in the GSH/GSSG ratio and similar histopathological lesions as observed in the duodenum were also observed in the jejunum following 90 days of exposure. Cytokine levels (e.g., interleukin-1β) were generally depressed or unaltered at the termination of the study. Overall, the data suggest that Cr(VI) in drinking water can induce oxidative stress, villous cytotoxicity, and crypt hyperplasia in the mouse intestine and may underlie the MOA of intestinal carcinogenesis in mice. PMID:21712504

  15. Combined nano-biotechnology for in-situ remediation of mixed contamination of groundwater by hexavalent chromium and chlorinated solvents

    Czech Academy of Sciences Publication Activity Database

    Němeček, J.; Pokorný, P.; Lhotský, O.; Knytl, V.; Najmanová, P.; Steinová, J.; Černík, M.; Filipová, Alena; Filip, J.; Cajthaml, Tomáš

    2016-01-01

    Roč. 563, SEP 1 (2016), s. 822-834 ISSN 0048-9697 R&D Projects: GA TA ČR TE01020218 Institutional support: RVO:61388971 Keywords : Chlorinated solvents * Hexavalent chromium * NZVI Subject RIV: EE - Microbiology, Virology Impact factor: 4.900, year: 2016

  16. The Survey of Melia Azaderach L. ash in Removal of Hexavalent Chromium from Synthetic Electroplating Industry Wastewater

    Directory of Open Access Journals (Sweden)

    MT Ghaneian

    2014-11-01

    Conclusion: Melia azedarach ash is an effective adsorbent in removal of hexavalent chromium from synthetic electroplating industries wastewater. In addition, the use of this biosorbent in preparation and application aspects is simple and cheap compared to many other natural and man-made adsorbent.

  17. Nanoscale zero-valent iron application for in situ reduction of hexavalent chromium and its effects on indigenous microorganism populations

    Czech Academy of Sciences Publication Activity Database

    Němeček, J.; Lhotský, O.; Cajthaml, Tomáš

    485-486, č. 2 (2014), s. 739-747 ISSN 0048-9697 R&D Projects: GA TA ČR TE01020218; GA MŠk ED0005/01/01; GA TA ČR TA01021792 Institutional support: RVO:61388971 Keywords : nanoparticles * hexavalent chromium * bioremediation Subject RIV: EE - Microbiology, Virology Impact factor: 4.099, year: 2014

  18. Oral ingestion of hexavalent chromium through drinking water and cancer mortality in an industrial area of Greece - An ecological study

    Directory of Open Access Journals (Sweden)

    Stoltidis Melina

    2011-05-01

    Full Text Available Abstract Background Hexavalent chromium is a known carcinogen when inhaled, but its carcinogenic potential when orally ingested remains controversial. Water contaminated with hexavalent chromium is a worldwide problem, making this a question of significant public health importance. Methods We conducted an ecological mortality study within the Oinofita region of Greece, where water has been contaminated with hexavalent chromium. We calculated gender, age, and period standardized mortality ratios (SMRs for all deaths, cancer deaths, and specific cancer types of Oinofita residents over an 11-year period (1999 - 2009, using the greater prefecture of Voiotia as the standard population. Results A total of 474 deaths were observed. The SMR for all cause mortality was 98 (95% CI 89-107 and for all cancer mortality 114 (95% CI 94-136. The SMR for primary liver cancer was 1104 (95% CI 405-2403, p-value Conclusions Elevated cancer mortality in the Oinofita area of Greece supports the hypothesis of hexavalent chromium carcinogenicity via the oral ingestion pathway of exposure. Further studies are needed to determine whether this association is causal, and to establish preventive guidelines and public health recommendations.

  19. N-acetylcysteine attenuates hexavalent chromium-induced hypersensitivity through inhibition of cell death, ROS-related signaling and cytokine expression.

    Directory of Open Access Journals (Sweden)

    Yu-Hsuan Lee

    Full Text Available Chromium hypersensitivity (chromium-induced allergic contact dermatitis is an important issue in occupational skin disease. Hexavalent chromium (Cr (VI can activate the Akt, Nuclear factor κB (NF-κB, and Mitogen-activated protein kinase (MAPK pathways and induce cell death, via the effects of reactive oxygen species (ROS. Recently, cell death stimuli have been proposed to regulate the release of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α and interleukin-1 (IL-1. However, the exact effects of ROS on the signaling molecules and cytotoxicity involved in Cr(VI-induced hypersensitivity have not yet been fully demonstrated. N-acetylcysteine (NAC could increase glutathione levels in the skin and act as an antioxidant. In this study, we investigated the effects of NAC on attenuating the Cr(VI-triggered ROS signaling in both normal keratinocyte cells (HaCaT cells and a guinea pig (GP model. The results showed the induction of apoptosis, autophagy and ROS were observed after different concentrations of Cr(VI treatment. HaCaT cells pretreated with NAC exhibited a decrease in apoptosis and autophagy, which could affect cell viability. In addition, Cr (VI activated the Akt, NF-κB and MAPK pathways thereby increasing IL-1α and TNF-α production. However, all of these stimulation phenomena could be inhibited by NAC in both of in vitro and in vivo studies. These novel findings indicate that NAC may prevent the development of chromium hypersensitivity by inhibiting of ROS-induced cell death and cytokine expression.

  20. An evaluation of in vivo models for toxicokinetics of hexavalent chromium in the stomach

    Energy Technology Data Exchange (ETDEWEB)

    Sasso, A.F., E-mail: sasso.alan@epa.gov; Schlosser, P.M., E-mail: schlosser.paul@epa.gov

    2015-09-15

    Hexavalent chromium (Cr6) is a drinking water contaminant that has been detected in most of the water systems throughout the United States. In 2-year drinking water bioassays, the National Toxicology Program (NTP) found clear evidence of carcinogenic activity in male and female rats and mice. Because reduction of Cr6 to trivalent chromium (Cr3) is an important detoxifying step in the gastrointestinal (GI) tract prior to systemic absorption, models have been developed to estimate the extent of reduction in humans and animals. The objective of this work was to use a revised model of ex vivo Cr6 reduction kinetics in gastric juice to analyze the potential reduction kinetics under in vivo conditions for mice, rats and humans. A published physiologically-based pharmacokinetic (PBPK) model was adapted to incorporate the new reduction model. This paper focuses on the toxicokinetics of Cr6 in the stomach compartment, where most of the extracellular Cr6 reduction is believed to occur in humans. Within the range of doses administered by the NTP bioassays, neither the original nor revised models predict saturation of stomach reducing capacity to occur in vivo if applying default parameters. However, both models still indicate that mice exhibit the lowest extent of reduction in the stomach, meaning that a higher percentage of the Cr6 dose may escape stomach reduction in that species. Similarly, both models predict that humans exhibit the highest extent of reduction at low doses. - Highlights: • We outline a new in vivo model for hexavalent chromium reduction in the stomach. • We examine in vivo reduction for mice, rats, and humans under varying conditions. • Species differences in toxicokinetics may explain susceptibility. • We show that a simplified stomach reduction model is adequate for extrapolation. • Internal dose uncertainties still exist.

  1. Effet des polyamines sur la réduction du chrome hexavalent par des souches bactériennes et leur résistance

    Directory of Open Access Journals (Sweden)

    Tahri Joutey, N.

    2014-01-01

    Full Text Available Effect of polyamines on the reduction of hexavalent chromium by bacterial strains and their resistance. Polyamines are involved in several functions in bacteria. In this study, we examined the role of polyamines in hexavalent chromium (Cr[VI] reduction by three bacterial strains isolated from sites contaminated by tannery effluents. The strains were identified as Serratia proteamaculans, Leucobacter chromiireducens and Brevibacterium frigoritolerans. The inhibition of polyamine synthesis by α-difluoromethylornithine (DFMO caused a decrease in Cr(VI tolerance in the bacterial isolates, indicating the role of endogenous polyamines in resistance to Cr(VI. The exogenous application of polyamines (putrescine, spermidine, cadaverine was found to stimulate growth and Cr(VI reduction by the bacterial strains in Luria-Bertani medium. The results show the importance of polyamines in response to heavy metal stresses, especially Cr(VI toxicity.

  2. Insights into controls on hexavalent chromium in groundwater provided by environmental tracers, Sacramento Valley, California, USA

    Science.gov (United States)

    Manning, Andrew H.; Mills, Christopher T.; Morrison, Jean M.; Ball, Lyndsay B.

    2015-01-01

    Environmental tracers are useful for determining groundwater age and recharge source, yet their application in studies of geogenic Cr(VI) in groundwater has been limited. Environmental tracer data from 166 wells located in the Sacramento Valley, northern California, were interpreted and compared to Cr concentrations to determine the origin and age of groundwater with elevated Cr(VI), and better understand where Cr(VI) becomes mobilized and how it evolves along flowpaths. In addition to major ion and trace element concentrations, the dataset includes δ18O, δ2H, 3H concentration, 14C activity (of dissolved inorganic C), δ13C, 3He/4He ratio, and noble gas concentrations (He, Ne, Ar, Kr, Xe). Noble gas recharge temperatures (NGTs) were computed, and age-related tracers were interpreted in combination to constrain the age distribution in samples and sort them into six different age categories spanning from 10,000 yr old. Nearly all measured Cr is in the form of Cr(IV). Concentrations range from 3 mg L−1), and commonly have δ18O values enriched relative to local precipitation. These samples likely contain irrigation water and are elevated due to accelerated mobilization of Cr(VI) in the unsaturated zone (UZ) in irrigated areas. Group 2 samples are from throughout the valley and typically contain water 1000–10,000 yr old, have δ18O values consistent with local precipitation, and have unexpectedly warm NGTs. Chromium(VI) concentrations in Group 2 samples may be elevated for multiple reasons, but the hypothesis most consistent with all available data (notably, the warm NGTs) is a relatively long UZ residence time due to recharge through a deep UZ near the margin of the basin. A possible explanation for why Cr(VI) may be primarily mobilized in the UZ rather than farther along flowpaths in the oxic portion of the saturated zone is more dynamic cycling of Mn in the UZ due to transient moisture and redox conditions.

  3. Characterization of TBP containing polysiloxane membrane/insulator/semiconductor structures for hexavalent chromium detection

    Energy Technology Data Exchange (ETDEWEB)

    Zazoua, A. [Universite de Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria); Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Kherrat, R.; Samar, M.H. [Universite de Annaba, BP 12, El-Hadjar, Annaba (Algeria); Errachid, A. [Laboratori de Nanobioenginyeria-IBEC, CIBER, Parc Cientific de Barcelona (PCB)-Departament d' Electronica. Universitat de Barcelona, C/Marti i Franques 1, 08028 Barcelona (Spain); Jaffrezic-Renault, N. [LSA - UMR 5180 CNRS - Universite Claude Bernard Lyon 1, 69622 Villeurbanne cedex (France)], E-mail: nicole.jaffrezic@univ-lyon1.fr; Bessueille, F.; Leonard, D. [LSA - UMR 5180 CNRS - Universite Claude Bernard Lyon 1, 69622 Villeurbanne cedex (France)

    2008-07-01

    A hexavalent chromium-sensitive EMIS sensor (electrolyte membrane insulator semiconductor sensor) is prepared by deposition of a tributylphosphate (TBP) ionophore-containing siloprene membrane on a Si/SiO{sub 2}/Si{sub 3}N{sub 4} structure. The developed EMIS sensor was studied by means of impedance spectroscopy, capacitance-voltage, X-ray photoelectron spectrometry and FT-IR spectroscopy. From the flat-band shift of the EMIS structure, the nersntian response to the anionic species Cr{sub 2}O{sub 7}{sup -} was demonstrated. The linear range of detection is 10{sup -4} M to 10{sup -1} M and the detection limit is 10{sup -5} M. Sulfate and chloride anions are shown not to be interfering whereas carbonate ions present a pK{sup pot} equal to 0.19.

  4. Modacrylic anion-exchange fibers for Cr(VI) removal from chromium-plating rinse water in batch and flow-through column experiments.

    Science.gov (United States)

    Lee, Seung-Chan; Kang, Jin-Kyu; Sim, Eun-Hye; Choi, Nag-Choul; Kim, Song-Bae

    2017-11-10

    The aim of this study was to investigate Cr(VI) removal from chromium-plating rinse water using modacrylic anion-exchange fibers (KaracaronTM KC31). Batch experiments were performed with synthetic Cr(VI) solutions to characterize the KC31 fibers in Cr(VI) removal. Cr(VI) removal by the fibers was affected by solution pH; the Cr(VI) removal capacity was the highest at pH 2 and decreased gradually with a pH increase from 2 to 12. In regeneration and reuse experiments, the Cr(VI) removal capacity remained above 37.0 mg g -1 over five adsorption-desorption cycles, demonstrating that the fibers could be successfully regenerated with NaCl solution and reused. The maximum Cr(VI) removal capacity was determined to be 250.3 mg g -1 from the Langmuir model. In Fourier-transform infrared spectra, a Cr = O peak newly appeared at 897 cm -1 after Cr(VI) removal, whereas a Cr-O peak was detected at 772 cm -1 due to the association of Cr(VI) ions with ion-exchange sites. X-ray photoelectron spectroscopy analyses demonstrated that Cr(VI) was partially reduced to Cr(III) after the ion exchange on the surfaces of the fibers. Batch experiments with chromium-plating rinse water (Cr(VI) concentration = 1178.8 mg L -1 ) showed that the fibers had a Cr(VI) removal capacity of 28.1-186.4 mg g -1 under the given conditions (fiber dose = 1-10 g L -1 ). Column experiments (column length = 10 cm, inner diameter = 2.5 cm) were conducted to examine Cr(VI) removal from chromium-plating rinse water by the fibers under flow-through column conditions. The Cr(VI) removal capacities for the fibers at flow rates of 0.5 and 1.0 mL min -1 were 214.8 and 171.5 mg g -1 , respectively. This study demonstrates that KC31 fibers are effective in the removal of Cr(VI) ions from chromium-plating rinse water.

  5. COST EFFECTIVE CONTROL OF HEXAVALENT CHROMIUM AIR EMISSIONS FROM FUNCTIONAL CHROMIUM ELECTROPLATING

    Science.gov (United States)

    This paper will summrize thie pollution prevention (p2) method to control stack emissions from hard chromium plating operations performed by the USEPA's National Risk Management Research Laboratory (NRMRL) over the last four years. During literature research and user surveys, it...

  6. Effect of Process Variables, Adsorption Kinetics and Equilibrium Studies of Hexavalent Chromium Removal from Aqueous Solution by Date Seeds and its Activated Carbon by ZnCl2

    Directory of Open Access Journals (Sweden)

    Samar K. Theydan

    2018-03-01

    Full Text Available The adsorption of hexavalent chromium by preparing activated carbon from date seeds with zinc chloride as chemical activator and granular date seeds was studied in a batch system. The characteristics of date seeds and prepared activated carbon (ZAC were determined and found to have a surface area 500.01 m2/g and 1050.01 m2/g , respectively and iodine number of 485.78 mg/g and 1012.91 mg/g, respectively. The effects of PH value (2-12, initial sorbate concentration(50-450mg/L, adsorbent weight (0.004-0.036g and contact time (30-150 min on the adsorption process were studied . For Cr(VI adsorption on ZAC, at 120 min time contact, pH solution 2 and 0.02 adsorbent weight will achieve an amount of 35.6 mg/g adsorbed . While when use date seeds as adsorbent , conditions of 3 solution pH, 0.02 absorbent weight , and 120 contact time gave 26.49 mg/g adsorbed amount. Using both Langmuir, Freundlich and Sips models were explain the dsorption isotherms. It declare that the Sips model fits well with the experimental data with a maximum Cr( VI adsorption capacity for (ZAC and granular date stone 233.493 and 208.055 mg/g, respectively . The kinetics data which obtained at different initial Cr(VI concentrations were examined by using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models . The result gained showed that the second-order model was only describing well the empirical kinetics data of both (ZAC and granular date seeds. It was noticed that the granular date seeds has adsorption performance lower than the (ZAC.

  7. Biosorption of hexavalent Chromium by the agricultural wastes of the cotton and barberry plants

    Directory of Open Access Journals (Sweden)

    Najme Boosaeidi

    2017-09-01

    Full Text Available Hexavalent chromium, a highly toxic metal ion employed in industrial activities, is considered as a first priority pollutant. In this study, the capsule walls of the boll of cotton (cotton waste, CW and the waste obtained from pruning barberry bushes (barberry waste, BW were investigated as cheap and locally available adsorbents for Cr (VI removal. The adsorption behavior, equilibrium, and kinetic properties have been studied through batch experiments. Specifically, the sample pH showed a significant effect and an initial pH of 2.0 was most favorable for the effective removal of chromium. The equilibrium adsorption data were well fitted to the Langmuir adsorption equation with the maximum adsorption capacities of 20.7and 15.5mg/gfor CW and BW, respectively. The kinetic evaluations showed a rapid rate of adsorption (within 10 min that followed the pseudo-second order kinetic model. In competitive adsorption tests, Cl̶ had the least effect on the adsorption efficiency of Cr (VI, especially for CW. The results indicate the potential for the application of the studied agricultural wastes as adsorbents to reduce Cr (VI concentration in aqueous samples.

  8. Efficient Catalytic Reduction of Hexavalent Chromium With Pd-decorated Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Dang; Choi, Hyun Chul [Chonnam National University, Gwangju (Korea, Republic of)

    2016-05-15

    Heavy metal pollution is currently a serious environmental issue. Chromium (Cr) and chromium compounds are commonly found in wastewater discharged by various industries such as wood preservation, leather tanning, electroplating, metal finishing, and the production of chemicals. Pd nanoparticles can easily be introduced into CNTs by performing DCC-activated amidation. Our TEM and XRD results indicate that well-dispersed metallic Pd nanoparticles are anchored on the surface of the amidated CNTs. The XPS results suggest that the Pd content of the sample is approximately 9.8 atomic %. In comparison with the commercial Pd catalyst, the prepared Pd-CNTs were demonstrated to exhibit good catalytic activity in the reduction of 4-NP by NaBH4. Moreover, the Pd-CNT catalyst can easily be separated by performing a simple filtration and reused over at least 10 cycles. This Pd-CNT catalyst is therefore believed to have significant potential for use as a reusable catalyst in the reduction of Cr(Vi)

  9. Field screening for hexavalent chromium in soil: A fast-turnaround field method based on water extraction

    International Nuclear Information System (INIS)

    McCain, R.G.; Baechler, M.A.

    1994-01-01

    Sodium dichromate has been identified as a contaminant of concern at several waste sites on the Hanford Site. Although chromium standards for soil are typically stated in terms of total chrome, much of the toxicity and carcinogenicity are attributed to the hexavalent state, which typically exists as a relatively mobile anion. Investigation and removal of crushed drums potentially containing residual sodium dichromate required a field test for hexavalent chromium to support characterization and remediation activities. Previous experience with a commercially available field test kit had been unsuccessful. This stimulated an effort to determine potential sources of error in the field test and led to a number of modifications that significantly improved the reliability of the test

  10. Elevated Frequencies of Micronuclei and other Nuclear Abnormalities of Chrome Plating Workers Occupationally Exposed to Hexavalent Chromium

    OpenAIRE

    Sudha, S; Kripa, SK; Shibily, P; Shyn, J

    2011-01-01

    Background Biomonitoring provides a useful tool to estimate the genetic risk from exposure to genotoxic agents. The aim of this study was to assess the potential cytogenetic damage associated with occupational exposure to hexavalent chromium by using micronuclei (MN) as a biomarker. Methods This was a cross-sectional study and all participants were males. Both the exposed and control individuals were selected from Coimbatore, Southern India. Exfoliated buccal cells from 44 chrome plating work...

  11. A novel solid phase extraction procedure on Amberlite XAD-1180 for speciation of Cr(III), Cr(VI) and total chromium in environmental and pharmaceutical samples

    International Nuclear Information System (INIS)

    Narin, Ibrahim; Kars, Ayse; Soylak, Mustafa

    2008-01-01

    Due to the toxicity of chromium, species depend on their chemical properties and bioavailabilities, speciation of chromium is very important in environmental samples. A speciation procedure for chromium(III), chromium(VI) and total chromium in environmental samples is presented in this work, prior to flame atomic absorption spectrometric determination of chromium. The procedure is based on the adsorption of Cr(III)-diphenylcarbazone complex on Amberlite XAD-1180 resin. After oxidation of Cr(III), the developed solid phase extraction system was applied to determinate the total chromium. Cr(III) was calculated as the difference between the total Cr content and the Cr(VI) content. The analytical conditions for the quantitative recoveries of Cr(VI) on Amberlite XAD-1180 resin were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was found to be 75. The detection limits (LOD) based on three times sigma of the blank (N: 21) for Cr(VI) and total chromium were 7.7 and 8.6 μg/L, respectively. Satisfactory results for the analysis of total chromium in the stream sediment (GBW7310) certified reference material for the validation of the presented method was obtained. The procedure was applied to food, water and pharmaceutical samples successfully

  12. The removal of Cr(VI from aqueous solution by almond green hull waste material: kinetic and equilibrium studies

    Directory of Open Access Journals (Sweden)

    Negin Nasseh

    2017-12-01

    Full Text Available The discharge of industrial effluents containing hexavalent chromium into the environment can be very harmful to living things. Therefore, prior to effluent discharge into the environment, hexavalent chromium should be removed from contaminated water and especially from wastewaters. In the present work, almond green hull powder (AGHP was investigated for the removal of hexavalent chromium from wastewater. The effects of pH (2–10, adsorbent dose (2–24 g L−1, Cr(VI concentration (10–100 mg L−1, contact time (1–60 min, and temperature (5–50 °C were studied. All the experiments were performed in triplicate and average results were reported. The surface morphology, pore volume and size, pH of zero point charge (pHZPC and surface functional groups of AGHP were characterized. Isotherm and kinetic evaluations were also conducted in the present study. The results revealed that the adsorption of Cr(VI by AGHP was an adsorbate, adsorbent, and temperature dependent process that was favorable under acidic conditions. Furthermore, AGHP absorbed over 99% of chromium from the solutions containing 10–100 mg L−1 of Cr(VI based on the Freundlich model. In summary, hexavalent chromium was not found in almond kernel. Biosorption onto AGHP is an affordable and economical adsorption process for treating Cr(VI-laden industrial wastewater.

  13. Acute toxicity of sodium chloride, pentachlorophenol, Guthion, and hexavalent chromium to fathead minnows (Pimephales promelas) and goldfish (Carassius auratus)

    Energy Technology Data Exchange (ETDEWEB)

    Adelman, I.R.; Smith, L.L. Jr.; Siesennop, G.D.

    1976-02-01

    The 96-h LC50's for sodium chloride were 7650 and 7341 mg/liter, for pentachlorophenol 0.21 and 0.22 mg/liter, for Guthion 1.9 and 2.4 mg/liter, and for hexavalent chromium 48 and 120 mg/liter, for fathead minnows (Pimephales promelas) and goldfish (Carassius auratus), respectively. Threshold LC50's were reached in 6 days for sodium chloride (7650 and 7322 mg/liter for fathead minnows and goldfish, respectively), and pentachlorophenol (0.21 and 0.21 mg/liter), but were not attained in 11 days (termination of testing) with Guthion (0.76 and 0.80 mg/liter) and hexavalent chromium (18 and 33 mg/liter). With pentachlorophenol and Guthion goldfish were initially more resistant, but by termination there was no significant difference in LC50's between the two species. With hexavalent chromium the goldfish were more resistant throughout the 11-day test, and with sodium chloride goldfish were initially more resistant but at attainment of a threshold LC50 were less resistant. Use of toxicity curves for assessment of acute mortality permits interpretation not possible in 96-h tests where LC50's are computed at 24-h intervals.

  14. Comparative cytotoxicity and genotoxicity of soluble and particulate hexavalent chromium in human and hawksbill sea turtle (Eretmochelys imbricate) skin cells

    OpenAIRE

    Young, Jamie L.; Wise, Sandra S.; Xie, Hong; Zhu, Cairong; Fukuda, Tomokazu; Wise, John Pierce

    2015-01-01

    Chromium is both a global marine pollutant and a known human health hazard. In this study, we compare the cytotoxicity and genotoxicity of both soluble and particulate chromate in human and hawksbill sea turtle (Eretmochelys imbricata) skin fibroblasts. Our data show that both soluble and particulate Cr(VI) induce concentration-dependent increases in cytotoxicity, genotoxicity, and intracellular Cr ion concentrations in both human and hawksbill sea turtle fibroblasts. Based on administered co...

  15. Recovery and reuse of hexavalent chromium from aqueous solutions by a hybrid technique of electrodialysis and ion exchange

    OpenAIRE

    Gayathri, R.; Senthil Kumar, P.

    2010-01-01

    The chrome plating industry is one of the highly polluting industries whose effluent mainly consists of chromium(VI). This compound is highly toxic to aquatic life and human health. The rinse water constituents reflect the chrome plating bath characteristics; generally dead tank wash water contains about 1% of the plating bath concentration. Other metals and metal compounds usually considered as toxic can be precipitated out by suitably adjusting the pH of the wastewaters. However, Cr(VI) is ...

  16. Quantifying Cr(VI) Production and Export from Serpentine Soil of the California Coast Range.

    Science.gov (United States)

    McClain, Cynthia N; Fendorf, Scott; Webb, Samuel M; Maher, Kate

    2017-01-03

    Hexavalent chromium (Cr(VI)) is generated in serpentine soils and exported to surface and groundwaters at levels above health-based drinking water standards. Although Cr(VI) concentrations are elevated in serpentine soil pore water, few studies have reported field evidence documenting Cr(VI) production rates and fluxes that govern Cr(VI) transport from soil to water sources. We report Cr speciation (i) in four serpentine soil depth profiles derived from the California Coast Range serpentinite belt and (ii) in local surface waters. Within soils, we detected Cr(VI) in the same horizons where Cr(III)-minerals are colocated with biogenic Mn(III/IV)-oxides, suggesting Cr(VI) generation through oxidation by Mn-oxides. Water-extractable Cr(VI) concentrations increase with depth constituting a 7.8 to 12 kg/km 2 reservoir of Cr(VI) in soil. Here, Cr(VI) is produced at a rate of 0.3 to 4.8 kg Cr(VI)/km 2 /yr and subsequently flushed from soil during water infiltration, exporting 0.01 to 3.9 kg Cr(VI)/km 2 /yr at concentrations ranging from 25 to 172 μg/L. Although soil-derived Cr(VI) is leached from soil at concentrations exceeding 10 μg/L, due to reduction and dilution during transport to streams, Cr(VI) levels measured in local surface waters largely remain below California's drinking water limit.

  17. Cr(VI) occurrence and geochemistry in water from public-supply wells in California

    Science.gov (United States)

    Izbicki, John; Wright, Michael; Seymour, Whitney A.; McCleskey, R. Blaine; Fram, Miranda S.; Belitz, Kenneth; Esser, Bradley K.

    2015-01-01

    Hexavalent chromium, Cr(VI), in 918 wells sampled throughout California between 2004 and 2012 by the Groundwater Ambient Monitoring and Assessment-Priority Basin Project (GAMA-PBP) ranged from less than the study reporting limit of 1 microgram per liter (μg/L) to 32 μg/L. Statewide, Cr(VI) was reported in 31 percent of wells and equaled or exceeded the recently established (2014) California Maximum Contaminant Level (MCL) for Cr(VI) of 10 μg/L in 4 percent of wells. Cr(VI) data collected for regulatory purposes overestimated Cr(VI) occurrence compared to spatially-distributed GAMA-PBP data. Ninety percent of chromium was present as Cr(VI), which was detected more frequently and at higher concentrations in alkaline (pH ≥ 8), oxic water; and more frequently in agricultural and urban land uses compared to native land uses. Chemical, isotopic (tritium and carbon-14), and noble-gas data show high Cr(VI) in water from wells in alluvial aquifers in the southern California deserts result from long groundwater-residence times and geochemical reactions such as silicate weathering that increase pH, while oxic conditions persist. High Cr(VI) in water from wells in alluvial aquifers along the west-side of the Central Valley results from high-chromium in source rock eroded to form those aquifers, and areal recharge processes (including irrigation return) that can mobilize chromium from the unsaturated zone. Cr(VI) co-occurred with oxyanions having similar chemistry, including vanadium, selenium, and uranium. Cr(VI) was positively correlated with nitrate, consistent with increased concentrations in areas of agricultural land use and mobilization of chromium from the unsaturated zone by irrigation return.

  18. Column study of enhanced Cr(VI) removal and longevity by coupled abiotic and biotic processes using Fe0 and mixed anaerobic culture

    DEFF Research Database (Denmark)

    Zhong, Jiawei; Yin, Weizhao; Li, Yongtao

    2017-01-01

    In this study, Fe(0) and mixed anaerobic culture were integrated in one column to investigate the coupled abiotic and biotic effects on hexa-valent chromium (Cr(VI)) removal and column longevity with an abiotic Fe(0) column in the control experiments. According to the breakthrough study, a slower...

  19. Electrochemical removal of hexavalent chromium from wastewater using Platinum-Iron/Iron-carbon nanotubes and bipolar Electrodes

    Directory of Open Access Journals (Sweden)

    Hoshyar Hossini

    2015-01-01

    Full Text Available Background: In recent decades, electrocoagulation (EC has engrossed much attention as an environmental-friendly and effectiveness process. In addition, the EC process is a potential suitable way for treatment of wastewater with concern to costs and environment. The object of this study was electrochemical evaluation of chromium removal from industrial wastewater using Platinum and carbon nanotubes electrodes. Materials and Methods: The effect of key variables including pH (3–9, hexavalent chromium concentration (50–300 mg/l, supporting electrolyte (NaCl, KCl, Na2CO3 and KNO3 and its dosage, Oxidation-Reduction variations, sludge generation rate and current density (2–20 mA/cm2 was determined. Results: Based on experimental data, optimum conditions were determined in 20, 120 min, pH 3, NaCl 0.5% and 100 mg/L initial concentration of chromium. Conclusions: Removal of hexavalent chromium from the wastewater could be successfully performanced using Platinum-Iron/Iron-carbon nanotubes and bipolar Electrodes.

  20. A Comparative Survey on Parameters Influencing on Hexavalent Chromium Measurement as an Occupational Carcinogen

    Directory of Open Access Journals (Sweden)

    A. Tirgar

    2008-07-01

    Full Text Available Introduction & Objective: Hexavalent chromium, Cr+6, is a very harmful pollutant and a relatively unstable compound that is present in many industries. It is a known human respiratory carcinogen and occupational exposure to this chemical is associated with different health hazards. The purpose of this study was to evaluate the effects of four parameters including: type of sampling head, sampling height from the surface of electroplating solution, sampling duration, and sample storage duration on Cr+6 mist monitoring.Materials & Methods: To evaluate the influence of the main parameters as an experimental study, the 24 factorial design was applied at constant electroplating condition. A chromium electroplating bath with the ability to produce homogenous mist was used to create Cr+6 mist in laboratory setting. The National Institute for Occupational Safety and Health (NIOSH method 7600 was used to determine the Cr+6 concentration. Results: The results of 48 Cr+6 mist samples showed that Cr+6 concentration was higher: (1 for sampling by closed-face filter cassettes than for sampling by open-face filter cassettes (P<0.001; (2 for samples collected at 35 cm above the electroplating solution surface than for samples collected at 50 cm (P <0.001; (3 for sampling duration of 30 minutes than for sampling duration of 180 minutes (P <0.001; and, (4 for samples extracted immediately after sampling than for samples with delayed extraction (24 hours after sampling (P <0.001. Conclusion: It is concluded that the accuracy of Cr+6 mist sampling in electroplating shops will be enhanced when: (1 a closed-face filter cassette is used to prevent liquid splash contamination; (2 the sampling height is suitable as determined by further research; (3 the sampling duration is short (approximately 30 minutes; and, (4 the extraction of the Cr+6 sample is performed as soon as the sampling is completed.

  1. Mitigation of Hexavalent Chromium in Storm Water Resulting from Demolition of Large Concrete Structure at the East Tennessee Technology Park - 12286

    Energy Technology Data Exchange (ETDEWEB)

    Britto, Ronnie; Brown, Bridget; Hale, Timothy B.; Hensley, Janice L.; Johnson, Robert T.; Patel, Madhu [Tetra Tech, Inc. (United States); Emery, Jerry A. [Energy Solutions, Inc. (United States); Gaston, Clyde [LATA-SHARP Remediation Services - LSRS (United States); Queen, David C. [U.S. DOE-ORO (United States)

    2012-07-01

    American Recovery and Reinvestment Act (ARRA) funding was provided to supplement the environmental management program at several DOE sites, including the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. Demolition of the ETTP K-33 Building, the largest building to be demolished to date in Oak Ridge, was awarded to LSRS in FY-2010 under the ARRA program. The K-33 building was an 82 foot tall 2-story structure covering approximately 32 acres. Once this massive building was brought down to the ground, the debris was segregated and consolidated into piles of concrete rubble and steel across the remaining pad. The process of demolishing the building, tracking across concrete debris with heavy equipment, and stockpiling the concrete rubble caused it to become pulverized. During and after storm events, hexavalent chromium leached from the residual cement present in the large quantities of concrete. Storm water control measures were present to preclude migration of contaminants off-site, but these control measures were not designed to control hexavalent chromium dissolved in storm water from reaching nearby receiving water. The following was implemented to mitigate hexavalent chromium in storm water: - Steel wool was distributed around K-33 site catch basins and in water pools as an initial step in addressing hexavalent chromium. - Since the piles of concrete were too massive and unsafe to tarp, they were placed into windrows in an effort to reduce total surface area. - A Hach colorimetric field meter was acquired by the K-33 project to provide realtime results of hexavalent chromium in site surface water. - Three hexavalent chromium treatment systems were installed at three separate catch basins that receive integrated storm water flow from the K-33 site. Sodium bisulfite is being used as a reducing agent for the immobilization of hexavalent chromium while also assisting in lowering pH. Concentrations initially were 310 - 474 ppb of hexavalent chromium in

  2. Modeling of kinetics of Cr(VI) sorption onto grape stalk waste in a stirred batch reactor

    International Nuclear Information System (INIS)

    Escudero, Carlos; Fiol, Nuria; Poch, Jordi; Villaescusa, Isabel

    2009-01-01

    Recently, Cr(VI) removal by grape stalks has been postulated to follow two mechanisms, adsorption and reduction to trivalent chromium. Nevertheless, the rate at which both processes take place and the possible simultaneity of both processes has not been investigated. In this work, kinetics of Cr(VI) sorption onto grape stalk waste has been studied. Experiments were carried out at different temperatures but at a constant pH (3 ± 0.1) in a stirred batch reactor. Results showed that three steps take place in the process of Cr(VI) sorption onto grape stalk waste: Cr(VI) sorption, Cr(VI) reduction to Cr(III) and the adsorption of the formed Cr(III). Taking into account the evidences above mentioned, a model has been developed to predict Cr(VI) sorption on grape stalks on the basis of (i) irreversible reduction of Cr(VI) to Cr(III) reaction, whose reaction rate is assumed to be proportional to the Cr(VI) concentration in solution and (ii) adsorption and desorption of Cr(VI) and formed Cr(III) assuming that all the processes follow Langmuir type kinetics. The proposed model fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The proposed model would be helpful for researchers in the field of Cr(VI) biosorption to design and predict the performance of sorption processes.

  3. INFLUENCE OF HEXAVALENT CHROMIUM INITIAL CONCENTRATION ON RETARDATION FACTOR AND CONTAMINANT VELOCITY IN A SOIL MEDIA

    Directory of Open Access Journals (Sweden)

    K. SHIVA PRASHANTH KUMAR

    2016-02-01

    Full Text Available Sources of soil and ground water contamination are many and include many folds of accidental spills and leaks of toxic and hazardous chemicals. Preparation of ground water contamination model needs good understanding of the behavior of contaminant transport through soil media for predicting the level of contamination of ground water in the near future at the intended site conditions. Sorption is a natural process; due to its presence, the contaminant can move slowly as compared to the ground water and hence the effects of sorption must be taken into consideration while predicting the travel time of the contaminant to reach the ground water sources. This paper discusses the results of column test studies carried out in the laboratory under controlled conditions about the spreading of contaminant (Hexavalent chromium, Cr (VI through the clay mixed red soil at two different initial concentrations (800 mg/L and 4200 mg/L. The variations of the contaminant flow velocity and retardation factor for two different initial concentrations of contaminant were brought out and discussed. The contaminant flow velocity drastically coming down for a relative concentration of 0 to 0.2 and beyond this range, the contaminant flow velocity value is decreasing in a slow rate for both the lower and higher initial contaminant concentrations tested. At the lower relative concentration, the higher retardation factor was observed and it may be due to slowly filling the available sorption sites in the soil column.

  4. Early renal effects of occupational exposure to low-level hexavalent chromium

    Energy Technology Data Exchange (ETDEWEB)

    Nagaya, Teruo (Dept. of Public Health, Gifu Univ. School of Medicine, Tsukasa-machi (Japan)); Ishikawa, Noriko (Occupational Hygiene Center, Gifu Labour Standards Association, Hikie (Japan)); Hata, Hideo (Occupational Hygiene Center, Gifu Labour Standards Association, Hikie (Japan)); Takahashi, Akemi (Gifu-shi Central Public Health Center, Miyako-dori (Japan)); Yoshida, Izumi (Gifu-shi Central Public Health Center, Miyako-dori (Japan)); Okamoto, Yoshinari (Gifu-shi Central Public Health Center, Miyako-dori (Japan))

    1994-05-01

    To detect early renal effects of occupational exposure to hexavalent chromium (Cr), urinary total proteins (U-TP), urinary albumin (U-Alb) and urinary retinol-binding protein (U-RBP) were determined in 166 male Cr platers and 106 male controls. The mean employment time in Cr plating for the platers was 12.6 years. Urinary Cr (U-Cr), which was determined as an index of Cr exposure, ranged from ''not detected'' to 19.91 [mu]g/g creatinine in the platers. The U-Cr level was lower than those in other previous studies. Age-adjusted U-TP, U-Alb or U-RBP levels were not different between the platers and the controls. In the platers, a significant positive correlation was found between age-adjusted U-TP and U-Cr, but U-Cr had no significant relation to age-adjusted U-Alb or U-RBP level. Employment time had no effect on any age-adjusted urinary proteins. The Cr exposure may have been too low to induce definite renal dysfunction. Early renal effects of low-level Cr exposure may be mild, and may not be specific to renal function. (orig.)

  5. Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B

    2012-01-01

    Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

  6. Germination and sporophytic development of Regnellidium diphyllum Lindman (Marsileaceae in the presence of hexavalent chromium Germinação e desenvolvimento esporofítico de Regnellidium diphyllum Lindman (Marsileaceae na presença de cromo hexavalente

    Directory of Open Access Journals (Sweden)

    MA. Kieling-Rubio

    2010-12-01

    Full Text Available Regnellidium diphyllum Lindman is a heterosporous fern, growing in aquatic environments and surrounding wetlands, which is assumed to be threatened by increasing water pollution and disappearance of its natural habitats. Among contaminants, hexavalent chromium - Cr(VI - is known to be present in effluents from some leather tanning factories. Megaspore germination tests were performed using Meyer's solution, at concentrations 0 (control, 0.1, 0.5, 1, 5, 10, 15, 20, 30, 50, and 80 mg.L-1, from a standard solution of Titrisol® 1000 mg.L-1. The primary development of apomictic sporophytes was studied using solutions containing 0.025 to 4.8 mg.L-1 of Cr(VI. The experiments were conducted in a growth chamber at 24 ± 1 ºC and for a 12-hour photoperiod under fluorescent lights, providing a nominal irradiance of 77 µmol.m-2/s. Significant differences in megaspore germination, with subsequent sporophytic development, were verified from 0.5 mg.L-1 Cr(VI concentration onwards. Growth of primary root and primary and secondary leaves was significantly reduced at 3.2 mg.L-1 Cr(VI concentration or higher. Considering the pollution from Cr(VI in some areas of R. diphyllum natural occurrence, these data indicate that low reproductive rates and disappearance of populations are likely to occur in these situations.Regnellidium diphyllum Lindman é uma filicínea heterosporada que se desenvolve em ambientes aquáticos e áreas úmidas circundantes, sendo considerada ameaçada pelo aumento da poluição e desaparecimento dos seus hábitats naturais. Entre os contaminantes, o cromo hexavalente - Cr(VI - é conhecido por estar presente nos efluentes de algumas indústrias de curtimento de couro. Testes de germinação foram realizados em meio líquido de Meyer, com concentrações de 0(controle; 0,1; 0,5; 1; 5; 10; 15; 20; 30; 50; e 80 mg.L-1 de Cr(VI, a partir de uma solução padrão de Titrisol® a 1000 mg.L-1. O desenvolvimento primário dos esporófitos apom

  7. Assessment of immunotoxicity in female Fischer 344/N and Sprague Dawley rats and female B6C3F1 mice exposed to hexavalent chromium via the drinking water.

    Science.gov (United States)

    Shipkowski, Kelly A; Sheth, Christopher M; Smith, Matthew J; Hooth, Michelle J; White, Kimber L; Germolec, Dori R

    2017-12-01

    Sodium dichromate dihydrate (SDD), an inorganic compound containing hexavalent chromium (Cr(VI)), is a common environmental contaminant of groundwater sources due to widespread industrial use. There are indications in the literature that Cr(VI) may induce immunotoxic effects following dermal exposure, including acting as both an irritant and a sensitizer; however, the potential immunomodulatory effects of Cr(VI) following oral exposure are relatively unknown. Following the detection of Cr(VI) in drinking water sources, the National Toxicology Program (NTP) conducted extensive evaluations of the toxicity and carcinogenicity of SDD following drinking water exposure, including studies to assess the potential for Cr(VI) to modulate immune function. For the immunotoxicity assessments, female Fischer 344/N (F344/N) and Sprague Dawley (SD) rats and female B 6 C 3 F 1 mice were exposed to SDD in drinking water for 28 consecutive days and evaluated for alterations in cellular and humoral immune function as well as innate immunity. Rats were exposed to concentrations of 0, 14.3, 57.3, 172, or 516 ppm SDD while mice were exposed to concentrations of 0, 15.6, 31.3, 62.5, 125, or 250 ppm SDD. Final mean body weight and body weight gain were decreased relative to controls in 250 ppm B 6 C 3 F 1 mice and 516 ppm SD rats. Water consumption was significantly decreased in F344/N and SD rats exposed to 172 and 516 ppm SDD; this was attributed to poor palatability of the SDD drinking water solutions. Several red blood cell-specific parameters were significantly (5-7%) decreased in 250 ppm mice; however, these parameters were unaffected in rats. Sporadic increases in the spleen IgM antibody response to sheep red blood cells (SRBC) were observed, however, these increases were not dose-dependent and were not reproducible. No significant effects were observed in the other immunological parameters evaluated. Overall, exposure to Cr(VI) in drinking water had limited effects on

  8. Utilization of cross-linked carboxymethyl κ-carrageenan as adsorbent for hexavalent chromium (Cr+6) ion

    International Nuclear Information System (INIS)

    Antonio, Princess Joyce R.; Punzalan, Mark Emile H.; Saturno, Rochelle Anne B.; Bayquen, Aristea V.

    2009-01-01

    The sorption behavior of cross-linked carboxymethyl κ-carrageenan as an alternative adsorbent for hexavalent chromium was studies. The κ-carrageenan had been carboxymethylated three times with 40% NaOH and monochloroacetic acid (MCA) in 80% isopropyl alcohol at 40 0 C. Carboxymethylated κ-carrageenan was crosslinked using Co 60 irradiation facility at PNRI. Batch experiments were conducted using prepared stock solution of Cr 6+ (70 ppm) under different sorption parameters at room temperature. These parameters include effects of pH, initial metal ion concentration, and contact time. Carboxymethylation and cross-linking was successfully achieved under optimum parameters. It was observed that cross-linked carboxymethyl κ-carrageenan best adsorbs chromium (VI) ion at pH 6, removing 41.59% of the metal ions present in the solution. Freundlich isotherm gave the highest correlation, R 2 , which is equal to 0.9880. This suggests the existence of mutilayer adsorption of the hexavalent chromium ions. Maximum adsorption was found to be at contact time of 2.5 hours and the concentration of the solution remains almost constant after 5 hours. The adsorption kinetics could be approximated favorably by the Lagergren pseudo-second-order kinetic model giving a correlation, R 2 , of 0.9985 and adsorption capacity, qmax, equal to 27.88 mg g +1 . (author)

  9. The electrochemical aspect of the corrosion of austenitic stainless steels, in nitric acid and in the presence of hexavalent chromium (1961); Aspect electrochimique de la corrosion d'aciers inoxydables austenitiques en milieu nitrique et en presence de chrome hexavalent (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Coriou, H; Hure, J; Plante, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The corrosion of austenitic stainless steels in boiling nitric acid markedly increases when the medium contains hexavalent chromium ions. Because of several redox phenomena, the potential of the steel generally changes in course of time. Measurements show a relation between the weight loss and the potential of specimens. Additions of Mn(VII) and Ce(IV) are compared with that of Cr(VI), and show that the relation is a general one. The attack cf the metal in oxidizing media is largely intergranular, leading to exfoliation of the grains, although the steel studied is not sensitive to the classical Huey and Strauss tests. Also even in the absence of any other oxidizing reaction, the current density observed when the steel is anodically polarized under potentiostatic conditions does not correspond to the actual weight loss of the metal. (authors) [French] La corrosion d'aciers inoxydables austenitiques en milieu nitrique bouillant augmente notablement quand le milieu contient des ions chrome a l'etat hexavalent. Par suite de divers phenomenes d'oxydo-reduction, le potentiel de l'acier evolue generalement au cours du temps. Les mesures effectuees permettent d'etablir une relation entre les pertes de poids et le potentiel des echantillons. L'addition de Mn(VI) et Ce(IV) est compare a celle de Cr(VI) et montre que la relation precedente s'applique de facon generale. L'attaque du metal en milieu oxydant est en grande, partie due a une corrosion intergranulaire conduisant a un dechaussement des grains bien que l'acier etudie ne soit pas sensible aux tests classiques de Huey et de Strauss. Aussi, meme en l'absence de toute autre reaction d'oxydation l'intensite qu l'on observerait en soumettant l'acier a un potentiel anodique dans un montage potentiostatique ne correspondrait pas a la perte de poids reelle du metal. (auteurs)

  10. Study on Cr(VI) Leaching from Cement and Cement Composites

    Science.gov (United States)

    Palascakova, Lenka; Kanuchova, Maria

    2018-01-01

    This paper reports an experimental study on hexavalent chromium leaching from cement samples and cement composites containing silica fume and zeolite additions that were subjected to various leaching agents. The water-soluble Cr(VI) concentrations in cements ranged from 0.2 to 3.2 mg/kg and represented only 1.8% of the total chromium content. The presence of chromium compounds with both chromium oxidation states of III and VI was detected in the cement samples by X-ray photoelectron spectroscopy (XPS). Leaching tests were performed in a Britton-Robinson buffer to simulate natural conditions and showed increased dissolution of Cr(VI) up to 6 mg/kg. The highest amount of leached hexavalent chromium was detected after leaching in HCl. The findings revealed that the leaching of chromium from cements was higher by 55–80% than that from the cement composites. A minimum concentration was observed for all cement samples when studying the relationship between the soluble Cr(VI) and the cement storage time. PMID:29690550

  11. NASA and ESA Collaboration on Hexavalent Chrome Alternatives: Pretreatments Only Final Test Report

    Science.gov (United States)

    Kessel, Kurt R.

    2015-01-01

    Hexavalent chromium (hex chrome or CR(VI)) is a widely used element within applied coating systems because of its self-healing and corrosion-resistant properties. The replacement of hex chrome in the processing of aluminum for aviation and aerospace applications remains a goal of great significance. Aluminum is the major manufacturing material of structures and components in the space flight arena. The National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are engaged in a collaborative effort to test and evaluate alternatives to hexavalent chromium containing corrosion coating systems. NASA and ESA share common risks related to material obsolescence associated with hexavalent chromium used in corrosion-resistant coatings.

  12. Characteristics and mechanisms of hexavalent chromium removal by biochar from sugar beet tailing

    International Nuclear Information System (INIS)

    Dong Xiaoling; Ma, Lena Q.; Li Yuncong

    2011-01-01

    Highlights: → Biochar from sugar beet tailing effectively removed Cr(VI) from solution. → Most of the Cr on the biochar was Cr(III). → Cr(VI) removal was via electrostatic attraction to biochar. → Reduction of Cr(VI) to Cr(III) ion and complexation between Cr(III) ion and biochar function groups were also important. → The maximum sorption capacity of biochar for Cr(VI) was123 mg/g. - Abstract: Removal of Cr(VI) from aqueous solutions using biochar from sugar beet tailing (SBT) was investigated as a function of pH, contact time, and biochar mass via batch experiments. The surface characteristics of SBT biochar before and after Cr(VI) sorption was investigated with scanning electron microscopy equipped with energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Desorption and X-ray photoelectron spectroscopy studies showed that most of the Cr bound to SBT biochar was Cr(III). These results indicated that the electrostatic attraction of Cr(VI) to positively charged biochar surface, reduction of Cr(VI) to Cr(III) ion, and complexation between Cr(III) ion and SBT's function groups were probably responsible for Cr(VI) removal by SBT biochar. An initial solution with a pH of 2.0 was most favorable for Cr(VI) removal. The sorption process can be described by the pseudo-second order equation and Langmuir isotherm. The maximum sorption capacity for Cr(VI) was 123 mg/g under an acidic medium, which was comparable to other low-cost sorbents.

  13. Optimization of factors affecting hexavalent chromium removal from simulated electroplating wastewater by synthesized magnetite nanoparticles.

    Science.gov (United States)

    Ataabadi, Mitra; Hoodaji, Mehran; Tahmourespour, Arezoo; Kalbasi, Mahmoud; Abdouss, Majid

    2015-01-01

    Hexavalent chromium is a mutagen and carcinogen that is of significant concern in water and wastewater. In the present study, magnetite nanoparticles (n-Mag) were investigated as a potential remediation technology for the decontamination of Cr (VI)-contaminated wastewater. Synthesized n-Mag was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET-N2 technology. To screen and optimize the factors affecting Cr (VI) removal efficiency by synthesized nanoparticles, Plackett-Burman (PB) and Taguchi experimental designs were used respectively. The crystalline produced n-Mag was in the size range of 60-70 nm and had a specific surface area (SSA) of 31.55 m(2) g(-1). Results of PB design showed that the most significant factors affecting Cr (VI) removal efficiency were initial Cr (VI) concentration, pH, n-Mag dosage, and temperature. In a pH of 2, 20 mg L(-1) of Cr (VI) concentration, 4 g L(-1)of n-Mag, temperature of 40 °C, 220 rpm of shaking speed, and 60 min of contact time, the complete removal efficiency of Cr (VI) was achieved. Batch experiments revealed that the removal of Cr (VI) by n-Mag was consistent with pseudo-second order reaction kinetics. The competition from common coexisting ions such as NO₃(-), SO₄(2-), and Cl(-) were not considerable, unless in the higher concentration of SO₄(2-). These results indicated that the readily synthesized magnetite nanoparticles have promising applications for the removal of Cr (VI) from aqueous solution.

  14. Oral Chromium Exposure and Toxicity

    Science.gov (United States)

    Sun, Hong; Brocato, Jason

    2015-01-01

    Hexavalent chromium [Cr(VI)] is a known carcinogen when inhaled. However, inhalational exposure to Cr(VI) affects only a small portion of the population, mainly by occupational exposures. In contrast, oral exposure to Cr(VI) is widespread and affects many people throughout the globe. In 2008, the National Toxicology Program (NTP) released a 2-year study demonstrating that ingested Cr(VI) was carcinogenic in rats and mice. The effects of Cr(VI) oral exposure is mitigated by reduction in the gut, however a portion evades the reductive detoxification and reaches target tissues. Once Cr(VI) enters the cell, it ultimately gets reduced to Cr(III), which mediates its toxicity via induction of oxidative stress during the reduction while Cr intermediates react with protein and DNA. Cr(III) can form adducts with DNA that may lead to mutations. This review will discuss the potential adverse effects of oral exposure to Cr(VI) by presenting up-to-date human and animal studies, examining the underlying mechanisms that mediate Cr(VI) toxicity, as well as highlighting opportunities for future research. PMID:26231506

  15. New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang [College of Environmental Science and Engineering, Anhui Normal University, South Jiuhua Road, 189, 241002 Wuhu (China); Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Fiol, Núria [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Villaescusa, Isabel, E-mail: Isabel.Villaescusa@udg.edu [Chemical Engineering Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain); Poch, Jordi [Applied Mathematics Department, Escola Politècnica Superior, Universitat de Girona, Ma Aurèlia Capmany, 61, 17071 Girona (Spain)

    2016-01-15

    In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data.

  16. New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

    International Nuclear Information System (INIS)

    Liu, Chang; Fiol, Núria; Villaescusa, Isabel; Poch, Jordi

    2016-01-01

    In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture. - Highlights: • A kinetic model including Cr(VI) reduction, Cr(VI) and Cr(III) sorption/desorption • Synergistic effect of Cu(II) on Cr(VI) elimination included in the model • Model validation by checking it against independent sets of data

  17. Influence of plants on the reduction of hexavalent chromium in wetland sediments

    Energy Technology Data Exchange (ETDEWEB)

    Zazo, Juan A. [Department of Chemical Engineering, Universidad Autonoma de Madrid, Madrid, 28049 (Spain)], E-mail: juan.zazo@uam.es; Paull, Jeffery S.; Jaffe, Peter R. [Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2008-11-15

    This work addresses the effect that plants (Typha latifolia and Carex lurida) have on the reduction of Cr(VI) in wetland sediments. Experiments were carried out using tubular microcosms, where chemical species were monitored along the longitudinal flow axis. Cr(VI) removal was enhanced by the presence of plants. This is explained by a decrease in the redox potential promoted by organic root exudates released by plants. Under these conditions sulfate reduction is enhanced, increasing the concentration of sulfide species in the sediment pore water, which reduce Cr(VI). Evapotranspiration induced by plants also contributed to enhance the reduction of Cr(VI) by concentrating all chemical species in the sediment pore water. Both exudates release and evapotranspiration have a diurnal component that affects Cr(VI) reduction. Concentration profiles were fitted to a kinetic model linking sulfide and Cr(VI) concentrations corrected for evapotranspiration. This expression captures both the longitudinal as well as the diurnal Cr(VI) concentration profiles. - The presence of plants enhances the reduction of Cr(VI) in wetland sediments by modifying the governing biogeochemical cycle.

  18. Recovery and reuse of hexavalent chromium from aqueous solutions by a hybrid technique of electrodialysis and ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Gayathri, R. [Sengunthar Engineering College, Tiruchengode (India). Dept. of Civil Engineering], e-mail: gay3civil@gmail.com; Senthil Kumar, P. [SSN College of Engineering, Chennai (India). Dept. of Chemical Engineering], E-mail: senthilkumarp@ssn.edu.in

    2010-01-15

    The chrome plating industry is one of the highly polluting industries whose effluent mainly consists of chromium(VI). This compound is highly toxic to aquatic life and human health. The rinse water constituents reflect the chrome plating bath characteristics; generally dead tank wash water contains about 1% of the plating bath concentration. Other metals and metal compounds usually considered as toxic can be precipitated out by suitably adjusting the pH of the wastewaters. However, Cr(VI) is soluble in almost all pH ranges and therefore an efficient treatment is required for the removal and recovery of chromium, and also for the reuse of wastewaters. The present study aims to recover the chromium by a hybrid technique of electrodialysis and ion exchange for the removal and concentration of chromate ions from the effluent. The different modes of operation like batch recirculation process, batch recirculation process with continuous dipping and continuous process were carried out to remove and recover the chromium from the effluent and the percentage reductions of chromium were found to be 98.69%, 99.18% and 100%, respectively. (author)

  19. Recovery and reuse of hexavalent chromium from aqueous solutions by a hybrid technique of electrodialysis and ion exchange

    International Nuclear Information System (INIS)

    Gayathri, R.; Senthil Kumar, P.

    2010-01-01

    The chrome plating industry is one of the highly polluting industries whose effluent mainly consists of chromium(VI). This compound is highly toxic to aquatic life and human health. The rinse water constituents reflect the chrome plating bath characteristics; generally dead tank wash water contains about 1% of the plating bath concentration. Other metals and metal compounds usually considered as toxic can be precipitated out by suitably adjusting the pH of the wastewaters. However, Cr(VI) is soluble in almost all pH ranges and therefore an efficient treatment is required for the removal and recovery of chromium, and also for the reuse of wastewaters. The present study aims to recover the chromium by a hybrid technique of electrodialysis and ion exchange for the removal and concentration of chromate ions from the effluent. The different modes of operation like batch recirculation process, batch recirculation process with continuous dipping and continuous process were carried out to remove and recover the chromium from the effluent and the percentage reductions of chromium were found to be 98.69%, 99.18% and 100%, respectively. (author)

  20. Recovery and reuse of hexavalent chromium from aqueous solutions by a hybrid technique of electrodialysis and ion exchange

    Directory of Open Access Journals (Sweden)

    R. Gayathri

    2010-03-01

    Full Text Available The chrome plating industry is one of the highly polluting industries whose effluent mainly consists of chromium(VI. This compound is highly toxic to aquatic life and human health. The rinse water constituents reflect the chrome plating bath characteristics; generally dead tank wash water contains about 1% of the plating bath concentration. Other metals and metal compounds usually considered as toxic can be precipitated out by suitably adjusting the pH of the wastewaters. However, Cr(VI is soluble in almost all pH ranges and therefore an efficient treatment is required for the removal and recovery of chromium, and also for the reuse of wastewaters. The present study aims to recover the chromium by a hybrid technique of electrodialysis and ion exchange for the removal and concentration of chromate ions from the effluent. The different modes of operation like batch recirculation process, batch recirculation process with continuous dipping and continuous process were carried out to remove and recover the chromium from the effluent and the percentage reductions of chromium were found to be 98.69%, 99.18% and 100%, respectively.

  1. Comparative cytotoxicity and genotoxicity of soluble and particulate hexavalent chromium in human and hawksbill sea turtle (Eretmochelys imbricata) skin cells.

    Science.gov (United States)

    Young, Jamie L; Wise, Sandra S; Xie, Hong; Zhu, Cairong; Fukuda, Tomokazu; Wise, John Pierce

    2015-12-01

    Chromium is both a global marine pollutant and a known human health hazard. In this study, we compare the cytotoxicity and genotoxicity of both soluble and particulate chromate in human and hawksbill sea turtle (Eretmochelys imbricata) skin fibroblasts. Our data show that both soluble and particulate Cr(VI) induce concentration-dependent increases in cytotoxicity, genotoxicity, and intracellular Cr ion concentrations in both human and hawksbill sea turtle fibroblasts. Based on administered concentration, particulate and soluble Cr(VI) were more cytotoxic and clastogenic to human cells than sea turtle cells. When the analysis was based on the intracellular concentration of Cr, the data showed that the response of both species was similar. The one exception was the cytotoxicity of intracellular Cr ions from soluble Cr(VI), which caused more cytotoxicity in sea turtle cells (LC50=271μM) than that of human cells (LC50=471μM), but its clastogenicity was similar between the two species. Thus, adjusting for differences in uptake indicated that the explanation for the difference in potency was mostly due to uptake rather than differently affected mechanisms. Overall these data indicate that sea turtles may be a useful sentinel for human health responses to marine pollution. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Comparative cytotoxicity and genotoxicity of soluble and particulate hexavalent chromium in human and hawksbill sea turtle (Eretmochelys imbricate) skin cells

    Science.gov (United States)

    Young, Jamie L.; Wise, Sandra S.; Xie, Hong; Zhu, Cairong; Fukuda, Tomokazu; Wise, John Pierce

    2015-01-01

    Chromium is both a global marine pollutant and a known human health hazard. In this study, we compare the cytotoxicity and genotoxicity of both soluble and particulate chromate in human and hawksbill sea turtle (Eretmochelys imbricata) skin fibroblasts. Our data show that both soluble and particulate Cr(VI) induce concentration-dependent increases in cytotoxicity, genotoxicity, and intracellular Cr ion concentrations in both human and hawksbill sea turtle fibroblasts. Based on administered concentration, particulate and soluble Cr(VI) were more cytotoxic and clastogenic to human cells than sea turtle cells. When the analysis was based on the intracellular concentration of Cr, the data showed the response of both species was similar. The one exception was the cytotoxicity of intracellular Cr ions from soluble Cr(VI), which caused more cytotoxicity in sea turtle cells (LC50=271 uM) that human cells (LC50=471 uM), but its clastogenicity was similar between the two species. Thus, adjusting for differences in uptake indicated the explanation for the difference in potency was mostly due to uptake rather than differently affected mechanisms. Overall these data indicate sea turtles may be a useful sentinel for human health responses to marine pollution. PMID:26440299

  3. Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: A potential source of geogenic Cr(VI) to groundwater

    International Nuclear Information System (INIS)

    Mills, Christopher T.; Morrison, Jean M.; Goldhaber, Martin B.; Ellefsen, Karl J.

    2011-01-01

    Highlights: → Southern Sacramento Valley soil and sediment has abundant naturally-occurring Cr(III). → Cr(III) resides mainly in chromite but some is associated with clays and Fe oxides. → Cr(VI) is mostly absent in surface soil but ubiquitous in deeper soil and sediment. → Cr(VI) increased linearly with time during lab soil incubations with no additions. → Cation exchange processes resulted in greater Cr(VI) generation rates. - Abstract: Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization's maximum contaminant level for drinking water (50 μg L -1 ) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacramento Valley of California where Cr(VI) concentrations in groundwater can approach or exceed 50 μg L -1 . To characterize Cr geochemistry in the area, samples from several soil auger cores (approximately 4 m deep) and drill cores (approximately 25 m deep) were analyzed for total concentrations of 44 major, minor and trace elements, Cr associated with labile Mn and Fe oxides, and Cr(VI). Total concentrations of Cr in these samples ranged from 140 to 2220 mg per kg soil. Between 9 and 70 mg per kg soil was released by selective extractions that target Fe oxides, but essentially no Cr was associated with the abundant reactive Mn oxides (up to ∼1000 mg hydroxylamine-reducible Mn per kg soil was present). Both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between Cr released in a 4-acid digestion versus total Cr (lithium metaborate fusion digestion) suggest that the majority of total Cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the Coast Range Mountains. Chromium(VI) in the samples studied ranged from 0 to 42

  4. Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: A potential source of geogenic Cr(VI) to groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Christopher T., E-mail: cmills@usgs.gov [United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver Federal Center, MS 964D, Denver, CO 80225 (United States); Morrison, Jean M.; Goldhaber, Martin B.; Ellefsen, Karl J. [United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Denver Federal Center, MS 964D, Denver, CO 80225 (United States)

    2011-08-15

    Highlights: > Southern Sacramento Valley soil and sediment has abundant naturally-occurring Cr(III). > Cr(III) resides mainly in chromite but some is associated with clays and Fe oxides. > Cr(VI) is mostly absent in surface soil but ubiquitous in deeper soil and sediment. > Cr(VI) increased linearly with time during lab soil incubations with no additions. > Cation exchange processes resulted in greater Cr(VI) generation rates. - Abstract: Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization's maximum contaminant level for drinking water (50 {mu}g L{sup -1}) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacramento Valley of California where Cr(VI) concentrations in groundwater can approach or exceed 50 {mu}g L{sup -1}. To characterize Cr geochemistry in the area, samples from several soil auger cores (approximately 4 m deep) and drill cores (approximately 25 m deep) were analyzed for total concentrations of 44 major, minor and trace elements, Cr associated with labile Mn and Fe oxides, and Cr(VI). Total concentrations of Cr in these samples ranged from 140 to 2220 mg per kg soil. Between 9 and 70 mg per kg soil was released by selective extractions that target Fe oxides, but essentially no Cr was associated with the abundant reactive Mn oxides (up to {approx}1000 mg hydroxylamine-reducible Mn per kg soil was present). Both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between Cr released in a 4-acid digestion versus total Cr (lithium metaborate fusion digestion) suggest that the majority of total Cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the Coast Range Mountains. Chromium(VI) in the samples studied ranged

  5. Chronic exposure to sublethal hexavalent chromium affects organ histopathology and serum cortisol profile of a teleost, Channa punctatus (Bloch)

    International Nuclear Information System (INIS)

    Mishra, Ashish K.; Mohanty, Banalata

    2009-01-01

    Effects of chronic exposures (one and two months) to sublethal doses of hexavalent chromium (2 and 4 mg/L potassium dichromate) on organ histopathology and serum cortisol profile were investigated and their overall impact on growth and behavior of a teleost fish, Channa punctatus was elucidated. Histopathological lesions were distinct in the vital organs gill, kidney and liver. The gill lamellae became lifted, fused, and showed oedema. Hyperplasia and hypertrophy of lamellar epithelial cells were distinct with desquamation. Hypertrophy of epithelial cells of renal tubules and reduction in tubular lumens were observed in the trunk kidney. The atrophy of the head kidney interrenal cells and decreased serum cortisol level indicated exhaustion of interrenal activity. Hepatocyte vacuolization and shrinkage, nuclear pyknosis and increase of sinusoidal spaces were observed in the liver. Abnormal behavioral patterns and reduced growth rate were also noticed in the exposed fish. The chronic hexavalent chromium exposure thus by affecting histopathology of gill, kidney (including interrenal tissue) and liver could impair the vital functions of respiration, excretion, metabolic regulation and maintenance of stress homeostasis which in the long-run may pose serious threat to fish health and affect their population.

  6. Chronic exposure to sublethal hexavalent chromium affects organ histopathology and serum cortisol profile of a teleost, Channa punctatus (Bloch)

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Ashish K. [Department of Zoology, University of Allahabad, Allahabad-211002 (India); Mohanty, Banalata, E-mail: drbana_mohanty@rediffmail.com [Department of Zoology, University of Allahabad, Allahabad-211002 (India)

    2009-09-01

    Effects of chronic exposures (one and two months) to sublethal doses of hexavalent chromium (2 and 4 mg/L potassium dichromate) on organ histopathology and serum cortisol profile were investigated and their overall impact on growth and behavior of a teleost fish, Channa punctatus was elucidated. Histopathological lesions were distinct in the vital organs gill, kidney and liver. The gill lamellae became lifted, fused, and showed oedema. Hyperplasia and hypertrophy of lamellar epithelial cells were distinct with desquamation. Hypertrophy of epithelial cells of renal tubules and reduction in tubular lumens were observed in the trunk kidney. The atrophy of the head kidney interrenal cells and decreased serum cortisol level indicated exhaustion of interrenal activity. Hepatocyte vacuolization and shrinkage, nuclear pyknosis and increase of sinusoidal spaces were observed in the liver. Abnormal behavioral patterns and reduced growth rate were also noticed in the exposed fish. The chronic hexavalent chromium exposure thus by affecting histopathology of gill, kidney (including interrenal tissue) and liver could impair the vital functions of respiration, excretion, metabolic regulation and maintenance of stress homeostasis which in the long-run may pose serious threat to fish health and affect their population.

  7. Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Pingxiao, E-mail: pppxwu@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Li, Shuzhen [School of Chemical and Environmental Engineering, Wuyi University, Jiangmen, Guangdong Province 529020 (China); Ju, Liting [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Zhu, Nengwu [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China); Wu, Jinhua; Li, Ping [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Dang, Zhi [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. Black-Right-Pointing-Pointer The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. Black-Right-Pointing-Pointer XPS and XANES provided some direct information about the reduction mechanisms. Black-Right-Pointing-Pointer The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe{sup 0}, and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe{sup 0} was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

  8. Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

    International Nuclear Information System (INIS)

    Wu, Pingxiao; Li, Shuzhen; Ju, Liting; Zhu, Nengwu; Wu, Jinhua; Li, Ping; Dang, Zhi

    2012-01-01

    Highlights: ► Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. ► The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. ► XPS and XANES provided some direct information about the reduction mechanisms. ► The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe 0 , and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe 0 was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

  9. Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation.

    Science.gov (United States)

    Liao, Yingping; Min, Xiaobo; Yang, Zhihui; Chai, Liyuan; Zhang, Shujuan; Wang, Yangyang

    2014-01-01

    Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils.

  10. Remediation of Cr(VI) contaminated soil using long-duration sodium thiosulfate supported by micro–nano networks

    International Nuclear Information System (INIS)

    He, Lulu; Wang, Min; Zhang, Guilong; Qiu, Guannan; Cai, Dongqing; Wu, Zhengyan; Zhang, Xin

    2015-01-01

    Highlights: • This work aims to develop a long-duration remediation agent (LRA). • LRA was obtained using Na 2 S 2 O 3 supported by attapulgite (ATP) micro–nano networks. • ATP micro–nano networks was induced by high-energy electron beam irradiation. • LRA can effectively control the migration of Cr(VI) and reducing Cr(VI) to Cr(III). • LRA displayed high performance on the remediation of heavy metal contaminated soil. - Abstract: In this work, a long-duration remediation agent (LRA) on hexavalent chromium (Cr(VI)) was developed using sodium thiosulfate (ST) supported by attapulgite (ATP) micro–nano networks induced through high-energy electron beam (HEEB) irradiation. The ATP networks could effectively reduce the leaching amount of Cr(VI) in soil. More importantly, the ATP networks could significantly control the leaching behavior of ST, and then prolong the duration and increase the reduction efficiency of ST on Cr(VI). As a result, LRA displayed high performance on controlling the migration of Cr(VI) and reducing Cr(VI) to Cr(III). Additionally, pot experiment indicated that LRA could effectively decrease the absorbed amount of Cr(VI) in corn, and reduce the inhibition effect of Cr(VI) on the growth of corn. Therefore, this work could provide a facile approach to remediate the Cr(VI)-contaminated soil and lower the harmful effect of Cr(VI) on crop

  11. Remediation of Cr(VI) contaminated soil using long-duration sodium thiosulfate supported by micro–nano networks

    Energy Technology Data Exchange (ETDEWEB)

    He, Lulu [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China); Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Wang, Min; Zhang, Guilong [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Qiu, Guannan [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Cai, Dongqing, E-mail: dqcai@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences and Anhui Province, Hefei, Anhui 230031 (China); Bioenergy Forest Research Center of State Forestry Administration, Hefei 230031 (China); Zhang, Xin, E-mail: xinzhang@ahau.edu.cn [School of Life Sciences, Anhui Agricultural University, Hefei 230036 (China)

    2015-08-30

    Highlights: • This work aims to develop a long-duration remediation agent (LRA). • LRA was obtained using Na{sub 2}S{sub 2}O{sub 3} supported by attapulgite (ATP) micro–nano networks. • ATP micro–nano networks was induced by high-energy electron beam irradiation. • LRA can effectively control the migration of Cr(VI) and reducing Cr(VI) to Cr(III). • LRA displayed high performance on the remediation of heavy metal contaminated soil. - Abstract: In this work, a long-duration remediation agent (LRA) on hexavalent chromium (Cr(VI)) was developed using sodium thiosulfate (ST) supported by attapulgite (ATP) micro–nano networks induced through high-energy electron beam (HEEB) irradiation. The ATP networks could effectively reduce the leaching amount of Cr(VI) in soil. More importantly, the ATP networks could significantly control the leaching behavior of ST, and then prolong the duration and increase the reduction efficiency of ST on Cr(VI). As a result, LRA displayed high performance on controlling the migration of Cr(VI) and reducing Cr(VI) to Cr(III). Additionally, pot experiment indicated that LRA could effectively decrease the absorbed amount of Cr(VI) in corn, and reduce the inhibition effect of Cr(VI) on the growth of corn. Therefore, this work could provide a facile approach to remediate the Cr(VI)-contaminated soil and lower the harmful effect of Cr(VI) on crop.

  12. Lithium salts as leachable corrosion inhibitors and potential replacement for hexavalent chromium in organic coatings for the protection of aluminum alloys

    NARCIS (Netherlands)

    Visser, P; Liu, Y; Terryn, H.A.; Mol, J.M.C.

    2016-01-01

    Lithium salts are being investigated as leachable corrosion inhibitor and potential replacement for hexavalent chromium in organic coatings. Model coatings loaded with lithium carbonate or lithium oxalate demonstrated active corrosion inhibition and the formation of a protective layer in a

  13. Adsorption of hexavalent chromium on modified corn stalk using different cross-linking agents

    Science.gov (United States)

    Chen, Suhong; Zhu, Yi; Han, Zhijun; Feng, Gao; Jia, Yuling; Fu, Kaifang; Yue, Qinyan

    2017-12-01

    In this study, four different types of adsorbents modified from corn stalk were synthesized after the reaction with epichlorohydrin, N,N-dimethylformamide, triethylamine and different cross-linking agents. The surface functional groups and thermal stability of modified corn stalk (MCSs) were characterized using FTIR and TG analysis, respectively. The feasibility of using MCSs to remove Cr(VI) were evaluated. Adsorption isotherms were determined and modeled with Langmuir, Freundlich and Temkin equations. The experimental results showed that MCS modified using diethylenetriamine (DETA) had the best modification effect, and the adsorption capacity of Cr(VI) reached as high as 227.27 mg/g at 323 K. Thermodynamic study showed that the Cr(VI) adsorption onto MCSs was endothermic processes. As a result, MCS by using DETA as cross-linking agent has good potential for the removal of Cr(VI) from aqueous solutions.

  14. Cancer mortality in a Chinese population exposed to hexavalent chromium in drinking water

    Science.gov (United States)

    Beaumont, J.J.; Sedman, R.M.; Reynolds, S.D.; Sherman, C.D.; Li, L.-H.; Howd, R.A.; Sandy, M.S.; Zeise, L.; Alexeeff, G.V.

    2008-01-01

    BACKGROUND: In 1987, investigators in Liaoning Province, China, reported that mortality rates for all cancer, stomach cancer, and lung cancer in 1970-1978 were higher in villages with hexavalent chromium (Cr)-contaminated drinking water than in the general population. The investigators reported rates, but did not report statistical measures of association or precision. METHODS: Using reports and other communications from investigators at the local Jinzhou Health and Anti-Epidemic Station, we obtained data on Cr contamination of groundwater and cancer mortality in 9 study regions near a ferrochromium factory. We estimated:(1) person-years at risk in the study regions, based on census and population growth rate data, (2) mortality counts, based on estimated person-years at risk and previously reported mortality rates, and (3) rate ratios and 95% confidence intervals. RESULTS: The all-cancer mortality rate in the combined 5 study regions with Cr-contaminated water was negligibly elevated in comparison with the rate in the 4 combined study regions without contaminated water (rate ratio = 1.13; 95% confidence interval = 0.86-1.46), but was somewhat more elevated in comparison with the whole province (1.23; 0.97-1.53). Stomach cancer mortality in the regions with contaminated water was more substantially elevated in comparison with the regions without contaminated water (1.82; 1.11-2.91) and the whole province (1.69; 1.12-2.44). Lung cancer mortality was slightly elevated in comparison with the unexposed study regions (1.15; 0.62-2.07), and more strongly elevated in comparison with the whole province (1.78; 1.03-2.87). Mortality from other cancers combined was not elevated in comparison with either the unexposed study regions (0.86; 0.53-1.36) or the whole province (0.92; 0.58-1.38). CONCLUSIONS: While these data are limited, they are consistent with increased stomach cancer risk in a population exposed to Cr in drinking water. ?? 2008 Lippincott Williams & Wilkins, Inc.

  15. Adsorption and desorption for dynamics transport of hexavalent chromium Cr(Ⅵ) in soil column

    Science.gov (United States)

    Tong, J.

    2017-12-01

    Batch experiments have been carried out to study the adsorption of heavy metals in soils, and the migration and transformation of hexavalent chromium Cr(Ⅵ) in the soil of a vegetable base were studied by dynamic adsorption and desorption soil column experiments. The aim of this study was to investigate the effect of initial concentration and pH value on the adsorption process of Cr(Ⅵ). Breakthrough curve were used to evaluate the capacity of Cr(Ⅵ) adsorption in soil columns. The results show that the higher the initial concentration, the worse the adsorption capacity of Cr(Ⅵ). The adsorption of Cr(Ⅵ) was strongly sensitive to pH value. The capacity of Cr(Ⅵ) adsorption is maximized at very low pH value. This may be due to changes in pH that cause a series of complex reactions in Cr(Ⅵ). In a strongly acidic environment, the reaction of Cr(Ⅵ) with hydrogen ions is accompanied by the formation of Cr3+, which reacts with the soil free iron-aluminum oxide to produce hydroxide in the soil. The results of the desorption experiments indicate that Cr(Ⅵ) is more likely to leach from this soil, but if the eluent is strong acid solution, the leaching process will be slow and persistent. The program CXTFIT was used to fit the breakthrough curve to estimate parameters. The results of the calculation of the dispersion coefficient (D) can be obtained by this program. The two-site model fit the breakthrough curve data of Cr(Ⅵ) well, and the parameters calculated by CXTFIT can be used to explain the behavior of Cr(Ⅵ) migration and transformation in soil columns. When pH=2, the retardation factor (R) reach at 79.71 while the value of the R is generally around 10 in other experiments. The partitioning coefficient β shows that more than half of the adsorption sites are rate-limited in this adsorption process and non-equilibrium effects the Cr(Ⅵ) transport process in this soil.

  16. Influence of hexavalent chromium on lactate-enriched Hanford groundwater microbial communities.

    Energy Technology Data Exchange (ETDEWEB)

    Somenahally, Anil C [ORNL; Mosher, Jennifer J [ORNL; Yuan, Tong [University of Oklahoma; Podar, Mircea [ORNL; Phelps, Tommy Joe [ORNL; Brown, Steven D [ORNL; Yang, Zamin Koo [ORNL; Hazen, Terry C [ORNL; Arkin, Adam [Lawrence Berkeley National Laboratory (LBNL); Palumbo, Anthony Vito [ORNL; Zhou, Jizhong [University of Oklahoma; Elias, Dwayne A [ORNL

    2013-01-01

    Microbial reduction and immobilization of chromate (Cr(VI)) is a plausible bioremediation strategy. However, higher Cr(VI) concentrations may impose stress on native Cr-reducing communities. We sought to determine if Cr(VI) would influence the lactate enriched native microbial community structure and function in groundwater from the Cr contaminated site at Hanford, WA. Steady state continuous flow bioreactors were amended with lactate and Cr(VI) (0.0, 0.1 and 3.0 mg/L). Microbial growth, metabolites, Cr(VI) concentrations, 16S rRNA gene sequences and GeoChip based functional gene composition in bioreactors were monitored for 15 weeks. Temporal trends and some differences in growth, metabolite profiles, and community composition were observed, largely between Low-Cr and High-Cr bioreactors. In both High-Cr and Low-Cr bioreactors, Cr(VI) was reduced in the bioreactors. With lactate enrichment, the native communities did not significantly differ between Cr concentrations. Native bacterial communities were diverse, whereas after lactate enrichment, Pelosinus spp., and Sporotalea spp., were the most predominant groups in all bioreactors. Similarly, the Archaea diversity significantly decreased from Methanosaeta (35%), Methanosarcina (17%), Halobacteriales (12%), Methanoregula (8%) and others, to mostly Methanosarcina spp. (95%) after lactate enrichment. Composition of several key functional genes was distinct in Low-Cr bioreactors compared to High-Cr. Among the Cr resistant probes (chrA), Burkholderia vietnamiensis, Comamonas testosterone and Ralstonia pickettii proliferated in Cr amended bioreactors. In-situ fermentative conditions facilitated Cr(VI) reduction, and as a result the 3.0 mg/L Cr(VI) did not appear to give chromate reducing strains a competitive advantage for proliferation or for increasing Cr-reduction.

  17. Modelling biological Cr(VI) reduction in aquifer microcosm column systems.

    Science.gov (United States)

    Molokwane, Pulane E; Chirwa, Evans M N

    2013-01-01

    Several chrome processing facilities in South Africa release hexavalent chromium (Cr(VI)) into groundwater resources. Pump-and-treat remediation processes have been implemented at some of the sites but have not been successful in reducing contamination levels. The current study is aimed at developing an environmentally friendly, cost-effective and self-sustained biological method to curb the spread of chromium at the contaminated sites. An indigenous Cr(VI)-reducing mixed culture of bacteria was demonstrated to reduce high levels of Cr(VI) in laboratory samples. The effect of Cr(VI) on the removal rate was evaluated at concentrations up to 400 mg/L. Following the detailed evaluation of fundamental processes for biological Cr(VI) reduction, a predictive model for Cr(VI) breakthrough through aquifer microcosm reactors was developed. The reaction rate in batch followed non-competitive rate kinetics with a Cr(VI) inhibition threshold concentration of approximately 99 mg/L. This study evaluates the application of the kinetic parameters determined in the batch reactors to the continuous flow process. The model developed from advection-reaction rate kinetics in a porous media fitted best the effluent Cr(VI) concentration. The model was also used to elucidate the logistic nature of biomass growth in the reactor systems.

  18. Bio-reduction of Cr(VI) by exopolysaccharides (EPS) from indigenous bacterial species of Sukinda chromite mine, India.

    Science.gov (United States)

    Harish, R; Samuel, Jastin; Mishra, R; Chandrasekaran, N; Mukherjee, A

    2012-07-01

    Chrome mining activity has contributed intensively towards pollution of hexavalent chromium around Sukinda Valley, Orissa, India. In an attempt to study the specific contribution of exopolysaccharides (EPS) extracted from indigenous isolates towards Cr(VI) reduction, three chromium (VI) tolerant strains were isolated from the effluent mining sludge. Based on the tolerance towards Cr(VI) and EPS production capacity, one of them was selected for further work. The taxonomic identity of the selected strain was confirmed to be Enterobacter cloacae (showing 98% similarity in BLAST search to E. cloacae) through 16S rRNA analysis. The EPS production was observed to increase with increasing Cr(VI) concentration in the growth medium, highest being 0.078 at 100 mg/l Cr(VI). The extracted EPS from Enterobacter cloacae SUKCr1D was able to reduce 31.7% of Cr(VI) at 10 mg/l concentration, which was relevant to the prevailing natural concentrations at Sukinda mine effluent sludge. The FT-IR spectral studies confirmed the surface chemical interactions of hexavalent chromium with EPS.

  19. Cr(VI) reduction in wastewater using a bimetallic galvanic reactor

    International Nuclear Information System (INIS)

    Lugo-Lugo, Violeta; Barrera-Diaz, Carlos; Bilyeu, Bryan; Balderas-Hernandez, Patricia; Urena-Nunez, Fernando; Sanchez-Mendieta, Victor

    2010-01-01

    The electrochemical reduction of Cr(VI)-Cr(III) in wastewater by iron and copper-iron bimetallic plates was evaluated and optimized. Iron has been used as a reducing agent, but in this work a copper-iron galvanic system in the form of bimetallic plates is applied to reducing hexavalent chromium. The optimal pH (2) and ratio of copper to iron surface areas (3.5:1) were determined in batch studies, achieving a 100% reduction in about 25 min. The Cr(VI) reduction kinetics for the bimetallic system fit a first order mechanism with a correlation of 0.9935. Thermodynamic analysis shows that the Cr(VI) reduction is possible at any pH value. However, at pH values above 3.0 for iron and 5.5 for chromium insoluble species appear, indicating that the reaction will be hindered. Continuous column studies indicate that the bimetallic copper-iron galvanic system has a reduction capacity of 9.5890 mg Cr(VI) cm -2 iron, whereas iron alone only has a capacity of 0.1269 mg Cr(VI) cm -2 . The bimetallic copper-iron galvanic system is much more effective in reducing hexavalent chromium than iron alone. The exhausted plates were analyzed by SEM, EDS, and XRD to determine the mechanism and the surface effects, especially surface fouling.

  20. Cr(Vi) reduction capacity of activated sludge as affected by nitrogen and carbon sources, microbial acclimation and cell multiplication

    International Nuclear Information System (INIS)

    Ferro Orozco, A.M.; Contreras, E.M.; Zaritzky, N.E.

    2010-01-01

    The objectives of the present work were: (i) to analyze the capacity of activated sludge to reduce hexavalent chromium using different carbon sources as electron donors in batch reactors, (ii) to determine the relationship between biomass growth and the amount of Cr(VI) reduced considering the effect of the nitrogen to carbon source ratio, and (iii) to determine the effect of the Cr(VI) acclimation stage on the performance of the biological chromium reduction assessing the stability of the Cr(VI) reduction capacity of the activated sludge. The highest specific Cr(VI) removal rate (q Cr ) was attained with cheese whey or lactose as electron donors decreasing in the following order: cheese whey ∼ lactose > glucose > citrate > acetate. Batch assays with different nitrogen to carbon source ratio demonstrated that biological Cr(VI) reduction is associated to the cell multiplication phase; as a result, maximum Cr(VI) removal rates occur when there is no substrate limitation. The biomass can be acclimated to the presence of Cr(VI) and generate new cells that maintain the ability to reduce chromate. Therefore, the activated sludge process could be applied to a continuous Cr(VI) removal process.

  1. Experimental Monitoring of Cr(VI) Bio-reduction Using Electrochemical Geophysics

    International Nuclear Information System (INIS)

    Birsen Canan; Gary R. Olhoeft; William A. Smith

    2007-01-01

    Many Department of Energy (DOE) sites are contaminated with highly carcinogenic hexavalent chromium (Cr(VI)). In this research, we explore the feasibility of applying complex resistivity to the detection and monitoring of microbially-induced reduction of hexavalent chromium (Cr(VI)) to a less toxic form (Cr(III)). We hope to measure the change in ionic concentration that occurs during this reduction reaction. This form of reduction promises to be an attractive alternative to more expensive remedial treatment methods. The specific goal of this research is to define the minimum and maximum concentration of the chemical and biological compounds in contaminated samples for which the Cr(VI) - Cr(III) reduction processes could be detected via complex resistivity. There are three sets of experiments, each comprised of three sample columns. The first experiment compares three concentrations of Cr(VI) at the same bacterial cell concentration. The second experiment establishes background samples with, and without, Cr(VI) and bacterial cells. The third experiment examines the influence of three different bacterial cell counts on the same concentration of Cr(VI). A polarization relaxation mechanism was observed between 10 and 50 Hz. The polarization mechanism, unfortunately, was not unique to bio-chemically active samples. Spectral analysis of complex resistivity data, however, showed that the frequency where the phase minimum occurred was not constant for bio-chemically active samples throughout the experiment. A significant shifts in phase minima occurred between 10 to 20 Hz from the initiation to completion of Cr(VI) reduction. This phenomena was quantified using the Cole-Cole model and the Marquardt-Levenberg nonlinear least square minimization method. The data suggests that the relaxation time and the time constant of this relaxation are the Cole-Cole parameters most sensitive to changes in biologically-induced reduction of Cr(VI)

  2. Effects of non-dissolved redox mediators on a hexavalent chromium bioreduction process

    Directory of Open Access Journals (Sweden)

    Jing Lian

    2016-03-01

    Full Text Available The effects of six non-dissolved redox mediators (RM immobilized in cellulose acetate beads on enhancing Cr(VI reduction by Mangrovibacter plantisponsor CR1 were investigated. In addition, the voltammetric behaviours and electron transfer capacities of the redox mediators were examined using electrochemical methods. Compared to the control beads, the Cr(VI bioreduction rate with 1-chloroanthraquinone cellulose acetate beads (1-CAQ/CA beads was increased up to 4.5-fold, which was mainly attributed to enhanced electron transfer by 1-CAQ. The redox mediators also improved the oxidation–reduction potential values of the Cr(VI bioreduction processes, which might assist in Cr(VI bioreduction. The role of the redox mediators was discussed based on the cyclic voltammetric characteristics (E0' of the redox mediators and the electrochemical impedance spectroscopy characteristics (Rct of the RM/CA beads. A linear correlation was found for the reaction constant k and the 1-CAQ concentration (C1-CAQ, which was k = 1.5674 C1-CAQ + 4.8506 (R2 = 0.9683. The Cr(VI bioreduction was affected by temperature, and the optimum pH for the Cr(VI bioreduction was 6.5. The results of repeated-batch operations showed that 1-CAQ/CA beads exhibited good stability and persistence. This study contributes to a better understanding of the effects of the redox mediator on Cr(VI bioreduction process and demonstrates its promising potential for environmental bioremediation applications.

  3. Chromium(VI) generation in vadose zone soils and alluvial sediments of the southwestern Sacramento Valley, California: a potential source of geogenic Cr(VI) to groundwater

    Science.gov (United States)

    Mills, Christopher T.; Morrison, Jean M.; Goldhaber, Martin B.; Ellefsen, Karl J.

    2011-01-01

    Concentrations of geogenic Cr(VI) in groundwater that exceed the World Health Organization’s maximum contaminant level for drinking water (50 μg L−1) occur in several locations globally. The major mechanism for mobilization of this Cr(VI) at these sites is the weathering of Cr(III) from ultramafic rocks and its subsequent oxidation on Mn oxides. This process may be occurring in the southern Sacramento Valley of California where Cr(VI) concentrations in groundwater can approach or exceed 50 μg L−1. To characterize Cr geochemistry in the area, samples from several soil auger cores (approximately 4 m deep) and drill cores (approximately 25 m deep) were analyzed for total concentrations of 44 major, minor and trace elements, Cr associated with labile Mn and Fe oxides, and Cr(VI). Total concentrations of Cr in these samples ranged from 140 to 2220 mg per kg soil. Between 9 and 70 mg per kg soil was released by selective extractions that target Fe oxides, but essentially no Cr was associated with the abundant reactive Mn oxides (up to ~1000 mg hydroxylamine-reducible Mn per kg soil was present). Both borehole magnetic susceptibility surveys performed at some of the drill core sites and relative differences between Cr released in a 4-acid digestion versus total Cr (lithium metaborate fusion digestion) suggest that the majority of total Cr in the samples is present in refractory chromite minerals transported from ultramafic exposures in the Coast Range Mountains. Chromium(VI) in the samples studied ranged from 0 to 42 μg kg−1, representing a minute fraction of total Cr. Chromium(VI) content was typically below detection in surface soils (top 10 cm) where soil organic matter was high, and increased with increasing depth in the soil auger cores as organic matter decreased. Maximum concentrations of Cr(VI) were up to 3 times greater in the deeper drill core samples than the shallow auger cores. Although Cr(VI) in these vadose zone soils and sediments was only a

  4. Electrochemical processes for the environmental remediation of toxic Cr(VI): A review

    International Nuclear Information System (INIS)

    Jin, Wei; Du, Hao; Zheng, Shili; Zhang, Yi

    2016-01-01

    Highlights: • Recent advances in electrochemical technologies for practical Cr(VI) treatment applications was reviewed. • The mechanism and performance of electrocoagulation, electrochemical reduction, electrodialysis, electro-electrodialysis and electrodeionization were discussed and compared. • The remained challenges and future perspectives were commented. - Abstract: Hexavalent chromium Cr(VI) is extremely toxic and classified as one of the 17 chemicals posing the greatest threat to humans. Large amounts of Cr(VI) compounds are directly or indirectly discharged into the environment, therefore considerable efforts have been made to control the Cr(VI) concentration below the recommended level. It has been demonstrated that electrochemical technique is one of the most efficient and environmental benign approach for the Cr(VI) removal. This review aims at recent advances in electrochemical technology for practical Cr(VI) treatment applications. By using the “clean reagent” of electron, Cr(VI) can be completely eliminated or separated via different electrochemical techniques such as electrocoagulation, electrochemical reduction, electrodialysis, electro-electrodialysis and electrodeionization. Besides, the mechanism and performance of different strategies are commented and compared. The treatment process is largely dependent on variables such as pH, electrode materials, cell configuration and techniques integration. Furthermore, the remained limitation and challenges for the electrochemical Cr(VI) remediation are also discussed.

  5. Simultaneous Cr(VI) bio-reduction and methane production by anaerobic granular sludge.

    Science.gov (United States)

    Hu, Qian; Sun, Jiaji; Sun, Dezhi; Tian, Lan; Ji, Yanan; Qiu, Bin

    2018-08-01

    Wastewater containing toxic hexavalent chromium (Cr(VI)) were treated with well-organized anaerobic granular sludge in this study. Results showed that the anaerobic granular sludge rapidly removed Cr(VI), and 2000 µg·L -1 Cr(VI) was completely eliminated within 6 min, which was much faster than the reported duration of removal by reported artificial materials. Sucrose added as a carbon source acted as an initial electron donor to reduce Cr(VI) to Cr(III). This process was considered as the main mechanism of Cr(VI) removal. Methane production by anaerobic granular sludge was improved by the addition of Cr(VI) at a concentration lower than 500 µg·L -1 . Anaerobic granular sludge had a well-organized structure, which presented good resistance against toxic Cr(VI). Trichoccus accelerated the degradation of organic substances to generate acetates with a low Cr(VI) concentration, thereby enhancing methane production by acetotrophic methanogens. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Modelling Cr(VI) removal by a combined carbon-activated sludge system

    International Nuclear Information System (INIS)

    Orozco, A. Micaela Ferro; Contreras, Edgardo M.; Zaritzky, Noemi E.

    2008-01-01

    The combined carbon-activated sludge process has been proposed as an alternative to protect the biomass against toxic substances in wastewaters; however, the information about the effect of powdered-activated carbon (PAC) addition in activated sludge reactors for the treatment of wastewaters containing Cr(VI) is limited. The objectives of the present study were: (a) to evaluate the removal of hexavalent chromium by (i) activated sludge microorganisms in aerobic batch reactors, (ii) powdered-activated carbon, and (iii) the combined action of powdered-activated carbon and biomass; (b) to propose mathematical models that interpret the experimental results. Different Cr(VI) removal systems were tested: (S1) biomass (activated sludge), (S2) PAC, and (S3) the combined activated carbon-biomass system. A Monod-based mathematical model was used to describe the kinetics of Cr(VI) removal in the system S1. A first-order kinetics with respect to Cr(VI) and PAC respectively, was proposed to model the removal of Cr(VI) in the system S2. Cr(VI) removal in the combined carbon-biomass system (S3) was faster than both Cr(VI) removal using PAC or activated sludge individually. Results showed that the removal of Cr(VI) using the activated carbon-biomass system (S3) was adequately described by combining the kinetic equations proposed for the systems S1 and S2

  7. Carcinogenicity of chromium and chemoprevention: a brief update

    Directory of Open Access Journals (Sweden)

    Wang Y

    2017-08-01

    Full Text Available Yafei Wang,1,* Hong Su,1,* Yuanliang Gu,1 Xin Song,1 Jinshun Zhao1,2 1Department of Preventative Medicine, Zhejiang Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, Ningbo, People’s Republic of China; 2Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA *These authors contributed equally to this work Abstract: Chromium has two main valence states: hexavalent chromium (Cr[VI] and trivalent chromium (Cr[III]. Cr(VI, a well-established human carcinogen, can enter cells by way of a sulfate/phosphate anion-transport system, and then be reduced to lower-valence intermediates consisting of pentavalent chromium (Cr[V], tetravalent chromium (Cr[IV] or Cr(III via cellular reductants. These intermediates may directly or indirectly result in DNA damage or DNA–protein cross-links. Although Cr(III complexes cannot pass easily through cell membranes, they have the ability to accumulate around cells to induce cell-surface morphological alteration and result in cell-membrane lipid injuries via disruption of cellular functions and integrity, and finally to cause DNA damage. In recent years, more research, including in vitro, in vivo, and epidemiological studies, has been conducted to evaluate the genotoxicity/carcinogenicity induced by Cr(VI and/or Cr(III compounds. At the same time, various therapeutic agents, especially antioxidants, have been explored through in vitro and in vivo studies for preventing chromium-induced genotoxicity/carcinogenesis. This review aims to provide a brief update on the carcinogenicity of Cr(VI and Cr(III and chemoprevention with different antioxidants. Keywords: hexavalent chromium, Cr(VI, trivalent chromium, Cr(III, genotoxicity, carcinogenicity, chemoprevention, antioxidant 

  8. Mechanism of electron transfer in the bioadsorption of hexavalent chromium within Leersia hexandra Swartz granules by X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Li Jianping, E-mail: likianping@263.net [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004 (China) and Guangxi Key Laboratory of Environmental Engineering, Protection and Assessment, Guilin 541004 (China); Lin Qingyu [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin 541004 (China); Zhang Xuehong [Guangxi Key Laboratory of Environmental Engineering, Protection and Assessment, Guilin 541004 (China)

    2010-10-15

    Leersia hexandra Swartz biogranules were used to adsorb Cr(VI) from aqueous solutions. Batch biosorption experiments showed that the Cr(VI) concentration sharply decreases in the first 15 min. The main functional groups that may be involved in chromium sorption were determined using Fourier transform infrared spectroscopy. The use of X-ray photoelectron spectroscopy confirmed the reduction of Cr(VI) to Cr(III) through L. hexandra Sw. Results indicate that Cr(III) is the dominant species on the surface of the biogranules and that the redox reaction can be accomplished within 40 min. The mechanism of electron transfer during Cr(VI) reduction to Cr(III) was investigated. Protonation of the oxygen-containing groups produces electrostatic-sorption power over Cr(VI). The nitrogen-containing groups serve as the electron-donor groups in the process of reduction-sorption. Moreover, after the complete reduction of Cr(VI), the pH of the suspension significantly increases.

  9. Removal of Cr(VI) ions by sewage sludge compost biomass from aqueous solutions: Reduction to Cr(III) and biosorption

    Science.gov (United States)

    Chen, Huixia; Dou, Junfeng; Xu, Hongbin

    2017-12-01

    Sewage sludge compost biomass was used as a novel biosorbent to remove hexavalent chromium from water. Surface area analysis, scanning electron microscopy, fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and point zero charge was applied to study the microstructure, compositions and chemical bonding states of the biomass adsorbent. Effects of contact time, biomass dosage, agitation speed, pH, the initial concentration of Cr(VI) and Cr(Ⅲ) on its adsorption removal were also performed in the batch experiments. A model describing adsorption, desorption and reduction phenomena during the sorption process has been referenced to model Cr(VI) sorption onto sewage sludge compost biomass. The result of characterization test shows that adsorption of Cr(VI) onto sewage sludge compost biomass followed by the partial reduction to Cr(Ⅲ) by biomass groups such as hydroxyl, carboxyl, and amino groups. The absorption kinetics model in the description of adsorption-coupled reduction of Cr(VI) fits successfully the kinetic data obtained at different temperatures and describes the kinetics profile of total, hexavalent and trivalent chromium. The study shows that sewage sludge compost biomass could be used as a potential biosorbent for removal of hexavalent chromium from wastewaters.

  10. Application of EIS to In Situ Characterization of Hydrothermal Sealing of Anodized Aluminum Alloys: Comparison between Hexavalent Chromium-Based Sealing, Hot Water Sealing and Cerium-Based Sealing

    OpenAIRE

    Carangelo, Anna; Curioni, Michele; Acquesta, Annalisa; Monetta, Tullio; Bellucci, Francesco

    2016-01-01

    Chromic acid anodizing has been used for almost a century to enhance corrosion protection of aerospace alloys. For some applications,hydrothermal sealing in hexavalent chromium-containing solution is required to enhance further the corrosion resistance but, due toenvironmental concerns, the use of hexavalent chromium must be discontinued. Good progress has been made to replace chromatesduring anodizing but comparatively less effort has focused on the sealing process. In this work, for the fir...

  11. Efficiencies and Optimization of Weak Base Anion Ion-Exchange Resin for Groundwater Hexavalent Chromium Removal at Hanford

    International Nuclear Information System (INIS)

    Nesham, Dean O.; Ivarson, Kristine A.; Hanson, James P.; Miller, Charles W.; Meyers, P.; Jaschke, Naomi M.

    2014-01-01

    The U.S. Department of Energy's (DOE's) contractor, CH2M HILL Plateau Remediation Company, has successfully converted a series of groundwater treatment facilities to use a new treatment resin that is delivering more than $3 million in annual cost savings and efficiency in treating groundwater contamination at the DOE Hanford Site in southeastern Washington State. During the production era, the nuclear reactors at the Hanford Site required a continuous supply of high-quality cooling water during operations. Cooling water consumption ranged from about 151,417 to 378,541 L/min (40,000 to 100,000 gal/min) per reactor, depending on specific operating conditions. Water from the Columbia River was filtered and treated chemically prior to use as cooling water, including the addition of sodium dichromate as a corrosion inhibitor. Hexavalent chromium was the primary component of the sodium dichromate and was introduced into the groundwater at the Hanford Site as a result of planned and unplanned discharges from the reactors starting in 1944. Groundwater contamination by hexavalent chromium and other contaminants related to nuclear reactor operations resulted in the need for groundwater remedial actions within the Hanford Site reactor areas. Beginning in 1995, groundwater treatment methods were evaluated, leading to the use of pump-and-treat facilities with ion exchange using Dowex 21K, a regenerable, strong-base anion exchange resin. This required regeneration of the resin, which was performed offsite. In 2008, DOE recognized that regulatory agreements would require significant expansion for the groundwater chromium treatment capacity. As a result, CH2M HILL performed testing at the Hanford Site in 2009 and 2010 to demonstrate resin performance in the specific groundwater chemistry at different waste sites. The testing demonstrated that a weak-base anion, single-use resin, specifically ResinTech SIR-700 ®, was effective at removing chromium, had a significantly higher

  12. IRIS Toxicological Review of Hexavalent Chromium Part 1: Experimental Animal Studies (Preliminary Assessment Materials)

    Science.gov (United States)

    In April 2014, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for Cr(VI) to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in...

  13. IRIS Toxicological Review of Hexavalent Chromium Part 2: Human, Toxicokinetic, and Mechanistic Studies (Preliminary Assessment Materials)

    Science.gov (United States)

    In August 2014, EPA released the second part of draft literature searches and associated search strategies, evidence tables, and exposure response arrays for Cr(VI) to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA w...

  14. Removal of hexavalent chromium from aqueous solution using polypyrrole-polyaniline nanofibers

    CSIR Research Space (South Africa)

    Bhaumik, M

    2012-02-01

    Full Text Available Polypyrrole-polyaniline (PPy-PANI) nanofibers as adsorbent of Cr(VI) were prepared without template via coupling of propagating PPy+ and PANI+ free radicals by simultaneous polymerization of Py and ANI monomers in presence of FeCl3 oxidant...

  15. IN SITU ABIOTIC DETOXIFICATION AND IMMOBILIZATION OF HEXAVALENT CHROMIUM IN THE CAPILLARY FRINGE ZONE

    Science.gov (United States)

    Detailed site characterization data from the former electroplating shop at the U.S. Coast Guard Air Support Center, Elizabeth City, North Carolina suggested that the elevated Cr(VI) in the capillary fringe area had contaminated the ground water at the site. Most of the mobile Cr(...

  16. Investigation of alternative phosphating treatments for nickel and hexavalent chromium elimination; Investigacao de tratamentos alternativos de fosfatizacao para eliminacao do niquel e cromo hexavalente

    Energy Technology Data Exchange (ETDEWEB)

    Jazbinsek, Luiz Antonio Rossi

    2014-07-01

    The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate

  17. Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

    Energy Technology Data Exchange (ETDEWEB)

    Greunz, Theresia, E-mail: theresia.greunz@jku.at [Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterisation (CDL-MS-MACH), Center for Surface and Nanoanalytics (ZONA), Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Duchaczek, Hubert; Sagl, Raffaela [voestalpine Stahl GmbH, voestalpine-Straße 3, 4031 Linz (Austria); Duchoslav, Jiri; Steinberger, Roland [Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterisation (CDL-MS-MACH), Center for Surface and Nanoanalytics (ZONA), Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Strauß, Bernhard [voestalpine Stahl GmbH, voestalpine-Straße 3, 4031 Linz (Austria); Stifter, David [Christian Doppler Laboratory for Microscopic and Spectroscopic Material Characterisation (CDL-MS-MACH), Center for Surface and Nanoanalytics (ZONA), Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria)

    2017-02-28

    Highlights: • Common methods are not suitable for a reliable determination of Cr(VI) in organic coatings on steel. • Our proposed method is a combination of XPS and ultra-low-angle microtomy (ULAM). • The results allow referring to legal regulations of the Cr(VI) concentration. • For this method no accurate sample parameters are required. - Abstract: Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1–3 μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (<10 nm) and that the lowest commonly achievable lateral resolution is a number of times higher than the coating thickness (∼2 μm), a bulk analysis was achieved with XPS line scans on extended wedge-shaped tapers through the coating. For that purpose a special sample preparation step performed on an ultra-microtome was required prior to analysis. Since a temperature increase leads to a reduction of Cr(VI) we extend our method on samples, which were subjected to different curing temperatures. We show that our proposed approach now allows to determine the elemental and Cr(VI) concentration and distribution inside the coating.

  18. Dynamics of Hexavalent Chromium in Four Types of Aquaculture Ponds and Its Effects on the Morphology and Behavior of Cultured Clarias gariepinus (Burchell 1822).

    Science.gov (United States)

    Mustapha, Moshood Keke

    2017-04-01

    Hexavalent chromium is a bio accumulative toxic metal in water and fish. It enters aquaculture ponds mainly through anthropogenic sources. Hexavalent chromium concentrations and its effects on the morphology and behavior of Clarias gariepinus were investigated from four aquaculture ponds for 12 weeks. Chromium was measured using diphenyl carbohdrazide method; alkalinity and hardness were measured using colometric method and analyzed with Bench Photometer. Temperature and pH were measured using pH/EC/TDS/Temp combined tester. Temporal and spatial replications of samples were done with triplicates morphological and behavioural effects of the metal on fish were observed visually. Chromium ranged from no detection to 0.05 mg/L, alkalinity 105 to 245 mg/L, hardness 80 to 165 mg/L, pH 6.35 to 8.03 and temperature 29.1 to 35.9°C. Trend in the chromium concentrations in the ponds is natural > earthen > concrete > collapsible. There was a significant difference ( P temperature among the four ponds. Significant positive correlation also existed between alkalinity, water hardness, pH, with chromium. Morphological and behavioural changes observed in the fish include irregular swimming, frequent coming to the surface, dark body colouration, mucous secretion on the body, erosion of gill epithelium, fin disintegration, abdominal distension and lethargy. High chromium concentration in natural pond was due to anthropogenic run-off of materials in to the pond. Acidic pH, low alkalinity, low water hardness also contributed to the high chromium concentration. Morphological and behavioural changes observed were attributed to the high concentrations, toxicity and bio accumulative effect of the metal. Toxicity of chromium to fish in aquaculture could threaten food security. Watershed best management practices and remediation could be adopted to reduce the effects of toxicity of chromium on pond water quality, fish flesh quality and fish welfare.

  19. Biosorption of hexavalent chromium in a tannery industry wastewater using fungi species

    International Nuclear Information System (INIS)

    Sivakumar, D.

    2016-01-01

    The isolated fungi species of different kinds from chromium contaminated soil sites located in Nagalkeni, Chennai were used for reducing chromium(VI) in a tannery industry wastewater of Nagalkeni, Chennai. The experiments were conducted to know biosorption potential of isolated fungi species for removing chromium(VI) in a tannery industry wastewater against the different p H, fungi biomass and chromium(VI) concentration (dilution ratio). The results of this study indicated that the order of maximum removal of chromium(VI) by an isolated fungi species at an optimum pH of 3, fungi biomass of 4g and an initial chromium(VI) concentration of 18.125 mg/L (dilution ratio 4) is A. niger > A. flavus > A. fumigatus > A. nidulans > A. heteromorphus > A. foetidus > A. viridinutans. This study found that the maximum removal of chromium(VI) was achieved by Aspergillus niger (96.3 %) than other fungi species at chromium(VI) concentration of 18.125 mg/L in a tannery industry wastewater. The chromium removal from tannery industry wastewater was validated by checking chromium removal in an aqueous solution and by checking the removal efficiency of other parameters in a tannery industry wastewater using same isolated A. niger. Biosorption model was proposed to simulate the experimental condition for removing chromium(VI) in a tannery industry wastewater by all isolated fungi species. The R2 and x2 values of the proposed model predicted that the proposed biosorption model is very much useful for predicting the trend of reduction potential of chromium(VI) in a tannery industry wastewater by all isolated fungi species. This study suggested that one could select the type of fungi species, ion concentration level, selection of treatment period, quantity of biomass to be used, and p H level of the medium, to achieve the highest reduction of any toxic metals from any contaminated water, wastewater and soil environment.

  20. Development of analytical procedures for determination of total chromium by quadrupole ICP-MS and high-resolution ICP-MS, and hexavalent chromium by HPLC-ICP-MS, in different materials used in the automotive industry.

    Science.gov (United States)

    Séby, F; Gagean, M; Garraud, H; Castetbon, A; Donard, O F X

    2003-10-01

    A European directive was recently adopted limiting the use of hazardous substances such as Pb, Hg, Cd, and Cr(VI) in vehicle manufacturing. From July 2003 a maximum of 2 g Cr(VI) will be authorised per vehicle in corrosion-preventing coatings of key components. As no standardised procedures are available to check if produced vehicles are in agreement with this directive, the objective of this work was to develop analytical procedures for total chromium and Cr(VI) determination in these materials. The first step of this study was to optimise digestion procedures for total chromium determination in plastic and metallic materials by inductively coupled plasma mass spectrometry (ICP-MS). High resolution (HR) ICP-MS was used to examine the influence of polyatomic interferences on the detection of the (52)Cr(+) and (53)Cr(+) isotopes. If there was strong interference with m/ z 52 for plastic materials, it was possible to use quadrupole ICP-MS for m/ z 53 if digestions were performed with HNO(3)+H(2)O(2). This mixture was also necessary for digestion of chromium from metallic materials. Extraction procedures in alkaline medium (NH(4)(+)/NH(3) buffer solution at pH 8.9) assisted by sonication were developed for determining Cr(VI) in four different corrosion-preventing coatings by HPLC-ICP-MS. After optimisation and validation with the only solid reference material certified for its Cr(VI) content (BCR 545; welding dusts), the efficiency of this extraction procedure for screw coatings was compared with that described in the EN ISO 3613 standard generally used in routine laboratories. For coatings comprising zinc and aluminium passivated in depth with chromium oxides the extraction procedure developed herein enabled determination of higher Cr(VI) concentrations. This was also observed for the screw covered with a chromium passivant layer on zinc-nickel. For coating comprising a chromium passivant layer on alkaline zinc the standardized extraction procedure was more efficient

  1. Toxicokinetics of hexavalent chromium in the rat after intratracheal administration of chromates of different solubilities

    NARCIS (Netherlands)

    Bragt, P.C.; Dura, E.A. van

    1983-01-01

    The kinetics of chromium in the rat after a single intratracheal dose of sodium, zinc or lead 51Cr-chromate have been investigated. Sodium chromate and the less soluble zinc chromate were absorbed into the blood and this resulted in increased excretion of chromium into the urine. The insoluble lead

  2. Fixed bed adsorption of hexavalent chromium onto natural zeolite from air stream

    Directory of Open Access Journals (Sweden)

    F. Golbabaei

    2014-07-01

    Conclusion: Due to the extensive use of chromium in various industries and regulatory requirements related to workplace health and safety, Cr emission control in the occupational environment is essential. The adsorption process is one of the controlling measures of chromium emissions. The results indicated that natural zeolite has a high efficiency in Cr (VI adsorption.

  3. Stabilization and solidification of chromium-contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Cherne, C.A.; Thomson, B.M. [Univ. of New Mexico, Albuquerque, NM (United States). Civil Engineering Dept.; Conway, R. [Sandia National Labs., Albuquerque, NM (United States)

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.

  4. Stabilization and solidification of chromium-contaminated soil

    International Nuclear Information System (INIS)

    Cherne, C.A.; Thomson, B.M.

    1997-11-01

    Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments

  5. Construction of a subtractive library from hexavalent chromium treated winter flounder (Pseudopleuronectes americanus) reveals alterations in non-selenium glutathione peroxidases

    International Nuclear Information System (INIS)

    Chapman, Laura M.; Roling, Jonathan A.; Bingham, Lacey K.; Herald, Matt R.; Baldwin, William S.

    2004-01-01

    Chromium is released during several industrial processes and has accumulated in some estuarine areas. Its effects on mammals have been widely studied, but relatively little information is available on its effects on fish. Gene expression changes are useful biomarkers that can provide information about toxicant exposure and effects, as well as the health of an organism and its ability to adapt to its surroundings. Therefore, we investigated the effects of Cr(VI) on gene expression in the sediment dwelling fish, winter flounder (Pseudopleuronectes americanus). Winter flounder ranging from 300 to 360 g were injected i.p. with Cr(VI) as chromium oxide at 25 μg/kg chromium in 0.15N KCl. Twenty-four hours following injections, winter flounder were euthanized with MS-222 and the livers were excised. Half of the livers were used to make cytosol and the other half were used to isolate mRNA for subtractive hybridization. Subtractive clones obtained were spotted onto nylon filters, which revealed several genes with potentially altered expression due to Cr(VI), including an α class GST, 1-Cys peroxiredoxin (a non-selenium glutathione peroxidase), a P-450 2X subfamily member, two elongation factors (EF-1 gamma and EF-2), and complement component C3. Semi-quantitative RT-PCR was performed and confirmed that Cr(VI) down-regulated complement component C3, an EST, and two potential glutathione peroxidases, GSTA3 and 1-Cys peroxiredoxin. In addition, cytosolic GSH peroxidase activity was reduced, and silver stained SDS-PAGE gels from glutathione-affinity purified cytosol demonstrated that a 27.1 kDa GSH-binding protein was down-regulated greater than 50%. Taken together, Cr(VI) significantly altered the expression of several genes including two potential glutathione peroxidases in winter flounder

  6. Synthesis, Characterization and Hexavalent Chromium Adsorption Characteristics of Aluminum- and Sucrose-Incorporated Tobermorite

    Directory of Open Access Journals (Sweden)

    Zhiguang Zhao

    2017-05-01

    Full Text Available Tobermorites were synthesized from the lime-quartz slurries with incorporations of aluminum and sucrose under hydrothermal conditions, and then used for adsorption of Cr(VI. The chemical components, and structural and morphological properties of tobermorite were characterized by X-ray diffraction (XRD, thermogravimetric-differential scanning calorimetry (TG-DSC, Fourier transform infrared spectroscopy (FT-IR, nuclear magnetic resonance (NMR, scanning electron microscopy (SEM, X-ray photoelectron spectroscopic (XPS and N2 adsorption–desorption measurements. The formation and crystallinity of tobermorite could be largely enhanced by adding 2.3 wt.% aluminum hydroxide or 13.3 wt.% sucrose. Sucrose also played a significantly positive role in increasing the surface area. The adsorption performances for Cr(VI were tested using a batch method taking into account the effects of pH, the adsorption kinetics, and the adsorption isotherms. The adsorption capacities of the aluminum- and sucrose-incorporated tobermorites reached up to 31.65 mg/g and 28.92 mg/g, respectively. Thus, the synthesized tobermorites showed good adsorption properties for removal of Cr(VI, making this material a promising candidate for efficient bulk wastewater treatment.

  7. Effect of Set Potential on Hexavalent Chromium Reduction and Electricity Generation from Biocathode Microbial Fuel Cells

    KAUST Repository

    Huang, Liping

    2011-06-01

    Setting a biocathode potential at ?300 mV improved the subsequent performance of an MFC for Cr(VI) reduction compared to a control (no set potential). With this set potential, the startup time was reduced to 19 days, the reduction of Cr(VI) was improved to 19.7 mg/L d, and the maximum power density was increased to 6.4 W/m3 compared to the control (26 days, 14.0 mg/L d and 4.1 W/m3). Set potentials of ?150 mV and ?300 mV also improved system performance and led to similarly higher utilization of metabolic energy gained (PMEG) than set potentials of +200 mV and ?450 mV. We observed putative pili at ?150 and ?300 mV potentials, and aggregated precipitates on bacterial surfaces in both poised and nonpoised controls. These tests show that there are optimal potentials that can be set for developing a Cr(VI) biocathode. © 2011 American Chemical Society.

  8. Effect of Set Potential on Hexavalent Chromium Reduction and Electricity Generation from Biocathode Microbial Fuel Cells

    KAUST Repository

    Huang, Liping; Chai, Xiaolei; Chen, Guohua; Logan, Bruce E

    2011-01-01

    Setting a biocathode potential at ?300 mV improved the subsequent performance of an MFC for Cr(VI) reduction compared to a control (no set potential). With this set potential, the startup time was reduced to 19 days, the reduction of Cr(VI) was improved to 19.7 mg/L d, and the maximum power density was increased to 6.4 W/m3 compared to the control (26 days, 14.0 mg/L d and 4.1 W/m3). Set potentials of ?150 mV and ?300 mV also improved system performance and led to similarly higher utilization of metabolic energy gained (PMEG) than set potentials of +200 mV and ?450 mV. We observed putative pili at ?150 and ?300 mV potentials, and aggregated precipitates on bacterial surfaces in both poised and nonpoised controls. These tests show that there are optimal potentials that can be set for developing a Cr(VI) biocathode. © 2011 American Chemical Society.

  9. Evaluation of sustained release polylactate electron donors for removal of hexavalent chromium from contaminated groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Brodie, E.L.; Joyner, D. C.; Faybishenko, B.; Conrad, M. E.; Rios-Velazquez, C.; Mork, B.; Willet, A.; Koenigsberg, S.; Herman, D.; Firestone, M. K.; Hazen, T. C.; Malave, Josue; Martinez, Ramon

    2011-02-15

    To evaluate the efficacy of bioimmobilization of Cr(VI) in groundwater at the Department of Energy Hanford site, we conducted a series of microcosm experiments using a range of commercial electron donors with varying degrees of lactate polymerization (polylactate). These experiments were conducted using Hanford Formation sediments (coarse sand and gravel) immersed in Hanford groundwater, which were amended with Cr(VI) and several types of lactate-based electron donors (Hydrogen Release Compound, HRC; primer-HRC, pHRC; extended release HRC) and the polylactate-cysteine form (Metal Remediation Compound, MRC). The results showed that polylactate compounds stimulated an increase in bacterial biomass and activity to a greater extent than sodium lactate when applied at equivalent carbon concentrations. At the same time, concentrations of headspace hydrogen and methane increased and correlated with changes in the microbial community structure. Enrichment of Pseudomonas spp. occurred with all lactate additions, and enrichment of sulfate-reducing Desulfosporosinus spp. occurred with almost complete sulfate reduction. The results of these experiments demonstrate that amendment with the pHRC and MRC forms result in effective removal of Cr(VI) from solution most likely by both direct (enzymatic) and indirect (microbially generated reductant) mechanisms.

  10. Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium.

    Science.gov (United States)

    Narvekar, Sneha; Vaidya, Varsha K

    2009-10-01

    Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions.

  11. Combined abiotic and biotic in-situ reduction of hexavalent chromium in groundwater using nZVI and whey: A remedial pilot test

    Czech Academy of Sciences Publication Activity Database

    Němeček, J.; Pokorný, P.; Lacinová, L.; Černík, M.; Masopustová, Z.; Lhotský, O.; Filipová, Alena; Cajthaml, Tomáš

    2015-01-01

    Roč. 300, DEC 2015 (2015), s. 670-679 ISSN 0304-3894 R&D Projects: GA TA ČR TE01020218 Grant - others:Advanced Technologies and Innovation (CZ) CZ.1.05/2.1.00/01.0005 Institutional support: RVO:61388971 Keywords : Hexavalent chromium * nZVI * Geofixation Subject RIV: EE - Microbiology, Virology Impact factor: 4.836, year: 2015

  12. Reduction of hexavalent chromium by ferrous iron: A process of chromium isotope fractionation and its relevance to natural environments

    DEFF Research Database (Denmark)

    Døssing, Lasse Nørbye; Dideriksen, Knud; Stipp, Susan Louise Svane

    2011-01-01

    Stable chromium (Cr) isotopes can be used as a tracer for changing redox conditions in modern marine systems and in the geological record. We have investigated isotope fractionation during reduction of Cr(VI)aq by Fe(II)aq. Reduction of Cr(VI)aq by Fe(II)aq in batch experiments leads to significant...

  13. CoQ10 Deficiency May Indicate Mitochondrial Dysfunction in Cr(VI Toxicity

    Directory of Open Access Journals (Sweden)

    Xiali Zhong

    2017-04-01

    Full Text Available To investigate the toxic mechanism of hexavalent chromium Cr(VI and search for an antidote for Cr(VI-induced cytotoxicity, a study of mitochondrial dysfunction induced by Cr(VI and cell survival by recovering mitochondrial function was performed. In the present study, we found that the gene expression of electron transfer flavoprotein dehydrogenase (ETFDH was strongly downregulated by Cr(VI exposure. The levels of coenzyme 10 (CoQ10 and mitochondrial biogenesis presented by mitochondrial mass and mitochondrial DNA copy number were also significantly reduced after Cr(VI exposure. The subsequent, Cr(VI-induced mitochondrial damage and apoptosis were characterized by reactive oxygen species (ROS accumulation, caspase-3 and caspase-9 activation, decreased superoxide dismutase (SOD and ATP production, increased methane dicarboxylic aldehyde (MDA content, mitochondrial membrane depolarization and mitochondrial permeability transition pore (MPTP opening, increased Ca2+ levels, Cyt c release, decreased Bcl-2 expression, and significantly elevated Bax expression. The Cr(VI-induced deleterious changes were attenuated by pretreatment with CoQ10 in L-02 hepatocytes. These data suggest that Cr(VI induces CoQ10 deficiency in L-02 hepatocytes, indicating that this deficiency may be a biomarker of mitochondrial dysfunction in Cr(VI poisoning and that exogenous administration of CoQ10 may restore mitochondrial function and protect the liver from Cr(VI exposure.

  14. Removal of chromium hexavalent of residual water from tannery using hydrotalcite; Remocion de cromo hexavalente de aguas residuales de teneria utilizando hidrotalcita

    Energy Technology Data Exchange (ETDEWEB)

    Martinez G, S.; Martinez, V.; Bulbulian, S. [Instituto nacional de Investigaciones Nucleares, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)

    2000-07-01

    One of the main problems of leather tanned is the treatment that must be give to the waste water polluted with chrome which stays in trivalent form, but it is easily oxidated at chromium hexavalent. This work pretends to find an elimination media for chromium (VI) from water using the original synthetic hydrotalcite and calcined as sorbent by its anion exchange and memory effect properties. The tannery water was characterized by X-ray diffraction, thermal gravimetric analysis, specific surface and infrared spectroscopy. (Author)

  15. Increase of chromium tolerance in Scenedesmus acutus after sulfur starvation: Chromium uptake and compartmentalization in two strains with different sensitivities to Cr(VI).

    Science.gov (United States)

    Marieschi, M; Gorbi, G; Zanni, C; Sardella, A; Torelli, A

    2015-10-01

    In photosynthetic organisms sulfate constitutes the main sulfur source for the biosynthesis of GSH and its precursor Cys. Hence, sulfur availability can modulate the capacity to cope with environmental stresses, a phenomenon known as SIR/SED (Sulfur Induced Resistance or Sulfur Enhanced Defence). Since chromate may compete for sulfate transport into the cells, in this study chromium accumulation and tolerance were investigated in relation to sulfur availability in two strains of the unicellular green alga Scenedesmus acutus with different Cr-sensitivities. Paradoxically, sulfur deprivation has been demonstrated to induce a transient increase of Cr-tolerance in both strains. Sulfur deprivation is known to enhance the sulfate uptake/assimilation pathway leading to important consequences on Cr-tolerance: (i) reduced chromate uptake due to the induction of high affinity sulfate transporters (ii) higher production of cysteine and GSH which can play a role both through the formation of unsoluble complexes and their sequestration in inert compartments. To investigate the role of the above mentioned mechanisms, Cr accumulation in total cells and in different cell compartments (cell wall, membranes, soluble and miscellaneous fractions) was analyzed in both sulfur-starved and unstarved cells. Both strains mainly accumulated chromium in the soluble fraction, but the uptake was higher in the wild-type. In this type a short period of sulfur starvation before Cr(VI) treatment lowered chromium accumulation to the level observed in the unstarved Cr-tolerant strain, in which Cr uptake seems instead less influenced by S-starvation, since no significant decrease was observed. The increase in Cr-tolerance following S-starvation seems thus to rely on different mechanisms in the two strains, suggesting the induction of a mechanism constitutively active in the Cr-tolerant strain, maybe a high affinity sulfate transporter also in the wild-type. Changes observed in the cell wall and

  16. The electrochemical aspect of the corrosion of austenitic stainless steels, in nitric acid and in the presence of hexavalent chromium (1961); Aspect electrochimique de la corrosion d'aciers inoxydables austenitiques en milieu nitrique et en presence de chrome hexavalent (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Coriou, H.; Hure, J.; Plante, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The corrosion of austenitic stainless steels in boiling nitric acid markedly increases when the medium contains hexavalent chromium ions. Because of several redox phenomena, the potential of the steel generally changes in course of time. Measurements show a relation between the weight loss and the potential of specimens. Additions of Mn(VII) and Ce(IV) are compared with that of Cr(VI), and show that the relation is a general one. The attack cf the metal in oxidizing media is largely intergranular, leading to exfoliation of the grains, although the steel studied is not sensitive to the classical Huey and Strauss tests. Also even in the absence of any other oxidizing reaction, the current density observed when the steel is anodically polarized under potentiostatic conditions does not correspond to the actual weight loss of the metal. (authors) [French] La corrosion d'aciers inoxydables austenitiques en milieu nitrique bouillant augmente notablement quand le milieu contient des ions chrome a l'etat hexavalent. Par suite de divers phenomenes d'oxydo-reduction, le potentiel de l'acier evolue generalement au cours du temps. Les mesures effectuees permettent d'etablir une relation entre les pertes de poids et le potentiel des echantillons. L'addition de Mn(VI) et Ce(IV) est compare a celle de Cr(VI) et montre que la relation precedente s'applique de facon generale. L'attaque du metal en milieu oxydant est en grande, partie due a une corrosion intergranulaire conduisant a un dechaussement des grains bien que l'acier etudie ne soit pas sensible aux tests classiques de Huey et de Strauss. Aussi, meme en l'absence de toute autre reaction d'oxydation l'intensite qu l'on observerait en soumettant l'acier a un potentiel anodique dans un montage potentiostatique ne correspondrait pas a la perte de poids reelle du metal. (auteurs)

  17. Characterization and recovery of hexavalent chromium salts of an environmental liability; Caracterizacion y recuperacion de sales de cromo hexavalente de un pasivo ambiental

    Energy Technology Data Exchange (ETDEWEB)

    Rangel C, A. A.; Isarain C, E. [Centro de Innovacion Aplicada en Tecnologias Competitivas, Omega 201, Fracc. Industrial Delta, 37545 Leon, Guanajuato (Mexico); Maldonado V, M., E-mail: r.cordova.alexander@gmail.com [Hospital Regional de Alta Especialidad del Bajio, Bulevard Milenio No. 130, San Carlos la Roncha, 37660 Leon, Guanajuato (Mexico)

    2015-07-01

    The purpose of this study was to examine a diverse group of washing solutions for its use in the recovery of the industrial waste hexavalent chromium, in compliance with the Mexican regulation NOM-147-SEMARNAT/SSA1-2004. The recovery process consisted of a simple random sampling and a physical-chemical characterization with consideration to the high solubility of hexavalent chromium compounds. A test was performed which implemented five different washing solutions (water, sulfuric acid, citric acid, sodium hydroxide, calcium and hydroxide). This was followed by a factorial experimental design to optimize resources with a removal efficiency of 80% and hence a recovery of 33 g/kg as CaCrO{sub 4} (calcium chromate). Chromium hexavalent concentration in the leachate was quantified using UV-Vis spectrometry at a wavelength λ = 540 nm, while the salts recovered by evaporation were characterized using X-ray fluorescence analysis, leading to the conclusion that precipitate can be used as raw material, the main elements are Cr, Ca, Fe and Mg, and their concentration depends on the washing solution. (Author)

  18. NASA and ESA Collaboration on Hexavalent Chrome Alternatives - Pretreatments with Primers Screening Final Test Report

    Science.gov (United States)

    Rothgeb, Matthew J.; Kessel, Kurt R.

    2015-01-01

    Hexavalent chromium (hex chrome or Cr(VI)) is a widely used element within applied coating systems because of its self-healing and corrosion-resistant properties. The replacement of hex chrome in the processing of aluminum for aviation and aerospace applications remains a goal of great significance. Aluminum is the major manufacturing material of structures and components in the space flight arena. The National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) are engaged in a collaborative effort to test and evaluate alternatives to hexavalent chromium containing corrosion coating systems. NASA and ESA share common risks related to material obsolescence associated with hexavalent chromium used in corrosion-resistant coatings. In the United States, Occupational Safety and Health Administration (OSHA) studies have concluded that hexavalent chromium is carcinogenic and poses significant risk to human health. On May 5, 2011, amendments to the Defense Federal Acquisition Regulation Supplement (DFARS) were issued in the Federal Register. Subpart 223.73 prohibits contracts from requiring hexavalent chromium in deliverables unless certain exceptions apply. Subpart 252.223-7008 provides the contract clause prohibiting contractors and subcontractors from using or delivering hexavalent chromium in a concentration greater than 0.1 percent by weight for all new contracts associated with supplies, maintenance and repair services, and construction materials. ESA faces its own increasingly stringent regulations within European directives such as Registration, Evaluation, Authorization and Restriction of Chemical (REACH) substances and the Restriction of Hazardous Substances Directive (RoHS) which have set a mid-2017 sunset date for hexavalent chromium. NASA and ESA continue to search for an alternative to hexavalent chromium in coatings applications that meet their performance requirements in corrosion protection, cost, operability, and health and

  19. Combination of synchrotron radiation X-ray microprobe and nuclear microprobe for chromium and chromium oxidation states quantitative mapping in single cells

    International Nuclear Information System (INIS)

    Ortega, Richard; Deves, Guillaume; Fayard, Barbara; Salome, Murielle; Susini, Jean

    2003-01-01

    Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation has not been elucidated yet. In this study, chromium oxidation state distribution maps in cells exposed to soluble (Na 2 CrO 4 ), or insoluble (PbCrO 4 ), Cr(VI) compounds have been obtained by use of the ESRF ID-21 X-ray microscope. In addition, the quantitative maps of element distributions in cells have been determined using the nuclear microprobe of Bordeaux-Gradignan. Nuclear microprobe quantitative analysis revealed interesting features on chromium, and lead, cellular uptake. It is suggested that cells can enhance PbCrO 4 solubility, resulting in chromium, but not lead uptake. The differential carcinogenic potential of soluble and insoluble Cr(VI) compounds is discussed with regard to chromium intracellular quantitative distribution

  20. Fixed bed adsorption of hexavalent chromium onto natural zeolite from air stream

    OpenAIRE

    F. Golbabaei; E. Rahmanzadeh; G. R. Moussavi; A. Faghihi zarandi; M. R. Baneshi

    2014-01-01

    Introduction: Chromium (VI) is a known human carcinogenic agent which is used in numerous industrial processes such as electroplating, welding, textile, cement and steel fabrication. The aim of this study was to determine the effectiveness of natural zeolite on the fixed bed adsorption of Cr (VI) from air stream. . Material and Method: In this experimental study, chromium mists were generated by a nebulizer (3A model, Italy). Performance of natural zeolite in the Cr (VI) adsorption and ...

  1. Removal of Cr(VI) by nanoscale zero-valent iron (nZVI) from soil contaminated with tannery wastes.

    Science.gov (United States)

    Singh, Ritu; Misra, Virendra; Singh, Rana Pratap

    2012-02-01

    The illegal disposal of tannery wastes at Rania, Kanpur has resulted in accumulation of hexavalent chromium [Cr(VI)], a toxic heavy metal in soil posing risk to human health and environment. 27 soil samples were collected at various depths from Rania for the assessment of Cr(VI) level in soil. Out of 27 samples, five samples had shown significant level of Cr(VI) with an average concentration of 15.84 mg Kg(-1). Varied doses of nanoscale zero-valent iron (nZVI) were applied on Cr(VI) containing soil samples for remediation of Cr(VI). Results showed that 0.10 g L(-1) nZVI completely reduces Cr(VI) within 120 min following pseudo first order kinetics. Further, to test the efficacy of nZVI in field, soil windrow experiments were performed at the contaminated site. nZVI showed significant Cr(VI) reduction at field also, indicating it an effective tool for managing sites contaminated with Cr(VI).

  2. Occupational exposure to hexavalent chromium and cancers of the gastrointestinal tract: a meta-analysis.

    Science.gov (United States)

    Gatto, Nicole M; Kelsh, Michael A; Mai, Diem Ha; Suh, Mina; Proctor, Deborah M

    2010-08-01

    We conducted a systematic literature review and meta-analysis of oral cavity, esophageal, stomach, small intestine, colon, and rectal cancers among workers occupationally exposed to Cr(VI). Using PubMed, studies published from 1950 to 2009 evaluating the relationship between Cr(VI) exposure and GI cancers were identified. Measures of effect and variability were extracted from 32 studies meeting specific inclusion criteria, and meta-analysis summary relative risk measures were calculated using random effects models and inverse variance weighting methods. Meta-standardized mortality ratios (SMRs) were, for cancer of the: oral cavity [1.02 (95% CI=0.77-1.34)]; esophagus [1.17 (95% CI=0.90-1.51)]; stomach [1.09 (95% CI=0.93-1.28)]; colon [0.89 (95% CI=0.70-1.12)]; and rectum [1.17 (95% CI=0.98-1.39)]. Analyses of more highly exposed subgroups included in the studies or subgroups based on geographic region or by industry with recognized Cr(VI) exposures (welding, chrome plating, chromate production, and pigment production) did not result in elevated meta-SMRs except for esophageal cancer among US cohorts [meta-SMR=1.49 (95% CI=1.06-2.09)]. However, that finding was based on a subgroup of only four studies, one of which was a PMR study. Potential confounding by socioeconomic status (SES), diet and/or smoking, or limitations due to the healthy-worker effect (HWE) were evaluated, and while smoking, diet and SES may be important factors that may have upwardly biased the meta-SMRs, HWE is not likely to have significantly affected the summary results. None of three studies reporting small intestine cancers observed a statistically significant increased risk. These meta-analyses and literature review indicate that Cr(VI)-exposed workers are not at a greater risk of GI cancers than the general population.

  3. Study of hexavalent chromium sorption by hydrotalcites synthesized using ultrasound vs microwave irradiation

    OpenAIRE

    Paredes-Carrera, S.P.; Valencia-Martínez, R.F.; Valenzuela-Zapata, M.A.; Sánchez-Ochoa, J.C.; Castro-Sotelo, L.V.

    2015-01-01

    The increase of water contamination caused by toxic compounds is a matter of primary concern, the case in point is the state of Guanajuato in Mexico, where one of Ihe main contaminants found in wastewater is Cr(VI), a widely used compound in the tanning process. The development of an efficient technology to remove this substance from water is absolutely necessary. In this work a comparative study of different anionic clays and activated carbon as a reference, was proposed to eliminate this po...

  4. Isolation and characterization of Bacillus cereus IST105 from electroplating effluent for detoxification of hexavalent chromium.

    Science.gov (United States)

    Naik, Umesh Chandra; Srivastava, Shaili; Thakur, Indu Shekhar

    2011-08-01

    Electroplating industries are the main sources of heavy metals, chromium, nickel, lead, zinc, cadmium and copper. The highest concentrations of chromium (VI) in the effluent cause a direct hazards to human and animals. Therefore, there is a need of an effective and affordable biotechnological solution for removal of chromium from electroplating effluent. Bacterial strains were isolated from electroplating effluent to find out higher tolerant isolate against chromate. The isolate was identified by 16S rDNA sequence analysis. Absorbed chromium level of bacterium was determined by inductively coupled plasma-atomic emission spectrometer (ICP-AES), atomic absorption spectrophotometer (AAS), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray analysis (EDX). Removal of metals by bacterium from the electroplating effluent eventually led to the detoxification of effluent confirmed by MTT assay. Conformational changes of functional groups of bacterial cell surface were studied through Fourier transform infrared spectroscopy. The chromate tolerant isolate was identified as Bacillus cereus. Bacterium has potency to remove more than 75% of chromium as measured by ICP-AES and AAS. The study indicated the accumulation of chromium (VI) on bacterial cell surface which was confirmed by the SEM-EDX and TEM analysis. The biosorption of metals from the electroplating effluent eventually led to the detoxification of effluent. The increased survivability of Huh7 cells cultured with treated effluent also confirmed the detoxification as examined by MTT assay. Isolated strain B. cereus was able to remove and detoxify chromium (VI). It would be an efficient tool of the biotechnological approach in mitigating the heavy metal pollutants.

  5. Mathematical models applied to the Cr(III) and Cr(VI) breakthrough curves.

    Science.gov (United States)

    Ramirez C, Margarita; Pereira da Silva, Mônica; Ferreira L, Selma G; Vasco E, Oscar

    2007-07-19

    Trivalent and hexavalent chromium continuous biosorption was studied using residual brewer Saccharomyces cerevisiae immobilized in volcanic rock. The columns used in the process had a diameter of 4.5 cm and a length of 140 cm, working at an inlet flow rate of 15 mL/min. Breakthrough curves were used to study the yeast biosorption behavior in the process. The saturation time (ts) was 21 and 45 h for Cr(III) and Cr(VI), respectively, and a breakthrough time (tb) of 4 h for Cr(III) and 5 h for Cr(VI). The uptake capacity of the biosorbent for Cr(III) and Cr(VI) were 48 and 60 mg/g, respectively. Two non-diffusional mathematical models with parameters t0 and sigma were used to adjust the experimental data obtained. Microsoft Excel tools were used for the mathematical solution of the two parameters used.

  6. Study on the DNA-protein crosslinks induced by chromium (VI) in SPC-A1

    Science.gov (United States)

    Liu, Yanqun; Ding, Jianjun; Lu, Xiongbing; You, Hao

    2018-01-01

    Objective: This study was designed to investigate the effect of chromium (VI) on DNA-protein crosslinks (DPC) of SPC-A1 cells. Methods: We exposed SPC-A1 cells were cultured in 1640 medium and treated with the SPC-A1 cells in vitro to different concentrations of Hexavalent chromium Cr(VI) for 2h, the KC1-SDS precipitation assay were used to measure the DNA-protein cross-linking effect. Results: All the different concentrations of Cr(VI) could cause the increase of DPC coefficient in SPC-A1 cells. But this effect was not significant (P>0.05) at low concentrations; while in high concentration Cr(VI) induced SPC-A1 cells could produce DNA-protein cross-linking effect significantly (P<0.05). Conclusions: chromium (VI) could induce DNA-protein crosslink.

  7. Chromium sorption and Cr(VI) reduction to Cr(III) by grape stalks and yohimbe bark.

    Science.gov (United States)

    Fiol, Núria; Escudero, Carlos; Villaescusa, Isabel

    2008-07-01

    In this work, two low cost sorbents, grape stalks and yohimbe bark wastes were used to remove Cr(VI) and Cr(III) from aqueous solutions. Batch experiments were designed to obtain Cr(VI) and Cr(III) sorption data. The mechanism of Cr(III) and Cr(VI) removal and Cr(VI) reduction to Cr(III) by the two vegetable wastes, has been investigated. Fourier transform infrared rays (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis on solid phase were performed to determine the main functional groups that might be involved in metal uptake and to confirm the presence of Cr(III) on the sorbent, respectively. Results put into evidence that both sorbents are able to reduce Cr(VI) to its trivalent form.

  8. Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae)

    International Nuclear Information System (INIS)

    Sorensen, Mary A.; Jensen, Peter D.; Walton, William E.; Trumble, John T.

    2006-01-01

    Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC 5 s values for perchlorate and chromium were 74 ± 8.0 mg/L and 0.41 ± 0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC 5 values for perchlorate and Cr (VI) were 17,000 ± 3200 and 38 ± 1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes. - While pollution with hexavalent chromium may adversely affect Culex quinquefasciatus larvae, levels of perchlorate currently in the environment will not impact these insects

  9. Acute and chronic activity of perchlorate and hexavalent chromium contamination on the survival and development of Culex quinquefasciatus Say (Diptera: Culicidae)

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, Mary A. [Department of Entomology, University of California, Riverside, CA 92521 (United States)]. E-mail: mary.sorensen@email.ucr.edu; Jensen, Peter D. [Department of Entomology, University of California, Riverside, CA 92521 (United States); Walton, William E. [Department of Entomology, University of California, Riverside, CA 92521 (United States); Trumble, John T. [Department of Entomology, University of California, Riverside, CA 92521 (United States)

    2006-12-15

    Effects of water contamination with perchlorate and hexavalent chromium [Cr (VI)] on the mosquito Culex quinquefasciatus were assessed. The chronic (10-day) LC{sub 5}s values for perchlorate and chromium were 74 {+-} 8.0 mg/L and 0.41 {+-} 0.15 mg/L, respectively. Relative Growth Index, a measure of growth and mortality rates in a population, was significantly reduced within 5 days for levels of perchlorate as low as 25 mg/L and for levels of chromium as low as 0.16 mg/L. Neither compound altered wing length of surviving adults. In combination, contaminants were synergistic, causing 14% more mortality than predicted. Acute (24-h) LC{sub 5} values for perchlorate and Cr (VI) were 17,000 {+-} 3200 and 38 {+-} 1.3 mg/L, respectively. Effects on mosquito larvae in contaminated environments are likely to be observed for Cr (VI) but not for perchlorate, which generally does not occur at levels as high as those shown here to affect larval mosquitoes. - While pollution with hexavalent chromium may adversely affect Culex quinquefasciatus larvae, levels of perchlorate currently in the environment will not impact these insects.

  10. ENZYME MARKERS ACTIVITY AND BILE FORMATION FUNCTION OF LIVER IN CASES OF TUBERCULOSTATICS AND HEXAVALENT CHROMIUM COMPOUNDS AFFECTION IN RATS

    Directory of Open Access Journals (Sweden)

    N. I. Burmas

    2016-05-01

    Full Text Available Background. Currently, the growing incidence of toxic lesions of the liver is associated with industrial chemicalization and uncontrolled use of hepatotoxic drugs in everyday life. There are about one thousand drugs with high or low hepatotoxicity, such as anti-TB drugs. Objective. In this research we studied the intracellular enzymes activity and bile formation function of the liver in rats of different ages in cases of tuberculostatic (isoniazid and rifampicin affection and chromium (potassium dichromate intoxication. Methods. The experimental affection of rats of different ages was performed by combined injection of hexavalent chromium compounds (a solution of potassium dichromate, 3 mg/kg, isoniazid (0.05 g/kg and rifampicin (0.25 g/kg. On the 7th and 14th days the rats were injected with enterosorbent Sorbex (150 mg/kg. Enzyme markers activity of the liver was evaluated due to alanine and aspartate aminotransferases (ALT and AST and alkaline phosphatase (ALP rates. Bile formation function of the liver was evaluated by total bilirubin and bile acids content in blood. Results. The disorders in hepatocytes plasma membranes permeability were defined by the increased rates of ALT, AST and alkaline phosphatase in blood serum which were decreased in the liver. It was determined that total bilirubin and bile acids content in blood serum of the affected animals increased. It influenced hepatocytes excretion in bile capillaries and caused cholestasis and revenues decrease in bile. Conclusions. The most significant metabolic disorders in cases of chrome-isoniazid-rifampicin affection were defined in immature and senior animals in comparison with mature animals.

  11. Groundwater contaminated with hexavalent chromium [Cr (VI]: a health survey and clinical examination of community inhabitants (Kanpur, India.

    Directory of Open Access Journals (Sweden)

    Priti Sharma

    Full Text Available BACKGROUND: We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing in Kanpur, India. METHODS: The health status of residents living in areas with high Cr (VI groundwater contamination (N = 186 were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI levels (N = 230. Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI was measured in groundwater samples by diphenylcarbazide reagent method. RESULTS: Residents from communities with known Cr (VI contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1 and 39.3% vs. 21% females (AOR = 2.44; skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48 and 25% vs. 4.9% females (AOR = 6.57. Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females, lower MCVs (among 62.8% males and less platelets (among 68% males and 72% females than matched controls. There were no differences in leucocytes count and spirometry parameters. CONCLUSIONS: Living in communities with Cr (VI groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up.

  12. Groundwater contaminated with hexavalent chromium [Cr (VI)]: a health survey and clinical examination of community inhabitants (Kanpur, India).

    Science.gov (United States)

    Sharma, Priti; Bihari, Vipin; Agarwal, Sudhir K; Verma, Vipin; Kesavachandran, Chandrasekharan N; Pangtey, Balram S; Mathur, Neeraj; Singh, Kunwar Pal; Srivastava, Mithlesh; Goel, Sudhir K

    2012-01-01

    We assessed the health effects of hexavalent chromium groundwater contamination (from tanneries and chrome sulfate manufacturing) in Kanpur, India. The health status of residents living in areas with high Cr (VI) groundwater contamination (N = 186) were compared to residents with similar social and demographic features living in communities having no elevated Cr (VI) levels (N = 230). Subjects were recruited at health camps in both the areas. Health status was evaluated with health questionnaires, spirometry and blood hematology measures. Cr (VI) was measured in groundwater samples by diphenylcarbazide reagent method. Residents from communities with known Cr (VI) contamination had more self-reports of digestive and dermatological disorders and hematological abnormalities. GI distress was reported in 39.2% vs. 17.2% males (AOR = 3.1) and 39.3% vs. 21% females (AOR = 2.44); skin abnormalities in 24.5% vs. 9.2% males (AOR = 3.48) and 25% vs. 4.9% females (AOR = 6.57). Residents from affected communities had greater RBCs (among 30.7% males and 46.1% females), lower MCVs (among 62.8% males) and less platelets (among 68% males and 72% females) than matched controls. There were no differences in leucocytes count and spirometry parameters. Living in communities with Cr (VI) groundwater is associated with gastrointestinal and dermatological complaints and abnormal hematological function. Limitations of this study include small sample size and the lack of long term follow-up.

  13. Elevated Frequencies of Micronuclei and other Nuclear Abnormalities of Chrome Plating Workers Occupationally Exposed to Hexavalent Chromium.

    Science.gov (United States)

    Sudha, S; Kripa, S K; Shibily, P; Shyn, J

    2011-01-01

    Biomonitoring provides a useful tool to estimate the genetic risk from exposure to genotoxic agents. The aim of this study was to assess the potential cytogenetic damage associated with occupational exposure to hexavalent chromium by using micronuclei (MN) as a biomarker. This was a cross-sectional study and all participants were males. Both the exposed and control individuals were selected from Coimbatore, Southern India. Exfoliated buccal cells from 44 chrome plating workers and 40 age and sex matched control subjects were examined for MN frequency and nuclear abnormalities (NA) other than micronuclei, such as binucleates, broken eggs, karyorrhexis, karyolysis and pyknosis. Results showed statistically significant difference between chrome plating workers and control groups. MN and NA frequencies in chrome plating workers were significantly higher than those in control groups (p chrome plating workers are under risk of significant cytogenetic damage. Therefore, there is a need to educate those who work with heavy metals about the potential hazard of occupational exposure and the importance of using protective measures.

  14. Biological reduction of hexavalent chromium and mechanism analysis of detoxification by enterobacter sp. HT1 isolated from tannery effluents, Mongolia

    Directory of Open Access Journals (Sweden)

    N Marjangul

    2014-12-01

    Full Text Available Enterobacter sp. HT1, Cr (VI resistant bacterial strain was isolated from the wastewater sample of the tannery in Mongolia. Batch experiments on hexavalent chromium removal was carried out at 10, 20, and 30 mg/L of Cr (VI added as potassium dichromate (K2Cr2O7, at pH 7 and temperature of 30 °C using pure culture of Enterobacter sp. HT1 as inoculum.  The isolated HT1 is capable of reduction nearly 100% of Cr (VI resulting in the decrease of Cr (VI from 10 to 0.2 mg/L within 20 hours. When the concentration of Cr (VI increased to 20 and 30mg/L, almost complete reduction of Cr (VI could achieve after 72 and 96 hours, respectively.DOI: http://doi.dx.org/10.5564/mjc.v15i0.322 Mongolian Journal of Chemistry 15 (41, 2014, p47-52

  15. An Investigation on the Extraction and Quantitation of a Hexavalent Chromium in Acrylonitrile Butadiene Styrene Copolymer (ABS) and Printed Circuit Board (PCB) by Ion Chromatography Coupled with Inductively Coupled Plasma Atomic Emission Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Sang Ho; Kim, Yu Na [Mokpo National University, Muan (Korea, Republic of)

    2012-06-15

    A hexavalent chromium (Cr (VI)) is one of the hazardous substances regulated by the RoHS. The determination of Cr (VI) in various polymers and printed circuit board (PCB) has been very important. In this study, the three different analytical methods were investigated for the determination of a hexavalent chromium in Acrylonitrile Butadiene Styrene copolymer (ABS) and PCB. The results by three analytical methods were obtained and compared. An analytical method by UV-Visible spectrometer has been generally used for the determination of Cr (VI) in a sample, but a hexavalent chromium should complex with diphenylcarbazide for the detection in the method. The complexation did make an adverse effect on the quantitative analysis of Cr (VI) in ABS. The analytical method using diphenylcarbazide was also not applicable to printed circuit board (PCB) because PCB contained lots of irons. The irons interfered with the analysis of hexavalent chromium because those also could complex with diphenylcarbazide. In this study, hexavalent chromiums in PCB have been separated by ion chromatography (IC), then directly and selectively detected by inductively coupled plasma atomic emission spectrometry (ICP-AES). The quantity of Cr (VI) in PCB was 0.1 mg/kg

  16. Determination of chromium (VI) in primary and secondary fertilizer and their respective precursors.

    Science.gov (United States)

    Krüger, Oliver; Fiedler, Francesca; Adam, Christian; Vogel, Christian; Senz, Rainer

    2017-09-01

    Hexavalent chromium species (Cr(VI)) are often carcinogenic, of high acute toxicity, highly mobile, and thus pose a severe risk to health and environment. Fertilizers usually contain significant amounts of chromium. Therefore, a reliable analysis of chromium and the fraction of Cr(VI) are crucial for safe use of fertilizers. This problem is expected to increase in the future, since more and more recycled fertilizers emerge due to increasing fertilizer demand and respective supply risks. However, existing analytical methods have been developed for conventional fertilizers and have to be tested whether they are suitable for the new materials. Thus, we performed a wet-chemical extraction for Cr(VI) on several matrices as well as respective quality control experiments including spiking with Cr(III) and Cr(VI) compounds. We found the Cr(VI) amounts to be below 2 mg/kg except for a thermally post-treated sewage sludge ash (SSA) that showed 12.3 mg/kg. The presence of organic matter e.g. in sludge or precipitated struvite caused a reduction of spiked Cr(VI) and thus no satisfying recovery for quality control. Cr(VI) reduction was also observed for SSA, presumably due to the presence of Fe(II) compounds. Even though the tested procedure can be hampered in some recycled fertilizer matrices, it might be adapted to be applicable also for these complex samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Chromium VI and stomach cancer: a meta-analysis of the current epidemiological evidence.

    Science.gov (United States)

    Welling, Roberta; Beaumont, James J; Petersen, Scott J; Alexeeff, George V; Steinmaus, Craig

    2015-02-01

    Chromium VI (hexavalent chromium, Cr(VI)) is an established cause of lung cancer, but its association with gastrointestinal cancer is less clear. The goal of this study was to examine whether the current human epidemiological research on occupationally inhaled Cr(VI) supports the hypothesis that Cr(VI) is associated with human stomach cancer. Following a thorough literature search and review of individual studies, we used meta-analysis to summarise the current epidemiological literature on inhaled Cr(VI) and stomach cancer, explore major sources of heterogeneity, and assess other elements of causal inference. We identified 56 cohort and case-control studies and 74 individual relative risk (RR) estimates on stomach cancer and Cr(VI) exposure or work in an occupation associated with high Cr(VI) exposure including chromium production, chrome plating, leather work and work with Portland cement. The summary RR for all studies combined was 1.27 (95% CI 1.18 to 1.38). In analyses limited to only those studies identifying increased risks of lung cancer, the summary RR for stomach cancer was higher (RR=1.41, 95% CI 1.18 to 1.69). Overall, these results suggest that Cr(VI) is a stomach carcinogen in humans, which is consistent with the tumour results reported in rodent studies. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  18. A highly sensitive and selective detection of Cr(VI) and ascorbic acid based on nitrogen-doped carbon dots.

    Science.gov (United States)

    Zhang, Yuhua; Fang, Xian; Zhao, Hong; Li, Zengxi

    2018-05-01

    A highly sensitive and selective detection of hexavalent chromium (Cr(VI)) and ascorbic acid (AA) was proposed using nitrogen-doped carbon dots (N-CDs). In the absence of AA, the quantitative detection of Cr(VI) was realized through Cr(VI) acting as a quencher to quench the fluorescence of N-CDs by inner filter effect (IFE) and static quenching effect. Under the optimal conditions, the linear range for Cr(VI) detection was from 0.01 to 250μM with a detection limit of 5nM (S/N = 3). In the presence of AA, the fluorescence intensity could be rapidly enhanced compared with the fluorescence of N-CDs/Cr(VI) system since Cr(VI) can be reduced into trivalent chromium (Cr(III)) by AA. And a wide linear range for AA detection was obtained from 1 to 750μM. The detection limit was 0.3μM (S/N = 3). More importantly, this method can be successfully applied to the detection of Cr(VI) in real water samples, and AA in vitamins C tablets and human serum sample. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

    Science.gov (United States)

    Greunz, Theresia; Duchaczek, Hubert; Sagl, Raffaela; Duchoslav, Jiri; Steinberger, Roland; Strauß, Bernhard; Stifter, David

    2017-02-01

    Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1-3 μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (distribution inside the coating.

  20. Gemini Surfactant-Modified Activated Carbon for Remediation of Hexavalent Chromium from Water

    Directory of Open Access Journals (Sweden)

    Yingying Zhou

    2018-01-01

    Full Text Available Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB were used to pre-treat and generate activated carbon. The removal efficiency of the surfactant-modified activated carbon through adsorption of chromium(VI was investigated under controlled laboratory conditions. Fourier-transform infrared spectroscopy (FT-IR and scanning electron microscopy (SEM were used to investigate the surface changes of surfactant-modified activated carbon. The effect of important parameters such as adsorbent dosage, pH, ionic strength and contact time were also investigated. The chromium(VI was adsorbed more significantly on the Gemini surfactant-modified activated carbon than on the conventional surfactant-modified activated carbon. The correlation coefficients show the data best fit the Freundlich model, which confirms the monolayer adsorption of chromium(VI onto Gemini surfactant-modified activated carbon. From this assessment, the surfactant-modified (especially Gemini surfactant-modified activated carbon in this study showed promise for practical applications to treat water pollution.

  1. Chromium allergy

    DEFF Research Database (Denmark)

    Hansen, M B; Johansen, J D; Menné, Torkil

    2003-01-01

    Most studies investigating chromium allergy have been performed with Cr(VI). However, real exposure to chromium from leather products includes both Cr(III) and Cr(VI). We have determined and compared the minimum elicitation threshold (MET) concentration for Cr(III) and Cr(VI) in Cr(VI)-sensitive ......Most studies investigating chromium allergy have been performed with Cr(VI). However, real exposure to chromium from leather products includes both Cr(III) and Cr(VI). We have determined and compared the minimum elicitation threshold (MET) concentration for Cr(III) and Cr(VI) in Cr......(III) was concluded to play an important role in chromium allergy, because Cr(III) and Cr(VI) were both capable of eliciting eczema at low concentrations. Rather than regarding chromium dermatitis as a result of Cr(VI) allergy alone, it may be more correct to consider it as a result of a combined Cr(III) and Cr......(VI) allergy....

  2. Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter

    Energy Technology Data Exchange (ETDEWEB)

    Sedumedi, Hilda N. [Department of Chemistry, Tshwane University of Technology, P.O. Box 56208, Arcadia, 0007, Pretoria (South Africa); Mandiwana, Khakhathi L., E-mail: MandiwanaKL@tut.ac.za [Department of Chemistry, Tshwane University of Technology, P.O. Box 56208, Arcadia, 0007, Pretoria (South Africa); Ngobeni, Prince; Panichev, Nikolay [Department of Chemistry, Tshwane University of Technology, P.O. Box 56208, Arcadia, 0007, Pretoria (South Africa)

    2009-12-30

    The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1 M Na{sub 2}CO{sub 3} and filtered through hydrophilic PDVF 0.45 {mu}m filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 {mu}g g{sup -1} (cyclone dust), 2710 {mu}g g{sup -1} (fine dust), and 7800 {mu}g g{sup -1} (slimes dust) which exceeded the maximum acceptable risk concentration (20 {mu}g g{sup -1}). The concentration of Cr(VI) in environmental samples of grass (3.4 {+-} 0.2), soil (7.7 {+-} 0.2), and tree bark (11.8 {+-} 1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.

  3. Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter.

    Science.gov (United States)

    Sedumedi, Hilda N; Mandiwana, Khakhathi L; Ngobeni, Prince; Panichev, Nikolay

    2009-12-30

    The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1M Na(2)CO(3) and filtered through hydrophilic PDVF 0.45 microm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 microg g(-1) (cyclone dust), 2710 microg g(-1) (fine dust), and 7800 microg g(-1) (slimes dust) which exceeded the maximum acceptable risk concentration (20 microg g(-1)). The concentration of Cr(VI) in environmental samples of grass (3.4+/-0.2), soil (7.7+/-0.2), and tree bark (11.8+/-1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.

  4. Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter

    International Nuclear Information System (INIS)

    Sedumedi, Hilda N.; Mandiwana, Khakhathi L.; Ngobeni, Prince; Panichev, Nikolay

    2009-01-01

    The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1 M Na 2 CO 3 and filtered through hydrophilic PDVF 0.45 μm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 μg g -1 (cyclone dust), 2710 μg g -1 (fine dust), and 7800 μg g -1 (slimes dust) which exceeded the maximum acceptable risk concentration (20 μg g -1 ). The concentration of Cr(VI) in environmental samples of grass (3.4 ± 0.2), soil (7.7 ± 0.2), and tree bark (11.8 ± 1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.

  5. Modulation of hexavalent chromium toxicity on Οriganum vulgare in an acidic soil amended with peat, lime, and zeolite.

    Science.gov (United States)

    Antoniadis, Vasileios; Zanni, Anna A; Levizou, Efi; Shaheen, Sabry M; Dimirkou, Anthoula; Bolan, Nanthi; Rinklebe, Jörg

    2018-03-01

    Dynamics of chromate (Cr(VI)) in contaminated soils may be modulated by decreasing its phytoavailability via the addition of organic matter-rich amendments, which might accelerate Cr(VI) reduction to inert chromite (Cr(III)) or high-cation exchange capacity amendments. We studied Cr(VI) phytoavailability of oregano in a Cr(VI)-spiked acidic soil non-treated (S) and treated with peat (SP), lime (SL), and zeolite (SZ). The addition of Cr(VI) increased the concentrations of Cr(VI) and Cr(III) in soils and plants, especially in the lime-amended soil. The plant biomass decreased in the lime-amended soil compared to the un-spiked soil (control) due to decreased plant phosphorus concentrations and high Cr(VI) concentrations in root at that treatment. Oregano in the peat-amended soil exhibited significantly less toxic effects, due to the role of organic matter in reducing toxic Cr(VI) to Cr(III) and boosted plant vigour in this treatment. In the lime-amended soil, the parameters of soil Cr(VI), soil Cr(III), and root Cr(III) increased significantly compared to the non-amended soil, indicating that Cr(VI) reduction to Cr(III) was accelerated at high pH. Added zeolite failed to decreased Cr(VI) level to soil and plant. Oregano achieved a total uptake of Cr(III) and Cr(VI) of 0.275 mg in plant kg -1 soil in a pot in the non-amended soil. We conclude that peat as soil amendment might be considered as a suitable option for decreasing Cr(VI) toxicity in soil and plant, and that oregano as tolerant plant species has a certain potential to be used as a Cr accumulator. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Method for in situ or ex situ bioremediation of hexavalent chromium contaminated soils and/or groundwater

    Science.gov (United States)

    Turick, Charles E.; Apel, William W.

    1997-10-28

    A method of reducing the concentration of Cr(VI) in a liquid aqueous residue comprises the steps of providing anaerobic Cr(VI) reducing bacteria, mixing the liquid aqueous residue with a nutrient medium to form a mixture, and contacting the mixture with the anaerobic Cr(VI) reducing bacteria such that Cr(VI) is reduced to Cr(III). The anaerobic Cr(VI) reducing bacteria appear to be ubiquitous in soil and can be selected by collecting a soil sample, diluting the soil sample with a sterile diluent to form a diluted sample, mixing the diluted sample with an effective amount of a nutrient medium and an effective amount of Cr(VI) to form a mixture, and incubating the mixture in the substantial absence of oxygen such that growth of Cr(VI) sensitive microorganisms is inhibited and growth of the anaerobic Cr(VI) reducing bacteria is stimulated. A method of in situ bioremediation of Cr(VI) contaminated soil and/or groundwater is also disclosed.

  7. Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

    Science.gov (United States)

    Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

    2017-09-05

    Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

  8. Removal of Chromium from Industrial Wastewater Using Silicon Nanoparticle

    Directory of Open Access Journals (Sweden)

    Laleh Ranandeh Kalankesh

    2015-03-01

    Full Text Available Hexavalent chromium is a pollutant found in surface and underground waters that causes serious environmental hazards. Chromium enters water as a result of industrial activities such as electroplating, dyeing, leather tanning, and metal manufacturing. The objective of the present laboratory-experimental study was to remove chromate from industrial effluents using silicon nanoparticles. The experiments were performed with both simulated synthetic wastewater and true wastewater. Various parameters such as pH, contact time, and different concentrations of Cr(VI and SiO2 were examined. The data obtained were analyzed using the Excel and SPSS Ver. 16. It was found that Cr(VI removal increased with decreasing pH and increasing contact time. The highest Cr(VI removal was achieved at pH=3 and a contact time of 120 minutes. It was also observed that removal observed to obey the Langmuir isotherm and pseudo second-order kinetic models, respectively. The findings indicate that silicon nanoparticles are capable of removeing Cr(VI from industrial effluents. Given the Cr(VI removal efficiency of 93.6% achieved under optimum conditions and  the removal efficiency of 88.6% achieved in real samples, the method may be recommended as a highly efficient one for removing Cr(VI from industrial wastewaters.

  9. Using Fluorescence XANES Measurement to Correct the Content of Hexavalent Chromium in Chromate Conversion Coatings Determined by Diphenyl Carbazide Color Test

    International Nuclear Information System (INIS)

    Nishino, Junichi; Ofuchi, Hironori; Taniguchi, Yosuke; Honma, Tetsuo; Sekikawa, Toshikazu; Otani, Haruka; Bando, Akio

    2007-01-01

    The Restriction of the use of certain Hazardous Substances (RoHS) directive will take effect on July 1 of this year. From that date, the use of chromate conversion coatings containing hexavalent chromium will not be permitted. By comparing the concentration of Cr6+ determined by the diphenyl carbazide color test and by fluorescence XANES (X-Ray Absorption Near Edge Structure) measurement, we can correct for the Cr6+ content of the color test. This will enable the use of the diphenyl carbazide color test to check product shipments in compliance with the RoHS directive

  10. Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace.

    Science.gov (United States)

    Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T

    2016-01-01

    Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr(6+)). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr(6+). GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr(6+) ranged from 50-7800 µg/min, and Cr(6+) generation rates per g electrode ranged from 1-270 µg/g. Elemental Cr generation rates spanned 13-330 µg/g. Manganese emission rates ranged from 50-300 µg/g. Nickel emission rates ranged from 4-140 µg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as five times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes in this

  11. Total Reducing Capacity in Aquifer Minerals and Sediments: Quantifying the Potential to Attenuate Cr(VI) in Groundwater

    International Nuclear Information System (INIS)

    Sisman, S. Lara

    2015-01-01

    Hexavalent chromium, Cr(VI), is present in the environment as a byproduct of industrial processes. Due to its mobility and toxicity, it is crucial to attenuate or remove Cr(VI) from the environment. The objective of this investigation was to quantify potential natural attenuation, or reduction capacity, of reactive minerals and aquifer sediments. Samples of reduced-iron containing minerals such as ilmenite, as well as Puye Formation sediments representing a contaminated aquifer in New Mexico, were reacted with chromate. The change in Cr(VI) during the reaction was used to calculate reduction capacity. This study found that minerals that contain reduced iron, such as ilmenite, have high reducing capacities. The data indicated that sample history may impact reduction capacity tests due to surface passivation. Further, this investigation identified areas for future research including: a) refining the relationships between iron content, magnetic susceptibility and reduction capacity, and b) long term kinetic testing using fresh aquifer sediments.

  12. Total Reducing Capacity in Aquifer Minerals and Sediments: Quantifying the Potential to Attenuate Cr(VI) in Groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Sisman, S. Lara [Univ. of Virginia, Charlottesville, VA (United States); Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-07-20

    Hexavalent chromium, Cr(VI), is present in the environment as a byproduct of industrial processes. Due to its mobility and toxicity, it is crucial to attenuate or remove Cr(VI) from the environment. The objective of this investigation was to quantify potential natural attenuation, or reduction capacity, of reactive minerals and aquifer sediments. Samples of reduced-iron containing minerals such as ilmenite, as well as Puye Formation sediments representing a contaminated aquifer in New Mexico, were reacted with chromate. The change in Cr(VI) during the reaction was used to calculate reduction capacity. This study found that minerals that contain reduced iron, such as ilmenite, have high reducing capacities. The data indicated that sample history may impact reduction capacity tests due to surface passivation. Further, this investigation identified areas for future research including: a) refining the relationships between iron content, magnetic susceptibility and reduction capacity, and b) long term kinetic testing using fresh aquifer sediments.

  13. Environmental biochemistry of chromium.

    Science.gov (United States)

    Losi, M E; Amrhein, C; Frankenberger, W T

    1994-01-01

    Chromium is a d-block transitional element with many industrial uses. It occurs naturally in various crustal materials and is discharged to the environment as industrial waste. Although it can occur in a number of oxidation states, only 3+ and 6+ are found in environmental systems. The environmental behavior of Cr is largely a function of its oxidation state. Hexavalent Cr compounds (mainly chromates and dichromates) are considered toxic to a variety of terrestrial and aquatic organisms and are mobile in soil/water systems, much more so than trivalent Cr compounds. This is largely because of differing chemical properties: Hexavalent Cr compounds are strong oxidizers and highly soluble, while trivalent Cr compounds tend to form relatively inert precipitates at near-neutral pH. The trivalent state is generally considered to be the stable form in equilibrium with most soil/water systems. A diagram of the Cr cycle in soils and water is given in Fig. 6 (Bartlett 1991). This illustration provides a summary of environmentally relevant reactions. Beginning with hexavalent Cr that is released into the environment as industrial waste, there are a number of possible fates, including pollution of soil and surface water and leaching into groundwater, where it may remain stable and, in turn, can be taken up by plants or animals, and adsorption/precipitation, involving soil colloids and/or organic matter. Herein lies much of the environmental concern associated with the hexavalent form. A portion of the Cr(VI) will be reduced to the trivalent form by inorganic electron donors, such as Fe2+ and S2-, or by bioprocesses involving organic matter. Following this conversion, Cr3+ can be expected to precipitate as oxides and hydroxides or to form complexes with numerous ligands. This fraction includes a vast majority of global Cr reserves. Soluble Cr3+ complexes, such as those formed with citrate, can undergo oxidation when they come in contact with manganese dioxide, thus reforming

  14. Optimization of hexavalent chromium removal from aqueous solution using acid-modified granular activated carbon as adsorbent through response surface methodology

    International Nuclear Information System (INIS)

    Daoud, Waseem; Ebadi, Taghi; Fahimifar, Ahmad

    2015-01-01

    Response surface methodology (RSM) was applied to evaluate the effect of the main operational variables, including initial pH, initial chromium ion concentration, bulk density of GAC and time on the removal of hexavalent chromium Cr(Ⅵ) from contaminated groundwater by permeable reactive barriers (PRB) with acid-modified granular activated carbon (GAC) as an adsorbent material. The removal rates of Cr(Ⅵ) under different values of these parameters were investigated and results indicated high adsorption capacity at low pH and low initial metal ion concentration of Cr(Ⅵ), but the bulk density of GAC slightly influenced the process efficiency. According to the ANOVA (analysis of variance) results, the model presents high R 2 values of 94.35% for Cr(Ⅵ) removal efficiency, which indicates that the accuracy of the polynomial models was good. Also, quadratic regression models with estimated coefficients were developed to describe the pollutant removals

  15. Optimization of hexavalent chromium removal from aqueous solution using acid-modified granular activated carbon as adsorbent through response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Daoud, Waseem; Ebadi, Taghi; Fahimifar, Ahmad [Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of)

    2015-06-15

    Response surface methodology (RSM) was applied to evaluate the effect of the main operational variables, including initial pH, initial chromium ion concentration, bulk density of GAC and time on the removal of hexavalent chromium Cr(Ⅵ) from contaminated groundwater by permeable reactive barriers (PRB) with acid-modified granular activated carbon (GAC) as an adsorbent material. The removal rates of Cr(Ⅵ) under different values of these parameters were investigated and results indicated high adsorption capacity at low pH and low initial metal ion concentration of Cr(Ⅵ), but the bulk density of GAC slightly influenced the process efficiency. According to the ANOVA (analysis of variance) results, the model presents high R{sup 2} values of 94.35% for Cr(Ⅵ) removal efficiency, which indicates that the accuracy of the polynomial models was good. Also, quadratic regression models with estimated coefficients were developed to describe the pollutant removals.

  16. Effects of chromium on the immune system.

    Science.gov (United States)

    Shrivastava, Richa; Upreti, R K; Seth, P K; Chaturvedi, U C

    2002-09-06

    Chromium is a naturally occurring heavy metal found commonly in the environment in trivalent, Cr(III), and hexavalent, Cr(VI), forms. Cr(VI) compounds have been declared as a potent occupational carcinogen among workers in chrome plating, stainless steel, and pigment industries. The reduction of Cr(VI) to Cr(III) results in the formation of reactive intermediates that together with oxidative stress oxidative tissue damage and a cascade of cellular events including modulation of apoptosis regulatory gene p53, contribute to the cytotoxicity, genotoxicity and carcinogenicity of Cr(VI)-containing compounds. On the other hand, chromium is an essential nutrient required to promote the action of insulin in body tissues so that the body can use sugars, proteins and fats. Chromium is of significant importance in altering the immune response by immunostimulatory or immunosuppressive processes as shown by its effects on T and B lymphocytes, macrophages, cytokine production and the immune response that may induce hypersensitivity reactions. This review gives an overview of the effects of chromium on the immune system of the body. Copyright 2002 Federation of European Microbiological Societies

  17. Can iron oxides remove Cr(VI) from drinking water at sub-ppb levels?

    Science.gov (United States)

    Kaprara, Efthymia; Simeonidis, Konstantinos; Samaras, Petros; Zouboulis, Anastasios; Mitrakas, Manassis

    2013-04-01

    Hexavalent chromium [Cr(VI)] has long been recognized as a potential carcinogen via inhalation, in contrast to trivalent chromium [Cr(III)] which is 100 times less toxic and also a necessary nutrient, essential to human glucidic metabolism. Nowadays there is an increasing concern that Cr(VI) is also carcinogenic by the oral route of exposure, while an increased number of publications indicate that Cr(VI) is a common natural pollutant. Hexavalent chromium formation is attributed to natural oxidation of Cr(III) in ultramafic derived soils and ophiolithic rocks. To verify this theory, drinking water samples were collected from targeted areas of Greece e.g. areas in which the geological background is predominated by ultramafic minerals and the water supply depends mainly on groundwater resources. Valuable guide for the samples collection was the geological map of Greece and emphasis was given to regions where the natural occurrence of Cr(VI) is thought to be more possible. A wide range of Cr concentrations (2-100 μg/L) were detected in the areas studied, with most of them ranging below the current limit of 50 μg/L, and the Cr(VI) concentration being more than 90% of the total. Since the Cr(VI) affects significant part of population worldwide, a debate was established concerning the enforcement of stringent regulation, which also demands the drinking water treatment processes re-evaluation in view of Cr(VI) removal at sub-ppb level. In this regard, adsorption has evolved as the front line of defense for chromium removal. The motivation of this work was to investigate the efficiency of iron oxides for the adsorption of Cr(VI) from drinking water and its removal at sub-ppb levels. The adsorbents examined included iron oxy-hydroxides and magnetite prepared using common low cost iron salts. Their effectiveness as Cr(VI) adsorbents was evaluated through the decrease of a Cr(VI) concentration of 100μg/L prepared in NSF water at pH 7. Preliminary batch experiments did not

  18. Ni0 encapsulated in N-doped carbon nanotubes for catalytic reduction of highly toxic hexavalent chromium

    Science.gov (United States)

    Yao, Yunjin; Zhang, Jie; Chen, Hao; Yu, Maojing; Gao, Mengxue; Hu, Yi; Wang, Shaobin

    2018-05-01

    N-doped carbon nanotubes encapsulating Ni0 nanoparticles (Ni@N-C) were fabricated via thermal reduction of dicyandiamide and NiCl2·6H2O, and used to remove CrVI in polluted water. The resultant products present an excellent catalytic activity for CrVI reduction using formic acid under relatively mild conditions. The CrVI reduction efficiency of Ni@N-C was significantly affected by the preparation conditions including the mass of nickel salt and synthesis temperatures. The impacts of several reaction parameters, such as initial concentrations of CrVI and formic acid, solution pH and temperatures, as well as inorganic anions in solution on CrVI reduction efficiency were also evaluated in view of scalable industrial applications. Owing to the synergistic effects amongst tubes-coated Ni0, doped nitrogen, oxygen containing groups, and the configuration of carbon nanotubes, Ni@N-C catalysts exhibit excellent catalytic activity and recyclable capability for CrVI reduction. Carbon shell can efficiently protect inner Ni0 core and N species from corrosion and subsequent leaching, while Ni0 endows the Ni@N-C catalysts with ferromagnetism, so that the composites can be easily separated via a permanent magnet. This study opens up an avenue for design of N-doped carbon nanotubes encapsulating Ni0 nanoparticles with high CrVI removal efficiency and magnetic recyclability as low-cost catalysts for industrial applications.

  19. Ameliorative effects of nano-elemental selenium against hexavalent chromium-induced apoptosis in broiler liver.

    Science.gov (United States)

    Xueting, Liu; Rehman, Mujeeb Ur; Mehmood, Khalid; Huang, Shucheng; Tian, Xinxin; Wu, Xiaoxing; Zhou, Donghai

    2018-06-01

    The current study examined the ameliorative effects of nano-elemental selenium (Nano-Se) against chromium-VI (K 2 Cr 2 O 7 )-induced apoptosis in chickens. The expression of apoptosis-related genes was evaluated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot. A total of 60, one-day-old broiler chickens allotted to six equal groups, i.e., control group (standard diet), Cr(VI)-exposed group (K 2 Cr 2 O 7 via drinking water), Nano-Se group (Nano-Se at 0.5 mg/kg via diet), protection group (K 2 Cr 2 O 7  + Nano-Se), cure group (K 2 Cr 2 O 7 for initial 2 weeks and then Nano-Se), and prevention group (opposite to the cure group) and were detected by the activities of pro-apoptosis (Bax, Caspase-3) and anti-apoptosis (Bcl-2) genes expression at day 35 of the experiment. Intense apoptosis was observed in liver tissues of chickens exposed to K 2 Cr 2 O 7 . The Nano-Se supplementation caused a significant decrease (P Nano-Se experimental groups as compare to control and Cr(VI)-exposed group. The results quantified by the RT-qPCR were further confirmed by the western blot analysis. Altogether, these results suggest anti-apoptotic effects of Nano-Se in the chicken liver, which is interesting for further study. The present findings suggested that Nano-Se has protective effects against K 2 Cr 2 O 7 -induced apoptosis in broilers liver and can serve a key role as a protective agent against apoptosis.

  20. Application of chromium stable isotopes to the evaluation of Cr(VI) contamination in groundwater and rock leachates from central Euboea and the Assopos basin (Greece)

    DEFF Research Database (Denmark)

    Economou-Eliopoulos, Maria; Frei, Robert; Atsarou, Cathy

    2014-01-01

    Major and trace elements (a) in groundwater, ultramafic rocks from natural outcrops and soil samples from cultivated sites of Central Euboea and Assopos basin, and (b) in experimentally produced laboratory water leachates of rocks and soils were investigated by SEM/EDS, XRD and ICP/MS. In addition......, stable chromium isotopes (expressed as δ53Cr values) were measured in groundwater and leachates in order to identify potential sources for Cr-contamination. The higher Cr(VI) concentrations in soil leachates compared to those in the rock pulp leachates potentially can be explained by the presence...... of larger amounts of Fe (Fe(II)) and Mn (Mn-oxides acting as oxidizing catalysts). Assuming that redox processes produce significant Cr isotope fractionation (groundwater δ53Cr values range between 0.8 and 1.98‰), the compilation of the obtained analytical data suggests that the dominant cause of Cr isotope...

  1. Performance Evaluation of Electro-Fenton Process (EFP in Removal of Hexavalent Chromium in the Presence of Cyanide, as an Interfering Agent, from Synthetic Wastewaters

    Directory of Open Access Journals (Sweden)

    Ali Reza Rahmani

    2014-06-01

    Full Text Available Background: Chromium (VI is a hazardous pollutant that enters into the environment through different industrial wastewater. Therefore, Choice a suitable method for removal of the pollutant before discharging into the environment is necessary. The aim of this work was performance evaluation of Electro-Fenton process (EFP in removal of hexavalent chromium in the presence of cyanide, as an interfering agent, from synthetic wastewaters. Methods: In this experimental study, a reactor with 1 L useful volume and 4 electrodes made ​​of iron was used. pH, initial concentration of  chromium (VI, voltage, hydrogen peroxide and cyanide concentration, as an interfering agent, were investigated in order to determine the process efficiency. Results: Results reveals that the considered parameters were affected on the efficiency of the process. In optimum condition, pH=3 and voltage=20 V, initial concentration=100 mg/L, concentration of hydrogen peroxide=50 mL/L the maximum efficiency was reached up to 97%. Cyanide Presence, in the same condition, reduced the efficiency under 50 % and also, the efficiency was decreased by changing the parameters level from optimum condition. Conclusion: Results indicate the proper efficiency of chromium (VI by EFP process; however presence of other pollutants such as cyanide can cause efficiency decrease which must be considered in the process application.

  2. Development of iron-based nanoparticles for Cr(VI removal from drinking water

    Directory of Open Access Journals (Sweden)

    Vourlias G.

    2013-01-01

    Full Text Available A great deal of research over recent decades has been motivated by the requirement to lower the concentration of chromium in drinking water. This study has been conducted to determine the feasibility of iron-based nanoparticles for chromium removal from contaminated water. Single Fe, Fe3O4 and binary Fe/Fe3O4 nanoparticles were grown at the 45-80 nm size range using the solar physical vapor deposition technique and tested as potential hexavalent chromium removing agents from aqueous solutions. Due to their higher electron donation ability compared to the Fe3O4 ones, single Fe nanoparticles exhibited the highest Cr(VI removal capacity of more than 3 µg/mg while maintaining a residual concentration 50 µg/L, equal to the regulation limit for drinking water. In combination to their facile and fast magnetic separation, the applicability of the studied particles in water treatment facilities should be considered.

  3. Polyacrylonitrile/polyaniline core/shell nanofiber mat for removal of hexavalent chromium from aqueous solution: mechanism and applications

    KAUST Repository

    Wang, Jianqiang

    2013-01-01

    Polyacrylonitrile/polyaniline core/shell nanofibers were prepared via electrospinning followed by in situ polymerization of aniline. Nanofibers with different morphology were obtained by changing the polymerization temperature. When used as absorbent for Cr(vi) ions, the core/shell nanofiber mats exhibit excellent adsorption capability. The equilibrium capacity is 24.96, 37.24, and 52.00 mg g-1 for 105, 156, and 207 mg L-1 initial Cr(vi) solution, respectively, and the adsorption capacity increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(vi) ions in the presence of competing ions albeit a small decrease in adsorption is observed. The mats can be regenerated and reused after treatment with NaOH making them promising candidates as practical adsorbents for Cr(vi) removal. © The Royal Society of Chemistry 2013.

  4. Biological Cr(VI) removal using bio-filters and constructed wetlands.

    Science.gov (United States)

    Michailides, Michail K; Sultana, Mar-Yam; Tekerlekopoulou, Athanasia G; Akratos, Christos S; Vayenas, Dimitrios V

    2013-01-01

    The bioreduction of hexavalent chromium from aqueous solution was carried out using suspended growth and packed-bed reactors under a draw-fill operating mode, and horizontal subsurface constructed wetlands. Reactors were inoculated with industrial sludge from the Hellenic Aerospace Industry using sugar as substrate. In the suspended growth reactors, the maximum Cr(VI) reduction rate (about 2 mg/L h) was achieved for an initial concentration of 12.85 mg/L, while in the attached growth reactors, a similar reduction rate was achieved even with high initial concentrations (109 mg/L), thus confirming the advantage of these systems. Two horizontal subsurface constructed wetlands (CWs) pilot-scale units were also built and operated. The units contained fine gravel. One unit was planted with common reeds and one was kept unplanted. The mean influent concentrations of Cr(VI) were 5.61 and 5.47 mg/L for the planted and unplanted units, respectively. The performance of the planted CW units was very effective as mean Cr(VI) removal efficiency was 85% and efficiency maximum reached 100%. On the contrary, the unplanted CW achieved very low Cr(VI) removal with a mean value of 26%. Both attached growth reactors and CWs proved efficient and viable means for Cr(VI) reduction.

  5. Nitrification inhibition by hexavalent chromium Cr(VI)--Microbial ecology, gene expression and off-gas emissions.

    Science.gov (United States)

    Kim, Young Mo; Park, Hongkeun; Chandran, Kartik

    2016-04-01

    The goal of this study was to investigate the responses in the physiology, microbial ecology and gene expression of nitrifying bacteria to imposition of and recovery from Cr(VI) loading in a lab-scale nitrification bioreactor. Exposure to Cr(VI) in the reactor strongly inhibited nitrification performance resulting in a parallel decrease in nitrate production and ammonia consumption. Cr(VI) exposure also led to an overall decrease in total bacterial concentrations in the reactor. However, the fraction of ammonia oxidizing bacteria (AOB) decreased to a greater extent than the fraction of nitrite oxidizing bacteria (NOB). In terms of functional gene expression, a rapid decrease in the transcript concentrations of amoA gene coding for ammonia oxidation in AOB was observed in response to the Cr(VI) shock. In contrast, transcript concentrations of the nxrA gene coding for nitrite oxidation in NOB were relatively unchanged compared to Cr(VI) pre-exposure levels. Therefore, Cr(VI) exposure selectively and directly inhibited activity of AOB, which indirectly resulted in substrate (nitrite) limitation to NOB. Significantly, trends in amoA expression preceded performance trends both during imposition of and recovery from inhibition. During recovery from the Cr(VI) shock, the high ammonia concentrations in the bioreactor resulted in an irreversible shift towards AOB populations, which are expected to be more competitive in high ammonia environments. An inadvertent impact during recovery was increased emission of nitrous oxide (N2O) and nitric oxide (NO), consistent with recent findings linking AOB activity and the production of these gases. Therefore, Cr(VI) exposure elicited multiple responses on the microbial ecology, gene expression and both aqueous and gaseous nitrogenous conversion in a nitrification process. A complementary interrogation of these multiple responses facilitated an understanding of both direct and indirect inhibitory impacts on nitrification. Copyright

  6. Graphene/biofilm composites for enhancement of hexavalent chromium reduction and electricity production in a biocathode microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Song, Tian-shun [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Jiangsu Branch of China Academy of Science & Technology Development, Nanjing (China); Jin, Yuejuan; Bao, Jingjing [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Kang, Dongzhou, E-mail: kangdz@ybu.edu.cn [College of Pharmacy, Yanbian University, Yanji 133002 (China); Xie, Jingjing, E-mail: xiej@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211816 (China); College of Life Science and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816 (China); Jiangsu Branch of China Academy of Science & Technology Development, Nanjing (China); College of Pharmacy, Yanbian University, Yanji 133002 (China); Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing 211816 (China)

    2016-11-05

    Highlights: • Graphene/biofilm was microbially fabricated to cathode of a Cr(VI)-reducing MFC. • High Cr(VI) reduction rate was generated by self-assembled graphene biocathode MFC. • Graphene biocathode improves the electricity production of Cr(VI)-reducing MFC. • High surface area of the graphene provides more adsorption sites for Cr(VI). • Graphene biocathode improves the electron transfer rate in the MFC. - Abstract: In this study, a simple method of biocathode fabrication in a Cr(VI)-reducing microbial fuel cell (MFC) is demonstrated. A self-assembling graphene was decorated onto the biocathode microbially, constructing a graphene/biofilm, in situ. The maximum power density of the MFC with a graphene biocathode is 5.7 times that of the MFC with a graphite felt biocathode. Cr(VI) reduction was also enhanced, resulting in 100% removal of Cr(VI) within 48 h, at 40 mg/L Cr(VI), compared with only 58.3% removal of Cr(VI) in the MFC with a graphite felt biocathode. Cyclic voltammogram analyses showed that the graphene biocathode had faster electron transfer kinetics than the graphite felt version. Energy dispersive spectrometer (EDS) and X-ray photoelectron spectra (XPS) analysis revealed a possible adsorption-reduction mechanism for Cr(VI) reduction via the graphene biocathode. This study attempts to improve the efficiency of the biocathode in the Cr(VI)-reducing MFC, and provides a useful candidate method for the treatment of Cr(VI) contaminated wastewater, under neutral conditions.

  7. Tea waste biomass activated carbon electrode for simultaneous removal of Cr(VI) and fluoride by capacitive deionization.

    Science.gov (United States)

    Gaikwad, Mahendra S; Balomajumder, Chandrajit

    2017-10-01

    Capacitive deionization is promising less energy based desalination technique to achieve pure water. In the present study microporous activated carbon was prepared from tea waste biomass by chemical and thermal modification. Further TWBAC was used for preparation of the electrode. The TWBAC electrode was applied in the self-made CDI set up for simultaneous removal of hexavalent chromium [Cr(VI)] and fluoride (F) form mixed feed solution of Cr(VI) and F. The performance of TWBAC electrode was found effective for simultaneous removal of Cr(VI) and F from mixed feed solution. The maximum electrosorption capacity of Cr(VI) and F were found 0.77 and 0.74 mg g -1 for 10 mg L -1 and 2.83 and 2.49 mg g -1 for 100 mg L -1 mixed feed solution respectively. The higher removal of Cr(VI) was found due to the electrosorption selectivity of the divalent CrO 4 2- is higher than that of the monovalent F - . Multicomponent isotherm modeling and kinetic study were carried out in this study. TWBAC CDI electrode could be useful for treatment of a low concentrated Cr(VI) and F containing wastewater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Chromium in Drinking Water: Sources, Metabolism, and Cancer Risks

    Science.gov (United States)

    2011-01-01

    Drinking water supplies in many geographic areas contain chromium in the +3 and +6 oxidation states. Public health concerns are centered on the presence of hexavalent Cr that is classified as a known human carcinogen via inhalation. Cr(VI) has high environmental mobility and can originate from anthropogenic and natural sources. Acidic environments with high organic content promote the reduction of Cr(VI) to nontoxic Cr(III). The opposite process of Cr(VI) formation from Cr(III) also occurs, particularly in the presence of common minerals containing Mn(IV) oxides. Limited epidemiological evidence for Cr(VI) ingestion is suggestive of elevated risks for stomach cancers. Exposure of animals to Cr(VI) in drinking water induced tumors in the alimentary tract, with linear and supralinear responses in the mouse small intestine. Chromate, the predominant form of Cr(VI) at neutral pH, is taken up by all cells through sulfate channels and is activated nonenzymatically by ubiquitously present ascorbate and small thiols. The most abundant form of DNA damage induced by Cr(VI) is Cr-DNA adducts, which cause mutations and chromosomal breaks. Emerging evidence points to two-way interactions between DNA damage and epigenetic changes that collectively determine the spectrum of genomic rearrangements and profiles of gene expression in tumors. Extensive formation of DNA adducts, clear positivity in genotoxicity assays with high predictive values for carcinogenicity, the shape of tumor–dose responses in mice, and a biological signature of mutagenic carcinogens (multispecies, multisite, and trans-sex tumorigenic potency) strongly support the importance of the DNA-reactive mutagenic mechanisms in carcinogenic effects of Cr(VI). Bioavailability results and kinetic considerations suggest that 10–20% of ingested low-dose Cr(VI) escapes human gastric inactivation. The directly mutagenic mode of action and the incompleteness of gastric detoxification argue against a threshold in low

  9. Soil retention of hexavalent chromium released from construction and demolition waste in a road-base-application scenario.

    Science.gov (United States)

    Butera, Stefania; Trapp, Stefan; Astrup, Thomas F; Christensen, Thomas H

    2015-11-15

    We investigated the retention of Cr(VI) in three subsoils with low organic matter content in laboratory experiments at concentration levels relevant to represent leachates from construction and demolition waste (C&DW) reused as unbound material in road construction. The retention mechanism appeared to be reduction and subsequent precipitation as Cr(III) on the soil. The reduction process was slow and in several experiments it was still proceeding at the end of the six-month experimental period. The overall retention reaction fit well with a second-order reaction governed by actual Cr(VI) concentration and reduction capacity of the soil. The experimentally determined reduction capacities and second-order kinetic parameters were used to model, for a 100-year period, the one-dimensional migration of Cr(VI) in the subsoil under a layer of C&DW. The resulting Cr(VI) concentration would be negligible below 7-70 cm depth. However, in rigid climates and with high water infiltration through the road pavement, the reduction reaction could be so slow that Cr(VI) might migrate as deep as 200 cm under the road. The reaction parameters and the model can form the basis for systematically assessing under which scenarios Cr(VI) from C&DW could lead to an environmental issue for ground- and receiving surface waters. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Photoreduction of chromium(VI) in the presence of algae, Chlorella vulgaris

    International Nuclear Information System (INIS)

    Deng Lin; Wang Hongli; Deng Nansheng

    2006-01-01

    In this thesis, the photochemical reduction of hexavalent chromium Cr(VI) in the presence of algae, Chlorella vulgaris, was investigated under the irradiation of metal halide lamps (λ=365nm, 250W). The affecting factors of photochemical reduction were studied in detail, such as exposure time, initial Cr(VI) concentration, initial algae concentration and pH. The rate of Cr(VI) photochemical reduction increased with algae concentration increasing, exposure time increasing, initial Cr(VI) concentration decreasing and the decrease of pH. When pH increased to 6, the rate of Cr(VI) photochemical reduction nearly vanished. When initial Cr(VI) concentration ranged from 0.4 to 1.0mgL -1 and initial algae concentration ranged from ABS algae (the absorbency of algae)=0.025 to ABS algae =0.180, According to the results of kinetic analyses, the kinetic equation of Cr(VI) photochemical reduction in aqueous solution with algae under 250W metal halide lamps was V 0 =kC 0 0.1718 A algae 0.5235 (C 0 was initial concentration of Cr(VI); A algae was initial concentration of algae) under the condition of pH 4

  11. Photoreduction of chromium(VI) in the presence of algae, Chlorella vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Deng Lin [School of Resources and Environmental Science, Wuhan University, Wuhan 430072 (China); Wang Hongli [School of Resources and Environmental Science, Wuhan University, Wuhan 430072 (China); Deng Nansheng [School of Resources and Environmental Science, Wuhan University, Wuhan 430072 (China)]. E-mail: nsdengwhu@163.com

    2006-11-16

    In this thesis, the photochemical reduction of hexavalent chromium Cr(VI) in the presence of algae, Chlorella vulgaris, was investigated under the irradiation of metal halide lamps ({lambda}=365nm, 250W). The affecting factors of photochemical reduction were studied in detail, such as exposure time, initial Cr(VI) concentration, initial algae concentration and pH. The rate of Cr(VI) photochemical reduction increased with algae concentration increasing, exposure time increasing, initial Cr(VI) concentration decreasing and the decrease of pH. When pH increased to 6, the rate of Cr(VI) photochemical reduction nearly vanished. When initial Cr(VI) concentration ranged from 0.4 to 1.0mgL{sup -1} and initial algae concentration ranged from ABS{sub algae} (the absorbency of algae)=0.025 to ABS{sub algae}=0.180, According to the results of kinetic analyses, the kinetic equation of Cr(VI) photochemical reduction in aqueous solution with algae under 250W metal halide lamps was V{sub 0}=kC{sub 0}{sup 0.1718}A{sub algae}{sup 0.5235} (C{sub 0} was initial concentration of Cr(VI); A{sub algae} was initial concentration of algae) under the condition of pH 4.

  12. Chromium(VI) bioremediation by probiotics.

    Science.gov (United States)

    Younan, Soraia; Sakita, Gabriel Z; Albuquerque, Talita R; Keller, Rogéria; Bremer-Neto, Hermann

    2016-09-01

    Chromium is a common mineral in the earth's crust and can be released into the environment from anthropogenic sources. Intake of hexavalent chromium (Cr(VI)) through drinking water and food causes toxic effects, leading to serious diseases, and is a commonly reported environmental problem. Microorganisms can mitigate or prevent the toxic effects caused by heavy metals in addition to having effective resistance mechanisms to prevent cell damage and bind to these metals, sequestering them from the cell surface and removing them from the body. Species of Lactobacillus, Streptococcus, Bacillus and Bifidobacterium present in the human mouth and gut and in fermented foods have the ability to bind and detoxify some of these substances. This review address the primary topics related to Cr(VI) poisoning in animals and humans and the use of probiotics as a way to mitigate or prevent the toxic effects caused by Cr(VI). Further advances in the genetic knowledge of such microorganisms may lead to discoveries which will clarify the most active microorganisms that act as bioprotectants in bodies exposed to Cr(VI) and are an affordable option for people and animals intoxicated by the oral route. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  13. Hexavalent chromium content in stainless steel welding fumes is dependent on the welding process and shield gas type.

    Science.gov (United States)

    Keane, Michael; Stone, Samuel; Chen, Bean; Slaven, James; Schwegler-Berry, Diane; Antonini, James

    2009-02-01

    Occupational exposure to welding fumes is a known health hazard. To isolate elements in stainless steel welding fumes with high potential for adverse health outcomes, fumes were generated using a robotic gas metal arc system, using four shield gases of varying oxygen content. The objective was to measure Cr(VI) concentrations in a broad spectrum of gas metal arc welding processes, and identify processes of exceptionally high or low Cr(VI) content. The gases used were 95% Ar/5% O(2), 98% Ar/2% O(2), 95% Ar/5%CO(2), and 75% He/25% Ar. The welder was operated in axial spray mode (Ar/O(2), Ar/CO(2)), short-circuit (SC) mode (Ar/CO(2) low voltage and He/Ar), and pulsed axial-spray mode (98% Ar/2% O(2)). Results indicate large differences in Cr(VI) in the fumes, with Ar/O(2) (Pulsed)>Ar/O(2)>Ar/CO(2)>Ar/CO(2) (SC)>He/Ar; values were 3000+/-300, 2800+/-85, 2600+/-120, 1400+/-190, and 320+/-290 ppm respectively (means +/- standard errors for 2 runs and 3 replicates per run). Respective rates of Cr(VI) generation were 1.5, 3.2, 4.4, 1.3, and 0.46 microg/min; generation rates were also calculated in terms of microg Cr(VI) per metre of wire used. The generation rates of Cr(VI) increased with increasing O(3) concentrations. Particle size measurements indicated similar distributions, but somewhat higher >0.6 microm fractions for the short-circuit mode samples. Fumes were also sampled into 2 selected size ranges, a microspatter fraction (>or=0.6 microm) and a fine (welding type and shield gas type, and this presents an opportunity to tailor welding practices to lessen Cr(VI) exposures in workplaces by selecting low Cr(VI)-generating processes. Short-circuit processes generated less Cr(VI) than axial-spray methods, and inert gas shielding gave lower Cr(VI) content than shielding with active gases. A short circuit He/Ar shielded process and a pulsed axial spray Ar/O(2) process were both identified as having substantially lower Cr(VI) generation rates per unit of wire used relative

  14. Validation of an electrothermal atomization atomic absorption spectrometry method for quantification of total chromium and chromium(VI) in wild mushrooms and underlying soils.

    Science.gov (United States)

    Figueiredo, Estela; Soares, M Elisa; Baptista, Paula; Castro, Marisa; Bastos, M Lourdes

    2007-08-22

    An ETAAS method was validated to quantify total Cr and Cr(VI) in mushrooms and the underlying soils. The method includes a sample pretreatment for total Cr dissolution using a wet acid digestion procedure and a selective alkaline extraction for Cr(VI). The limits of detection were, expressed in microg/L, 0.15 and 0.17 for total Cr and Cr(VI), respectively. The linearity ranges under the optimized conditions were 0.15-25.0 and 0.17-20.0 microg/L for total Cr and Cr(VI), respectively. The limits of quantification were, expressed in microg/g of dry weight, 0.0163 and 0.0085 for total and hexavalent chromium, respectively. The precision of the instrumental method for total Cr and Cr(VI) was lower than 1.6%, and for the analytical method, it was lower than 10%. The accuracy of the method for Cr(VI) quantification was evaluated by the standard additions method, with the recoveries being higher than 90% for all of the added concentrations. For total Cr, certified reference materials (lichen CRM 482 and soil sample NCS ZC73001) were used. An interference study was also carried out in a mushroom simulated matrix, and it was verified that the deviations of the expected values were lower than 4.0% for both total Cr and Cr(VI). The validated method was applied to the evaluation of total Cr and Cr(VI) in 34 wild mushrooms and 34 respective underlying soil samples collected in two different regions of Portugal (Beira Interior and TrAs-os-Montes), with different locations regarded as noncontaminated or contaminated areas. The species were identified by a mycologist and subdivided into 10 genera and 15 species: Amanita (rubescens, muscaria, and ponderosa), Boletus (regius), Lactarius (deliciosus, vellereus, and piperatus), Suillus (granulatus and luteus), Tricholoma (acerbum), Agaricus (sylvicola), Volvariella (gloiocephala), Lecopaxillus (giganteus), Macrolepiota (procera), and Psilocybe (fascicularis). The mean values found for total Cr were 1.14 and 1.11 microg/g of dry weight

  15. Biosorption of chromium from electroplating and galvanizing industrial effluents under extreme conditions using Chlorella vulgaris

    Directory of Open Access Journals (Sweden)

    G. Sibi

    2016-07-01

    Full Text Available Hexavalent chromium [Cr(VI] is a toxic oxidized form and an important metal pollutant in the water bodies. Biosorption of chromium(VI offers a potential alternative to conventional metal removal methods. Dried biomass of Chlorella vulgaris was used as biosorbent for the removal of Cr(VI from electroplating and galvanizing industry effluents as a function of biosorbent dosage, contact time, pH, salinity and initial metal ion concentration. Batch experiments were conducted for biosorption and the optimum conditions were 1 g/L biomass, 4 h contact time, pH 2 and 2.893 mS/cm of electrical conductivity. The chromium biosorption was strictly pH dependent with a maximum Cr removal of 63.2 mg/L at pH 2. Highest Cr removal at a concentration of 81.3 mg/L was observed at Electrical conductivity (EC value of 2.893 mS/cm. A comparison of Langmuir and Freundlich isotherm models revealed that Freundlich isotherm model fitted the experimental data based on R2, qmax and standard error values. The results suggest that C. vulgaris biomass could be considered a promising low-cost biosorbent for the removal of Cr(VI from electroplating and galvanizing industry effluents. Keywords: Biosorption, Chlorella vulgaris, Microalgae, Hexavalent chromium

  16. Development of analytical procedures for the determination of hexavalent chromium in corrosion prevention coatings used in the automotive industry.

    Science.gov (United States)

    Séby, F; Castetbon, A; Ortega, R; Guimon, C; Niveau, F; Barrois-Oudin, N; Garraud, H; Donard, O F X

    2008-05-01

    The European directive 2000/53/EC limits the use of Cr(VI) in vehicle manufacturing. Although a maximum of 2 g of Cr(VI) was authorised per vehicle for corrosion prevention coatings of key components, since July 2007 its use has been prohibited except for some particular applications. Therefore, the objective of this work was to develop direct analytical procedures for Cr(VI) determination in the different steel coatings used for screws. Instead of working directly with screws, the optimisation of the procedures was carried out with metallic plates homogeneously coated to improve the data comparability. Extraction of Cr(VI) from the metallic parts was performed by sonication. Two extraction solutions were tested: a direct water extraction solution used in standard protocols and an ammonium/ammonia buffer solution at pH 8.9. The extracts were further analysed for Cr speciation by high-performance liquid chromatography (HPLC) inductively coupled plasma (ICP) atomic emission spectrometry or HPLC ICP mass spectrometry depending on the concentration level. When possible, the coatings were also directly analysed by solid speciation techniques (X-ray photoelectron spectroscopy, XPS, and X-ray absorption near-edge structure, XANES) for validation of the results. Very good results between the different analytical approaches were obtained for the sample of coating made up of a heated paint containing Zn, Al and Cr when using the extracting buffer solution at pH 8.9. After a repeated four-step extraction procedure on the same portion test, taking into account the depth of the surface layer reached, good agreement with XPS and XANES results was obtained. In contrast, for the coatings composed of an alkaline Zn layer where Cr(VI) and Cr(III) are deposited, only the extraction procedure using water allowed the detection of Cr(VI). To elucidate the Cr(VI) reduction during extraction at pH 8.9, the reactivity of Cr(VI) towards different species of Zn generally present in the

  17. Automated Ground-Water Sampling and Analysis of Hexavalent Chromium using a “Universal” Sampling/Analytical System

    Directory of Open Access Journals (Sweden)

    Richard J. Venedam

    2005-02-01

    Full Text Available The capabilities of a “universal platform” for the deployment of analyticalsensors in the field for long-term monitoring of environmental contaminants were expandedin this investigation. The platform was previously used to monitor trichloroethene inmonitoring wells and at groundwater treatment systems (1,2. The platform was interfacedwith chromium (VI and conductivity analytical systems to monitor shallow wells installedadjacent to the Columbia River at the 100-D Area of the Hanford Site, Washington. Agroundwater plume of hexavalent chromium is discharging into the Columbia River throughthe gravels beds used by spawning salmon. The sampling/analytical platform was deployedfor the purpose of collecting data on subsurface hexavalent chromium concentrations atmore frequent intervals than was possible with the previous sampling and analysis methodsemployed a the Site.

  18. Effective adsorption of hexavalent chromium through a three center (3c) co-operative interaction with an ionic liquid and biopolymer

    International Nuclear Information System (INIS)

    Santhana Krishna Kumar, A.; Gupta, Timsi; Kakan, Shruti Singh; Kalidhasan, S.; Manasi,; Rajesh, Vidya; Rajesh, N.

    2012-01-01

    Highlights: ► Tetraoctylammoniumbromide impregnated chitosan was prepared by ultrasonication. ► Physico-chemical characterization of the adsorbent was studied in detail. ► The sorbent has an adsorption capacity of 63.69 mg g −1 for chromium(VI). ► The mechanism involves a three center interaction with positive co-operative effect. ► Adsorbent is effectively regenerated with ammonium hydroxide. - Abstract: Biopolymers as well as ionic liquids are known for their potential applications. In this work, we report the utility of chitosan as an excellent platform for impregnating the ionic liquid, tetraoctylammonium bromide by ultrasonication and its subsequent adsorption for chromium(VI). The effective mass transfer due to sonication coupled with the hydrogen bonding interaction between chitosan-ionic liquid and the electrostatic interaction involving the amino groups in chitosan and hexavalent chromium governs this three center (3c) co-operative mechanism. The adsorption followed a pseudo second order kinetics with a Langmuir adsorption capacity of 63.69 mg g −1 . Various isotherm models were used to correlate the experimental data and the adsorption process is exothermic with a decreased randomness at the solid–solution interface. The thermodynamics of the spontaneous adsorption process could be explained through a positive co-operative effect between the host (chitosan) and the guest (ionic liquid). The adsorbed chromium(VI) could be converted to ammonium chromate using ammonium hydroxide, thereby regenerating the adsorbent. The method could be translated into action in the form of practical application to a real sample containing chromium.

  19. Electrochemically enhanced reduction of hexavalent chromium in contaminated clay: Kinetics, energy consumption, and application of pulse current

    DEFF Research Database (Denmark)

    Sun, Tian Ran; Pamukcu, Sibel; Ottosen, Lisbeth M.

    2015-01-01

    the dependency of reaction rate on energy consumption. A modified electrophoresis cell with platinum wires as working electrodes was used to run experiments. Results showed that the reduction rate of Cr(VI) was significantly increased by application of current with the pseudo-first-order rate constant kpse from......,Fe)(OH)3] precipitates. XRD analysis suggested that the [(Cr,Fe)(OH)3] formed at the clay surface and grew into the pore fluid. SEM-EDX results indicated that the overall Fe(III):Cr(III) ratio of the precipitates was approximately 1.26:1. Application of pulse current decreased the non-productive energy......Electrochemically enhanced reduction of Cr(VI) in clay medium is a technique based on inputting extra energy into the clay to drive the favorable redox reaction. In this study, the reducing reagent Fe(II) was transported into Cr(VI) spiked kaolinite clay by direct current to investigate...

  20. Removal combined with reduction of hexavalent chromium from aqueous solution by Fe-ethylene glycol complex microspheres

    Science.gov (United States)

    Zhang, Yong-Xing; Jia, Yong

    2016-12-01

    Three-dimensional Fe-ethylene glycol (Fe-EG) complex microspheres were synthesized by a facile hydrothermal method, and were characterized by field emission scanning electron microscopy and transmission electron microscopy. The adsorption as well as reduction properties of the obtained Fe-EG complex microspheres towards Cr(VI) ions were studied. The experiment data of adsorption kinetic and isotherm were fitted by nonlinear regression approach. In neutral condition, the maximum adsorption capacity was 49.78 mg g-1 at room temperature, and was increased with the increasing of temperature. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy revealed that adsorption of Cr(VI) was a feasible, spontaneous and endothermic process. Spectroscopic analysis revealed the adsorption of Cr(VI) was a physical adsorption process. The adsorbed CrO42- ions were partly reduced to Cr(OH)3 by Fe(II) ions and the organic groups in the Fe-EG complex.

  1. Soil retention of hexavalent chromium released from construction and demolition waste in a road-base-application scenario

    DEFF Research Database (Denmark)

    Butera, Stefania; Trapp, Stefan; Astrup, Thomas Fruergaard

    2015-01-01

    We investigated the retention of Cr(VI) in three subsoils with low organic matter content in laboratory experiments at concentration levels relevant to represent leachates from construction and demolition waste (C&DW) reused as unbound material in road construction. The retention mechanism appeared...... depth. However, in rigid climates and with high water infiltration through the road pavement, the reduction reaction could be so slow that Cr(VI) might migrate as deep as 200 cm under the road. The reaction parameters and the model can form the basis for systematically assessing under which scenarios Cr...

  2. Microfluidic Paper-based Analytical Device for the Determination of Hexavalent Chromium by Photolithographic Fabrication Using a Photomask Printed with 3D Printer.

    Science.gov (United States)

    Asano, Hitoshi; Shiraishi, Yukihide

    2018-01-01

    This article describes a simple and inexpensive microfluidic paper-based analytical device (μPAD) for the determination of hexavalent chromium (Cr VI ) in water samples. The μPADs were fabricated on paper by photolithography using a photomask printed with a 3D printer and functionalized with reagents for a colorimetric assay. In the μPAD, Cr VI reacts with 1,5-diphenylcarbazide to form a violet-colored complex. Images of μPADs were captured with a digital camera; then the red, green, and blue color intensity of each detection zone were measured using images processing software. The green intensity analysis was the best sensitive among the RGB color. A linear working range (40 - 400 ppm; R 2 = 0.981) between the Cr VI and green intensity was obtained with a detection limit of 30 ppm. All of the recoveries were between 94 and 109% in recovery studies on water samples, and good results were obtained.

  3. Size-separated particle fractions of stainless steel welding fume particles - A multi-analytical characterization focusing on surface oxide speciation and release of hexavalent chromium.

    Science.gov (United States)

    Mei, N; Belleville, L; Cha, Y; Olofsson, U; Odnevall Wallinder, I; Persson, K-A; Hedberg, Y S

    2018-01-15

    Welding fume of stainless steels is potentially health hazardous. The aim of this study was to investigate the manganese (Mn) and chromium (Cr) speciation of welding fume particles and their extent of metal release relevant for an inhalation scenario, as a function of particle size, welding method (manual metal arc welding, metal arc welding using an active shielding gas), different electrodes (solid wires and flux-cored wires) and shielding gases, and base alloy (austenitic AISI 304L and duplex stainless steel LDX2101). Metal release investigations were performed in phosphate buffered saline (PBS), pH 7.3, 37°, 24h. The particles were characterized by means of microscopic, spectroscopic, and electroanalytical methods. Cr was predominantly released from particles of the welding fume when exposed in PBS [3-96% of the total amount of Cr, of which up to 70% as Cr(VI)], followed by Mn, nickel, and iron. Duplex stainless steel welded with a flux-cored wire generated a welding fume that released most Cr(VI). Nano-sized particles released a significantly higher amount of nickel compared with micron-sized particle fractions. The welding fume did not contain any solitary known chromate compounds, but multi-elemental highly oxidized oxide(s) (iron, Cr, and Mn, possibly bismuth and silicon). Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Optimizing the application of magnetic nanoparticles in Cr(VI) removal

    Science.gov (United States)

    Simeonidis, Konstantinos; Kaprara, Efthymia; Mitrakas, Manassis; Tziomaki, Magdalini; Angelakeris, Mavroidis; Vourlias, Georgios; Andritsos, Nikolaos

    2013-04-01

    The presence of heavy metals in aqueous systems is an intense health and environmental problem as implied by their harmful effects on human and other life forms. Among them, chromium is considered as an acutely hazardous compound contaminating the surface water from industrial wastes or entering the groundwater, the major source of drinking water, by leaching of chromite rocks. Chromium occurs in two stable oxidation states, Cr(III) and Cr(VI), with the hexavalent form being much more soluble and mobile in water having the ability to enter easily into living tissues or cells and thus become more toxic. Despite the established risks from Cr(VI)-containing water consumption and the increasing number of incidents, the E.U. tolerance limit for total chromium in potable water still stands at 50 μg/L. However, in the last years a worldwide debate concerning the establishment of a separate and very strict limit for the hexavalent form takes place. In practice, Cr(VI) is usually removed from water by various methods such as chemical coagulation/filtration, ion exchange, reverse osmosis and adsorption. Adsorption is considered as the simplest method which may become very effective if the process is facilitated by the incorporation of a Cr(VI) to Cr(III) reduction stage. This work studies the potential of using magnetic nanoparticles as adsorbing agents for Cr(VI) removal at the concentration levels met in contaminated drinking water. A variety of nanoparticles consisting of ferrites MFe2O4 (M=Fe, Co, Ni, Cu, Mn, Mg, Zn) were prepared by precipitating the corresponding bivalent or trivalent sulfate salts under controlled acidity and temperature. Electron microscopy and X-ray diffraction techniques were used to verify their crystal structure and determine the morphological characteristics. The mean particle size of the samples was found in the range 10-50 nm. Batch Cr(VI) removal tests were performed in aqueous nanoparticles dispersions showing the efficiency of ferrite

  5. Polyacrylonitrile/polyaniline core/shell nanofiber mat for removal of hexavalent chromium from aqueous solution: mechanism and applications

    KAUST Repository

    Wang, Jianqiang; Pan, Kai; Giannelis, Emmanuel P.; Cao, Bing

    2013-01-01

    increases with temperature. The adsorption follows a pseudo second order kinetics model and is best fit using the Langmuir isotherm model. The mats show excellent selectivity towards Cr(vi) ions in the presence of competing ions albeit a small decrease

  6. Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor

    International Nuclear Information System (INIS)

    Arroyo, M.G.; Perez-Herranz, V.; Montanes, M.T.; Garcia-Anton, J.; Guinon, J.L.

    2009-01-01

    In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H 2 SO 4 . The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe 2+ ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe 3+ ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H 2 SO 4 , the reduction of Cr(VI) to Cr(III) by Fe 2+ ions is preferred, but the coagulation of Fe 3+ and Cr(III) is favoured at the lower H 2 SO 4 concentrations.

  7. Effect of pH and chloride concentration on the removal of hexavalent chromium in a batch electrocoagulation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo, M.G. [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Perez-Herranz, V., E-mail: vperez@iqn.upv.es [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain); Montanes, M.T.; Garcia-Anton, J.; Guinon, J.L. [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2009-09-30

    In this work, the effect of pH and chloride ions concentration on the removal of Cr(VI) from wastewater by batch electrocoagulation using iron plate electrodes has been investigated. The initial solution pH was adjusted with different concentrations of H{sub 2}SO{sub 4}. The presence of chloride ions enhances the anode dissolution due to pitting corrosion. Fe{sup 2+} ions formed during the anode dissolution cause the reduction of Cr(VI) to form Cr(III), which are co-precipitated with Fe{sup 3+} ions at relatively low pH. The reduction degree of Cr(VI) to Cr(III) and the solubility of metal hydroxide species (both chromic and iron hydroxides) depend on pH. At higher concentrations of H{sub 2}SO{sub 4}, the reduction of Cr(VI) to Cr(III) by Fe{sup 2+} ions is preferred, but the coagulation of Fe{sup 3+} and Cr(III) is favoured at the lower H{sub 2}SO{sub 4} concentrations.

  8. Removal of Hexavalent Chromium by Adsorption on Microwave Assisted Activated Carbon Prepared from Stems of Leucas Aspera

    Science.gov (United States)

    Shanmugalingam, A.; Murugesan, A.

    2018-05-01

    This study reports adsorption of Cr(VI) ions from aqueous solution using activated carbon that was prepared from stems of Leucas aspera. Eight hundred and fifty watts power of microwave radiation, 12 min of radiation time, 60% of ZnCl2 solution and 24 h of impregnation time are the optimal parameters to prepare efficient carbon effective activated carbon. It was designated as MWLAC (Microwave assisted Zinc chloride activated Leucas aspera carbon). Various adsorption characteristics such as dose of the adsorbent, agitation time, initial Cr(VI) ion concentration, pH of the solution and temperature on adsorption were studied for removal of Cr(VI) ions from aqueous solution by batch mode. Also the equilibrium adsorption was analyzed by the Langmuir, Freundlich, Tempkin and D-R isotherm models. The order of best describing isotherms was given based on R2 value. The pseudo-second-order kinetic model best fitted with the Cr(VI) adsorption data. Thermodynamic parameters were also determined and results suggest that the adsorption process is a spontaneous, endothermic and proceeded with increased randomness.

  9. Removal combined with reduction of hexavalent chromium from aqueous solution by Fe-ethylene glycol complex microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong-Xing [School of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000 (China); Jia, Yong, E-mail: yjiaahedu@163.com [School of Pharmacy, Anhui University of Chinese Medicine, Hefei 230012 (China)

    2016-12-15

    Highlights: • Fe-EG complex microspheres were synthesized by a hydrothermal method. • The removal properties towards Cr(VI) ions were investigated. • The adsorption and reduction mechanism was revealed by FTIR and XPS. - Abstract: Three-dimensional Fe-ethylene glycol (Fe-EG) complex microspheres were synthesized by a facile hydrothermal method, and were characterized by field emission scanning electron microscopy and transmission electron microscopy. The adsorption as well as reduction properties of the obtained Fe-EG complex microspheres towards Cr(VI) ions were studied. The experiment data of adsorption kinetic and isotherm were fitted by nonlinear regression approach. In neutral condition, the maximum adsorption capacity was 49.78 mg g{sup −1} at room temperature, and was increased with the increasing of temperature. Thermodynamic parameters including the Gibbs free energy, standard enthalpy and standard entropy revealed that adsorption of Cr(VI) was a feasible, spontaneous and endothermic process. Spectroscopic analysis revealed the adsorption of Cr(VI) was a physical adsorption process. The adsorbed CrO{sub 4}{sup 2−} ions were partly reduced to Cr(OH){sub 3} by Fe(II) ions and the organic groups in the Fe-EG complex.

  10. Electro-migration of heavy metals in an aged electroplating contaminated soil affected by the coexisting hexavalent chromium.

    Science.gov (United States)

    Zhang, Weihua; Zhuang, Luwen; Tong, Lizhi; Lo, Irene M C; Qiu, Rongliang

    2012-02-01

    Cr(VI) was often reported to oxidize soil organic matter at acidic environments due to its high ORP, probably thus changing cationic metal species bound to soil organic matter, and influencing their electro-migration patterns. However, such an effect on the electro-migration was not confirmed in most previous studies. Therefore, this study applied a fixed voltage direct current field on an aged electroplating contaminated clayed soil, with a special interest in the direct or indirect influence of Cr(VI) on the electro-migration of other coexisting metals. After 353 h electrokinetic process, 81% of Zn, 53% of Ni and 22% of Cu in the original soil were electro-migrated into the electrolyte, and most of the remaining concentrated near the cathode. The Cr(VI) oxidized some soil organic matter along its migration pathway, with a pronounced reaction occurred near the anode at low pHs. The resulting Cr(III) reversed its original movement, and migrated towards the cathode, leading to the occurrence of a second Cr concentration peak in the soil. Metal species analyses showed that the amount of metals bound to soil organic matter significantly decreased, while a substantial increase in the Cr species bound to Fe/Mn (hydro-)oxides was observed, suggesting an enhancement of cationic metal electro-migration by the reduction of Cr(VI) into Cr(III). However, the Cr(VI) may form some stable lead chromate precipitates, and in turn demobilize Pb in the soil, as the results showed a low Pb removal and an increase in its acid-extractable and residual fractions after electrokinetic remediation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Diverse anaerobic Cr(VI) tolerant bacteria from Cr(VI)-contaminated 100H site at Hanford

    Science.gov (United States)

    Chakraborty, R.; Phan, R.; Lam, S.; Leung, C.; Brodie, E. L.; Hazen, T. C.

    2007-12-01

    Hexavalent Chromium [Cr(VI)] is a widespread contaminant found in soil, sediment, and ground water. Cr(VI) is more soluble, toxic, carcinogenic, and mutagenic compared to its reduced form Cr(III). In order to stimulate microbially mediated reduction of Cr(VI), a poly-lactate compound HRC was injected into the chromium contaminated aquifers at site 100H at Hanford. Based on the results of the bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products, we recently investigated the diversity of the dominant anaerobic culturable microbial population present at this site and their role in Cr(VI) reduction. Positive enrichments set up at 30°C using specific defined anaerobic media resulted in the isolation of an iron reducing isolate strain HAF, a sulfate reducing isolate strain HBLS and a nitrate reducing isolate, strain HLN among several others. Preliminary 16S rDNA sequence analysis identifies strain HAF as Geobacter metallireducens, strain HLN as Pseudomonas stutzeri and strain HBLS as a member of Desulfovibrio species. Strain HAF isolated with acetate as the electron donor utilized propionate, glycerol and pyruvate as alternative carbon sources, and reduced metals like Mn(IV) and Cr(VI). Growth was optimal at 37°C, pH of 6.5 and 0% salinity. Strain HLN isolated with lactate as electron donor utilized acetate, glycerol and pyruvate as alternative carbon sources, and reduced metals like Mn(IV) and Cr(VI). Optimal growth was observed at 37°C, at a pH of 7.5 and 0.3% salinity. Anaerobic active washed cell suspension of strain HLN reduced almost 95 micromolar Cr(VI) within 4 hours relative to controls. Further, with 100 micromolar Cr(VI) as the sole electron acceptor, cells of strain HLN grew to cell numbers of 4.05X 107/ml over a period of 24hrs after an initial lag, demonstrating direct enzymatic Cr(VI) reduction by this species. 10mM lactate served as the sole electron donor. These results demonstrate that Cr(VI

  12. Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site.

    Science.gov (United States)

    Zhang, Kundi; Li, Fuli

    2011-05-01

    A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240(T) (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L(-1), which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 °C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L(-1) h(-1), respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal.

  13. Isolation and characterization of a chromium-resistant bacterium Serratia sp. Cr-10 from a chromate-contaminated site

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kundi; Li, Fuli [Chinese Academy of Sciences, Qingdao (China). Qingdao Inst. of Bioenergy and Bioprocess Technology

    2011-05-15

    A novel bacterium, Cr-10, was isolated from a chromium-contaminated site and capable of removing toxic chromium species from solution by reducing hexavalent chromium to an insoluble precipitate. Sequence analysis of 16S rRNA gene of strain Cr-10 showed that it was most closely related to Serratia rubidaea JCM 1240{sup T} (97.68%). Physiological and chemotaxonomic data also supported that strain Cr-10 was identified as Serratia sp., a genus which was never specially reported chromate-resistant before. Serratia sp., Cr-10 was tolerant to a concentration of 1,500 mg Cr(VI) L{sup -1}, which was the highest level reported until now. The optimum pH and temperature for reduction of Cr(VI) by Serratia sp. Cr-10 were found to be 7.0 and 37 C, respectively. The Cr(VI) reduction was significantly influenced by additional carbon sources, and among them fructose and lactose offered maximum reduction, with a rate of 0.28 and 0.25 mg Cr(VI) L{sup -1} h{sup -1}, respectively. The cell-free extracts and filtrate of the culture were able to reduce Cr(VI) while concentration of total chromium remained stable in the process, indicating that the enzyme-catalyzed mechanism was applied in Cr(VI) reduction by the isolate. Additionally, it was found that there was hardly any chromium on the cell surface of the strain, further supporting that reduction, rather than bioadsorption, plays a major role in the Cr(VI) removal. (orig.)

  14. Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiang [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Huang, Liping, E-mail: lipinghuang@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Pan, Yuzhen [College of Chemistry, Dalian University of Technology, Dalian 116024 (China); Quan, Xie [Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Li Puma, Gianluca, E-mail: g.lipuma@lboro.ac.uk [Environmental Nanocatalysis & Photoreaction Engineering, Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2017-01-05

    Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO{sub 4}{sup −}) and dichromate (Cr{sub 2}O{sub 7}{sup 2−}) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

  15. Impact of Fe(III) as an effective electron-shuttle mediator for enhanced Cr(VI) reduction in microbial fuel cells: Reduction of diffusional resistances and cathode overpotentials

    International Nuclear Information System (INIS)

    Wang, Qiang; Huang, Liping; Pan, Yuzhen; Quan, Xie; Li Puma, Gianluca

    2017-01-01

    Highlights: • Fe(III) shuttles electrons for enhanced reduction of Cr(VI) in MFCs. • The coulombic efficiency increases by 1.6 fold in the presence of Fe(III). • The reduction of Cr(VI) occurs via an indirect Fe(III) mediation mechanism. • Fe(III) decreases the diffusional resistances and the cathode overpotentials. - Abstract: The role of Fe(III) was investigated as an electron-shuttle mediator to enhance the reduction rate of the toxic heavy metal hexavalent chromium (Cr(VI)) in wastewaters, using microbial fuel cells (MFCs). The direct reduction of chromate (CrO_4"−) and dichromate (Cr_2O_7"2"−) anions in MFCs was hampered by the electrical repulsion between the negatively charged cathode and Cr(VI) functional groups. In contrast, in the presence of Fe(III), the conversion of Cr(VI) and the cathodic coulombic efficiency in the MFCs were 65.6% and 81.7%, respectively, 1.6 times and 1.4 folds as those recorded in the absence of Fe(III). Multiple analytical approaches, including linear sweep voltammetry, Tafel plot, cyclic voltammetry, electrochemical impedance spectroscopy and kinetic calculations demonstrated that the complete reduction of Cr(VI) occurred through an indirect mechanism mediated by Fe(III). The direct reduction of Cr(VI) with cathode electrons in the presence of Fe(III) was insignificant. Fe(III) played a critical role in decreasing both the diffusional resistance of Cr(VI) species and the overpotential for Cr(VI) reduction. This study demonstrated that the reduction of Cr(VI) in MFCs was effective in the presence of Fe(III), providing an alternative and environmentally benign approach for efficient remediation of Cr(VI) contaminated sites with simultaneous production of renewable energy.

  16. Citric-acid preacidification enhanced electrokinetic remediation for removal of chromium from chromium-residue-contaminated soil.

    Science.gov (United States)

    Meng, Fansheng; Xue, Hao; Wang, Yeyao; Zheng, Binghui; Wang, Juling

    2018-02-01

    Electrokinetic experiments were conducted on chromium-residue-contaminated soils collected from a chemical plant in China. Acidification-electrokinetic remediation technology was proposed in order to solve the problem of removing inefficient with ordinary electrokinetic. The results showed that electrokinetic remediation removal efficiency of chromium from chromium-contaminated soil was significantly enhanced with acidizing pretreatment. The total chromium [Cr(T)] and hexavalent chromium [Cr(VI)] removal rate of the group acidized by citric acid (0.9 mol/L) for 5 days was increased from 6.23% and 19.01% in the acid-free experiments to 26.97% and 77.66% in the acidification-treated experiments, respectively. In addition, part of chromium with the state of carbonate-combined will be converted into water-soluble state through acidification to improve the removal efficiency. Within the appropriate concentration range, the higher concentration of acid was, the more chromium was released. So the removal efficiency of chromium depended on the acid concentration. The citric acid is also a kind of complexing agent, which produced complexation with Cr that was released by the electrokinetic treatment and then enhanced the removal efficiency. The major speciation of chromium that was removed from soils by acidification-electrokinetics remediation was acid-soluble speciation, revivification speciation and oxidation speciation, which reduced biological availability of chromium.

  17. A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Hasan, E-mail: samarhass@yahoo.com [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh); Minami, Hideto [Graduate School of Engineering, Kobe University, Kobe 657-8501 (Japan); Tauer, Klaus [Max Planck Institute of Colloid and Interfaces, Am Mühlenberg, 14476 Golm (Germany); Gafur, Mohammad Abdul [Pilot Plant and Process Development Centre, BCSIR, Dhaka 1205 (Bangladesh); Rahman, Mohammad Mahbubor [Department of Chemistry, Rajshahi University, Rajshahi 6205 (Bangladesh)

    2016-08-15

    A combination of maghemite polypyrrole (PPy/γ-Fe{sub 2}O{sub 3}) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl{sub 3} as a oxidant and p-toluene sulfonic acid ( p-TSA) as a dopant. In the reaction system FeCl{sub 3} functioned as a source of Fe(III) for the formation of γ-Fe{sub 2}O{sub 3}. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl{sub 2}. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV–visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water. - Highlights: • P(S-NIPAM-MAA-PEGMA) hydrogel particles were prepared. • P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe{sub 2}O{sub 3} nanocomposite hydrogel particles were prepared. • Oxidative polymerization of pyrrole and precipitation of γ-Fe{sub 2}O{sub 3

  18. Development and validation of a model of bio-barriers for remediation of Cr(VI) contaminated aquifers using laboratory column experiments.

    Science.gov (United States)

    Shashidhar, T; Bhallamudi, S Murty; Philip, Ligy

    2007-07-16

    Bench scale transport and biotransformation experiments and mathematical model simulations were carried out to study the effectiveness of bio-barriers for the containment of hexavalent chromium in contaminated confined aquifers. Experimental results showed that a 10cm thick bio-barrier with an initial biomass concentration of 0.205mg/g of soil was able to completely contain a Cr(VI) plume of 25mg/L concentration. It was also observed that pore water velocity and initial biomass concentration are the most significant parameters in the containment of Cr(VI). The mathematical model developed is based on one-dimensional advection-dispersion reaction equations for Cr(VI) and molasses in saturated, homogeneous porous medium. The transport of Cr(VI) and molasses is coupled with adsorption and Monod's inhibition kinetics for immobile bacteria. It was found that, in general, the model was able to simulate the experimental results satisfactorily. However, there was disparity between the numerically simulated and experimental breakthrough curves for Cr(VI) and molasses in cases where there was high clay content and high microbial activity. The mathematical model could contribute towards improved designs of future bio-barriers for the remediation of Cr(VI) contaminated aquifers.

  19. Assessment of heavy metal tolerance and hexavalent chromium reducing potential of Corynebacterium paurometabolum SKPD 1204 isolated from chromite mine seepage

    Directory of Open Access Journals (Sweden)

    Amal Kanti Paul

    2016-07-01

    Full Text Available Corynebacterium paurometabolum SKPD 1204 (MTCC 8730, a heavy metal tolerant and chromate reducing bacterium isolated from chromite mine seepage of Odisha, India has been evaluated for chromate reduction under batch culture. The isolate was found to tolerate metals like Co(II, Cu(II, Ni(II, Mn(II, Zn(II, Fe(III and Hg(II along with Cr(VI and was resistant to different antibiotics as evaluated by disc-diffusion method. The isolate, SKPD 1204 was found to reduce 62.5% of 2 mM Cr(VI in Vogel Bonner broth within 8 days of incubation. Chromate reduction capability of SKPD 1204 decreased with increase in Cr(VI concentration, but increased with increase in cell density and attained its maximum at 1010 cells/mL. Chromate reducing efficiency of SKPD 1204 was promoted in the presence of glycerol and glucose, while the highest reduction was recorded at pH 7.0 and 35 °C. The reduction process was inhibited by divalent cations Zn(II, Cd(II, Cu(II, and Ni(II, but not by Mn(II. Anions like nitrate, phosphate, sulphate and sulphite was found to be inhibitory to the process of Cr(VI reduction. Similarly, sodium fluoride, carbonyl cyanide m-chlorophenylhydrazone, sodium azide and N, N,-Di cyclohexyl carboiimide were inhibitory to chromate reduction, while 2,4-dinitrophenol appeared to be neither promotive nor inhibitory to the process.

  20. Rapid and efficient photocatalytic reduction of hexavalent chromium by using “water dispersible” TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Wang, Lei; Kang, Shi-Zhao; Li, Xiangqing; Qin, Lixia; Yan, Hao; Mu, Jin

    2016-01-01

    In the present work, “water dispersible” TiO 2 nanoparticles were prepared, and meanwhile, their photocatalytic activity was systematically tested for the reduction of aqueous Cr(VI) ions. It is found that the as-prepared “water dispersible” TiO 2 nanoparticles are a highly efficient photocatalyst for the reduction of Cr(VI) ions in water under UV irradiation, and suitable for the remediation of Cr(VI) ions wastewater with low concentration. Compared with commercial TiO 2 nanoparticles (P25), the “water dispersible” TiO 2 nanoparticles exhibit 3.8-fold higher photocatalytic activity. 100% Cr (VI) ions can be reduced into Cr(III) ions within 10 min when the Cr (VI) ions initial concentration is 10 mg L −1 . Moreover, the electrical energy consumption can be obviously decreased using the “water dispersible” TiO 2 nanoparticles. These results suggest that the “water dispersible” TiO 2 nanoparticles are a promising photocatalyst for rapid removal of Cr (VI) in environmental therapy. - Highlights: • “Water dispersible” TiO 2 nanoparticles with high photocatalytic activity. • 100% Cr (VI) (10 mg L −1 ) can be reduced within 10 min. • Obvious decrease of electrical energy consumption.

  1. Peat and coconut fiber as biofilters for chromium adsorption from contaminated wastewaters.

    Science.gov (United States)

    Henryk, Kołoczek; Jarosław, Chwastowski; Witold, Żukowski

    2016-01-01

    Batch adsorption experiments were performed for the removal of chromium (III) and chromium (VI) ions from aqueous solutions using Canadian peat and coconut fiber. The Langmuir model was used to describe the adsorption isotherm. The maximum adsorption for peat reached 18.75 mg/g for Cr(III) and 8.02 mg/g for Cr(VI), whereas the value for fiber was slightly higher and reached 19.21 mg/g for Cr(III) and 9.54 mg/g for Cr(VI). Both chromium forms could be easily eluted from the materials. The adsorption of chromium forms to organic matter could be explained in terms of formation of donor-acceptor chemical covalent bound with hydroxyl groups as ligands and chromium as the central atom in the formed complex. The chromate-reducing activities were monitored with the use of electron paramagnetic resonance spectroscopy. The results showed that both adsorption and reduction occurred simultaneously and the maximum adsorption capacity of hexavalent chromium being equal to 95% for fiber and 92% for peat was obtained at pH 1.5. The reduction of Cr(VI) in wastewaters began immediately and disappeared after 20 h. Both materials contained yeast and fungi species which can be responsible for reduction of chromium compounds, due to their enzymatic activity (Chwastowski and Koloczek (Acta Biochim Pol 60: 829-834, 2013)). The reduction of Cr(VI) is a two-phase process, the first phase being rapid and based on chemical reaction and the second phase having biological features. After the recovery step, both types of organic materials can be used again for chromium adsorption without any loss in the metal uptake. Both of the materials could be used as biofilters in the wastewater treatment plants.

  2. Preparation of chitosan-stabilized Fe{sup 0} nanoparticles for removal of hexavalent chromium in water

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Bing [Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Jin, Zhaohui, E-mail: jinzh@nankai.edu.cn [Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Li, Tielong; Qi, Xinhua [Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China)

    2009-09-01

    Chitosan-stabilized Fe{sup 0} nanoparticles (CTO-Fe{sup 0}) and Fe{sup 0} nanoparticles synthesized in ethanol-water mixed system (EW-Fe{sup 0}) were tested for reduction of Cr(VI) in water. Fourier transform infrared (FTIR) study suggested that nitrogen and oxygen atoms are the binding sites for chitosan on iron which was accountable for the stability of Fe{sup 0} nanoparticles. While the EW-Fe{sup 0} ignites spontaneously when exposed to air, the CTO-Fe{sup 0} was still in zero valence state after exposure to air over 2-month period as shown by X-ray powder diffraction patterns. Batch experiments demonstrated that the maximum Cr(VI) reduction rates for CTO-Fe{sup 0} was about 3 times higher than EW-Fe{sup 0}. Characterizations with high-resolution X-ray photoelectron spectroscopy (HR-XPS) revealed that Cr(VI) was reduced to Cr(III) and Fe(III) was the only component present on the Fe{sup 0} nanoparticles surface. Additionally, chitosan can inhibited the formation of Fe(III)-Cr(III) precipitation due to its high ability to chelate Fe(III) which resulted in k{sub obs} for CTO-Fe{sup 0} was about 1-3 times higher than EW-Fe{sup 0}. Due to the fast reaction kinetics and good stability against oxidation in air, the chitosan-stabilized Fe{sup 0} nanoparticles have the potential to become an effective agent for in situ subsurface environment remediation.

  3. Adsorption of Chromium from Aqueous Solution Using Polyaniline

    Directory of Open Access Journals (Sweden)

    Majid Riahi Samani

    2011-10-01

    Full Text Available New group of polymers have been synthesized that are conductive of electricity so they are called conducting polymers. One of the most conducting polymers is "polyaniline". In the present study, polyaniline was synthesized by oxidizing aniline monomer under strongly acidic conditions using potassium iodate as an initiator of oxidative polymerization. Synthesized polyaniline as a powder used as an adsorbent to remove chromium from aqueous solution. Experiments were conducted in batch mode with variables such as amount of polyaniline, chromium solution pH and adsorbtion isotherms. Due to presence of Cr (III in solution after using polyaniline, removal mechanism is the combination of surface adsorption and reduction. It seems that polyaniline reduces the Cr(VI to Cr(III and adsorbs the Cr(III and a part of remaining  Cr(VI. It is well known that nitrogen atom in compounds of amine derivative makes co-ordinate bond with positive charge of metals due to the presence of electron in sp3 orbital of nitrogen. The majority of total chromium removal  occurred at 30minute for polyaniline  and the optimum  time for  hexavalent chromium  removal was about 5 min. Polyaniline has the maximum total cheomiume removal at pH, 3-9. The maximum hexavalent chromium removal occurred at acidic pH for polyanilines. The equilibrium adsorption data for polyaniline fitted both Freundlich’s and Langmuir’s isotherms. This research shows that polyaniline can be used as an adsorbent  for removal chromium from aqueous solution.

  4. Study by mass spectrometry of the formation of cluster ions generated by laser ablation/ionization of inorganic compounds: application to the differentiation of trivalent and hexavalent chromium compounds

    International Nuclear Information System (INIS)

    Aubriet, Frederic

    1999-01-01

    The introduction of new ionization techniques allows a fast growth of mass spectrometry applications in an increasing number of fields. More particularly, the introduction of laser ablation/ionization process and the design of new instruments (laser microprobes), has been very important for a better knowledge of inorganic compound mass spectrometry. The purposes of this work were mainly focussed firstly in the understanding of cluster ions formation process by laser ablation/ionization and secondly in the development of a new mass spectrometry technique for the speciation between trivalent and hexavalent chromium compounds. We show that cluster ion formation are multiple. The difficulty to identify clearly the processes involved is due to the superposition of many mechanisms. Mostly, these processes are representative of the complexity of the gas-phase chemistry between the various species generated by laser ablation/ionization. Thus, four mechanisms for the cluster ion formation have been highlighted. The most frequently met correspond to aggregative processes of neutral molecules on precursor ions. The knowledge of the processes of cluster ion formation allows us to explain why it is possible to distinguish the oxidation number of chromium. The organigram of chromium valence speciation proposed is based on the calculation of the ratio of negative cluster ion intensities after systematic analysis of nearly twenty chromium reference compounds using the same instrumental conditions. The examination of mixtures between 1) calcium. silicon, trivalent iron or zinc oxides and 2) the standard chromium compound allows us to observe the influence of these oxides on the fingerprints of the pure chromium compounds and to determine up to which point and with which limitations, the methodology suggested, could be applied to the analysis of trivalent and hexavalent chromium compounds in complex and polyphasic matrices

  5. Removal of Hexavalent Chromium from Aqueous Solutions Using Magnetic Nanoparticles Coated with Alumina and Modified by Cetyl Trimethyl Ammonium Bromide

    Directory of Open Access Journals (Sweden)

    Mohammad Malakootian

    2015-12-01

    Full Text Available Introduction: The development of an effective method regarding chromium removal from the environment is of great importance. Therefore, the present study aimed to examiner magnetic nanoparticles coated with alumina modified by Cetyl Trimethyl Ammonium Bromide (CTAB in the removal of Cr6+ through magnetic solid phase extraction method. Materials & Methods: At first, iron oxide nanoparticles were synthesized, coated with alumina, modified with CTAB and characterized with suitable instruments. The factors affecting the process of chromium removal were investigated, including the concentration of CTAB, the pH, the amount of nanoparticles, the sample volume, a proper eluent, the adsorption and desorption time, and the effect of interfering ions. Moreover, the chromium concentration was determined by flame atomic absorption spectrometric (FAAS technique. The adsorption isotherm, adsorption capacity, and recoverability of the adsorbent were further examined. Results: The modified magnetic nanoparticles were demonstrated to be homogeneous, spherical, with a size lower than 20 nanometer having a magnetic property. The optimal conditions for chromium removal entailed 7*10-6 mol/L concentration of CTAB, pH range of 6-8, 0.1 g of the nanoparticles, 10 mL volume of the chromium sample (5 &mug mL-1, nitric acid 2 M as a suitable eluent, 15 minutes of adsorption and desorption, and no interference of interfering ions in the process of chromium separation. The process efficiency under optimal conditions was determined to be over 95%, which this process followed the Langmuir adsorption isotherm. The adsorption capacity proved to be 23.8 mg/g. Reusing after four times of adsorbent recovering was effective in the chromium removal (80%. The method accuracy for five measurement times was 4.155% and the method’s LOD was 0.081 mg/L. Conclusion: The method enjoys the benefits of convenient preparation of the adsorbent, high selectivity, high accuracy, short process

  6. Chromium

    Science.gov (United States)

    ... 2 Whole wheat bread, 2 slices 2 Red wine, 5 ounces 1–13 Apple, unpeeled, 1 medium ... chromium or a placebo) might simply show the benefits of supplementation in a chromium-deficient population. Overall, ...

  7. Removal of Cr(VI from Water Using a New Reactive Material: Magnesium Oxide Supported Nanoscale Zero-Valent Iron

    Directory of Open Access Journals (Sweden)

    Alessio Siciliano

    2016-08-01

    Full Text Available The chromium pollution of water is an important environmental and health issue. Cr(VI removal by means of metallic iron is an attractive method. Specifically, nanoscopic zero valent iron (NZVI shows great reactivity, however, its applicability needs to be further investigated. In the present paper, NZVI was supported on MgO grains to facilitate the treatments for remediation of chromium-contaminated waters. The performances and mechanisms of the developed composite, in the removal of hexavalent chromium, were investigated by means of batch and continuous tests. Kinetic studies, under different operating conditions, showed that reduction of Cr(VI could be expressed by a pseudo second-order reaction kinetic. The reaction rate increased with the square of Fe(0 amount, while it was inversely proportional to the initial chromium concentration. The process performance was satisfactory also under uncontrolled pH, and a limited influence of temperature was observed. The reactive material was efficiently reusable for many cycles without any regeneration treatment. The performances in continuous tests were close to 97% for about 80 pore volume of reactive material.

  8. Effect of Diethanolamine on Property of Thin Film TiO2 in Treating Hexavalent Chromium from Aqueous Solution

    International Nuclear Information System (INIS)

    Kajitvichyanukul, Puangrat; Jirapattarasakul, Sudarat

    2006-01-01

    In this research titanium dioxide thin film was synthesized from hydrolysis and condensation process by sol-gel method. Titanium alkoxide was used as initial substrate. The solvent was ethanal and the additive substance was diethanolamine. All substances are mixed altogether in different ratios. To study the effect of diethanolamine on properties of titanium dioxide thin film, various film analysis were performed which included mass weighing, adhesive test, corrosion test using acid and alkali, surface morphology analysis with scanning electron microscope (SEM), thin film structure analysis using X-ray diffraction (XRD), and photo activity by chromium removal test. It was found that diethanolmine enhanced the film strength and improved the adhesive property. The smooth surface was obtained. This thin film showed the effectiveness in chromium removal with high photo activity. Even tough the developed thin film can remove chromium (VI) efficiently, the reaction rate constant (k) was slightly reduced from that using the normal thin film titanium dioxide (without adding diethanolamine). In addition, the reaction time is required little longer to accomplish the chromium (VI) removal with the same performance

  9. Removal of Cr(VI) from wastewaters at semi-industrial electrochemical reactors with rotating ring electrodes

    International Nuclear Information System (INIS)

    Rodriguez R, Miriam G.; Mendoza, Victor; Puebla, Hector; Martinez D, Sergio A.

    2009-01-01

    In Mexico, most of the electroplating and textile industries are small facilities and release relatively large amounts of hexavalent chromium (Cr(VI)) in surface waters. In this work, the results obtained during the operation of a batch reactor with a capacity of 170 L, and three electrochemical flow reactors-in-series system with a total capacity of 510 L (both using iron rotating ring electrodes to remove Cr(VI) from wastewaters) are presented. The reactors were scaled up from a laboratory reactor to a semi-industrial level, based on the similarity (dynamical, geometrical and electrochemical). An empirical Cr(VI) removal model was validated in batch and continuous reactors at different operating conditions. Cr(VI) concentration of the industrial wastewaters was reduced from about 500 mg/L to values lower than 0.5 mg/L. A very important parameter that affects the process is the pH, which affects the solubility of the Fe(III). Finally, the electrochemical treated wastewater can be reused

  10. Cr(VI) and Cr(III) removal from aqueous solution by raw and modified lignocellulosic materials: a review.

    Science.gov (United States)

    Miretzky, P; Cirelli, A Fernandez

    2010-08-15

    In aqueous systems, chromium usually exists in both trivalent and hexavalent oxidation states, being Cr(VI) of particular importance and concern due to its great toxicity. Industrial sources of Cr(VI) are leather tanning, mining of chrome ore, production of steel and alloys, etc. The most common conventional method for Cr(VI) removal is reduction to Cr(III) at pH 2.0 and precipitation of Cr (OH)(3) with lime at pH 9-10. The disadvantage of precipitation is the disposal of the solid waste. Adsorption of Cr by different low cost materials seems to be a suitable choice for wastewater treatment. Many by-products of agriculture have proved to be suitable low cost adsorbents for Cr(VI) and Cr(III) removal from water. Lignocellulosic residues, which include both wood residues and agricultural residues, have adsorption capacity comparable to other natural sorbents, but they have the advantage of very low or no cost, great availability and simple operational process. This study is a review of the recent literature on the use of natural and modified lignocellulosic residues for Cr adsorption. The Cr maximum adsorption capacity and the adsorption mechanism under different experimental conditions are reported when possibly. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Removal of Cr(VI) from wastewaters at semi-industrial electrochemical reactors with rotating ring electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez R, Miriam G. [Depto. Energia, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Azcapotzalco, CP 07740, Mexico D.F. (Mexico); Mendoza, Victor [Depto. Electronica, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Azcapotzalco, CP 07740, Mexico D.F. (Mexico); Puebla, Hector [Depto. Energia, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Azcapotzalco, CP 07740, Mexico D.F. (Mexico); Martinez D, Sergio A. [Depto. Energia, Universidad Autonoma Metropolitana-Azcapotzalco, Av. San Pablo 180, Azcapotzalco, CP 07740, Mexico D.F. (Mexico)], E-mail: samd@correo.azc.uam.mx

    2009-04-30

    In Mexico, most of the electroplating and textile industries are small facilities and release relatively large amounts of hexavalent chromium (Cr(VI)) in surface waters. In this work, the results obtained during the operation of a batch reactor with a capacity of 170 L, and three electrochemical flow reactors-in-series system with a total capacity of 510 L (both using iron rotating ring electrodes to remove Cr(VI) from wastewaters) are presented. The reactors were scaled up from a laboratory reactor to a semi-industrial level, based on the similarity (dynamical, geometrical and electrochemical). An empirical Cr(VI) removal model was validated in batch and continuous reactors at different operating conditions. Cr(VI) concentration of the industrial wastewaters was reduced from about 500 mg/L to values lower than 0.5 mg/L. A very important parameter that affects the process is the pH, which affects the solubility of the Fe(III). Finally, the electrochemical treated wastewater can be reused.

  12. Error analysis of equilibrium studies for the almond shell activated carbon adsorption of Cr(VI) from aqueous solutions

    International Nuclear Information System (INIS)

    Demirbas, E.; Kobya, M.; Konukman, A.E.S.

    2008-01-01

    In this study, the preparation of activated carbon from almond shell with H 2 SO 4 activation and its ability to remove toxic hexavalent chromium from aqueous solutions are reported. The influences of several operating parameters such as pH, particle size and temperature on the adsorption capacity were investigated. Adsorption of Cr(VI) is found to be highly pH, particle size and temperature dependent. Four adsorption isotherm models namely, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich were used to analyze the equilibrium data. The Langmuir isotherm provided the best correlation for Cr(VI) onto the almond shell activated carbon (ASC). Adsorption capacity was calculated from the Langmuir isotherm as 190.3 mg/g at 323 K. Thermodynamic parameters were evaluated and the adsorption was endothermic showing monolayer adsorption of Cr(VI). Five error functions were used to treat the equilibrium data using non-linear optimization techniques for evaluating the fit of the isotherm equations. The highest correlation for the isotherm equations in this system was obtained for the Freundlich isotherm. ASC is found to be inexpensive and effective adsorbent for removal of Cr(VI) from aqueous solutions

  13. ENZYME MARKERS ACTIVITY AND BILE FORMATION FUNCTION OF LIVER IN CASES OF TUBERCULOSTATICS AND HEXAVALENT CHROMIUM COMPOUNDS AFFECTION IN RATS

    OpenAIRE

    N. I. Burmas; L. S. Fira; P. H. Lyhackyy

    2016-01-01

    Background. Currently, the growing incidence of toxic lesions of the liver is associated with industrial chemicalization and uncontrolled use of hepatotoxic drugs in everyday life. There are about one thousand drugs with high or low hepatotoxicity, such as anti-TB drugs. Objective. In this research we studied the intracellular enzymes activity and bile formation function of the liver in rats of different ages in cases of tuberculostatic (isoniazid and rifampicin) affection and chromium (p...

  14. Supercritical CO2 Assisted Synthesis of EDTA-Fe3O4 Nanocomposite with High Adsorption Capacity for Hexavalent Chromium

    Directory of Open Access Journals (Sweden)

    Gunjan Bisht

    2016-01-01

    Full Text Available Efficiency of EDTA functionalized nanoparticles in adsorption of chromium (VI from water was investigated in this study. Magnetic iron oxide nanoparticles (IONPs were synthesized by a simple chemical coprecipitation route and EDTA coating onto IONPs was attained via supercritical carbon dioxide (Sc CO2, a technology with green sustainable properties. The obtained nanoparticles were then characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and vibrating magnetometric analysis (VSM. The synthesized nanoparticle and its modified variant were evaluated as adsorbent for chromium (VI removal from water through batch adsorption technique and the effect of analytic concentration; contact time and adsorbent concentration were studied at pH 2. The results showed higher removal efficiency for modified magnetic iron oxide nanoparticles (MIONPs (i.e., 99.9% than their nonmodified variant IONPs, that is, 34.06% for the same concentration after 18 hours of incubation. Also maximum adsorption capacity (qe = 452.26 mg/g of MIONPs attained can be related to their preparation in Sc CO2 as qe calculated from IONPs, that is, 170.33 mg/g, is lower than that of MIONPs. The adsorption data fit well with Freundlich isotherm equation while kinetic adsorption studies of chromium (VI were modeled by pseudo-second-order model.

  15. Chromium Is Elevated in Fin Whale (Balaenoptera physalus) Skin Tissue and Is Genotoxic to Fin Whale Skin Cells

    Science.gov (United States)

    Wise, Catherine F.; Wise, Sandra S.; Thompson, W. Douglas; Perkins, Christopher; Wise, John Pierce

    2015-01-01

    Hexavalent chromium (Cr(VI)) is present in the marine environment and is a known carcinogen and reproductive toxicant. Cr(VI) is the form of chromium that is well absorbed through the cell membrane. It is also the most prevalent form in seawater. We measured the total Cr levels in skin biopsies obtained from healthy free-ranging fin whales from the Gulf of Maine and found elevated levels relative to marine mammals in other parts of the world. The levels in fin whale biopsies ranged from 1.71 ug/g to 19.6 ug/g with an average level of 10.07 ug/g. We also measured the cytotoxicity and genotoxicity of Cr(VI) in fin whale skin cells. We found that particulate and soluble Cr(VI) are both cytotoxic and genotoxic to fin whale skin cells in a concentration-dependent manner. The concentration range used in our cell culture studies used environmentally relevant concentrations based on the biopsy measurements. These data suggest that Cr(VI) may be a concern for whales in the Gulf of Maine. PMID:25805270

  16. Biosynthesized iron nanoparticles in aqueous extracts of Eichhornia crassipes and its mechanism in the hexavalent chromium removal

    Science.gov (United States)

    Wei, Yufen; Fang, Zhanqiang; Zheng, Liuchun; Tsang, Eric Pokeung

    2017-03-01

    Eichhornia crassipes (water hyacinth), a species of invasive weeds has caused serious ecological damage due to its extraordinary fertility and growth rate. However, it has not yet been exploited for use as a resource. This paper reported the synthesis and characterization of amorphous iron nanoparticles (Ec-Fe-NPs) from Fe(III) salts in aqueous extracts of Eichhornia crassipes. The nanoparticles were characterized by SEM, EDS, TEM, XPS, FTIR, DLS and the zeta potential methods. The characterization results confirmed the successful synthesis of amorphous iron nanoparticles with diameters of 20-80 nm. Moreover, the nanoparticles were mainly composed of zero valent iron nanoparticles which were coated with various organic matters in the extracts as a capping or stabilizing agents. Batch experiments showed that 89.9% of Cr(VI) was removed by the Ec-Fe-NPs much higher than by the extracts alone (20.4%) and Fe3O4 nanoparticles (47.3%). Based on the kinetics study and the XPS analysis, a removal mechanism dominated by adsorption and reduction with subsequently co-precipitation was proposed.

  17. In-situ porous reactive wall for treatment of Cr(VI) and trichloroethylene in groundwater

    International Nuclear Information System (INIS)

    Blowes, D.W.; Bennett, T.A.; Gillham, R.W.

    1997-01-01

    A permeable reactive wall for treating groundwater contaminated with hexavalent chromium (Cr(VI)) and trichloroethylene (TCE) was installed at the U.S. Coast Guard Support Center in Elizabeth City, NC in June, 1996. The porous reactive wall is 46 m long, 0.6 m wide, and 7.3 m deep. The reactive wall was installed in less then six hours using a continuous trenching technique which simultaneously removed the aquifer material and replaced it with reactive material. The wall is composed of 100% elemental iron in the form of iron filings. Preliminary laboratory experiments, with site groundwater and reactive materials similar to the full-scale wall components, were successful in decreasing 11 mg/L Cr(VI) to < 0.01 mg/L and 1700 μg/L TCE to < 1 μg/L. Detailed field monitoring commenced in November, 1996. The monitoring program includes groundwater sampling upgradient, downgradient and within the reactive wall, and collection of core samples for mineralogical and microbiological study. Preliminary results from the monitoring program indicate that the wall successfully removes Cr(VI) from influent concentrations of 6 mg/L to < 0.01 mg/L, and TCE from 5600 μg/L to 5.3 μg/L within the wall

  18. Reduction of Cr(VI) to Cr(III) using silicon nanowire arrays under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fellahi, Ouarda [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Barras, Alexandre [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Pan, Guo-Hui [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Dong Nanhu Road, Changchun 130033 (China); Coffinier, Yannick [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); Hadjersi, Toufik [Centre de Recherche en Technologie des Semi-conducteurs pour l' Energétique-CRTSE 02, Bd Frantz Fanon, BP. 140, Alger 7 Merveilles (Algeria); Maamache, Mustapha [Laboratoire de Physique Quantique et Systèmes Dynamiques, Département de Physique, Université de Sétif, Sétif 19000 (Algeria); Szunerits, Sabine [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, Avenue Poincaré—BP 70478, 59652 Villeneuve d' Ascq Cedex (France); and others

    2016-03-05

    Highlights: • Cr(VI) reduction to Cr(III) using silicon nanowires decorated with Cu nanoparticles. • The reduction takes place at room temperature and neutral pH under visible light. • The photocatalytic reduction was enhanced by addition of adipic or citric acid. - Abstract: We report an efficient visible light-induced reduction of hexavalent chromium Cr(VI) to trivalent Cr(III) by direct illumination of an aqueous solution of potassium dichromate (K{sub 2}Cr{sub 2}O{sub 7}) in the presence of hydrogenated silicon nanowires (H-SiNWs) or silicon nanowires decorated with copper nanoparticles (Cu NPs-SiNWs) as photocatalyst. The SiNW arrays investigated in this study were prepared by chemical etching of crystalline silicon in HF/AgNO{sub 3} aqueous solution. The Cu NPs were deposited on SiNW arrays via electroless deposition technique. Visible light irradiation of an aqueous solution of K{sub 2}Cr{sub 2}O{sub 7} (10{sup −4} M) in presence of H-SiNWs showed that these substrates were not efficient for Cr(VI) reduction. The reduction efficiency achieved was less than 10% after 120 min irradiation at λ > 420 nm. Addition of organic acids such as citric or adipic acid in the solution accelerated Cr(VI) reduction in a concentration-dependent manner. Interestingly, Cu NPs-SiNWs was found to be a very efficient interface for the reduction of Cr(VI) to Cr(III) in absence of organic acids. Almost a full reduction of Cr(VI) was achieved by direct visible light irradiation for 140 min using this photocatalyst.

  19. A new method in estimation of total hexavalent chromium in Portland pozzolan cement; Un nuevo método en la determinación del cromo hexavalente total en cemento Portland puzolánico.

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, R.; Sharma, D.

    2017-07-01

    Variamine blue was used first time for the detection of hexavalent chromium from cement samples. In present method, cement was treated sequentially with water, sulphate and carbonate buffer to extract soluble, sparingly soluble and insoluble hexavalent chromium respectively. Extracted Cr (VI) was determined using variamine blue as chromogenic reagent. The determination is based on the reaction of hexavalent chromium with potassium iodide in an acid medium to liberate iodine. This oxidizes variamine blue to form a violet coloured species having an absorption to maximum at 556 nm. Energy-dispersive X-ray spectroscopy (EDX) and Infrared Spectroscopy (IR) confirmed the complete extraction of hexavalent chromium by sequential extraction process. SRM 2701 (Reference material from NIST, USA) was used for revalidating the results. The percentage of recovery for proposed and reference method (diphelycarbazide method) varied from 98.5 to 101 and 97.5 to 100.5. Whereas, their relative error percentage varied from -1.5 to 0.33 and -2.5 to 0.5. [Spanish] El azul de variamina se utilizó por primera vez para la detección de cromo hexavalente en muestras de cemento. En el presente método, el cemento se trató secuencialmente con agua, y tampones sulfato y carbonato para extraer el cromo hexavalente soluble, poco soluble e insoluble, respectivamente. El Cr (VI) extraído se determinó utilizando azul de variamina como reactivo cromógeno, por reacción del cromo hexavalente con yoduro de potasio en un medio ácido para liberar yodo. Esto oxida al azul de variamina para formar una especie de color violeta con una absorción máxima a 556 nm. El análisis por energía dispersiva de rayos X (EDX) y la espectroscopía de infrarrojos (IR) confirmaron la extracción completa de cromo hexavalente mediante el proceso de extracción secuencial. Se utilizó SRM 2701 (material de referencia de NIST, EE.UU.) para validar los resultados. El porcentaje de recuperación para el m

  20. Cr(III) reactivity and foot dermatitis in Cr(VI) positive patients

    DEFF Research Database (Denmark)

    Hansen, Malene Barré; Menné, Torkil; Johansen, Jeanne Duus

    2006-01-01

    Chromium allergy has become synonymous with Cr(VI) allergy. However, real exposure to chromium from leather products may include both Cr(III) and Cr(VI). In this study, we investigate the reactivity to both Cr(VI) and Cr(III) in consecutive patients to analyse the relation between foot eczema/leather...... to Cr(III). The increased risk was not due to a higher degree of sensitivity to Cr(VI). Leather was reported most frequently as the suspected cause of chromium dermatitis (54%). However, Cr(VI) allergics having foot eczema and positive or doubtful Cr(III) reactions often had positive reactions to other...

  1. Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

    Science.gov (United States)

    Anah, L.; Astrini, N.

    2017-03-01

    The major problem in heavy metal pollution is that these metals are not biodegradable and accordingly accumulate in the bodies of living organisms, causing dangerous diseases and serious cell disorder. According to World Health Organization (WHO), the long term exposure of Cr(VI) levels of over 0.1 ppm causes respiratory problems, liver and kidney damage, and carcinogenicity.Due to its easy operation and of various cheap adsorbents development, adsorption has been proved to be efficient and most economically attractive technique and feasible to the removal of toxic heavy metal from wastewater. The study aimed to report the removal of Cr(VI) ions from aqueous solutions through adsorption process using carboxymethyl cellulose-graft-poly(acrylic acid) (CMC-g-PAA) hydrogel as adsorbent.Effect of pH was studied to remove hexavalent chromium.Graft copolymerization of poly(acrylic acid) onto carboxymethyl cellulose was carried out in the presence of benzoyl peroxide redox initiator and methylenbisacrylamide as crosslinker agent. Batch experiments were carried out to investigate the effects ofinitial pH.The adsorption of Cr(VI) ions as a function of pH was conducted in the initial pH range of 1 to 8. The results indicated that acidic pH strongly favored the adsorption. The optimum pH for adsorption of Cr(VI) ranged from 1 to 3, and the maximum uptake of Cr(VI) from the solution was 6.53 mg/g at pH 1 and 30°C. FTIR spectroscopy, SEM analyses were performed on the adsorbent before and after Cr(VI) binding. All analyses confirmed the complexation of Cr(VI) ions on the adsorbent.

  2. Study on the properties of chromium residue-cement matrices (CRCM) and the influences of superplasticizers on chromium(VI)-immobilising capability of cement matrices.

    Science.gov (United States)

    Shi, Hui-Sheng; Kan, Li-Li

    2009-03-15

    The study of cementitious activity of chromium residue (CR) was carried out to formulate the properties of chromium residue-cement matrices (CRCM) by blending CR with Ordinary Portland Cement (OPC). The particle size distribution, microstructures of CR were investigated by some apparatuses, and physical properties, leaching behavior of hexavalent chromium [Cr(VI)] of CRCM were also determined by some experiments. Three types of commonly used superplasticizers (sulphonated acetone formaldehyde superplasticizer (J1), polycarboxylate-based superplasticizer (J2) and naphthalene superplasticizer (J3)) were chosen to investigate their influences on the physical properties and the Cr(VI)-immobilisation in the leachate of the CRCM hardened pastes. The results show that the CR has a certain cementitious activity. The incorporation of CR improves the pore size distribution of CRCM. The Cr(VI) concentrations in the leachate of CRCM significantly decrease by incorporation of J2. Among three superplasticizers, J2 achieves lowest Cr(VI) leaching ratio. Based on this study, it is likely to develop CR as a potential new additive used in cement-based materials.

  3. Natural occurrence of hexavalent chromium in a sedimentary aquifer in Urânia, State of São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Christine Bourotte

    2009-06-01

    Full Text Available Anomalous concentrations of hexavalent chromium have been detected in ground-water of the Adamantina Aquifer inat least 54 municipalities located in the northwestern region of the State of São Paulo, southeast Brazil, occasionallyexceeding the permitted limit for human consumption (0.05 mg.L-1. An investigation was conducted in the municipality of Urânia, where the highest concentrations of chromium were detected regionally. It was defined that the originof this contamination is natural, since high concentrations of chromium were detected in aquifer sandstones (averageof 221 ppm and also in pyroxenes (6000 ppm, one of the main heavy minerals found in the sediments. Besides, noother possible diffuse or point sources of contamination were observed in the study area. Stratification of ground-waterquality was observed and the highest concentrations of Cr6+ were detected at the base of the aquifer (0.12 mg.L-1,where ground-water shows elevated values for redox potential (472.5 mV and pH (8.61. The origin of Cr6+ in water may be associated with the weathering of pyroxene (augite, followed by the oxidation of Cr3+ by manganese oxides. The highest concentrations of Cr6+ are probably related to desorption reactions, due to the anomalous alkaline pHfound in ground-water at the base of the aquifer.Concentrações anômalas de cromo hexavalente foram detectadas em águas subterrâneas do Aqüífero Adamantina em pelo menos 54 municipalidades localizadas na região noroeste do Estado de São Paulo, sudeste do Brasil, algumas vezes ultrapassando o limite máximo permitido para consumo humano (0,05 mg.L-1. Um estudo foi realizado no município de Urânia, onde as mais elevadas concentrações de cromo da região foram detectadas. A origem da contaminação foi definida como natural, pois foram detectadas concentrações de cromonos arenitos do aqüífero (média 221 ppm e em piroxênios (6000 ppm, um dos principais minerais pesados encontrados nos sedimentos

  4. Removal of Cr(VI) from aqueous solution by fungal biomass

    Energy Technology Data Exchange (ETDEWEB)

    Ahluwalia, Sarabjeet Singh [Department of Biotechnology, General Shivdev Singh Diwan Gurbachan Singh Khalsa College, Patiala, Punjab (India); Goyal, Dinesh [Department of Biotechnology and Environmental Sciences, Thapar University, Patiala, Punjab (India)

    2010-10-15

    Chromium compounds are released by industrial processes including leather production, mining, petroleum refining, in textile industry and dyeing. They are a significant threat to the environment and public health because of their toxicity. Removal of hexavalent chromium by living biomass of different fungi was effective in the order of Aspergillus terricola>Aspergillus niger>Acremonium strictum>Aureobasidium pullulans>Paecilomyces variotii>Aspergillus foetidus>Cladosporium resinae>Phanerochaete chrysosporium. Non-living dried fungal biomass showed higher potential for metal removal than living cells. Among all fungi dead biomass of P. chrysosporium, C. resinae and P. variotii had the maximum specific chromium uptake capacity, which was 11.02, 10.69 and 10.35 mg/g of dry biomass respectively at pH 4.0-5.0 in batch sorption. Removal of Cr(VI) by P. chrysosporium from multi-metallic synthetic solution as well as chrome effluent was significant by bringing down the residual concentration to 0.1 mg/L in the effluent, which falls within the permissible range and its removal was not affected by the presence of other metal ions such as Fe, Zn and Ni. Fourier transform infrared spectral analysis revealed the presence of carboxylate (C=O) and amine (-NH{sup +}{sub 3}-NH{sup +}{sub 2}) functional groups commonly present on the cell surface of all fungi, with possible involvement in chromium binding. The result indicates that non-living fungal biomass either obtained as a by-product of fermentation industry or mass produced using inexpensive culture media can be used for bioremediation of Cr(VI) from chrome effluent on large scale. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Adsorption studies for Cr(VI) onto magnetic particles covered with chitosan

    International Nuclear Information System (INIS)

    Yamaura, Mitiko; Yamamura, Amanda P. Gualberto; Costa, Caroline Hastenreiter

    2007-01-01

    The magnetic carrier, called magnetic biosorbent, was prepared using magnetite nanoparticles and a biopolymer from the chitin of exoskeletons of marine invertebrates, the chitosan. Experiments of adsorption in batch systems were carried out to investigate the removal of Cr(VI) ions from pH 3 solution using this magnetic biosorbent. Radioisotope Cr-51 was used as the radioactive tracer to mark the Cr in solution, so the concentrations of Cr(VI) ions were determined by gamma spectrometry with a NaI(Tl) detector. Dosage of magnetic biosorbent was studied in the adsorption of chromium ions from dilute metal ion solutions. The removal efficiency obtained was 97% at a dosage of 50 g L -1 . Freundlich and Langmuir isotherm models were used to evaluate the data of equilibrium isotherm in the range of Cr(VI) concentration from 50 mg L -1 to 1200 mg L -1 . The Langmuir model was found to best represent the equilibrium isotherm. Recovery of the Cr(VI) ions from loaded magnetic biosorbent was possible by desorption process using a NaOH solution of pH 10. The results demonstrated that the magnetic biosorbent is effective for the removal of hexavalent Cr ion from solutions by sorption process and the recovery by desorption process is possible. The suspended particles of the magnetic biosorbent exhibited a strong magnetization in the presence of a magnetic field, and being easily attracted and removed from aqueous solutions using a magnet, so indicating the application viability in magnetic separation process. (author)

  6. Carcinogenicity and mutagenicity of chromium.

    Science.gov (United States)

    Léonard, A; Lauwerys, R R

    1980-11-01

    Occupational exposure represents the main source of human contamination by chromium. For non-occupationally exposed people the major environmental exposure to chromium occurs as a consequence of its presence in food. Chromium must be considered as an essential element. Its deficiency impairs glucose metabolism. Trivalent chromium salts are poorly absorbed through the gastro-intestinal and respiratory tracts because they do not cross membranes easily. Hexavalent chromium can be absorbed by the oral and pulmonary routes and probably also through the skin. After its absorption, hexavalent chromium is rapidly reduced to the trivalent form which is probably the only form to be found in biological material. Epidemiological studies have shown that some chromium salts (mainly the slightly soluble hexavalent salts) are carcinogens. Lung cancers have, indeed, often been reported among workers in chromate-producing industry and, to a lesser extent, in workers from the chrome-pigment industry. The first attempts to produce cancers in experimental animals by inhalation or parenteral introduction gave negative or equivocal results but, from 1960, positive results have been obtained with various chromium compounds. As for the carcinogenic activity, the mutagenicity of chromium has mainly been found with hexavalent salts. In the majority of assay systems used, trivalent chromium appears inactive. It can be considered as evident, however, that the ultimate mutagen which binds to the genetic material is the trivalent form produced intracellularly from hexavalent chromium, the apparent lack of activity of the trivalent form being due to its poor cellular uptake.

  7. Chromium carcinogenicity: California strategies.

    Science.gov (United States)

    Alexeeff, G V; Satin, K; Painter, P; Zeise, L; Popejoy, C; Murchison, G

    1989-10-01

    Hexavalent chromium was identified by California as a toxic air contaminant (TAC) in January 1986. The California Department of Health Services (CDHS) concurred with the findings of the International Agency for Research on Cancer that there is sufficient evidence to demonstrate the carcinogenicity of chromium in both animals and humans. CDHS did not find any compelling evidence demonstrating the existence of a threshold with respect to chromium carcinogenesis. Experimental data was judged inadequate to assess potential human reproductive risks from ambient exposures. Other health effects were not expected to occur at ambient levels. The theoretically increased lifetime carcinogenic risk from a continuous lifetime exposure to hexavalent chromium fell within the range 12-146 cancer cases per nanogram hexavalent chromium per cubic meter of air per million people exposed, depending on the potency estimate used. The primary sources found to contribute significantly to the risk of exposure were chrome platers, chromic acid anodizing facilities and cooling towers utilizing hexavalent chromium as a corrosion inhibitor. Evaluation of genotoxicity data, animal studies and epidemiological studies indicates that further consideration should be given to the potential carcinogenicity of hexavalent chromium via the oral route.

  8. The effects of chromium(VI) on the thioredoxin system: Implications for redox regulation

    Science.gov (United States)

    Myers, Charles R.

    2014-01-01

    Hexavalent chromium [Cr(VI)] compounds are highly redox active and have long been recognized as potent cytotoxins and carcinogens. The intracellular reduction of Cr(VI) generates reactive Cr intermediates, which are themselves strong oxidants, as well as superoxide, hydrogen peroxide, and hydroxyl radical. These probably contribute to the oxidative damage and effects on redox-sensitive transcription factors that have been reported. However, the identification of events that initiate these signaling changes has been elusive. More recent studies show that Cr(VI) causes irreversible inhibition of thioredoxin reductase (TrxR) and oxidation of thioredoxin (Trx) and peroxiredoxin (Prx). Mitochondrial Trx2/Prx3 are more sensitive to Cr(VI) treatment than cytosolic Trx1/Prx1, although both compartments show thiol oxidation with higher doses or longer treatments. Thiol redox proteomics demonstrate that Trx2, Prx3, and Trx1 are among the most sensitive proteins in cells to Cr(VI) treatment. Their oxidation could therefore represent initiating events that have widespread implications for protein thiol redox control and for multiple aspects of redox signaling. This review summarizes the effects of Cr(VI) on the TrxR/Trx system and how these events could influence a number of downstream redox signaling systems that are influenced by Cr(VI) exposure. Some of the signaling events discussed include the activation of apoptosis signal regulating kinase and MAP kinases (p38 and JNK) and the modulation of a number of redox-sensitive transcription factors including AP-1, NF-κB, p53, and Nrf2. PMID:22542445

  9. Alkaline hydrothermal stabilization of Cr(VI) in soil using glass and aluminum from recycled municipal solid wastes.

    Science.gov (United States)

    Gattullo, Concetta Eliana; D'Alessandro, Caterina; Allegretta, Ignazio; Porfido, Carlo; Spagnuolo, Matteo; Terzano, Roberto

    2018-02-15

    Hexavalent chromium was stabilized in soil by using a mixture of glass and aluminum recovered from municipal solid wastes under alkaline hydrothermal conditions. Cr(VI) concentration was reduced by 94-98% already after 7days of treatment. After the same period, more than 90% of total Cr was stabilized in highly recalcitrant and scarcely mobile chemical forms, with 50% in the residual fraction (when the samples were treated at 1/10w/w mixture/soil ratio). Longer treatments increased Cr stabilization. X-ray microanalyses revealed that Cr was stabilized in geopolymeric structures within large aluminosilicate mineral aggregates (containing both amorphous and crystalline phases). 3D microstructural analyses showed a limited compaction of the soil with still a 20% internal porosity in the neoformed aggregates. Increased pH and salinity after the treatment can be restored by simple soil amendments and washing. Copyright © 2017. Published by Elsevier B.V.

  10. Prenatal exposure to chromium induces early reproductive senescence by increasing germ cell apoptosis and advancing germ cell cyst breakdown in the F1 offspring.

    Science.gov (United States)

    Sivakumar, Kirthiram K; Stanley, Jone A; Arosh, Joe A; Pepling, Melissa E; Burghardt, Robert C; Banu, Sakhila K

    2014-04-01

    Hexavalent chromium (CrVI), one of the more toxic heavy metals, is widely used in more than 50 industries such as chrome plating, welding, wood processing and tanneries. As one of the world's leading producers of chromium compounds, the U.S. is facing growing challenges in protecting human health against multiple adverse effects of CrVI. CrVI is rapidly converted to CrIII intracellularly, and can induce apoptosis through different mechanisms. Our previous studies demonstrated postnatal exposure to CrVI results in a delay or arrest in follicle development and puberty. Pregnant rats were treated with 25 ppm potassium dichromate (CrVI) from gestational day (GD) 9.5 to 14.5 through drinking water, placentae were removed on GD 20, and total Cr was estimated in the placentae; ovaries were removed from the F1 offspring on postnatal day (PND)-1 and various analyses were performed. Our results show that gestational exposure to CrVI resulted in (i) increased Cr concentration in the placenta, (ii) increased germ cell apoptosis by up-regulating p53/p27-Bax-caspase-3 proteins and by increasing p53-SOD-2 co-localization; (iii) accelerated germ cell cyst (GCC) breakdown; (iv) advanced primordial follicle assembly and primary follicle transition and (v) down regulation of p-AKT, p-ERK and XIAP. As a result of the above events, CrVI induced early reproductive senescence and decrease in litter size in F1 female progeny. Published by Elsevier Inc.

  11. Cr(III) and Cr(VI) in leather and elicitation of eczema

    DEFF Research Database (Denmark)

    Hansen, Malene Barré; Menne, Torkil; Johansen, Jeanne Duus

    2006-01-01

    The aim of the present study was to investigate the relation between the content of Cr(VI) and soluble Cr(III) in leather and the ability of the leather to elicit eczema in chromium allergic patients. An array of chromium-tanned leather samples was analysed for the content of total Cr(VI) and sol...

  12. Mechanistic insight into chromium(VI) reduction by oxalic acid in the presence of manganese(II)

    Energy Technology Data Exchange (ETDEWEB)

    Wrobel, Katarzyna; Corrales Escobosa, Alma Rosa; Gonzalez Ibarra, Alan Alexander; Mendez Garcia, Manuel; Yanez Barrientos, Eunice; Wrobel, Kazimierz, E-mail: kazimier@ugto.mx

    2015-12-30

    Over the past few decades, reduction of hexavalent chromium (Cr(VI)) has been studied in many physicochemical contexts. In this research, we reveal the mechanism underlying the favorable effect of Mn(II) observed during Cr(VI) reduction by oxalic acid using liquid chromatography with spectrophotometric diode array detector (HPLC–DAD), nitrogen microwave plasma atomic emission spectrometry (HPLC–MP-AES), and high resolution mass spectrometry (ESI–QTOFMS). Both reaction mixtures contained potassium dichromate (0.67 mM Cr(VI)) and oxalic acid (13.3 mM), pH 3, one reaction mixture contained manganese sulfate (0.33 mM Mn(II)). In the absence of Mn(II) only trace amounts of reaction intermediates were generated, most likely in the following pathways: (1) Cr(VI) → Cr(IV) and (2) Cr(VI) + Cr(IV) → 2Cr(V). In the presence of Mn(II), the active reducing species appeared to be Mn(II) bis-oxalato complex (J); the proposed reaction mechanism involves a one-electron transfer from J to any chromium compound containing Cr=O bond, which is reduced to Cr−OH, and the generation of Mn(III) bis-oxalato complex (K). Conversion of K to J was observed, confirming the catalytic role of Mn(II). Since no additional acidification was required, the results obtained in this study may be helpful in designing a new, environmentally friendly strategy for the remediation of environments contaminated with Cr(VI).

  13. Biological and chemical removal of Cr(VI) from waste water: cost and benefit analysis.

    Science.gov (United States)

    Demir, Aynur; Arisoy, Münevver

    2007-08-17

    The objective of the present study is cost and benefit analysis of biological and chemical removal of hexavalent chromium [Cr(VI)] ions. Cost and benefit analysis were done with refer to two separate studies on removal of Cr(VI), one of heavy metals with a crucial role concerning increase in environmental pollution and disturbance of ecological balance, through biological adsorption and chemical ion-exchange. Methods of biological and chemical removal were compared with regard to their cost and percentage in chrome removal. According to the result of the comparison, cost per unit in chemical removal was calculated 0.24 euros and the ratio of chrome removal was 99.68%, whereas those of biological removal were 0.14 and 59.3% euros. Therefore, it was seen that cost per unit in chemical removal and chrome removal ratio were higher than those of biological removal method. In the current study where chrome removal is seen as immeasurable benefit in terms of human health and the environment, percentages of chrome removal were taken as measurable benefit and cost per unit of the chemicals as measurable cost.

  14. Tolerance and Reduction of Chromium(VI by Bacillus sp. MNU16 Isolated from Contaminated Coal Mining Soil

    Directory of Open Access Journals (Sweden)

    Neha Upadhyay

    2017-05-01

    Full Text Available The bacterium MNU16 was isolated from contaminated soils of coal mine and subsequently screened for different plant growth promoting (PGP activities. The isolate was further identified by 16S rRNA sequencing as Bacillus subtilis MNU16 with IAA concentration (56.95 ± 0.43 6μg/ml, siderophore unit (9.73 ± 2.05%, phosphate solubilization (285.13 ± 1.05 μg/ml and ACC deaminase activity (116.79 ± 0.019 μmoles α-ketobutyrate/mg/24 h. Further, to evaluate the metal resistance profile of bacterium, the isolate was screened for multi-metal resistance (viz. 900 mg/L for Cr, 600 mg/L for As, 700 mg/L for Ni and 300 mg/L for Hg. Additionally, the resistance pattern of B. subtilis MNU16 against Cr(VI (from 50 to 300 mg/L treatments were evaluated. An enriched population was observed at 0–200 mg/L Cr(VI concentration while slight reductions were observed at 250 and 300 mg/L Cr(VI. Further, the chromium reduction ability at 50 mg/L of Cr(VI highlighted that the bacterium B. subtilis MNU16 reduced 75% of Cr(VI to 13.23 mg/L within 72 h. The localization of electron dense precipitates was observed in the TEM images of B. subtilis MNU16 which is might be due to the reduction of Cr(VI to Cr(III. The data of fluorescence microscopy and flow cytometry with respect to Cr(VI treatments (50–300 mg/L showed a similar pattern and clearly revealed the less toxic effect of hexavalent chromium upto 200 mg/L Cr(VI concentration. However, toxicity effects were more pronounced at 300 mg/L Cr(VI. Therefore, the present study suggests that the plant growth promoting potential and resistance efficacy of B. subtilis MNU16 will go a long way in developing an effective bioremediation approach for Cr(VI contaminated soils.

  15. Effective bioreduction of hexavalent chromium–contaminated water ...

    African Journals Online (AJOL)

    AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING ... Evaluation after reactor termination with SEM-EDX and XRD confirmed the ... Keywords: Bioreduction, fixed-film reactor, hexavalent chromium, microbial diversity ...

  16. High-performance towards removal of toxic hexavalent chromium from aqueous solution using graphene oxide-alpha cyclodextrin-polypyrrole nanocomposites

    CSIR Research Space (South Africa)

    Chauke, VP

    2015-07-01

    Full Text Available toxic Cr(VI) from water. The prepared GO-aCD-PPY NCs were successfully characterised with AT-FTIR, FE-SEM, HR-TEM, BET and XRD techniques. Adsorption experiments were performed in batch mode to determine optimum conditions that include temperature, p...

  17. Ratiometric fluorescent detection of chromium(VI) in real samples based on dual emissive carbon dots.

    Science.gov (United States)

    Ma, Yunxia; Chen, Yonglei; Liu, Juanjuan; Han, Yangxia; Ma, Sudai; Chen, Xingguo

    2018-08-01

    As we know, hexavalent chromium (Cr(VI)) was usually used as an additive to improve the color fastness during the printing and dyeing process, and thus posing tremendous threat to our health and living quality. In this work, the dual emissive carbon dots (DECDs) were synthesized through hydrothermal treatment of m-aminophenol and oxalic acid. The obtained DECDs not only exhibited dual emission fluorescence peaks (430 nm, 510 nm) under the single excitation wavelength of 380 nm, but also possessed good water solubility and excellent fluorescence stability. A ratiometric fluorescent method for the determination of Cr(VI) was developed using the DECDs as a probe. Under the optimal conditions, a linear range was obtained from 2 to 300 μM with a limit of detection of 0.4 μM. Furthermore, the proposed ratiometric fluorescent method was applied to the analysis of Cr(VI) in textile, steel, industrial wastewater and chromium residue samples with satisfactory recoveries (88.4-106.8%). Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Biological versus mineralogical chromium reduction: potential for reoxidation by manganese oxide.

    Science.gov (United States)

    Butler, Elizabeth C; Chen, Lixia; Hansel, Colleen M; Krumholz, Lee R; Elwood Madden, Andrew S; Lan, Ying

    2015-11-01

    Hexavalent chromium (Cr(vi), present predominantly as CrO4(2-) in water at neutral pH) is a common ground water pollutant, and reductive immobilization is a frequent remediation alternative. The Cr(iii) that forms upon microbial or abiotic reduction often co-precipitates with naturally present or added iron (Fe), and the stability of the resulting Fe-Cr precipitate is a function of its mineral properties. In this study, Fe-Cr solids were formed by microbial Cr(vi) reduction using Desulfovibrio vulgaris strain RCH1 in the presence of the Fe-bearing minerals hematite, aluminum substituted goethite (Al-goethite), and nontronite (NAu-2, Clay Minerals Society), or by abiotic Cr(vi) reduction by dithionite reduced NAu-2 or iron sulfide (FeS). The properties of the resulting Fe-Cr solids and their behavior upon exposure to the oxidant manganese (Mn) oxide (birnessite) differed significantly. In microcosms containing strain RCH1 and hematite or Al-goethite, there was significant initial loss of Cr(vi) in a pattern consistent with adsorption, and significant Cr(vi) was found in the resulting solids. The solid formed when Cr(vi) was reduced by FeS contained a high proportion of Cr(iii) and was poorly crystalline. In microcosms with strain RCH1 and hematite, Cr precipitates appeared to be concentrated in organic biofilms. Reaction between birnessite and the abiotically formed Cr(iii) solids led to production of significant dissolved Cr(vi) compared to the no-birnessite controls. This pattern was not observed in the solids generated by microbial Cr(vi) reduction, possibly due to re-reduction of any Cr(vi) generated upon oxidation by birnessite by active bacteria or microbial enzymes. The results of this study suggest that Fe-Cr precipitates formed in groundwater remediation may remain stable only in the presence of active anaerobic microbial reduction. If exposed to environmentally common Mn oxides such as birnessite in the absence of microbial activity, there is the potential

  19. Column study of enhanced Cr(VI) removal and longevity by coupled abiotic and biotic processes using Fe0 and mixed anaerobic culture.

    Science.gov (United States)

    Zhong, Jiawei; Yin, Weizhao; Li, Yongtao; Li, Ping; Wu, Jinhua; Jiang, Gangbiao; Gu, Jingjing; Liang, Hao

    2017-10-01

    In this study, Fe 0 and mixed anaerobic culture were integrated in one column to investigate the coupled abiotic and biotic effects on hexa-valent chromium (Cr(VI)) removal and column longevity with an abiotic Fe 0 column in the control experiments. According to the breakthrough study, a slower Cr(VI) breakthrough rate of 0.19 cm/PV was observed in the biotic Fe 0 column whereas the value in the abiotic Fe 0 column was 0.30 cm/PV, resulting in 64% longer life-span and 62% higher Cr(VI) removal capacity in the biotic Fe 0 column than the abiotic one. The solid phase characterization by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) confirmed that this enhancement was attributed to the higher consumption of iron and greater production of diverse reactive minerals (e.g., green rust, magnetite and lepidocrocite) induced by the synergistic interaction of Fe 0 and anaerobic culture, providing more reactive sites for Cr(VI) adsorption, reduction and co-precipitation. Furthermore, the decreasing breakthrough rates and growing iron corrosion along the biotic Fe 0 column demonstrated an inhomogeneous distribution of reactive zones in the column and its latter 3/5 section was considered to be the most reactive area for Cr(VI) removal. These results indicate that the inoculation of microorganisms in Fe 0 -based permeable reactive barriers will enable this technology a higher removal capacity and longer life-span for the remediation of Cr(VI)-contaminated groundwater. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Sandwich-like nano-system for simultaneous removal of Cr(VI) and Cd(II) from water and soil.

    Science.gov (United States)

    Wang, Dongfang; Zhang, Guilong; Dai, Zhangyu; Zhou, Linglin; Bian, Po; Zheng, Kang; Wu, Zhengyan; Cai, Dongqing

    2018-05-07

    In this work, a novel nano-system with sandwich-like structure was synthesized via face-to-face combination of two pieces of waste cotton fabrics (CFs) carrying ferrous sulfide (FeS) and carboxyl-functionalized ferroferric oxide (CFFM) respectively, and the obtained nano system was named as FeS/CFFM/CF. Therein, FeS has high reduction and adsorption capabilities for hexavalent chromium (Cr(VI)), CFFM possesses a high adsorption ability on cadmium ion (Cd(II)) through electrostatics attraction and chelation, and CF displays high immobilization ability for FeS and CFFM and adsorption performance on Cd(II). FeS/CFFM/CF could simultaneously remove Cr(VI) and Cd(II) from water, inhibit the uptake of Cr and Cd by fish and water spinach, ensuring the food safety. Besides, this technology could efficiently control migration of Cr(VI) and Cd(II) in sand-soil mixture, which was favorable to prevent their wide diffusion. Importantly, FeS/CFFM/CF possessed a high flexibility and could be conveniently produced with needed scale and shape, and easily separated from water and soil, displaying a promising approach to remediate Cr(VI)/Cd(II)-contaminated water and soil and a huge application potential.

  1. Ultratrace Determination of Cr(VI and Pb(II by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents

    Directory of Open Access Journals (Sweden)

    Jameel Ahmed Baig

    2013-01-01

    Full Text Available Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI and lead (Pb(II by dispersive liquid-liquid microextraction (DLLME using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS. For the current study, ammonium pyrrolidine dithiocarbamate (APDC, carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI and Pb(II were 0.037 and 0.054 µg/L, respectively. The enrichment factors in both cases were 400 with 40 mL of initial volumes. The relative standard deviations (RSDs, were 96%. The proposed method was successfully applied to the determination of Cr(VI and Pb(II at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method.

  2. Improved physiologically based pharmacokinetic model for oral exposures to chromium in mice, rats, and humans to address temporal variation and sensitive populations.

    Science.gov (United States)

    Kirman, C R; Suh, M; Proctor, D M; Hays, S M

    2017-06-15

    A physiologically based pharmacokinetic (PBPK) model for hexavalent chromium [Cr(VI)] in mice, rats, and humans developed previously (Kirman et al., 2012, 2013), was updated to reflect an improved understanding of the toxicokinetics of the gastrointestinal tract following oral exposures. Improvements were made to: (1) the reduction model, which describes the pH-dependent reduction of Cr(VI) to Cr(III) in the gastrointestinal tract under both fasted and fed states; (2) drinking water pattern simulations, to better describe dosimetry in rodents under the conditions of the NTP cancer bioassay; and (3) parameterize the model to characterize potentially sensitive human populations. Important species differences, sources of non-linear toxicokinetics, and human variation are identified and discussed within the context of human health risk assessment. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  3. Chromium resistance characteristics of Cr(VI) resistance genes ChrA and ChrB in Serratia sp. S2.

    Science.gov (United States)

    He, Yuan; Dong, Lanlan; Zhou, Simin; Jia, Yan; Gu, Ruijia; Bai, Qunhua; Gao, Jieying; Li, Yingli; Xiao, Hong

    2018-08-15

    To find an efficient chromium (VI) resistance system, with a highly efficient, economical, safe, and environmentally friendly chromium-removing strain, ChrA, ChrB, and ChrAB fragments of the chromium (VI) resistance gene in Serratia sp. S2 were cloned, and their prokaryotic expression vectors were constructed and transformed into E. coli BL21. The anti-chromium (VI) capacity and characteristics of engineered bacteria, role of ChrA and ChrB genes in the anti-chromium (VI) processes, and the mechanism of chromium metabolism, were explored. The PCR technique was used to amplify ChrA, ChrB, and ChrAB genes from the Serratia sp. S2 genome. ChrA, ChrB, and ChrAB genes were connected to the prokaryotic expression vector pET-28a and transferred into E. coli BL21 for prokaryotic expression. Cr-absorption and Cr-efflux ability of the engineered strains were determined. The effects of respiratory inhibitors and oxygenated anions on Cr-efflux of ChrA and ChrB engineered strains were explored. ChrA, ChrB, and ChrAB engineered strains were constructed successfully; there was no significant difference between the control strain and the ChrB engineered strain for Cr-metabolism (P > 0.05). Cr-absorption and Cr-efflux of ChrA and ChrAB engineered strains were significantly stronger than the control strain (P < 0.05). Oxyanions (sulfate and molybdate) and inhibitors (valinomycin and CN - ) could significantly inhibit the Cr-efflux capacities of ChrA and ChrAB engineered strains (P < 0.05), while NADPH could significantly promote such capacities (P < 0.05). The Cr-transporter, encoded by ChrA gene, confer the ability to pump out intracellular Cr on ChrA and ChrAB engineered strains. The ChrB gene plays a positive regulatory role in ChrA gene regulation. The Cr-metabolism ability of the ChrAB engineered strain is stronger than the ChrA engineered strain. ChrA and ChrAB genes in the Cr-resistance system may involve a variety of mechanisms, such as sulfate ion channel and

  4. Binder-free carbon nanotube electrode for electrochemical removal of chromium.

    Science.gov (United States)

    Wang, Haitao; Na, Chongzheng

    2014-11-26

    Electrochemical treatment of chromium-containing wastewater has the advantage of simultaneously reducing hexavalent chromium (CrVI) and reversibly adsorbing the trivalent product (CrIII), thereby minimizing the generation of waste for disposal and providing an opportunity for resource reuse. The application of electrochemical treatment of chromium is often limited by the available electrochemical surface area (ESA) of conventional electrodes with flat surfaces. Here, we report the preparation and evaluation of carbon nanotube (CNT) electrodes consisting of vertically aligned CNT arrays directly grown on stainless steel mesh (SSM). We show that the 3-D organization of CNT arrays increases ESA up to 13 times compared to SSM. The increase of ESA is correlated with the length of CNTs, consistent with a mechanism of roughness-induced ESA enhancement. The increase of ESA directly benefits CrVI reduction by proportionally accelerating reduction without compromising the electrode's ability to adsorb CrIII. Our results suggest that the rational design of electrodes with hierarchical structures represents a feasible approach to improve the performance of electrochemical treatment of contaminated water.

  5. Short-term toxicity of hexavalent-chromium to epipsammic diatoms of a microtidal estuary (Río de la Plata): Responses from the individual cell to the community structure

    International Nuclear Information System (INIS)

    Licursi, M.; Gómez, N.

    2013-01-01

    Highlights: •Diatom's nuclear abnormalities were significantly higher as consequence of chromium exposure. •Diatoms and chlorophytes increased in treatment microcosms. •Nitzschia palea proportion increased significantly in the treatment microcosms. -- Abstract: Diatoms are an integral and often dominant component of the benthic microalgal assemblage in estuarine and shallow coastal environments. Different toxic substances discharged into these ecosystems persist in the water, sediments, and biota for long periods. Among these pernicious agents, the toxicity in diatoms by metal is linked to different steps in the transmembrane and internal movements of the toxicant, causing perturbations in the normal structural and functional cellular components. These changes constitute an early, nontaxonomic warning signal that could potentially serve as an indicator of this type of pollution. The aim of this work was to study the environment-reflecting short-term responses at different levels of organization of epipsammic diatoms from the Río de la Plata estuary, Argentina that had been exposed to hexavalent chromium within experimental microcosms. To this end we monitored: (i) changes in the proportion of the diatoms in relation to other algal groups at the biofilm community level; (ii) shifts in species composition at the diatom-assemblage level; (iii) projected changes in the densities of the most representative species at the population level through comparison of relative growth rates and generation times; and (iv) the cytological changes at the cellular and subcellular levels as indicated by the appearance of teratological effects on individuals and nuclear alterations. The epipsammic biofilms were exposed for 96 h to chromium at a concentration similar to that measured in highly impacted sites along the coast (80 μg L −1 ). Chromium pollution, at this concentration and short exposure time did not affect the algal biomass and density of these mature biofilms. The

  6. Short-term toxicity of hexavalent-chromium to epipsammic diatoms of a microtidal estuary (Río de la Plata): Responses from the individual cell to the community structure

    Energy Technology Data Exchange (ETDEWEB)

    Licursi, M., E-mail: malena@ilpla.edu.ar; Gómez, N.

    2013-06-15

    Highlights: •Diatom's nuclear abnormalities were significantly higher as consequence of chromium exposure. •Diatoms and chlorophytes increased in treatment microcosms. •Nitzschia palea proportion increased significantly in the treatment microcosms. -- Abstract: Diatoms are an integral and often dominant component of the benthic microalgal assemblage in estuarine and shallow coastal environments. Different toxic substances discharged into these ecosystems persist in the water, sediments, and biota for long periods. Among these pernicious agents, the toxicity in diatoms by metal is linked to different steps in the transmembrane and internal movements of the toxicant, causing perturbations in the normal structural and functional cellular components. These changes constitute an early, nontaxonomic warning signal that could potentially serve as an indicator of this type of pollution. The aim of this work was to study the environment-reflecting short-term responses at different levels of organization of epipsammic diatoms from the Río de la Plata estuary, Argentina that had been exposed to hexavalent chromium within experimental microcosms. To this end we monitored: (i) changes in the proportion of the diatoms in relation to other algal groups at the biofilm community level; (ii) shifts in species composition at the diatom-assemblage level; (iii) projected changes in the densities of the most representative species at the population level through comparison of relative growth rates and generation times; and (iv) the cytological changes at the cellular and subcellular levels as indicated by the appearance of teratological effects on individuals and nuclear alterations. The epipsammic biofilms were exposed for 96 h to chromium at a concentration similar to that measured in highly impacted sites along the coast (80 μg L{sup −1}). Chromium pollution, at this concentration and short exposure time did not affect the algal biomass and density of these mature

  7. Removal of chromium (VI from aqueous medium using chemically modified banana peels as efficient low-cost adsorbent

    Directory of Open Access Journals (Sweden)

    Ashraf Ali

    2016-09-01

    Full Text Available The adsorptive removal of hexavalent chromium Cr(VI from aqueous solutions was investigated by acrylonitrile grafted banana peels (GBPs. Banana peels were treated with 10% HCl, followed by alkaline hydrolysis with 10% NaOH, and washed thoroughly. The bleaching of alkali hydrolyzed peels was carried out with sodium chlorate (NaClO3 in the presence of hydrogen peroxide and glacial acetic acid. The grafting co-polymerization of acrylonitrile onto the bleached pulp was initiated by Fenton’s reagent (Fe+2/H2O2. The optimum conditions for adsorption of Cr(VI were found to be the following: pH 3, adsorbent dose 4 g/L, concentration 400 mg/L and contact time of 120 min. The surface morphology of adsorbent was characterized by scanning electron microscopy (SEM before and after the adsorption. The adsorption of Cr(VI onto grafted banana peels (GBPs was recorded to be 96%. The adsorption data were fully fitted with the Freundlich and Langmuir isotherm model and followed a pseudo-second order kinetic model. Thermodynamic study showed that the adsorption is exothermic and spontaneous. Owing to high efficiency and low cost, grafted banana peels (GBPs can be used as effective adsorbent for Cr(VI removal from wastewater.

  8. Chromium base high performance materials: Where and how do they come from?

    Science.gov (United States)

    Choi, In-Kap

    1996-08-01

    The origin of chromium base performance materials (CBPM) is described. CBPM may include (1) trivalent chromium chemicals such as chromic acetate, chromic chloride, chromic bromide, chromic fluoride, chromic iodide, chromic phosphate, and chromic sulfate; (2) hexavalent chromium chemicals such as chromic acid, lithium chromate, sodium chromate, sodium dichromate, and potassium dichromate; (3) oxide forms of chromium such as black chrome, chromium dioxide, chromium oxide, and chromium hydroxide; and (4) other chromium compounds such as chromium aluminide, chromium boride, chromium carbide, chromium molybdate, chromium nitride, chromium silicide, chromium tungstate and lanthanum chromite. Extensive reviews of production processes, properties, and applications/end uses of CBPM are made.

  9. Sulfur-Doped Carbon Nitride Polymers for Photocatalytic Degradation of Organic Pollutant and Reduction of Cr(VI).

    Science.gov (United States)

    Zheng, Yun; Yu, Zihao; Lin, Feng; Guo, Fangsong; Alamry, Khalid A; Taib, Layla A; Asiri, Abdullah M; Wang, Xinchen

    2017-04-01

    As a promising conjugated polymer, binary carbon nitride has attracted extensive attention as a metal-free and visible-light-responsive photocatalyst in the area of photon-involving purification of water and air. Herein, we report sulfur-doped polymeric carbon nitride microrods that are synthesized through thermal polymerization based on trithiocyanuric acid and melamine (TM) supramolecular aggregates. By tuning the polymerization temperature, a series of sulfur-doped carbon nitride microrods are prepared. The degradation of Rhodamine B (RhB) and the reduction of hexavalent chromium Cr(VI) are selected as probe reactions to evaluate the photocatalytic activities. Results show that increasing pyrolysis temperature leads to a large specific surface area, strong visible-light absorption, and accelerated electron-hole separation. Compared to bulk carbon nitride, the highly porous sulfur-doped carbon nitride microrods fabricated at 650 °C exhibit remarkably higher photocatalytic activity for degradation of RhB and reduction of Cr(VI). This work highlights the importance of self-assembly approach and temperature-control strategy in the synthesis of photoactive materials for environmental remediation.

  10. Effect of Ionic and Chelate Assisted Hexavalent Chromium on Mung Bean Seedlings (Vigna radiata L. wilczek. var k-851 During Seedling Growth

    Directory of Open Access Journals (Sweden)

    Mohanty, Monalisa

    2013-04-01

    Full Text Available The effect of Cr+6 with and without chelating agents were assessed in mung bean seedlings grown hydroponically. It was noted that the growth parameters showed a declining trend with increasing Cr+6 concentrations without chelate application. Among the seedlings grown with chelated chromium complexes, Cr+6–DTPA (10µM showed highest growth rate of roots as well as shoots. At higher concentration of Chromium i.e. Cr+6 (100µM, there exhibited high chlorophyll content in mung bean leaves where the seedlings showed stunted growth. The seedlings treated without and with chelated chromium complexes showed increased proline content as compared to control. The enzymatic study showed that, the catalase activity was maximum in shoots as compared to roots and the reverse is true in the case of peroxidase activity i.e. the roots showed higher value than that of the shoots.

  11. Determination of Cr(VI) in wood specimen: A XANES study at the Cr K edge

    International Nuclear Information System (INIS)

    Strub, E.; Plarre, R.; Radtke, M.; Reinholz, U.; Riesemeier, H.; Schoknecht, U.; Urban, K.; Juengel, P.

    2008-01-01

    The content of chromium in different oxidation states in chromium-treated wood was studied with XANES (X-ray absorption near-edge structure) measurements at the Cr K absorption edge. It could be shown that wood samples treated with Cr(VI) (pine and beech) did still contain a measurable content of Cr(VI) after four weeks conditioning. If such wood samples were heat exposed for 2 h with 135 deg. C prior conditioning, Cr(VI) was no longer detected by XANES, indicating a complete reduction to chromium (III)

  12. Simultaneous speciation of arsenic, selenium, and chromium: Species stability, sample preservation, and analysis of ash and soil leachates

    Science.gov (United States)

    Wolf, R.E.; Morman, S.A.; Hageman, P.L.; Hoefen, T.M.; Plumlee, G.S.

    2011-01-01

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 ??C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present

  13. Simultaneous speciation of arsenic, selenium, and chromium: species, stability, sample preservation, and analysis of ash and soil leachates

    Science.gov (United States)

    Wolf, Ruth E.; Morman, Suzette A.; Hageman, Philip L.; Hoefen, Todd M.; Plumlee, Geoffrey S.

    2011-01-01

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10° C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present

  14. Simultaneous speciation of arsenic, selenium, and chromium: species stability, sample preservation, and analysis of ash and soil leachates

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Ruth E.; Morman, Suzette A.; Hageman, Philip L.; Hoefen, Todd M.; Plumlee, Geoffrey S. [Denver Federal Center, US Geological Survey, Denver, CO (United States)

    2011-11-15

    An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species can be determined in less than 3 min. A dynamic reaction cell (DRC)-ICP-MS system was used to detect the species eluted from the chromatographic column in order to reduce interferences. A variety of reaction cell gases and conditions may be utilized with the DRC-ICP-MS, and final selection of conditions is determined by data quality objectives. Results indicated all starting standards, reagents, and sample vials should be thoroughly tested for contamination. Tests on species stability indicated that refrigeration at 10 C was preferential to freezing for most species, particularly when all species were present, and that sample solutions and extracts should be analyzed as soon as possible to eliminate species instability and interconversion effects. A variety of environmental and geological samples, including waters and deionized water [leachates] and simulated biological leachates from soils and wildfire ashes have been analyzed using this method. Analytical spikes performed on each sample were used to evaluate data quality. Speciation analyses were conducted on deionized water leachates and simulated lung fluid leachates of ash and soils impacted by wildfires. These results show that, for leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent Cr(VI) form. In general, total and hexavalent chromium levels for samples taken from burned residential areas were higher than those obtained from non-residential forested areas. Arsenic, when found, was generally in the more oxidized As(V) form. Selenium (IV) and (VI) were present, but

  15. Antigenotoxic and Apoptotic Activity of Green Tea Polyphenol Extracts on Hexavalent Chromium-Induced DNA Damage in Peripheral Blood of CD-1 Mice: Analysis with Differential Acridine Orange/Ethidium Bromide Staining

    Directory of Open Access Journals (Sweden)

    María del Carmen García-Rodríguez

    2013-01-01

    Full Text Available This study was conducted to investigate the modulating effects of green tea polyphenols on genotoxic damage and apoptotic activity induced by hexavalent chromium [Cr (VI] in CD-1 mice. Animals were divided into the following groups: (i injected with vehicle; (ii treated with green tea polyphenols (30 mg/kg via gavage; (iii injected with CrO3 (20 mg/kg intraperitoneally; (iv treated with green tea polyphenols in addition to CrO3. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCEs obtained from peripheral blood at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB staining. Treatment of green tea polyphenols led to no significant changes in the MN-PCEs. However, CrO3 treatment significantly increased MN-PCEs at 24 and 48 h after injection. Green tea polyphenols treatment prior to CrO3 injection led to a decrease in MN-PCEs compared to the group treated with CrO3 only. The average of apoptotic cells was increased at 48 h after treatment compared to control mice, suggesting that apoptosis could contribute to eliminate the DNA damaged cells induced by Cr (VI. Our findings support the proposed protective effects of green tea polyphenols against the genotoxic damage induced by Cr (VI.

  16. Microbial interactions with chromium: basic biological processes and applications in environmental biotechnology.

    Science.gov (United States)

    Gutiérrez-Corona, J F; Romo-Rodríguez, P; Santos-Escobar, F; Espino-Saldaña, A E; Hernández-Escoto, H

    2016-12-01

    Chromium (Cr) is a highly toxic metal for microorganisms as well as plants and animal cells. Due to its widespread industrial use, Cr has become a serious pollutant in diverse environmental settings. The hexavalent form of the metal, Cr(VI), is considered a more toxic species than the relatively innocuous and less mobile Cr(III) form. The study of the interactions between microorganisms and Cr has been helpful to unravel the mechanisms allowing organisms to survive in the presence of high concentrations of Cr(VI) and to detoxify and remove the oxyanion. Various mechanisms of interactions with Cr have been identified in diverse species of bacteria and fungi, including biosorption, bioaccumulation, reduction of Cr(VI) to Cr(III), and chromate efflux. Some of these systems have been proposed as potential biotechnological tools for the bioremediation of Cr pollution using bioreactors or by in situ treatments. In this review, the interactions of microorganisms with Cr are summarised, emphasising the importance of new research avenues using advanced methodologies, including proteomic, transcriptomic, and metabolomic analyses, as well as the use of techniques based on X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy.

  17. Superb adsorption capacity of hierarchical calcined Ni/Mg/Al layered double hydroxides for Congo red and Cr(VI) ions

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Chunsheng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Xiaofeng [College of Environmental & Safety Engineering, Changzhou University, Changzhou 213164 (China); Zhu, Bicheng; Jiang, Chuanjia; Le, Yao [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2017-01-05

    Highlights: • Ni/Mg/Al layered double hydroxides (NMA-LDHs) synthesized. • NMA-LDHs with hierarchically hollow microsphere structure. • Calcined NMA-LDHs have large adsorption capacities for CR and Cr(VI) ions. - Abstract: The preparation of hierarchical porous materials as catalysts and sorbents has attracted much attention in the field of environmental pollution control. Herein, Ni/Mg/Al layered double hydroxides (NMA-LDHs) hierarchical flower-like hollow microspheres were synthesized by a hydrothermal method. After the NMA-LDHs was calcined at 600 °C, NMA-LDHs transformed into Ni/Mg/Al layered double oxides (NMA-LDOs), which maintained the hierarchical flower-like hollow structure. The crystal phase, morphology, and microstructure of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy elemental mapping, Fourier transform infrared spectroscopy, and nitrogen adsorption−desorption methods. Both the calcined and non-calcined NMA-LDHs were examined for their performance to remove Congo red (CR) and hexavalent chromium (Cr(VI)) ions in aqueous solution. The maximum monolayer adsorption capacities of CR and Cr(VI) ions over the NMA-LDOs sample were 1250 and 103.4 mg/g at 30 °C, respectively. Thermodynamic studies indicated that the adsorption process was endothermic in nature. In addition, the addition of coexisting anions negatively influenced the adsorption capacity of Cr(VI) ions, in the following order: CO{sub 3}{sup 2−} > SO{sub 4}{sup 2−} > H{sub 2}PO{sub 4}{sup −} > Cl{sup −}. This work will provide new insight into the design and fabrication of advanced adsorption materials for water pollutant removal.

  18. Duodenal crypt health following exposure to Cr(VI): Micronucleus scoring, γ-H2AX immunostaining, and synchrotron X-ray fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Chad M.; Wolf, Jeffrey C.; Elbekai, Reem H.; Paranjpe, Madhav G.; Seiter, Jennifer M.; Chappell, Mark A.; Tappero, Ryan V.; Suh, Mina; Proctor, Deborah M.; Bichteler, Anne; Haws, Laurie C.; Harris, Mark A.

    2015-08-01

    Lifetime exposure to high concentrations of hexavalent chromium [Cr(VI)] in drinking water results in intestinal damage and an increase in duodenal tumors in B6C3F1 mice. To assess whether these tumors could be the result of a direct mutagenic or genotoxic mode of action, we conducted a GLP-compliant 7-day drinking water study to assess crypt health along the entire length of the duodenum. Mice were exposed to water (vehicle control), 1.4, 21, or 180 ppm Cr(VI) via drinking water for 7 consecutive days. Crypt enterocytes in Swiss roll sections were scored as normal, mitotic, apoptotic, karyorrhectic, or as having micronuclei. A single oral gavage of 50 mg/kg cyclophosphamide served as a positive control for micronucleus induction. Exposure to 21 and 180 ppm Cr(VI) significantly increased the number of crypt enterocytes. Micronuclei and γ-H2AX immunostaining were not elevated in the crypts of Cr(VI)-treated mice. In contrast, treatment with cyclophosphamide significantly increased numbers of crypt micronuclei and qualitatively increased γ-H2AX immunostaining. Synchrotron-based X-ray fluorescence (XRF) microscopy revealed the presence of strong Cr fluorescence in duodenal villi, but negligible Cr fluorescence in the crypt compartment. Together, these data indicate that Cr(VI) does not adversely effect the crypt compartment where intestinal stem cells reside, and provide additional evidence that the mode of action for Cr(VI)-induced intestinal cancer in B6C3F1 mice involves chronic villous wounding resulting in compensatory crypt enterocyte hyperplasia.

  19. Effect of genotype, Cr(III and Cr(VI on plant growth and micronutrient status in Silene vulgaris (Moench

    Directory of Open Access Journals (Sweden)

    A. E. Pradas-del-Real

    2013-06-01

    Full Text Available Chromium released into the environment from industrial activities has become an important environmental concern. Silene vulgaris has been proven to be tolerant to many heavy metals, so it is considered an interesting species in the revegetation and restoration of polluted soils, but no information is available about its response to Cr. The objective of this work was to study uptake and influence on plant growth of Cr(III and Cr(VI in six genotypes (four hermaphrodites and two females of S. vulgaris from different sites of Madrid (Spain. Plants were treated for 12 days with 60 µM of Cr(III or Cr(VI in semihydroponics. Dry weights, soil-plant analysis development values (SPAD reading with chlorophylls and micronutrient and total Cr concentrations were determined. Metal uptake was higher in presence of Cr(VI than of Cr(III and poorly translocated to the shoots. In both cases S. vulgaris did not show visual toxicity symptoms, biomass reduction, or differences among SPAD values as consequence of Cr additions. However genotypes SV36 and SV38 showed Fe and Mn imbalance. This is the first report on the relatively good performance of hermaphrodite and female S. vulgaris genotypes in Cr uptake and physiological traits, but further studies will be necessary to elucidate the mechanisms by which the gender may influence these variables. S. vulgaris presented high diversity at genotypic level; the treatment with hexavalent Cr increased the differences among genotypes so the use of cuttings from an homogeneous genotype seems to be an adequate method for the study of this species.

  20. Supercritical CO2 Assisted Synthesis of EDTA-Fe3O4 Nano composite with High Adsorption Capacity for Hexavalent Chromium

    International Nuclear Information System (INIS)

    Bisht, G.; Neupane, S.; Makaju, R.

    2016-01-01

    Efficiency of EDTA functionalized nanoparticles in adsorption of chromium (Vi) from water was investigated in this study. Magnetic iron oxide nanoparticles (IONPs) were synthesized by a simple chemical coprecipitation route and EDTA coating onto IONPs was attained via supercritical carbon dioxide (Sc CO 2 ), a technology with green sustainable properties. The obtained nanoparticles were then characterized by UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating magnetometric analysis (VSM). The synthesized nanoparticle and its modified variant were evaluated as adsorbent for chromium (Vi) removal from water through batch adsorption technique and the effect of analytic concentration; contact time and adsorbent concentration were studied at ph 2. The results showed higher removal efficiency for modified magnetic iron oxide nanoparticles (MIONPs) (i.e., 99.9%) than their non modified variant IONPs, that is, 34.06% for the same concentration after 18 hours of incubation. Also maximum adsorption capacity (q e = 452.26 mg/g) of MIONPs attained can be related to their preparation in Sc CO 2 asq e calculated from IONPs, that is, 170.33 mg/g, is lower than that of MIONPs. The adsorption data fit well with Freundlich isotherm equation while kinetic adsorption studies of chromium (Vi) were modeled by pseudo-second-order model

  1. Short-term chromium (VI) exposure increases phosphorus uptake by the extraradical mycelium of the arbuscular mycorrhizal fungus Rhizophagus irregularis MUCL 41833.

    Science.gov (United States)

    Gil-Cardeza, María Lourdes; Calonne-Salmon, Maryline; Gómez, Elena; Declerck, Stéphane

    2017-11-01

    Hexavalent chromium is a potent carcinogen, while phosphorus is an essential nutrient. The role of arbuscular mycorrhizal fungi (AMF) in the uptake of P is well known and was also reported, at low levels, for Cr. However, it is unclear whether the uptake of Cr can impact the short-term uptake dynamics of P since both elements have a similar chemical structure and may thus potentially compete with each other during the uptake process. This study investigated the impact of Cr(VI) on short-term P uptake by the AMF Rhizophagus irregularis MUCL 41833 in Medicago truncatula. Bi-compartmented Petri plates were used to spatially separate a root compartment (RC) from a hyphal compartment (HC) using a whole plant in vitro culture system. The HC was supplemented with Cr(VI). Chromium(VI) as well as total Cr and P were monitored during 16 h within the HC and their concentrations determined by the end of the experiment within roots and shoots. Our results indicated that the uptake and translocation of Cr from hyphae to roots was a fast process: roots in which the extraradical myceli