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Sample records for bleached kraft mill

  1. The effects of bleach plant effluent recycle in kraft mill green liquors

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, B.M.; Uloth, V.C. [Pulp and Paper Research Inst. of Canada, Vancouver, BC (Canada); Dorris, G.M. [Pulp and Paper Research Inst. of Canada, Pointe Claire, PQ (Canada); Stafford, E. C.

    1995-12-31

    A new approach to reducing or eliminating effluent flows from a kraft mill through process changes and by recycling, was presented. A closed system experiment was conducted in which bleach plant effluents and green liquors were used to simulate effluent recycling to the recausticizing area in place of fresh water. Results showed that with current levels of water use, acid effluents from bleaching of softwood pulp could be recycled to the recausticizing area if a 5-18 per cent loss in causticizing efficiency and a 10 per cent decrease in the lime mud settling rate was tolerable. High levels of sodium chloride did not always reduce causticizing efficiency. It was found that bleach plant water usage was very high in the plants studied. New ways to minimize water use in the plant must be found if a significant degree of closure is to be achieved. 15 refs., 6 tabs., 8 figs.

  2. Degradation of Chlorophenols by Alcaligenes eutrophus JMP134(pJP4) in Bleached Kraft Mill Effluent

    OpenAIRE

    Valenzuela, J.; Bumann, U.; Cespedes, R.; Padilla, L.; Gonzalez, B

    1997-01-01

    The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degradation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semicontinuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichlorophenoxyacetate (400 ppm) or 2,4,6-trichlorophenol (40 to 100 ppm) were extens...

  3. Responses of white sucker (Catostomus commersoni) to 20 years of process and waste treatment changes at a bleached kraft pulp mill, and to mill shutdown.

    Science.gov (United States)

    Bowron, L K; Munkittrick, K R; McMaster, M E; Tetreault, G; Hewitt, L M

    2009-11-01

    The impacts of pulp mill effluents on white sucker (Catostomus commersoni) have been studied at Jackfish Bay, ON, Canada since the late 1980s. The site receives effluent from a large bleached kraft pulp mill which is the only source of chemical contamination in the area. Many laboratory studies have looked at the toxicological consequences of pulping process changes, but the benefit of these changes have not been looked at in wild fish. Jackfish Bay white sucker showed impacts on sexual maturity, gonad size, secondary sexual characteristics and circulating steroids hormone levels in the early years of the studies, and impacts were evaluated after installation of secondary treatment (1989), major pulping process changes (1995) and after the mill ceased pulp production and effluent release (2006). The addition of secondary treatment resulted in minor improvements in wild fish health, and the conversion to elemental chlorine free (ECF) bleaching at the mill was associated with more recovery in liver and gonad size. While some impacts persist at the exposure site, reproductive parameters showed further improvement during the mill shutdown period demonstrating that biologically active chemicals are still being discharged from modernized mills. PMID:19783055

  4. Milt characteristics, reproductive performance, and larval survival and development of white sucker exposed to bleached kraft mill effluent

    Energy Technology Data Exchange (ETDEWEB)

    McMaster, M.E.; Portt, C.B.; Munkittrick, K.R.; Dixon, D.G. (Department of Biology, University of Waterloo, Ontario, (Canada))

    1992-02-01

    White sucker from a Lake Superior bay which receives bleached kraft mill effluent (BKME) show increased hepatic mixed-function oxygenase (MFO) activity, reduced plasma sex steroid levels, decreased egg and gonad size, a decrease in the occurrence of secondary sexual characteristics, and an increased age to maturation. This study evaluated the reproductive performance of that white sucker population relative to a similar reference population. Spawning male white sucker from the BKME site had reduced spermatozoan motility but no significant differences in milt volume, spermatocrit levels, or seminal plasma constituents. BKME male and female fish had equal or greater fertilization potential compared to both male and female fish at the reference site. There was no difference either in the hatchability of the eggs or in larval size at hatch. BKME larvae did show reduced growth rates by 24 days posthatch but showed equal rates of yolk utilization. No difference in larval MFO activity was detected between sites at 21 days posthatch, indicating no parental transfer of induction to the progeny.

  5. Biochemical methane potential of kraft bleaching effluent and codigestion with other in-mill streams

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Dahl, Olli; Master, Emma;

    2016-01-01

    degradation and methane generation. Chemical oxygen demand (COD) removal ranged from 57%-76%, and methane generation was 220-280 mL/g COD contained in the wastewater, depending on the degree of dilution. When codigestion was tested, the composite consisting of total bleaching effluent, chemithermomechanical...

  6. Assessment of status of white sucker (Catostomus commersoni) populations exposed to bleached kraft pulp mill effluent.

    Science.gov (United States)

    Miller, David H; Tietge, Joseph E; McMaster, Mark E; Munkittrick, Kelly R; Xia, Xiangsheng; Ankley, Gerald T

    2013-07-01

    Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to investigate population dynamics for white sucker (Catostomus commersoni) exposed to pulp mill effluent at a well-studied site in Jackfish Bay, Lake Superior, Canada. The model uniquely combines a Leslie population projection matrix and the logistic equation to translate changes in the fecundity and the age structure of a breeding population of white sucker exposed to pulp mill effluent to alterations in population growth rate. Application of this density-dependent population projection model requires construction of a life table for the organism of interest, a measure of carrying capacity, and an estimation of the effect of stressors on vital rates. A white sucker population existing at carrying capacity and subsequently exposed to pulp mill effluent equivalent to a documented exposure experienced during the period 1988 to 1994 in Jackfish Bay would be expected to exhibit a 34% to 51% annual decrease in recruitment during the first 5 yr of exposure and approach a population size of 71% of carrying capacity. The Jackfish Bay study site contains monitoring data for biochemical endpoints in white sucker, including circulating sex steroid concentrations, that could be combined with population modeling to utilize the model demonstrated at the Jackfish Bay study site for investigation of other white sucker populations at sites that are less data-rich. PMID:23504660

  7. EXAMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND POLYCHLORINATED DIBENZOFURANS INTO PROCESS WATER OF KRAFT PULP BLEACHING MILL FROM ASPECT OF ENVIRONMENTAL WATER QUALITY

    Institute of Scientific and Technical Information of China (English)

    Hiroshi Ohi; Tomoya Yokoyama; Keiichi Nakamata

    2004-01-01

    Process water of a pulp mill with kraft cooking,oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. According to the new level, a concentration of dioxins consisting of polychlorinated dibenzo-p-dioxins (PCDDs),polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (PCBs) in environmental water is restricted to less than 1 pg- TEQ/L. We clarified that the 2,3,7,8-tetrachlorodibenzofuran (TCDF) concentrations were 0.5 pg/L or less. In addition, a main source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in the process water seemed to be an agrochemical in water supplied from a river.

  8. EXAMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND POLYCHLORINATED DIBENZOFURANS INTO PROCESS WATER OF KRAFT PULP BLEACHING MILL FROM ASPECT OF ENVIRONMENTAL WATER QUALITY

    Institute of Scientific and Technical Information of China (English)

    HiroshiOhi; TomoyaYokoyama; KeiichiNakamata

    2004-01-01

    Process water of a pulp mill with kraft cooking, oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. According to the new level, a concentration of dioxins consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (PCBs) in environmental water is restricted to less than 1 pg- TEQ/L. We clarified that the 2,3,7,8-tetrachlorodibenzofuran (TCDF) concentrations were 0.5 pg/L or less. In addition, a main source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in the process water seemed to be an agrochemical in water supplied from a river.

  9. Exposure to bleached kraft pulp mill effluent disrupts the pituitary-gonadal axis of white sucker at multiple sites

    Energy Technology Data Exchange (ETDEWEB)

    Van Der Kraak, G.J.; Munkittrick, K.R.; McMaster, M.E.; Portt, C.B.; Chang, J.P. (Department of Zoology, University of Guelph, Ontario (Canada))

    1992-08-01

    Recent studies have demonstrated reproductive problems in white sucker (Catostomus commersoni) exposed to bleached kraft pulp mill effluent (BKME) at Jackfish Bay on Lake Superior. These fish exhibit delayed sexual maturity, reduced gonadal size, reduced secondary sexual characteristics, and circulating steroid levels depressed relative to those of reference populations. The present studies were designed to evaluate sites in the pituitary-gonadal axis of prespawning white sucker affected by BKME exposure. At the time of entry to the spawning stream, plasma levels of immunoreactive gonadotropin (GtH)-II (LH-type GtH) in male and female white sucker were 30- and 50-fold lower, respectively, than the levels in fish from a reference site. A single intraperitoneal injection of D-Arg6, Pro9N-Et sGnRH (sGnRH-A, 0.1 mg/kg) increased plasma GtH levels in male and female fish at both sites, although the magnitude of the response was greatly reduced in BKME-exposed fish. Fish at the BKME site did not ovulate in response to sGnRH-A, while 10 of 10 fish from the reference site ovulated within 6 hr. Plasma 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) levels were depressed in BKME-exposed fish and unlike fish at the reference site, failed to increase in response to sGnRH-A. Testosterone levels in both sexes and 11-ketostestosterone levels in males were elevated in fish from the reference site but were not further increased by GnRH treatment. In contrast, BKME-exposed fish exhibit a transitory increase in testosterone levels in response to the GnRH analog. In vitro incubations of ovarian follicles obtained from fish at the BKME site revealed depressed basal secretion of testosterone and 17,20 beta-P and reduced responsiveness to the GtH analog human chorionic gonadotropin and to forskolin, a direct activator of adenylate cyclase.

  10. MINERAL ELEMENTS IN WOODS OF EUCALYPTUS AND BLACK WATTLE AND ITS INFLUENCE IN A BLEACHED KRAFT PULP MILL

    Directory of Open Access Journals (Sweden)

    André Fredo

    2009-09-01

    Full Text Available Effluents are one of the most important problems in a pulp mill regarding to environmental subjects. With the purpose to reduce them, the mills are closing the internal cycles and reducing the water consumption. The wood, as the most significant source of non-process elements to the system, is responsible for some troubles to the industrial process. With the aim of evaluating their intake and to offer some informations for closing the loop, the contents of Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, and Si were analysed in Acacia mearnsii, Eucalyptus dunnii, Eucalyptus globulus globulus, Eucalyptus grandis and Eucalyptus saligna woods. Wood samples were prepared by oven burning and acidic digestion methods, following analysis by ICP (inductively coupled plasm. Using also the results from silvicultural evaluation of trees and stands, they were calculated which elements were carried out from the site in larger amounts (K, Ca, Na, Al, Mn and Si and the species which exported largest amount of these elements (Eucalyptus dunnii and Eucalyptus globulus. The species with lower growth were Eucalyptus globulus and Eucalyptus dunnii, that leads to a bigger elements input and more potential industrial troubles. It was observed a range of 3.8 (Eucalyptus grandis up to 6 (Eucalyptus dunnii kg of analised mineral elements introduced to the process per ton of umbleached pulp produced. The Acacia mearnsii showed the lower level for Fe, Mn and Ni, being useful for oxygen, ozone and peroxide bleaching. The silicon observed in woods was in low concentration although the high values of this element in industrial liquor cycle. This leads to state that there is some contamination with soil when harvesting and handling the wood. Special care must be taken with both high ash and high mineral elements species, such as Eucalyptus dunnii and Eucalyptus globulus.

  11. Controlling bleached kraft pulp costs: a predictive modelling approach

    Energy Technology Data Exchange (ETDEWEB)

    Schroderus, S.K.

    1988-07-01

    A mathematical model is described which simulates the operation of a bleached kraft paper mill. The model can be used to analyze a wide range of operating conditions and mill configurations. It is structured into the following functional blocks: assignment of process parameters; cooking and brown stock washing; bleaching, evaporation and calculation of black liquor heating value; recovery boiler and recausticizing; secondary heat balance; and generation of heat and electrical power. Computer programs have been developed using the model, usable on inexpensive personal computers, which enable calculation of stream variables, consumption of wood, chemicals, and energy, and operating costs. Examples of model use are presented, calculated for a hypothetical mill featuring a continuous digester and a low-odor type recovery boiler. These examples illustrate the effect of operating conditions on operating costs. 24 refs., 7 figs.

  12. MINERAL ELEMENTS IN WOODS OF EUCALYPTUS AND BLACK WATTLE AND ITS INFLUENCE IN A BLEACHED KRAFT PULP MILL

    OpenAIRE

    André Fredo; Celso E. B. Foelkel; Sônia M. B. Frizzo; Silva, Maria C. M.

    2009-01-01

    Effluents are one of the most important problems in a pulp mill regarding to environmental subjects. With the purpose to reduce them, the mills are closing the internal cycles and reducing the water consumption. The wood, as the most significant source of non-process elements to the system, is responsible for some troubles to the industrial process. With the aim of evaluating their intake and to offer some informations for closing the loop, the contents of Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, a...

  13. Mill Designed Bio bleaching Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Institute of Paper Science Technology

    2004-01-30

    A key finding of this research program was that Laccase Mediator Systems (LMS) treatments on high-kappa kraft could be successfully accomplished providing substantial delignification (i.e., > 50%) without detrimental impact on viscosity and significantly improved yield properties. The efficiency of the LMS was evident since most of the lignin from the pulp was removed in less than one hour at 45 degrees C. Of the mediators investigated, violuric acid was the most effective vis-a-vis delignification. A comparative study between oxygen delignification and violuric acid revealed that under relatively mild conditions, a single or a double LMS{sub VA} treatment is comparable to a single or a double O stage. Of great notability was the retention of end viscosity of LMS{sub VA} treated pulps with respect to the end viscosity of oxygen treated pulps. These pulps could then be bleached to full brightness values employing conventional ECF bleaching technologies and the final pulp physical properties were equal and/or better than those bleached in a conventional ECF manner employing an aggressively O or OO stage initially. Spectral analyses of residual lignins isolated after LMS treated high-kappa kraft pulps revealed that similar to HBT, VA and NHA preferentially attack phenolic lignin moieties. In addition, a substantial decrease in aliphatic hydroxyl groups was also noted, suggesting side chain oxidation. In all cases, an increase in carboxylic acid was observed. Of notable importance was the different selectivity of NHA, VA and HBT towards lignin functional groups, despite the common N-OH moiety. C-5 condensed phenolic lignin groups were overall resistant to an LMS{sub NHA, HBT} treatments but to a lesser extent to an LMS{sub VA}. The inactiveness of these condensed lignin moieties was not observed when low-kappa kraft pulps were biobleached, suggesting that the LMS chemistry is influenced by the extent of delignification. We have also demonstrated that the current

  14. REPLACEMENT OF SOFTWOOD KRAFT PULP WITH ECF-BLEACHED BAMBOO KRAFT PULP IN FINE PAPER

    Directory of Open Access Journals (Sweden)

    Guanglei Zhao

    2010-06-01

    Full Text Available Non-wood fibers such as bamboo and wheat straw have been playing important roles in the pulp and paper industry in China. In this study an ECF-bleached bamboo kraft pulp was compared with a bleached softwood kraft pulp (NBSK as the reinforcement pulp in fine paper production. Areas that were examined include the refining of pure fibers, influence of bamboo on dewatering, retention, and sizing. The influence of bamboo kraft pulp as a part of a furnish replacing NBSK was compared as well. Results show that fiber shortening was more prominent with bamboo when refined. This resulted in a higher amount of fines, and addition wet-end chemicals may be required to compensate. Handsheets with bamboo as a reinforcement fiber showed similar mechanical and optical properties to handsheets containing NBSK.

  15. Effects of ozone on kraft process pulp mill effluent

    International Nuclear Information System (INIS)

    Effluent from a kraft process pulp mill was studied in a batch reactor for ozone doses between 50 and 200 mg O3/L to identify the suitability of ozone application locations in the treatment process and see the improvements in biotreatability of wastewaters from a kraft process pulp mill. Laboratory acclimatized seed were used for (Biochemical Oxygen Demand) BOD tests for ozonated and unozonated samples. The inhibitory effects were minimized by using optimum dilutions. The studies were divided into three major sections: characterization of mill effluent; ozone system calibration, and reactor design; and ozonation of mill effluent. Seed for BOD tests were acclimatized in batch units for primary, bleach and secondary effluents separately. The results were analyzed using the open-quote t close-quote test for paired experiments and an ANOVA table for statistical confirmation. Residuals were plotted to check the assumptions of constant variance and normal distribution. It was concluded that ozone is most effective for the removal of color and the increase of BOD in secondary effluent. 21 refs., 9 figs., 7 tabs

  16. Decolorization of kraft bleaching effluent by advanced oxidation processes using copper (II) as electron acceptor.

    Science.gov (United States)

    Yeber, María C; Oñate, Katherine P; Vidal, Gladys

    2007-04-01

    Two advanced oxidation processes (AOPs), TiO2/UV/O2 and TiO2/UV/Cu (II), were used to remove color from a Kraft bleaching effluent. The optimal decoloration rate was determined by multivariate analysis, obtaining a mathematical model to evaluate the effect among variables. TiO2 and Cu (II) concentrations and the reaction times were optimized. The experimental design resulted in a quadratic matrix of 30 experiments. Additionally, the pH influence on the color removal was determined by multivariate analysis. Results indicate that color removal was 94% at acidic pH (3.0) in the presence of Cu (11) as an electron acceptor. Under this condition, the biodegradation of the effluent increased from 0.3 to 0.6. Moreover, 70% of COD (chemical oxygen demand) was removed, and the ecotoxicity, measured by Daphnia magna, was reduced. Photocatalytic oxidation to remove the color contained in the Kraft mill bleaching effluent was effective under the following conditions: short reaction time, acidic pH values, and without the addition of oxygen due to the presence of Cu (II) in the effluent. Moreover, residual Cu (II) was a minimum (0.05.mg L(-1)) and was not toxic to the next biological stage. The experimental design methodology indicated that a quadratic polynomial model may be used to representthe efficiencyfor degradation of the Kraft bleach pulp effluent by a photocatalytic process. PMID:17438808

  17. ISOTHERMAL PYROLYSIS OF KRAFT PULP MILL SLUDGE

    OpenAIRE

    Syamsudin Syamsudin; Herri Susanto; Subagjo Subagjo

    2014-01-01

    Kraft pulp mill sludge cake composed of rejected wood fibers and activated sludge microorganisms. With a heating value about 14 MJ/kg (dried basis), this type of biomass had a potential as an alternative energy source. Unfortunately, it had an ash content of 27.6% and a moisture content of 80%. For reducing moisture content with minimum energy consumption, a combination of mechanical dewatering and thermal drying was studied previously. Meanwhile, experiments on isothermal pyrolysis had been ...

  18. Hemicellulases in the bleaching and characterisation of kraft pulps. Doctoral thesis

    Energy Technology Data Exchange (ETDEWEB)

    Suurnaekki, A.

    1996-03-01

    Xylanase-aided bleaching of kraft pulps is the major industrial application of hemicellulases in pulp processing. In addition to process aids, hemicellulases have recently also been shown to be promising tools in fibre analytics. In this work, the role of xylanase and mannanase pretreatments in the bleaching of softwood pulps produced by different sulphate cooking methods was studied. In addition, the action of hemicellulases in kraft fibres was characterized and exploited in the analysis of the suface composition of kraft pulps.

  19. PRESENCE OF HARDWOOD CHIPS AND ITS IMPACT ON PULP STRENGTH PROPERTIES IN THE PRODUCTION OF BLEACHED SOFTWOOD KRAFT PULP

    Directory of Open Access Journals (Sweden)

    Zhibin He

    2010-11-01

    Full Text Available The effect of hardwood admixture (15-25% birch or aspen in kraft cooking on the strength properties of the fully bleached pulp was investigated. Results obtained from both lab- and mill-processed ECF bleached pulps showed that adding 15-25% birch or aspen to the production of fully bleached softwood kraft pulp had a minor effect on the strength properties. No significant effect was observed for the hardwood admixture on the apparent density over a wide range of breaking length. Under the conditions studied, the results showed that pulping of mixed softwood/hardwood chips (chip blending resulted in overall better strength properties than the pulp blending at a given freeness. It was hypothesized that the softwood fibers would be cooked to a higher kappa number in the cooking of mixed softwood/hardwood chips for the same target kappa number, thus having higher fiber strength due to higher pulp viscosity and preservation of the hemicellulose. This was supported by the results from zero-span tensile strength of the long fiber fraction of the samples from chip blending and pulp blending. The implication is that some softwood kraft pulp mills can add up to 25% of hardwood chips to the kraft cooking of softwood chips without significantly affecting the overall pulp strength properties.

  20. Kraft pulp bleaching with molybdenum activated acid peroxide (P{sub Mo} stage); Branqueamento de polpa celulosica kraft de eucalipto com peroxido acido ativado por molibdenio

    Energy Technology Data Exchange (ETDEWEB)

    Rabelo, Marcos Sousa [Servico Nacional de Aprendizagem Industrial (SENAI), Lauro de Freitas, BA (Brazil). Dept. Regional da Bahia; Silva, Vanessa Lopes; Barros, Denise Pires de; Colodette, Jorge Luiz [Universidade Federal de Vicosa (UFV), MG (Brazil). Dept. de Engenharia Florestal; Sacon, Vera Maria; Silva, Marcelo Rodrigues da [Votorantim Celulose e Papel, Jacarei, SP (Brazil)

    2009-07-01

    Optimum conditions to run the P{sub Mo} stage for bleaching eucalyptus kraft pulp were 90 deg C, pH 3.5, 2 h, 0.1 kg/t Mo and 5 kg/t H{sub 2}O{sub 2}. The P{sub Mo} stage efficiency increased with decreasing pH (1.5-5.5) and increasing temperature (75-90 deg C), time (2-4 h), and hydrogen peroxide (3-10 kg/t) and molybdenum concentration (0.1-0.4 kg/t). The implementation of the P{sub Mo} stage, as replacement for the A stage, decreased total active chlorine demand of the OAZDP sequence by 6 kg/t to reach 90% ISO, both in laboratory and mill scale. Such practice resulted in decreased bleaching chemical costs to produce fully bleached pulp of 90% ISO. (author)

  1. ISOTHERMAL PYROLYSIS OF KRAFT PULP MILL SLUDGE

    Directory of Open Access Journals (Sweden)

    Syamsudin Syamsudin

    2014-12-01

    Full Text Available Kraft pulp mill sludge cake composed of rejected wood fibers and activated sludge microorganisms. With a heating value about 14 MJ/kg (dried basis, this type of biomass had a potential as an alternative energy source. Unfortunately, it had an ash content of 27.6% and a moisture content of 80%. For reducing moisture content with minimum energy consumption, a combination of mechanical dewatering and thermal drying was studied previously. Meanwhile, experiments on isothermal pyrolysis had been carried out for further improvement on ultimate and proximate analysis of solid fuel. Final mass of char obtained from pyrolysis at 500oC was not significantly different from that of 700oC, so pyrolysis was considered to be optimum at 500oC. A char obtained from pyrolysis at temperature of 500oC had a pore surface area of 77.049 m2/g (highest among other temperatures. Kinetic of isothermal pyrolysis was well represented with a first order modified volumetric model with a frequency factor of 0.782 1/s and an activation of 34.050 kJ/mol.

  2. Reduction of AOX in the Bleach Plant of a Pulp Mill

    OpenAIRE

    Barroca, Maria João M. C.; Seco, Isabel M.; Fernandes, Pedro M. M.; Ferreira, Licínio M. G. A.; Castro, José Almiro A. M.

    2001-01-01

    The reconfiguration of an existing five-stage bleaching D0E1D1E2D2 sequence is proposed to ensure the minimal formation of organochlorine compounds, expressed as AOX, in the bleach plant of a kraft pulp mill processing Eucalyptus globulus wood. This reduction of the load of AOX in the effluents can be achieved without introducing new and expensive technologies in the bleaching process. In practice, this goal can be achieved by eliminating the washing step between the D0 and the E1 stages. Wit...

  3. The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

    OpenAIRE

    Kátia Maria Morais Eiras; Jorge Luiz Colodette; Vanessa Lopes Silva

    2009-01-01

    Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX) content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxi...

  4. MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

    Directory of Open Access Journals (Sweden)

    Marcos S. Rabelo

    2008-08-01

    Full Text Available Molybdenum catalyzed peroxide bleaching (PMo Stage consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp and may originate from various sources, including (NH46Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyptus pulp were 90 ºC, pH 3.5, 2 h, 0.1 kg/adt Mo and 5 kg/adt H2O2. The PMo stage was more efficient to remove pulp hexenuronic acids than lignin. Its efficiency decreased with increasing pH in the range of 1.5-5.5, while it increased with increasing temperature and peroxide and molybdenum doses. The application of the PMo stage as replacement for the A-stage of the AZDP sequence significantly decreased chlorine dioxide demand. The PMo stage caused a decrease of 20-30% in the generation of organically bound chlorine. The quality parameters of the pulp produced during the PMo stage mill trial were comparable to those obtained with the reference A-stage.

  5. The role of bound chlorine in the brightness reversion of bleached hardwood kraft pulp

    Directory of Open Access Journals (Sweden)

    Kátia Maria Morais Eiras

    2009-01-01

    Full Text Available Our previous paper showed fragmentary evidence that pulp brightness reversion may be negatively affected by its organically bound chlorine (OX content. A thorough investigation on eucalyptus kraft pulp led to the conclusion that OX increases reversion of certain pulps but this trend is not universal. Alkaline bleaching stages decrease reversion regardless of pulp OX content. Pulps bleached with high temperature chlorine dioxide revert less than those bleached with conventional chlorine dioxide in sequences ending with a chlorine dioxide stage but similarly in sequences ending with a final peroxide stage. The use of secondary condensate for pulp washing decreases reversion.

  6. SYNERGISTIC EFFECTS BETWEEN BIRCH CHEMICAL MECHANICAL PULPS AND ASPEN BLEACHED KRAFT PULP

    Institute of Scientific and Technical Information of China (English)

    Eric C. Xu; Yajun Zhou

    2004-01-01

    In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes.The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.

  7. SYNERGISTIC EFFECTS BETWEEN BIRCH CHEMICAL MECHANICAL PULPS AND ASPEN BLEACHED KRAFT PULP

    Institute of Scientific and Technical Information of China (English)

    EricC.Xu; YajunZhou

    2004-01-01

    In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes. The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.

  8. Effects of the bleaching sequence on the optical brighteners action in eucalyptus kraft pulp

    Directory of Open Access Journals (Sweden)

    Mauro Manfredi

    2014-06-01

    Full Text Available During the bleaching process the pulp is treated with chemical reagents that can be retained in the pulp and interfere in the action of the optical brighteners. Different bleaching sequences can produce pulps at the same brightness but with different potential to whiteness increase when treated with optical brighteners. The objective of this study was to evaluate the influence of the bleaching sequence on the efficiency of disulphonated and tetrasulphonated optical brighteners. Eucalyptus kraft pulp was bleached using four different bleaching sequences. For each pulp three brightness targets were aimeds. For each bleaching sequence mathematical model was generated for predicting the final pulp whiteness according to the initial brightness and the optical brightener charge applied. The presence of organochlorine residues in the pulp reduced the effectiveness of the optical brighteners. Therefore, bleaching sequences that use low chlorine dioxide charge favors for greater gains in whiteness with the application of optical brighteners. The replacement of the final chlorine dioxide bleaching stage with a hydrogen peroxide one in the sequence increased the efficiency of the optical brightening agents.

  9. Acid hydrolysis of cellulosic fibres: Comparison of bleached kraft pulp, dissolving pulps and cotton textile cellulose.

    Science.gov (United States)

    Palme, Anna; Theliander, Hans; Brelid, Harald

    2016-01-20

    The behaviour of different cellulosic fibres during acid hydrolysis has been investigated and the levelling-off degree of polymerisation (LODP) has been determined. The study included a bleached kraft pulp (both never-dried and once-dried) and two dissolving pulps (once-dried). Additionally, cotton cellulose from new cotton sheets and sheets discarded after long-time use was studied. Experimental results from the investigation, together with results found in literature, imply that ultrastructural differences between different fibres affect their susceptibility towards acid hydrolysis. Drying of a bleached kraft pulp was found to enhance the rate of acid hydrolysis and also result in a decrease in LODP. This implies that the susceptibility of cellulosic fibres towards acid hydrolysis is affected by drying-induced stresses in the cellulose chains. In cotton cellulose, it was found that use and laundering gave a substantial loss in the degree of polymerisation (DP), but that the LODP was only marginally affected. PMID:26572472

  10. MOLYBDENUM CATALYZED ACID PEROXIDE BLEACHING OF EUCALYPTUS KRAFT PULP

    OpenAIRE

    Marcos S. Rabelo; Jorge L. Colodette; Vera M. Sacon; Marcelo R. Silva; Marco A. B. Azevedo

    2008-01-01

    Molybdenum catalyzed peroxide bleaching (PMo Stage) consists of pulp treatment with hydrogen peroxide under acidic conditions in the presence of a molybdenum catalyst. Molybdenum is applied in catalytic doses (50-200 mg/kg pulp) and may originate from various sources, including (NH4)6Mo7O24.4H2O, Na2MoO4.2H2O, siliconmolybdate, etc. This work is aimed at optimizing the PMo stage and evaluating its industrial application in the OAZDP sequence. Optimum PMo stage conditions for bleaching eucalyp...

  11. HYDROGEN PEROXIDE BLEACHING OF HARDWOOD KRAFT PULP WITH ADSORBED BIRCH XYLAN AND ITS EFFECT ON PAPER PROPERTIES

    Directory of Open Access Journals (Sweden)

    Hyejung Youn

    2011-02-01

    Full Text Available The adsorption of xylan on pulp fibers improves the strength properties of paper. However, the optical properties are decreased significantly. The objective of our research was to bleach hardwood kraft pulp with adsorbed birch xylan by hydrogen peroxide and study the effect of bleaching parameters on paper properties. The bleaching parameters studied included bleaching temperature, time, initial pH as well as MgSO4 dosage. The optical properties (whiteness, brightness, opacity and physical properties (tensile index, tearing index, bulk of handsheets made from the pulp bleached with different process variables were measured. The results showed that better optical properties were obtained with higher bleaching temperature, longer bleaching time, and more MgSO4 dosage. Bleaching from an initial pH of 11 provided the highest brightness value. On the other hand, strength properties were improved with decreasing of the bleaching temperature, and increasing the initial pH and MgSO4 dosage. The relationship between strength properties and bleaching time varied depending on bleaching temperature. According to the results, both good mechanical properties and optical properties could be achieved when the operating parameters were controlled properly. Therefore hydrogen peroxide bleaching was proved to be a suitable method for bleaching hardwood kraft pulp with adsorption of birch xylan.

  12. Application of xylanases from Amazon Forest fungal species in bleaching of eucalyptus kraft pulps

    Directory of Open Access Journals (Sweden)

    Roseli Garcia Medeiros

    2007-03-01

    Full Text Available Crude xylanase preparations from Penicillium corylophilum, Aspergillus niger and Trichoderma longibrachiatum were used to treat Eucalyptus kraft pulp, prior to chlorine dioxide and alkaline bleaching sequences. The enzyme pretreatment improved brightness and delignification of non-delignified and oxygen-bleached samples of eucalyptus kraft pulp. Xylanase preparations from T. longibrachiatum and P. corylophilum were more effective to reduce pulp kappa number. A small reduction in viscosity was obtained when the oxygen-bleached pulp was treated with xylanase preparation from A. niger. For all enzyme samples, the best release of chromophoric material from the pulp was at 237 nm. The enzyme preparation from P. corylophilum was responsible for the highest release of reducing sugar at a dosage interval of 10-20 IU/g dry weight pulp. Scanning electron microscopy studies of oxygen-bleached pulp after xylanase treatment revealed morphological changes, including holes, cracks, filament forming and peeling.Amostras de xilanases de extratos brutos de Penicillium corylophilum, Aspergillus niger e Trichoderma longibrachiatum foram utilizadas no branqueamento de polpa kraft de eucalipto antes das seqüências alcalina e dióxido de cloro. O pré-tratamento enzimático melhorou a alvura e o processo de deslignificação de amostras de polpa kraft de eucalipto não-tratada e tratada com oxigênio. Amostras de xilanases de T. longibrachiatum e P. corylophilum foram mais efetivas na redução do número kappa da polpa. A polpa tratada com oxigênio sofreu uma pequena redução na sua viscosidade quando incubada com amostra de xilanase de A. niger. Para todas as amostras de xilanases, a maior liberação de cromóforos da polpa foi a 237 nm. A amostra de xilanase de P. corylophilum liberou maior quantidade de açúcar redutor da polpa, utilizando dosagem de 10-20 UI/g de peso seco da polpa. Estudos de microscopia eletrônica de varredura revelaram várias altera

  13. Control of the Accumulation of Non-Process Elements in Pulp Mills with Bleach Filtrate Reuse: A Chemical Equilibrium Approach to Predicting the Partitioning of Metals in Pulp Mill and Bleach Plant Streams

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, W.J. Jr.; Rudie, A.W.; Schmidl, G.W.; Sinquefield, S.A.; Rorrer, G.L.; Laver, M.L.; Yantasee, W.; Ming, D.

    2000-08-01

    The overall goal of this project was to develop fundamental, experimentally based methods for predicting the solubility or organic and inorganic matter and their interactions in recycled effluent from kraft pulp mills and bleach plants. This included: characterizing the capacity of wood pulp and dissolved organic matter to bind metal ions, developing a thermodynamic database of properties needed to describe the solubility of inorganic matter in pulp mill streams, incorporation of the database into equilibrium calculation software for predicting the solubility of the metals of interest, and evaluating its capability to predict the distribution of the metals between pulp fibers, inorganic precipitates, and solution.

  14. Comparative study of lipophilic extractives of hardwoods and corresponding ECF bleached kraft pulps

    Directory of Open Access Journals (Sweden)

    Pascoal Neto, C.

    2006-07-01

    Full Text Available The lipophilic extractives of Eucalyptus globulus , Eucalyptus grandis , Eucalyptus urograndis , Betula verrucosa and Acacia mangium woods and of the corresponding ECF bleached kraft pulps, were characterised by GC-MS. The five hardwoods showed significant differences in the content and composition of the main families of extractives, namely fatty acids, long chain aliphatic alcohols and sterols. Significant differences in the composition persist after wood pulping and ECF bleaching of pulps. The fate of the various types of extractives during the wood and pulp processing is discussed. Long chain aliphatic acids and alcohols are quite stable during the pulp production and are retained to a great extent in the final bleached pulp; delta 5 sterols are mostly oxidised and partially retained in the pulps, while delta 7 sterols are completely degraded and/or dissolved. B. verrucosa and A. mangium bleached pulps show contents of fatty acids about 4 and 20 times higher than that of Eucalyptus pulps, respectively, while the content of long chain aliphatic alcohols in A. mangium pulp is of the order of 100 times higher than Eucalyptus and B. verrucosa pulps.

  15. Chronic effects of Pinus radiata and Eucalyptus globulus kraft mill effluents and phytosterols on Daphnia magna.

    Science.gov (United States)

    López, D; Chamorro, S; Silva, J; Bay-Schmith, E; Vidal, G

    2011-12-01

    Two kraft pulp mill effluents were compared in terms of their chronic toxicity to Daphnia magna. One resulted from pulping Pinus radiata and the other came from a parallel processing of Pinus radiata and Eucalyptus globulus (mixed kraft pulp mill effluent). The concentration of phytosterols found in the mixed kraft pulp mill effluent was higher than in the effluent from Pinus radiata, with values of 0.1082 and 0.02 μg/L, respectively. The phytosterols per se are responsible for 12.9% and 8.1% of the deviation from the natural shape, while the kraft pulp mill effluents account for 25.6%-27.8% of shape deviation. The role of β-sitosterol and stigmasterol is discussed in relation to endocrine disruption. PMID:21979137

  16. Recovery of ovary size, follicle cell apoptosis, and HSP70 expression in fish exposed to bleached pulp mill effluent

    Energy Technology Data Exchange (ETDEWEB)

    Janz, D. M.; Weber, L. P. [Oklahoma State Univ., Stillwater, OK (United States); McMaster, M. E.; Munkittrrick, K. R. [Environment Canada, Burlington, ON (Canada); Van Der Kraak, G. [Guelph Univ., Dept. of Zoology, ON (Canada)

    2001-03-01

    Apoptosis of granulosa cells that provide hormonal support for the oocyte is the normal mechanism by which atresia ( reduced ovarian size, decreased fecundity, delayed sexual maturation, alterations in plasma sex steroid levels, etc) occurs in mammals, birds and possibly fish. The objective of this study is to determine ovarian cell apoptosis, gonadosomatic index (GSI) and heat shock protein (HSP70) expression during the growth stage of ovarian development in white sucker fish in order to compare samples of fish collected upstream and downstream of a bleached kraft pulp mill in Ontario. Fish for the study were collected in two different years, before and after the pulp mill undertook a number of improvements to eliminate the release of process chemicals. Results showed a 3.4-fold increase in ovarian cell apoptosis in growing white sucker collected four km downstream of the bleached kraft pulp mill in 1996 (before the improvements) compared to fish collected from upstream sources. The elevated ovarian cell apoptosis was associated with significant reduction in gonadosomatic index in fish collected downstream. There were no differences in ovarian cell apoptosis or gonadosomatic index between fish collected upstream and four km downstream of the mill in September 1998 (after the improvements.) Based on the results, it may be concluded that chronic stimulation of ovarian cell apoptosis by certain components of bleached kraft pulp mill effluents represents an important cellular mechanism for reducing the size of ovaries and other related reproductive responses in female fish exposed to these effluents. Although the specific effluent components are not known, the improvements undertaken between 1996 and 1998 resulted in significant enough recovery of these responses to justify the belief in a cause-effect relationship. 32 refs., 1 tab., 2 figs.

  17. Influence of bleaching technologies on the aerobic biodegradability of effluents from Eucalyptus kraft pulps factories

    Directory of Open Access Journals (Sweden)

    Gladys Vidal

    1999-01-01

    Full Text Available Aerobic biodegradability of effluents from different Eucalyptus kraft pulp bleaching processes was studied. Bleaching effluents were obtained from: i Chlorine Bleaching (CB processes, with partial substitution of chlorine by chlorine dioxide and ii Total Chlorine Free (TCF processes. The overall biodegradability, in terms of Chemical Oxygen Demand (COD was higher for TCF effluents (96-98% than for CB ones (82-93%. Taking into account the higher organic load of CB effluents, this fact implied a much higher residual COD for them (100-180 mg/L than for TCF effluents (10-30 mg/L. Furthermore, a refractory fraction of molecular weight higher than 43,000 Da was found in CB effluent, which implied the necessity of a further specific treatment. The toxicity was completely removed after the biological treatmentA biodegradabilidade aerobica das águas residuais provenientes de diferentes procesos de branqueos de pulpa kraft foi estudada. Os efluentes são gerados no branqueo com cloro ou parcialmente sustituido com dioxido de cloro (CB ou bem em processos livres do cloro (TCF. A biodegradabilidade, quantificada como DQO foi maior para as águas do processo CB. Tendo em conta o elevado conteúdo orgânico do efluente CB obteinse uma maior concentraç&ão do DQO final neste efluente comparado com o efluente TCF. Uma fracçao recalcitrante maior a 43,000 Da no effluente BC foi encontrada, isto significa um tratamento adicional específico para sua eliminaçã o. A toxicidade foi totalmente eliminada despois do tratamento aeração.

  18. EFFECT OF BIRCH KRAFT PULP PRIMARY FINES ON BLEACHING AND SHEET PROPERTIES

    Directory of Open Access Journals (Sweden)

    Sari Anneli Asikainen

    2010-08-01

    Full Text Available By removing the primary fines from an oxygen-delignified mill birch pulp, a fiber fraction was obtained having low metals content and no extractives. After DEDeD bleaching the fiber fraction had somewhat higher brightness and better brightness stability than the birch pulp containing the primary fines. The fines fraction was enriched with lignin, extractives, xylan, and metals. Bleaching the fines fraction in a QQP sequence did not affect the extractives, whereas a ZeQP sequence clearly reduced the extractives content. In a biorefinery concept, the fines fraction could be utilized as a source of xylan, fatty acids, sterols, and betulinol. Another possibility is to use the fines fraction unbleached or separately bleached as a bonding material in various fiber furnishes.

  19. Kraft mill sludge to improve vegetal production in Chilean Andisol.

    Science.gov (United States)

    Gallardo, F; Mora, M L; Diez, M C

    2007-01-01

    The effect of kraft mill sludge addition (25 to 75 ton/ha) to soil derived from volcanic ashes (Andisol) on wheat (Triticum aestivum L.cv. Puken) biomass production, and in the nutrient absorption by the plants was evaluated. Respiration activity and seed germination tests were carried out on the soil/sludge mixtures, in order to evaluate possible toxic effects due to the sludge addition to the soil. Soil without sludge was used as a control treatment. The plants were grown in a greenhouse (25 degrees C, 14 h-photoperiod) during 120 days, then the plants were collected and dried at 65 degrees C for 72 h for the determination of biomass production (root and aerial) and analyzed for mineral content (Ca, Mg, K and P). The mixtures of soil/sludge showed no toxicity. Seed germination and respiration activity increased with the increment of the sludge. The accumulated CO2 in the soil without sludge was 41.66 mg CO2/100; this value shows a low microbial activity. The biomass increased with the increment of sludge addition to the soil and five times more biomass was obtained when 75 ton/ha sludge was added to the soil. The nutrient absorption efficiency was also improved with the sludge addition. PMID:17486832

  20. Development of hemicelluloses biorefineries for integration into kraft pulp mills

    Science.gov (United States)

    Ajao, Olumoye Abiodun

    The development and wide spread acceptance of production facilities for biofuels, biochemicals and biomaterials is an important condition for reducing reliance on limited fossil resources and transitioning towards a global biobased economy. Pulp and paper mills in North America are confronted with high energy prices, high production costs and intense competition from emerging economies and low demand for traditional products. Integrated forest biorefineries (IFBR) have been proposed as a mean to diversify their product streams, increase their revenue and become more sustainable. This is feasible because they have access to forest biomass, an established feedstock supply chain and wood processing experience. In addition, the integration of a biorefinery process that can share existing infrastructure and utilities on the site of pulp mill would significantly lower investment cost and associated risks. Kraft pulping mills are promising receptor processes for a biorefinery because they either possess a prehydrolysis step for extracting hemicelluloses sugars prior to wood pulping or it can be added by retrofit. The extracted hemicelluloses could be subsequently transformed into a wide range of value added products for the receptor mill. To successfully implement hemicelluloses biorefinery, novel processes that are technically and economically feasible are required. It is necessary to identify products that would be profitable, develop processes that are energy efficient and the receptor mill should be able to supply the energy, chemicals and material demands of the biorefinery unit. The objective of this thesis is to develop energy efficient and economically viable hemicelluloses biorefineries for integration into a Kraft pulping process. A dissolving pulp mill was the reference case study. The transformation of hemicellulosic sugars via a chemical and biochemical conversion pathway, with furfural and ethanol as representative products for each pathway was studied. In

  1. HYDROPHOBIZATION OF BLEACHED SOFTWOOD KRAFT FIBERS VIA ADSORPTION OF ORGANO-NANOCLAY

    Directory of Open Access Journals (Sweden)

    Jieming Chen,

    2012-07-01

    Full Text Available Montmorillonite clay particles that had been prepared with an alklyl-ammonium surfactant were used to modify the moisture-sensitivity of bleached softwood kraft fibers through solvent exchange and adsorption methods. Moisture absorption and water uptake of the wood pulp fibers were significantly lower after the organo-nanoclay treatment. Thermal stability, surface energy, and surface morphology of the treated fibers were characterized using Thermogravimetric Analysis (TGA, Inverse Gas Chromatography (IGC, Scanning Electron Microscopy-Energy Dispersive X-ray Analysis (SEM-EDX, and Transmission Electron Microscopy (TEM imaging. The Fourier Transform Infrared (FT-IR spectral characteristics of the treated fibers were obtained to better understand the modified surface functional groups of the treated fibers. The treated bio-fibers had nano-scale surface roughness and a much reduced surface energy. The contact angle of water on the treated fiber mat was found to be higher than 160º. The thermal stability of the treated fibers was not affected by the modification.

  2. ACIDS SOILS’ PH AND NUTRIENT IMPROVEMENT WHEN AMENDED WITH INORGANIC SOLID WASTES FROM KRAFT MILL

    OpenAIRE

    M ZAMBRANO; Parodi, V.; Baeza, J; Vidal, G.

    2007-01-01

    Kraft mill generates a large amount of dregs (D) and grits (G) as solid wastes due to the causticizing process. The disposal of these wastes is expensive in terms of land requirement and maintenance. On the other hand, solid wastes have alkalinity and buffer properties, which make them appropriate for use as amendments to acidic soils. The goal of this work was to determine the physical, chemical, toxicity and hazardousness characteristics of D & G. Additionally, the effect on acidic soils’ p...

  3. Removal of stigmasterol from Kraft mill effluent by aerobic biological treatment with steroidal metabolite detection.

    Science.gov (United States)

    Chamorro, Soledad; Vergara, Juan P; Jarpa, Mayra; Hernandez, Victor; Becerra, Jose; Vidal, Gladys

    2016-10-14

    Stigmasterol is a phytosterol contained in Kraft mill effluent that is able to increase over 100% after aerobic biological treatment. This compound can act as an endocrine disrupter as its structure is similar to that of cholesterol. The aim of this study was to evaluate the removal of stigmasterol from Kraft mill effluents treated by a moving bed biofilm reactor (MBBR) with steroidal metabolite detection. The MBBR was operated for 145 days, with a hydraulic retention time of 2 days. Stigmasterol and steroidal metabolites were detected by gas chromatography with a flame ionization detector during MBBR operation. The results show that the MBBR removed 87.4% of biological oxygen demand (BOD5), 61.5% of chemical oxygen demand (COD), 24.5% of phenol and 31.5% of lignin, expressed in average values. The MBBR system successfully removed 100% of the stigmasterol contained in the influent (33 µg L(-1)) after 5 weeks of operation. In that case, the organic load rate was 0.343 kg COD m(-3) d(-1). Furthermore, different steroidal compounds (e.g., testosterone propionate, stigmast-4-en-3-one, 5α-pregnan-12-one-20α-hydroxy, 5α-pregnane-3,11,20-trione and 3α-hydroxy-5α-androstane-11,17-dione were detected in the Kraft mill effluent as potential products of phytosterol biotransformation. PMID:27399163

  4. MASCULINIZATION OF FEMALE MOSQUITO FISH IN KRAFT MILL EFFLUENT -CONTAMINATED FENHOLLOWAY RIVER WATER IS ASSOCIATED WITH ANDROGEN RECEPTOR AGONIST ACTIVITY.

    Science.gov (United States)

    Female mosquitofish (Gambusia affinis holbrooki) downstream from Kraft paper mills in Florida display masculinization of the anal fin, an androgen-dependent trait. The current investigation was designed to determine if water contaminated with pulp-mill effluent (PME) from the Fen...

  5. Simulation and Optimization of a Generic Kraft Pulp Mill

    OpenAIRE

    Barahona Vazquez, Javier

    2010-01-01

    The Canadian pulp and paper industry is going through an economic crisis mainly due to a decrease of world demand and aggressive competition from emerging nations. In this context, the forest biorefinery which can be defined as the “full integration of the incoming biomass and other raw materials, including energy, for simultaneous production of fibres for paper products, chemicals and energy”, is one of the solutions for pulp and paper mills to diversify their core business and regain compet...

  6. Optimal Co-Generation in an Integrated Kraft Mill

    Directory of Open Access Journals (Sweden)

    S. Suh

    1982-01-01

    Full Text Available An optimal control system designed to minimize the consumption of high pressure steam (and thus minimizing energy costs while meeting the paper mill's demand for process steam and electric power is developed. An installation example is described and system performance and benefits are discussed. It should be noted that the theories developed in this paper can be readily extended to the design of an optimal control system which maximizes the electric generation under the given inlet steam flow.

  7. Optimal Co-Generation in an Integrated Kraft Mill

    OpenAIRE

    Suh, S.; Olsen, T. O.

    1982-01-01

    An optimal control system designed to minimize the consumption of high pressure steam (and thus minimizing energy costs) while meeting the paper mill's demand for process steam and electric power is developed. An installation example is described and system performance and benefits are discussed. It should be noted that the theories developed in this paper can be readily extended to the design of an optimal control system which maximizes the electric generation under the given inlet steam flow.

  8. ON THE RECOVERY OF HEMICELLULOSE BEFORE KRAFT PULPING

    OpenAIRE

    Carlos Vila; Javier Romero; José Luis Francisco,; Valentín Santos,; Juan Carlos Parajó

    2012-01-01

    To assess the feasibility of implementing hemicellulose recovery stages in kraft mills, Eucalyptus globulus wood samples were subjected to aqueous treatments with hot, compressed water (autohydrolysis processing) to achieve partial dissolution of xylan. Autohydrolyzed solids were subjected to kraft pulping under selected conditions to yield a pulp of low kappa number, and to an optimized TCF bleaching sequence made up of three stages (alkaline oxygen delignification, chelating, and pressurize...

  9. Prediction of kraft mill total reduced sulphur emissions using vapour-liquid equilibrium theory

    International Nuclear Information System (INIS)

    Most kraft pulp mills in Canada have installed some form of noncondensable gas (NCG) system to collect and treat air emissions that include odorous total reduced sulphur compounds with hydrogen sulphide and the organic compounds methyl mercaptan, dimethyl sulphide or dimethyl disulphide. However, the extent of these systems varies greatly. Therefore, in order to optimize the design and operation of these NCG systems, it would be beneficial to have a simple but accurate method of predicting emissions without direct measures. This paper presented a method to predict total reduced sulphur (TRS) emissions from kraft pulp mills using correlations based on the vapour-liquid equilibrium (VLE) theory. The brown stock washing area of the Howe Sound mill provided samples which were tested to determine the concentration of TRS compounds. Heat and material balances of the washing line were constructed using CADSim Plus simulation software. Emissions of these volatile sulphur compounds were simulated by incorporating a VLE module into the software. This study also extended the simulation balances to include NCG emissions from process equipment. It was concluded that the newly proposed method can be used to optimize the operation of NCG systems, to evaluate TRS control alternatives and to improve the accuracy of environmental reporting. 14 refs., 1 tab., 7 figs

  10. Effects of Kraft Mill effluent on the sexuality of fishes: An environmental early warning

    Energy Technology Data Exchange (ETDEWEB)

    Davis, W.P.; Bortone, S.A.

    1992-01-01

    Arrhenoid or masculinized female fish species of the live-bearing family, Poeciliidae, have been observed for over thirteen years in specific southern streams which receive waste effluents from pulping mills. The complex mixture of organic compounds in kraft mill effluent (KME) has inhibited specific identification of causal agent(s). However, microbially degraded phytosterols (e.g. sitosterol or stigmastanol) in experimental exposures induce the same intersexual states that characterize affected female poeciliids sampled from KME streams. KME-polluted streams often exhibit a drastic reduction of fish species diversity and degrees of physiological stress, all of which suggests reduced reproduction in surviving forms. A potential ontogenetic or developmental response is demonstrated in American eels captured in one of these streams as well. The authors examine available information, including laboratory and experimental field exposures, and suggest directions for additional research as well as the need for environmental concern.

  11. Investigating the relationship between toxicity and organic sum-parameters in kraft mill effluents.

    Science.gov (United States)

    Raptis, Catherine E; Juraske, Ronnie; Hellweg, Stefanie

    2014-12-01

    Elaborate toxicity diagnostics, such as toxicity identification evaluation (TIE) and effects-directed analysis (EDA) have helped in identifying the causative agents of effluent wastewater toxicity. However, simpler means of relating ecotoxicological effects to effluent composition could be useful for effluent management practices when there is no scope for more complex procedures. The aim of this work was to investigate and isolate the relationship between biological responses and commonly measured organic sum-parameters, such as chemical- and biochemical oxygen demand (COD and BOD, respectively) in kraft mill effluents. In a top-down approach, the whole effluent toxicity (WET) of effluent samples was first determined from Pseudokirchneriella subcapitata and Ceriodaphnia dubia bioassays. The theoretical toxicity that could be attributed to the metal content was then estimated, via a combination of equilibrium chemical speciation- and metal toxicity modelling. By assuming concentration addition, the metal toxicity was subtracted from the WET, isolating the toxicity thought to be caused by the organics. Strong and significant correlations between the 'corrected' toxicity and organic sum-parameters were found for both species. The growth of P. subcapitata was negatively associated with increasing COD concentrations, whereas reproduction of C. dubia was negatively associated with increasing BOD concentrations. The linear relationships, along with robust estimations of their uncertainty bounds, can provide valuable, albeit rough, guidance for kraft mill effluent management practices. PMID:25213683

  12. KRAFT MILL BIOREFINERY TO PRODUCE ACETIC ACID AND ETHANOL: TECHNICAL ECONOMIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    Haibo Mao

    2010-05-01

    Full Text Available The “near neutral hemicellulose extraction process” involves extraction of hemicellulose using green liquor prior to kraft pulping. Ancillary unit operations include hydrolysis of the extracted carbohydrates using sulfuric acid, removal of extracted lignin, liquid-liquid extraction of acetic acid, liming followed by separation of gypsum, fermentation of C5 and C6 sugars, and upgrading the acetic acid and ethanol products by distillation. The process described here is a variant of the “near neutral hemicellulose extraction process” that uses the minimal amount of green liquor to maximize sugar production while still maintaining the strength quality of the final kraft pulp. Production rates vary between 2.4 to 6.6 million gallons per year of acetic acid and 1.0 and 5.6 million gallons per year of ethanol, depending upon the pulp production rate. The discounted cash flow rate of return for the process is a strong function of plant size, and the capital investment depends on the complexity of the process. For a 1,000 ton per day pulp mill, the production cost for ethanol was estimated to vary between $1.63 and $2.07/gallon, and for acetic acid between $1.98 and $2.75 per gallon depending upon the capital equipment requirements for the new process. To make the process economically attractive, for smaller mill sizes the processing must be simplified to facilitate reductions in capital cost.

  13. ON THE RECOVERY OF HEMICELLULOSE BEFORE KRAFT PULPING

    Directory of Open Access Journals (Sweden)

    Carlos Vila,

    2012-07-01

    Full Text Available To assess the feasibility of implementing hemicellulose recovery stages in kraft mills, Eucalyptus globulus wood samples were subjected to aqueous treatments with hot, compressed water (autohydrolysis processing to achieve partial dissolution of xylan. Autohydrolyzed solids were subjected to kraft pulping under selected conditions to yield a pulp of low kappa number, and to an optimized TCF bleaching sequence made up of three stages (alkaline oxygen delignification, chelating, and pressurized hydrogen peroxide, with minimized additions of pulping and bleaching chemicals. The final product had a relatively low kappa number (1.4, 641 mL/g ISO intrinsic viscosity, and 86.4% brightness.

  14. Exposure of fish to biologically treated bleached-kraft effluent; 1: Biochemical, physiological and pathological assessment of Rocky Mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus)

    Energy Technology Data Exchange (ETDEWEB)

    Kloepper-Sams, P.J.; Owens, J.W. (Procter Gamble Co., Cincinnati, OH (United States)); Swanson, S.M. (SENTAR Consultants Ltd., Calgary, Alberta (Canada)); Marchant, T. (Univ. of Saskatchewan, Saskatoon (Canada). Dept. of Biology); Schryer, R. (SENTAR Consultants Ltd., Saskatoon, Saskatchewan (Canada))

    1994-09-01

    A suite of biochemical, physiological, and pathological measures was used to assess possible effects of exposure to bleached-kraft mill effluent (BKME) on wild longnose sucker (Catostomus catostomus=LS) and mountain whitefish (Prosopium williamsoni=MW) in the Wapiti/Smoke River system, as compared to similar populations in a reference river system without BKME inputs. Individual fish body burden data were examined for correlations between chemical exposure and biological response. General incidence of gross pathology and histopathology showed no relationship with exposure to BKME, and no neoplastic or preneoplastic lesions were observed in either exposed or reference fish. The few significant differences observed in LS blood parameters were not correlated with exposure to BKME and appeared to reflect habitat gradients. Liver somatic indexes were higher for female BKME-exposed LS, but were not significantly different in male LS nor in MW. Some differences in circulating sex steroid levels were observed in LS exposed to BKME (but not in MW, the species with higher contaminant body burdens). Steroid profile differences may have been related to natural differences in duration of spawning periods in the two fish populations. Other measures of reproductive capacity (relative gonad size, fecundity, young-of-the-year) showed no reductions in exposed fish. The detoxification enzyme cytochrome P4501A was induced in both species, with greater induction in MW than in LS. MW P4501A induction correlated well with some BKME exposure measures, but not with liver or gonad weights, pathology, reproductive capacity, or population-level parameters. Increased liver size and apparent differences in sex steroid profiles in LS did not translate to other health effects or population-level effects. Thus, exposure to this biologically treated BKME produced one consistent biochemical marker of exposure in the two fish species that was not associated with any adverse effects on fish health.

  15. Toxicity to Daphnia magna and Vibrio fischeri of Kraft bleach plant effluents treated by catalytic wet-air oxidation.

    Science.gov (United States)

    Pintar, Albin; Besson, Michèle; Gallezot, Pierre; Gibert, Janine; Martin, Dominique

    2004-01-01

    Two Kraft-pulp bleaching effluents from a sequence of treatments which include chlorine dioxide and caustic soda were treated by catalytic wet-air oxidation (CWAO) at T=463 K in trickle-bed and batch-recycle reactors packed with either TiO2 extrudates or Ru(3 wt%)/TiO2 catalyst. Chemical analyses (TOC removal, color, HPLC) and bioassays (48-h and 30-min acute toxicity tests using Daphnia magna and Vibrio fischeri, respectively) were used to get information about the toxicity impact of the starting effluents and of the treated solutions. Under the operating conditions, complex organic compounds are mostly oxidized into carbon dioxide and water, along with short-chain carboxylic acids. Bioassays were found as a complement to chemical analyses for ensuring the toxicological impact on the ecosystem. In spite of a large decrease of TOC, the solutions of end products were all more toxic to Daphnia magna than the starting effluents by factors ranging from 2 to 33. This observation is attributed to the synergistic effects of acetic acid and salts present in the solutions. On the other hand, toxicity reduction with respect to Vibrio fischeri was achieved: detoxification factors greater than unity were measured for end-product solutions treated in the presence of the Ru(3 wt%)/TiO2 catalyst, suggesting the absence of cumulative effect for this bacteria, or a lower sensitivity to the organic acids and salts. Bleach plant effluents treated by the CWAO process over the Ru/TiO2 catalyst were completely biodegradable. PMID:14675640

  16. Integrating a xylanase treatment into an industrial-type sequence for eucalyptus kraft pulp bleaching

    OpenAIRE

    Fillat Latorre, Úrsula; Roncero Vivero, María Blanca; Sacón, Vera Maria; Bassa, Alexandre

    2012-01-01

    The influence of a treatment with two commercial xylanases on pulp and effluents obtained after the bleaching stages in the OXAZDP (O, oxygen stage; X, xylanase treatment; A, acid stage; Z, ozone stage; D, chlorine dioxide stage; P, hydrogen peroxide stage) sequence was studied. Also, the potential saving in chlorine dioxide was assessed. The enzyme treatment was performed on pulp containing some black liquor since the operating conditions were close to the conditions used in the storage towe...

  17. Treatment of the effluent from a kraft bleach plant with the white-rot fungus Pleurotus ostreatoroseus sing

    Directory of Open Access Journals (Sweden)

    A.Z. Santos

    2002-12-01

    Full Text Available The ligninolytic fungus Pleurotus ostreatoroseus (synonymy of Pleurotus ëous was used to treat the first alkali extraction stage (E1 effluent of a kraft bleach plant. It was pelletized and used for two continuous experiments in a two-liter turbulent-flow bioreactor. In the first experiment, the average removal of color and of total phenols was 18.6 and 11.6%, respectively, after the addition of glucose. During the second experiment, which was developed with the addition of several quantities of glucose, the maximum removal of color, of total phenols and of lignin/chlorolignin was 19.4, 9.4 and 44.5%. For both experiments, the best results were obtained when the effluent was diluted and enriched with glucose. This indicated the need for an extra carbon source for the fungal treatment. Using the mycelial mass in suspension, three experiments were carried out. The best results were obtained with 20% fungus and shaking of the effluent. During the last three days of the experiment the average removal of color, of total phenols and of lignin/chlorolignin was 84.4± 6.1, 82.1± 5.7 and 72.4± 8.9, respectively. The results indicate the potential of Pleurotus ostreatoroseus for use in the treatment of E1 effluent.

  18. Process for purification of waste water produced by a Kraft process pulp and paper mill

    Science.gov (United States)

    Humphrey, M. F. (Inventor)

    1979-01-01

    The water from paper and pulp wastes obtained from a mill using the Kraft process is purified by precipitating lignins and lignin derivatives from the waste stream with quaternary ammonium compounds, removing other impurities by activated carbon produced from the cellulosic components of the water, and then separating the water from the precipitate and solids. The activated carbon also acts as an aid to the separation of the water and solids. If recovery of lignins is also desired, then the precipitate containing the lignins and quaternary ammonium compounds is dissolved in methanol. Upon acidification, the lignin is precipitated from the solution. The methanol and quaternary ammonium compound are recovered for reuse from the remainder.

  19. Economics of trigeneration in a kraft pulp mill for enhanced energy efficiency and reduced GHG emissions

    International Nuclear Information System (INIS)

    The potential to liberate steam production capacity for power generation has been assessed using actual energy consumption data and the recorded seasonal consumption fluctuations for a kraft pulp mill. The revenues from power production are compared with possible energy savings, achieved through enhancement of the process efficiency using an absorption heat pump (AHP). Bunker oil, wood bark and black liquor, the fuels used, have very different costs and heating values. The net present value (NPV) was used with a simple payback time (SPB) for the comparison of three cases: (i) power production from liberated steam capacity using a cogeneration unit (ii) maximised energy savings using an AHP and (iii) power production combined with heat upgrading and cold production using a trigeneration unit. The results show economic viability of all options investigated. The stand-alone AHP achieves the shortest SPB time, whereas the trigeneration option reaches the highest NPV and therefore the best overall economics

  20. A survey of present levels of radiocesium in Swedish pulp mill liquors and the implications for wood radiocesium transfer factors. Using Kraft mill liquors as an indicator of wood radiocesium contamination

    International Nuclear Information System (INIS)

    A survey was initiated to depict and compare the present activity levels in pulp mill liquors from various mill locations. The 137Cs levels in pulp mill liquors were compared with the mill location and the deposition pattern of the Chernobyl fallout and nuclear weapons fallout. The large input of wood (about 2500 m3 per day) to an average Nordic Kraft mill and the relatively long-term retention time for radiocesium in the Kraft mill recovery cycle enables representative sampling of substances directly related to the activity concentration in wood. (author)

  1. Production of cellulase from kraft paper mill sludge by Trichoderma reesei rut C-30.

    Science.gov (United States)

    Wang, Wei; Kang, Li; Lee, Yoon Y

    2010-05-01

    Paper mill sludge is a solid waste material generated from pulping and papermaking operations. Because of high glucan content and its well-dispersed structure, paper mill sludges are well suited for bioconversion into value-added products. It also has high ash content originated from inorganic additives used in papermaking, which causes hindrance to bioconversion. In this study, paper mill sludges from Kraft process were de-ashed by a centrifugal cleaner and successive treatment by sulfuric acid and sodium hydroxide, and used as a substrate for cellulase production. The treated sludge was the only carbon source for cellulase production, and predominantly inorganic nutrients were used as the nitrogen source for this bioprocess. The cellulase enzyme produced from the de-ashed sludge exhibited cellulase activity of 8 filter paper unit (FPU)/mL, close to that obtainable from pure cellulosic substrates. The yield of cellulase enzyme was 307 FPU/g glucan of de-ashed sludge. Specific activity was 8.0 FPU/mg protein. In activity tests conducted against the corn stover and alpha-cellulose, the xylanse activity was found to be higher than that of a commercial cellulase. Relatively high xylan content in the sludge appears to have induced high xylanase production. Simultaneous saccharification and fermentation (SSF) was performed using partially de-ashed sludge as the feedstock for ethanol production using Sacharomyces cerevisiae and the cellulase produced in-house from the sludge. With 6% (w/v) glucan feed, ethanol yield of 72% of theoretical maximum and 24.4 g/L ethanol concentration were achieved. These results were identical to those of the SSF using commercial cellulases. PMID:19997787

  2. Ecotoxicological studies with newly hatched larvae of Concholepas concholepas (Mollusca, Gastropoda): bioassay with secondary-treated kraft pulp mill effluents.

    Science.gov (United States)

    Manríquez, Patricio H; Llanos-Rivera, Alejandra; Galaz, Sylvana; Camaño, Andrés

    2013-12-01

    The Chilean abalone or "loco" (Concholepas concholepas, Bruguière 1789) represent the most economically important marine recourse exploited from inner inshore Management and Exploitation Areas for Benthic Resources along the Chilean coast. In this study, newly-hatched larvae of C. concholepas were investigated as a potential model species for marine ecotoxicological studies. The study developed a behavioral standard protocol for assessing the impact that kraft pulp mill effluents after secondary treatment have on C. concholepas larvae. Under controlled laboratory conditions, newly-hatched larvae were exposed to a series of different concentrations of kraft pulp mill effluents with secondary treatment (Pinus spp. and Eucalyptus spp.), potassium dichromate as standard reference toxicant and effluent-free control conditions. Regardless of the type of effluent the results indicated that diluted kraft pulp effluent with secondary treatment had reduced effect on larval survival. Low larval survivals were only recorded when they were exposed to high concentrations of the reference toxicant. This suggests that C. concholepas larval bioassay is a simple method for monitoring the effects of kraft pulp mill effluents with secondary treatment discharged into the sea. The results indicated that dilution of ca. 1% of the effluent with an elemental chlorine free (ECF) secondary treatment is appropriate for achieving low larval mortalities, such as those obtained under control conditions with filtered seawater, and to minimize their impact on early ontogenetic stages of marine invertebrates such as newly-hatched larvae of C. concholepas. The methodological aspects of toxicological testing and behavioral responses described here with newly-hatched larvae of C. concholepas can be used to evaluate in the future the potential effects of other stressful conditions as other pollutants or changes in seawater pH associated with ocean acidification. PMID:24099753

  3. Anaerobic biodegradability and toxicity of wastewaters from chlorine and total chlorine-free bleaching of eucalyptus kraft pulps.

    NARCIS (Netherlands)

    Vidal, G.; Soto, M.; Field, J.; Mendez-Pampin, R.; Lema, J.M.

    1997-01-01

    Chlorine bleaching effluents are problematic for anaerobic wastewater treatment due to their high methanogenic toxicity and low biodegradability. Presently, alternative bleaching processes are being introduced, such as elemental chlorine-free (ECF) and total chlorine-free (TCF) bleaching. The methan

  4. BIO-CONVENTIONAL BLEACHING OF KRAFT-AQ PULP OF A. CADAMBA BY CRUDE XYLANASES FROM COPRINELLUS DISSEMINATUS MLK-03 AND EFFECT OF RESIDUAL ENZYME ON EFFLUENT LOAD

    Directory of Open Access Journals (Sweden)

    Mohan Lal

    2011-04-01

    Full Text Available A new thermo-alkali-tolerant crude xylanase from Coprinellus disseminatus decreased kappa number by 34.38% and improved brightness and viscosity by 1.6 and 6.47% respectively after XE1-stage during prebleaching of Anthocephalus cadamba kraft-AQ pulp. At 2.4% chlorine demand, crude xylanase in a XECEHH (X= enzymatic prebleaching stage, E= extraction stage, C= chlorination stage, H= hypochlorite stage bleaching sequence improved pulp brightness, tensile index, burst index, and double fold numbers by 3.66%, 4.78%, 6.38%, and 11.11%, respectively with a reduction in viscosity (10.59% and tear index (10.77% compared to the control. Combined bleach effluent of the XECEHH sequence mitigated adsorable organic halides (AOX by 21% and increased chemical oxygen demand (COD, bio-chemical oxygen demand (BOD, and colour by 67.18%, 84.78%, and 97.53%, respectively, compared to the control. Residual enzymes that entered during enzymatic prebleaching stage decreased AOX, COD, BOD, and colour of combined effluent of the XECEHH bleaching sequence progressively and on 6th day, and these were reduced by 23.78%, 0.04%, 15.00%, and 0.61%, respectively, compared to the control.

  5. ECF bleaching with a final hydrogen peroxide stage: Impact of the chemical composition of Eucalyptus globulus kraft pulps

    OpenAIRE

    Loureiro, Pedro E. G.; Eva F. Domingues; Evtuguin, Dmitry V.; M. Graça Videira Sousa Carvalho

    2010-01-01

    Two industrial elemental chlorine free (ECF) bleaching sequences, D0(EOP)D1(EP)D2 and OQ(PO)DP, are compared with respect to the bulk content of lignin, carboxyl, hexeneuronic acids (HexA), and reducing groups after each bleaching stage. HexA groups contribute significantly to the total content of carboxyl groups, and their degradation during chlorine dioxide bleaching is reflected by a decrease of the carboxyl content. The higher degradation using an enhanced use of oxygen-based bleaching ch...

  6. SUBSTITUTION OF HIGH-YIELD-PULP FOR HARDWOOD BLEACHED KRAFT PULP IN PAPER PRODUCTION AND ITS EFFECT ON ALKENYL SUCCINIC ANHYDRIDE SIZING

    Directory of Open Access Journals (Sweden)

    Qijie Chen,

    2012-02-01

    Full Text Available In recent years there has been an increasing interest in using high-yield pulp (HYP as a partial replacement for hardwood bleached kraft pulp (HWBKP in the production of high-quality fine papers as a cost-effective way of improving the product performance. This study investigated the substitution of HYP for HWBKP and its effect on the Alkenyl Succinic Anhydride (ASA sizing performance. The results showed that the substitution of an aspen HYP for HWBKP can increase the ASA sizing performance at a HYP substitution as high as 15 to 20%. The ASA addition sequence has an influence on the ASA sizing performance and first adding ASA to the HYP followed by mixing with kraft pulps was the preferred method. Using precipitated calcium carbonate (PCC as a paper filler at a dosage of less than 20% can increase the ASA sizing performance due to the contribution of the calcium soap of the hydrolysed ASA. A PCC dosage greater than 20% resulted in a negative impact on the sizing performance. It was also found that different PCC loading sequences can also affect the ASA sizing performance.

  7. Fate of nitrogen in the chemical recovery cycle of a kraft pulp mill

    Energy Technology Data Exchange (ETDEWEB)

    Kymaelaeinen, M. [Aabo Akademi, Turku (Finland). Process Chemistry Group

    2001-07-01

    The kraft pulping process is the dominant chemical method for producing wood pulp. In the process, about half the mass of the wood is dissolved, separated from the wood fibers and transferred to the chemical recovery cycle. Nitrogen in the wood mostly dissolves and goes on to the recovery cycle. This reactive nitrogen is the source of NO{sub x} emissions in the recovery boiler. Little information has been available regarding the nitrogen elsewhere in the recovery cycle. Ammonia (NH{sub 3}) emissions have been observed at many mills, especially around the causticizing area, but the causes of the emissions have not been understood. Furthermore, the smelt exiting the boiler has been found to contain a significant part of the black liquor nitrogen. This finding, and the general lack of knowledge regarding nitrogen flow and behavior in the other parts of the recovery cycle, were the incentives for this work. The main routes of the reactive nitrogen, including the main formation and release points for NH{sub 3} in the recovery cycle, were clarified at two operating pulp mills. The key reaction and rates for NH{sub 3} formation under process conditions were determined. In addition, the formation of the ammonia precursor - the smelt nitrogen - was studied under black liquor combustion conditions. Further, NO formation in black liquor combustion was investigated by the single droplet experimental technique. The results provide an overall understanding of the behavior of nitrogen in the recovery cycle. The smelt nitrogen exiting the recovery boiler was equal to about one third of the black liquor nitrogen introduced to the boiler. The smelt nitrogen was found gradually to convert to ammonia in the liquor cycle during the subsequent green and white liquor processing. From the experimental kinetic studies, the key reaction for ammonia formation was identified as the hydrolysis of cyanate (OCN{sup -}) under alkaline conditions. All the smelt nitrogen was finally removed from

  8. ECF BLEACHING WITH A FINAL HYDROGEN PEROXIDE STAGE: IMPACT ON THE CHEMICAL COMPOSITION OF Eucalyptus globulus KRAFT PULPS

    Directory of Open Access Journals (Sweden)

    Pedro E. G. Loureiro

    2010-11-01

    Full Text Available Two industrial elemental chlorine free (ECF bleaching sequences, D0(EOPD1(EPD2 and OQ(PODP, are compared with respect to the bulk content of lignin, carboxyl, hexeneuronic acids (HexA, and reducing groups after each bleaching stage. HexA groups contribute significantly to the total content of carboxyl groups, and their degradation during chlorine dioxide bleaching is reflected by a decrease of the carboxyl content. The higher degradation using an enhanced use of oxygen-based bleaching chemicals is associated with a higher fiber charge reduction, mainly due to xylan depletion. Additionally, the effect of process variables of a laboratory final hydrogen peroxide stage on the chemical composition of the fully bleached pulp (D0(EOPD1P and OQ(PODP is studied. The ability of final peroxide bleaching to raise the content of carboxyl groups is dependent on the operating conditions and pulp bleaching history. A balance between carbohydrate oxidation and dissolution of oxidized groups determines the effect on fiber charge. The effect of hydrogen peroxide stabilizers added into the final stage on the content of carboxyl groups is also reported.

  9. Lignin Peroxidase Activity Is Not Important in Biological Bleaching and Delignification of Unbleached Kraft Pulp by Trametes versicolor

    OpenAIRE

    Archibald, Frederick S.

    1992-01-01

    The discovery in 1983 of fungal lignin peroxidases able to catalyze the oxidation of nonphenolic aromatic lignin model compounds and release some CO2 from lignin has been seen as a major advance in understanding how fungi degrade lignin. Recently, the fungus Trametes versicolor was shown to be capable of substantial decolorization and delignification of unbleached industrial kraft pulps over 2 to 5 days. The role, if any, of lignin peroxidase in this biobleaching was therefore examined. Sever...

  10. Decolorization and Detoxification of Extraction-Stage Effluent from Chlorine Bleaching of Kraft Pulp by Rhizopus oryzae

    OpenAIRE

    Nagarathnamma, R.; Bajpai, Pratima

    1999-01-01

    Rhizopus oryzae, a zygomycete, was found to decolorize, dechlorinate, and detoxify bleach plant effluent at lower cosubstrate concentrations than the basidiomycetes previously investigated. With glucose at 1 g/liter, this fungus removed 92 to 95% of the color, 50% of the chemical oxygen demand, 72% of the adsorbable organic halide, and 37% of the extractable organic halide in 24 h at temperatures of 25 to 45°C and a pH of 3 to 5. Even without added cosubstrate the fungus removed up to 78% of ...

  11. Process integration study of a kraft pulp mill converted to an ethanol production plant – part B: Techno-economic analysis

    International Nuclear Information System (INIS)

    In a previous study by the authors, energy efficiency measures in a conceptual kraft pulp mill converted to a lignocellulosic ethanol plant were investigated. The results suggested a number of different process designs which would give a substantial improvement in steam economy in the ethanol plant, compared to the original design. In the present study the different process designs are evaluated from an economic point-of-view, in order to determine if energy efficiency measures and increasing by-product sales decrease the production cost of ethanol from this specific process, or if the increased costs related to the implementation of these measures overshadow the benefits from increased by-product sales. The different energy efficiency measures are compared with less capital demanding alternatives (i.e. including low or no energy efficiency improvements) in order to assess the economic benefits of different strategies when converting a kraft pulp mill to ethanol production. The study indicates the economic importance of considering energy efficiency measures when repurposing a kraft pulp mill to an ethanol plant. It is also shown that, within the context of this study, a larger investment in measures will give better economic results than less capital demanding alternatives (with less improvement in energy efficiency). From an economic and energy efficiency viewpoint many of the suggested process designs will give approximately similar results, therefore the process design should be made based on other criteria (e.g. low complexity, low maintenance). - Highlights: ► Conversion of a kraft pulp mill to ethanol production. ► Heat integration of distillation/evaporation in a lignocellulosic ethanol plant. ► Energy efficiency measures lead to lower ethanol production cost. ► If capital costs and raw material prices are low the production cost could be as low as 365 €/m3 EtOH.

  12. Treatment of Pulp Mill D-Stage Bleaching Effluent Using a Pilot-Scale Electrocoagulation System.

    Science.gov (United States)

    Perng, Yuan-Shing; Wang, Eugene I-Chen

    2016-03-01

    A pilot-scale study was conducted using electrocoagulation technology to treat chlorine dioxide bleaching-stage effluent of a local pulp mill, with the purpose of evaluating the treatment performance. The operating variables were the current density (0 ~ 133.3 A/m(2)) and hydraulic retention time (HRT, 6.5 ~ 16.25 minutes). Water quality indicators investigated were the conductivity, suspended solids (SS), chemical oxygen demand (COD), true color, and hardness. The results showed that electrocoagulation technology can be used to treat D-stage bleaching effluent for water reuse. Under the operating conditions studied, the removal of conductivity and COD always increased with increases in either the current density or HRT. The highest removals obtained at 133.3 A/m(2) and an HRT of 16.25 minutes for conductivity, SS, COD, true color, and hardness were respectively 44.2, 98.5, 75.0, 85.9, and 36.9% with aluminum electrodes. Iron electrodes were not applicable to the D-stage effluent due to formation of dark-colored ferric complexes. PMID:26931536

  13. 阔叶木硫酸盐制浆和漂白中应用化学添加剂脱除抽提物%Using Additives for the Removal of Extractives in Kraft Pulping and Bleaching of Hardwood

    Institute of Scientific and Technical Information of China (English)

    胥成龙

    2004-01-01

    The effect of four additives (surfactants and dispersant) that were supplied by Hercules Chemicals Singapore Pte Ltd on kraft pulping and bleaching of Eucalyptus camaldulensis and Acacia mangium has been studied. The use of additives results in a more removal of extractives, and in a more uniform cook with lower screen rejects in eucalyptus, lower residual alkali, and in an improvement in brightness of eucalyptus pulps. At low additive charge level, a reduction of kappa number generated without clear loss of pulp yield in acacia cook.

  14. EFFECTS OF KRAFT MILL EFFLUENT (KME) ON SEXUALITY OF FISHES: AN ENVIRONMENTAL WARNING SYSTEM?

    Science.gov (United States)

    Arrhenoid or masculinized female fish species of the live-bearing family, Poeciliidae, have been observed for over thirteen years in specific southern streams which receive waste effluents from pulping mills. The complex mixture of organic compounds in KME has inhibited specific ...

  15. Kraft pulping and ECF bleaching of Eucalyptus globulus pretreated by the white-rot fungus Ceriporiopsis subvermispora - doi: 10.4025/actascitechnol.v34i3.12410

    Directory of Open Access Journals (Sweden)

    Claudio Salazar

    2012-05-01

    Full Text Available Eucalyptus globulus wood chips were decayed by the lignin-degrading fungus Ceriporiopsis subvermispora as a pretreatment step before kraft pulping. Weight and component losses of wood after the biotreatment were the following: weight (5%, glucans (1.5%, xylans (4.3%, lignin (5.7% and extractives (57.5%. The residual amount of lignin (expressed by the kappa number in pulps from biotreated wood chips was lower than that of pulps from the undecayed control. Depending on the delignification degree, kraft biopulps presented similar or up to 4% increase in pulp yield and 20% less hexenuronic acids (HexA than control pulps. The extended delignification with O2 decreases approximately 50% of the kappa number of the pulps and increases brightness, but had no effect in HexA reduction. The bleaching steps with chlorine dioxide (D0ED1 sequence decreased the kappa number up to 97%, increased pulp brightness up to 84% ISO and decreased HexA amount up to 91%. The use of C. subvermispora in biopulping of E. globulus generated important benefits during the production of kraft pulps that are reflected in a high pulp yield, low residual lignin content, low HexA amount, high brightness and viscosity of the biopulps as compared with pulps produced from untreated wood chips.

  16. Integrating the processes of a Kraft pulp and paper mill and its supply chain

    International Nuclear Information System (INIS)

    Highlights: • A process integration model that establishes material stream connections among typical Nordic forest industries is developed. • Potential benefit of the operating the different industries in one site is studied using pinch analysis. • Different scenarios considered to assess impact of prioritization on how to utilize excess biomass. • Results indicate large potential for improved biomass resource utilization. - Abstract: This paper investigates the possibility of combining different forest industries (a pulp and paper mill, its supply chain, and a wood-pellet plant) into an integrated industrial site in which they share a common heat and power utility. Advanced process integration and optimization techniques are used to study the site from both material and energy viewpoints. An existing pulp and paper mill is used as the site core plant and its pulp and paper production rates are kept fixed as they are in reality, while the other material flow links among the plants are based on the current industrial situation in Sweden. Different scenarios are evaluated in order to reflect the two main objectives that can be pursued (increased electricity production or biomass resource saving) and the two technologies that can be considered for the shared CHP system (boilers and product gas fired gas turbines). The corresponding non-integrated (standalone) configurations are compared to these scenarios to quantify the potential benefits of the integration. Investment opportunity is also calculated for the considered scenarios as an indicator of the economic convenience

  17. Acetone-butanol-ethanol production from Kraft paper mill sludge by simultaneous saccharification and fermentation.

    Science.gov (United States)

    Guan, Wenjian; Shi, Suan; Tu, Maobing; Lee, Yoon Y

    2016-01-01

    Paper mill sludge (PS), a solid waste from pulp and paper industry, was investigated as a feedstock for acetone-butanol-ethanol (ABE) production by simultaneous saccharification and fermentation (SSF). ABE fermentation of paper sludge by Clostridium acetobutylicum required partial removal of ash in PS to enhance its enzymatic digestibility. Enzymatic hydrolysis was found to be a rate-limiting step in the SSF. A total of 16.4-18.0g/L of ABE solvents were produced in the SSF of de-ashed PS with solid loading of 6.3-7.4% and enzyme loading of 10-15FPU/g-glucan, and the final solvent yield reached 0.27g/g sugars. No pretreatment and pH control were needed in ABE fermentation of paper sludge, which makes it an attractive feedstock for butanol production. The results suggested utilization of paper sludge should not only consider the benefits of buffering effect of CaCO3 in fermentation, but also take into account its inhibitory effect on enzymatic hydrolysis. PMID:26562687

  18. Anaerobic treatment of cellulose bleach plant wastewater: chlorinated organics and genotoxicity removal

    OpenAIRE

    T. R. Chaparro; E. C. Pires

    2011-01-01

    This study assessed the removal efficiency of organic matter and how it relates to the decrease of toxic and mutagenic effects when an anaerobic reactor is used to treat the bleaching effluent from two kraft pulp mills. Parameters such as COD (chemical oxygen demand), DOC (dissolved organic carbon), AOX (adsorbable organic halogen), ASL (acid soluble lignin), color, chlorides, total phenols and absorbance values in the UV-VIS spectral region were measured. The acute and chronic toxicity and g...

  19. BLEACHING EUCALYPTUS PULPS WITH SHORT SEQUENCES

    OpenAIRE

    Flaviana Reis Milagres; Jorge Luiz Colodette; Marcos Sousa Rabelo; Danila Morais de Carvalho

    2011-01-01

    Eucalyptus spp kraft pulp, due to its high content of hexenuronic acids, is quite easy to bleach. Therefore, investigations have been made attempting to decrease the number of stages in the bleaching process in order to minimize capital costs. This study focused on the evaluation of short ECF (Elemental Chlorine Free) and TCF (Totally Chlorine Free) sequences for bleaching oxygen delignified Eucalyptus spp kraft pulp to 90% ISO brightness: PMoDP (Molybdenum catalyzed acid peroxide, chlorine d...

  20. Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill

    Directory of Open Access Journals (Sweden)

    María Graciela Aguayo

    2012-12-01

    Full Text Available Tension (TW and opposite wood (OW of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively. The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EOD1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.

  1. Assessment of Population Status for a White Sucker (Catostomus commersoni) Population Exposed to Bleached Kraft Pulp Mill Effluent

    Science.gov (United States)

    Credible ecological risk assessments often need to include analysis of population-level impacts. In the present study, a predictive model was developed to translate changes in the fecundity and the age structure of a breeding population of white sucker (Catostomus commersoni) co...

  2. Evaluation of opportunities for heat integration of biomass-based Fischer–Tropsch crude production at Scandinavian kraft pulp and paper mill sites

    International Nuclear Information System (INIS)

    This study investigates heat integrated production of FT (Fischer–Tropsch) crude, where excess heat from the FT crude plant is delivered to a typical Scandinavian pulp and paper mill that produces fine paper. The sizes of FT crude plants are quantified, when the amount of excess heat from the FT plant exactly matches the heating demand otherwise satisfied by the bark boiler at the mill, considering a number of development pathways at the mill, including various degrees of steam savings and biorefinery options, such as lignin extraction. Performance of integrated production is compared with that of an FT stand-alone plant on the basis of wood fuel-to-FT crude efficiency, GHG (greenhouse gas) emissions balances and FT crude production cost. The results show that there exists a heat integration opportunity for an FT crude plant ranging from 0 up to 350 MW (LHV) of wood fuel depending on the development pathway for the mill. The results indicate higher overall efficiency and a generally lower production cost for the heat integrated, co-located production. Heat integrated production has a larger potential to contribute to GHG emission mitigation, assuming a future generation of grid electricity emitting equal to or less than an NGCC (natural gas combined cycle) power plant. - Highlights: • We investigate opportunities for heat integrated FT crude production at a mill. • Typical kraft pulp and paper mills have a potential for heat integrated production. • We compare the heat integrated production with stand-alone FT crude production. • Higher efficiency and lower production cost for heat integrated production. • Reduction of GHG emissions is strongly dependent on grid electricity emissions

  3. Integration of a kraft pulping mill into a forest biorefinery: pre-extraction of hemicellulose by steam explosion versus steam treatment.

    Science.gov (United States)

    Martin-Sampedro, Raquel; Eugenio, Maria E; Moreno, Jassir A; Revilla, Esteban; Villar, Juan C

    2014-02-01

    Growing interest in alternative and renewable energy sources has brought increasing attention to the integration of a pulp mill into a forest biorefinery, where other products could be produced in addition to pulp. To achieve this goal, hemicelluloses were extracted, either by steam explosion or by steam treatment, from Eucalyptus globulus wood prior to pulping. The effects of both pre-treatments in the subsequent kraft pulping and paper strength were evaluated. Results showed a similar degree of hemicelluloses extraction with both options (32-67% of pentosans), which increased with the severity of the conditions applied. Although both pre-treatments increased delignification during pulping, steam explosion was significantly better: 12.9 kappa number vs 22.6 for similar steam unexploded pulps and 40.7 for control pulp. Finally, similar reductions in paper strength were found regardless of the type of treatment and conditions assayed, which is attributed to the increase of curled and kinked fibers. PMID:24368272

  4. STUDIES ON XYLANASE AND LACCASE ENZYMATIC PREBLEACHING TO REDUCE CHLORINE-BASED CHEMICALS DURING CEH AND ECF BLEACHING

    Directory of Open Access Journals (Sweden)

    Vasanta V. Thakur,

    2012-02-01

    Full Text Available The biobleaching efficiency of xylanase and laccase enzymes was studied on kraft pulps from wood and nonwood based raw materials employed in the Indian paper industry. Treatment of these pulps with xylanase enzyme could result in improved properties, showing 2.0% ISO gain in pulp brightness and/or reducing the demand of chlorine-based bleach chemicals by up to 15% with simultaneous reduction of 20 to 25% in AOX generation in bleach effluents. Further, mill-scale trial results revealed that enzymatic prebleaching can be successfully employed with xylanases to reach the same bleach boosting efficacy. Laccase bleaching was also studied on hardwood pulp at a pH around 8.0, where most of the pulp mills in India are operating, in contrast to earlier studies on laccase enzyme bleaching, which were conducted at acidic pHs, i.e. 4.0 to 5.0. In case of laccase bleaching, interesting results were found wherein a bleach-boosting effect was observed even at pH 8.0. Further studies carried out with HOBT as mediator in comparison to the commonly used and expensive ABTS laccase mediator system (LMS resulted in improvement of the bleaching efficiency with reduction in demand of chlorine dioxide by more than 35%. Potential for further reduction was indicated by the brightness gain, when compared with a control using the DE(pD bleach sequence.

  5. Recycling of bleach plant filtrates by electrodialysis removal of inorganic non-process elements.; TOPICAL

    International Nuclear Information System (INIS)

    Water use in the pulp and paper industry is very significant, and the U.S. pulp and paper industries as well as other processing industries are actively pursuing water conservation and pollution prevention by in-process recycling of water. Bleach plant effluent is a large portion of the water discharged from a typical bleached kraft pulp mill. The recycling of bleach plant effluents to the kraft recovery cycle is widely regarded as an approach to low effluent bleached kraft pulp production. The focus of this work has been on developing an electrodialysis process for recycling the acidic bleach plant effluent of bleached Kraft pulp mills. Electrodialysis is uniquely suited as a selective kidney to remove non-process elements (NPEs) from bleach plant effluent before they reach the chemical recovery cycle. Using electrodialysis for selective NPE removal can prevent the problems caused by accumulation of inorganic NPEs in the pulping cycle and recovery boiler. In this work, acidic bleach plant filtrates from three mills using different bleaching sequences based on chlorine dioxide were characterized. The analyses showed no fundamental differences in the inorganic NPE composition or other characteristics among these filtrates. The majority of total dissolved solids in the effluents were found to be inorganic NPEs. Chloride and nitrate were present at significant levels in all effluent samples. Sodium was the predominant metal ion, while calcium and magnesium were also present at considerable levels. The feasibility of using electrodialysis to selectively remove inorganic NPEs from the acidic bleach effluent was successfully demonstrated in laboratory experiments with effluents from all these three mills. Although there were some variations in these effluents, chloride and potentially harmful cations, such as potassium, calcium, and magnesium, were removed efficiently from the bleach effluents into a small-volume, concentrated purge stream. This effective removal of

  6. OZONE BLEACHING AT NEUTRAL PH – A NEW CONCEPT

    OpenAIRE

    Fernando Carvalho; Denis Asbahr; Antonio A. R. Godoy; Jorge Luiz Colodette

    2010-01-01

    The effect of medium consistency ozone stage pH was evaluated for brown and oxygen delignified eucalyptus kraft pulp samples obtained from VCP - Luiz Antônio pulp mill. These samples were used as such or previously treated with the hot acid stage (A). The main objective of this study was to determine the viability of increasing the ozone stage pH aiming at decreasing bleaching variable costs. The ozone stage was studied in the pH range of 2.5-9.0, taking into account some important variables ...

  7. Evaluation of the use of powdered activated carbon in membrane bioreactor for the treatment of bleach pulp mill effluent.

    Science.gov (United States)

    Amaral, Míriam C S; Lange, Liséte C; Borges, Cristiano P

    2014-09-01

    In this paper, the use of powered activated carbon (PAC) in membrane bioreactor (MBR) employed in the treatment of bleach pulp mill effluents was evaluated. The MBR was operated with hydraulic residence time of 9.5 h and PAC concentration of 10 g/L. The addition of PAC to the MBR reduced the average concentration of chemical oxygen demand (COD) in the permeate from 215 mg/L (82% removal efficiency) to 135 mg/L (88% removal efficiency), producing an effluent that can be reused on bleaching stage. Moreover, the addition of PAC to the MBR resulted in the reduction in applied pressure and provided a more stable operation during the monitoring period. This occurrence was probably due to the increase of critical flux after the addition of PAC. The fouling mechanism was investigated and the results showed that controlling the concentration of soluble microbial products (SMP) and extracellular polymeric substance (EPS) by using PAC and keeping the operational flux below critical flux is of major importance for MBR operational sustainability. PMID:25327019

  8. High-rate anaerobic co-digestion of kraft mill fibre sludge and activated sludge by CSTRs with sludge recirculation.

    Science.gov (United States)

    Ekstrand, Eva-Maria; Karlsson, Marielle; Truong, Xu-Bin; Björn, Annika; Karlsson, Anna; Svensson, Bo H; Ejlertsson, Jörgen

    2016-10-01

    Kraft fibre sludge from the pulp and paper industry constitutes a new, widely available substrate for the biogas production industry, with high methane potential. In this study, anaerobic digestion of kraft fibre sludge was examined by applying continuously stirred tank reactors (CSTR) with sludge recirculation. Two lab-scale reactors (4L) were run for 800days, one on fibre sludge (R1), and the other on fibre sludge and activated sludge (R2). Additions of Mg, K and S stabilized reactor performance. Furthermore, the Ca:Mg ratio was important, and a stable process was achieved at a ratio below 16:1. Foaming was abated by short but frequent mixing. Co-digestion of fibre sludge and activated sludge resulted in more robust conditions, and high-rate operation at stable conditions was achieved at an organic loading rate of 4g volatile solids (VS)L(-1)day(-1), a hydraulic retention time of 4days and a methane production of 230±10NmL per g VS. PMID:27453288

  9. A comparison of kraft, PS, kraft-AQ and kraft-NaBH4 pulps of Brutia pine.

    Science.gov (United States)

    Copur, Y; Tozluoglu, A

    2008-03-01

    The aim of this work was to study the effect of adding PS, AQ and NaBH(4) into kraft pulping with special attention given to NaBH(4). Kraft, kraft-AQ, PS, and kraft-NaBH(4) pulps were produced under the same cooking conditions and the pulps produced were compared in terms of pulp and paper properties. Kraft method was modified by adding 0.1% AQ, 4% PS and 2% and 4% NaBH(4) and the resultant pulps displayed an increase in pulp yield and reduction in both kappa number and screening rejects. On the other hand, there observed an increase in both pulp yield and kappa number when the kraft was modified to PS method. The benefits of NaBH(4) addition into kraft pulping was a significant reduction in kappa number and screening rejects and a significant increase in pulp yield. The most notable outcome of NaBH(4) was 66.6% increase in pulp brightness when 4% NaBH(4) was added into kraft pulping. Of unrefined pulps, unrefined kraft pulp displayed the highest strength of pulp, which is described as tear index at a constant tensile index. Of refined pulps, kraft-AQ showed the highest pulp strength when refined to 6000 and 12,000 revs in PFI mill. PMID:17531474

  10. WOOD BASIC DENSITY EFFECT OF Eucalyptus grandis x Eucalyptus urophylla CLONES ON BLEACHED PULP QUALITY

    Directory of Open Access Journals (Sweden)

    Sheila Rodrigues dos Santos

    2010-08-01

    Full Text Available The study analyzed the wood basic density effect in two Eucalyptus grandis x Eucalyptus urophylla hybrid clones (440 kg/m3 e 508 kg/m3 on bleached pulp quality (fiber dimensions and physical-mechanical properties. The woods performance on pulping, bleaching and beating results were analyzed. The Kraft pulping was carried out in forced circulation digester in order to obtain 17±1 kappa number targets. The pulps were bleached to 90±1 using delignification oxygen and D0EOPD1 bleaching sequence. Bleached pulp of low basic density clone showed, significantly, lowest revolutions number in the PFI mill to reach tensile index of 70 N.m/g, low Schopper Riegler degree and generated sheets with higher values to bulk and opacity. These characteristics and properties allow concluding that bleached pulp of low basic density clone was the most indicated to produce printing and writing sheets. The bleached pulp of high basic density clone showed higher values of bulk and capillarity Klemm and lower water retention value when analyzed without beating. The bleached pulp of high basic density clone showed more favorable characteristics to the production of tissue papers.

  11. Mineral phases of green liquor dregs, slaker grits, lime mud and wood ash of a Kraft pulp and paper mill

    International Nuclear Information System (INIS)

    Four residues generated in a Kraft, pulp and paper plant, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimmetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. Emphasis was given on the identification of the mineral components of each material. The green liquor dregs and the lime mud contain Calcite and Gipsite. The slaker grits contains Calcite, Portlandite, Pirssonite, Larnite and Brucite. The Calcite phase, present in the dregs and in the lime mud, has small amounts of magnesium replacing calcium. The wood ash contains Quartz as the major crystalline mineral phase

  12. Hydrothermal carbonization of pulp mill streams.

    Science.gov (United States)

    Wikberg, Hanne; Ohra-Aho, Taina; Honkanen, Mari; Kanerva, Heimo; Harlin, Ali; Vippola, Minnamari; Laine, Christiane

    2016-07-01

    The progress of the conversion, the yield, the structure and the morphology of the produced carbonaceous materials as a function of time were systematically studied with pyrolysis-GC/FID and FESEM microscope. The conversion of galactoglucomannan, bleached kraft pulp and TEMPO oxidized cellulose nanofibrils followed the reaction route of glucose being slower though with fibrous material, higher molar mass and viscosity. The conversion of kraft lignin was minor following completely different reaction route. Carbonaceous particles of different shape and size were produced with yields between 23% and 73% after 4h with being higher for lignin than carbohydrates. According to the results, potential pulp mill streams represent lignocellulosic resources for generation of carbonaceous materials. PMID:27107340

  13. Biodegradability and toxicity assessment of bleach plant effluents treated anaerobically.

    Science.gov (United States)

    Chaparro, T R; Botta, C M; Pires, E C

    2010-01-01

    As part of an experimental project on the treatment of bleach plant effluents the results of biodegradability and toxicity assessment of effluents from a bench-scale horizontal anaerobic immobilized bioreactor (HAIB) are discussed in this paper. The biodegradability of the bleach plant effluents from a Kraft pulp mill treated in the HAIB was evaluated using the modified Zahn-Wellens test. The inoculum came from a pulp mill wastewater treatment plant and the dissolved organic carbon (DOC) was used as the indicator of organic matter removal. The acute and chronic toxicity removal during the anaerobic treatment was estimated using Daphnia similis and Ceriodaphnia silvestrii respectively. Moreover, the evaluation of chromosome aberrations (CA), micronucleus frequencies (MN) and mitotic index (IM) in Allium cepa cells were used as genotoxicity indicators. The results indicate that the effluents from the anaerobic reactor are amenable to aerobic polishing. Acute and chronic toxicity were reduced by 90 and 81%, respectively. The largest CA and MN incidence in the meristematic cells of A. cepa were observed after exposure to the raw bleach plant effluent. The HAIB was able to reduce the acute and chronic toxicity as well as chromosome aberrations and the occurrence of micronucleus. PMID:20861545

  14. Application of Biochemical Markers for Population Level Assessment of a White Sucker (Catostomus commersoni) Population Exposed to Bleached Kraft Pulp Mill Effluent

    Science.gov (United States)

    A need in ecological risk assessment is an approach that can be used to link chemically-induced alterations in molecular and biochemical endpoints to adverse outcomes in whole organisms and populations. A predictive population model was developed to translate changes in fecundit...

  15. Response of white sucker (Catostomus commersoni) to pulp and paper mill effluent in the Androscoggin River, Maine, USA.

    Science.gov (United States)

    Mower, Barry F; Munkittrick, Kelly R; McMaster, Mark E; Van Beneden, Rebecca J

    2011-01-01

    Adverse effects of pulp and paper mill effluent on fish populations have been well documented in many countries over the last two decades. Some of the initial studies were at mills with conventional chlorine bleaching and no secondary effluent treatment. Following installation of secondary treatment, changes in bleaching technology to elemental chlorine-free bleaching, and other process changes, adverse effects on fish were reduced or eliminated at some mills. Because no two mills are exactly alike, it is difficult to predict adverse impacts of any given mill on fish populations. In 1994, a study of female white sucker (Catostomus commersoni) in the Androscoggin River, Maine, USA, showed induction of mixed function oxidase, reductions in gonad size and plasma estradiol, and an increase in plasma testosterone in fish downstream of discharges from three large bleached kraft pulp and paper mills, and host community municipal sewage treatment plants (STP). After all three mills switched to elemental chlorine-free bleaching in the late 1990s, studies from 2001 to 2003 found that the pattern of reproductive impacts on white sucker populations measured in 1994 was not repeated. In addition, population estimates of white sucker from 2002 to 2003 using mark-recapture techniques found that densities and biomass were well within the range of those of a reference population, and of those reported in the literature for unimpacted populations. Detailed studies immediately above and below each mill/sewage treatment plant showed no evidence of reproductive effects. However, a clear pattern of eutrophication was noted, which increased cumulatively downstream below each mill/STP. PMID:20872897

  16. Pollution prevention for the kraft pulp and paper industry

    Energy Technology Data Exchange (ETDEWEB)

    1992-09-01

    The document is an annotated bibliography of publications related to pollution prevention in the Kraft segment of the pulp and paper industry. It is organized by process area as follows: chip preparation, chemical pulping, pulp washing, bleaching, chemical recovery, recausticizing, power generation, wastewater treatment, papermaking, and general plant. The document contains 269 citations.

  17. The metal binding properties of kraft lignin

    OpenAIRE

    Waltersson, Johanna

    2009-01-01

    There is a strong driving force to increase the competitiveness of the pulping industry by finding new business opportunities. In this context full utilisation of the wood raw material used in conventional pulping mills is of vital importance. One focus area is to increase the utilisation areas of lignin. LignoBoost is a new method to obtain kraft lignin of high purity. The aim of the project was to investigate and increase the ability of LignoBoost kraft lignins to bind metals in aqueous sol...

  18. Kraft kasvatab Nordea haaret Eestis / Vahur Kraft

    Index Scriptorium Estoniae

    Kraft, Vahur, 1961-

    2006-01-01

    Avades lähikuudel seitse uut harukontorit, toimub Nordea Panga juhatuse esimehe Vahur Krafti juhtimisel suurim laienemine ettevõtte ajaloos. Ühtlasi peab Kraft jätkuvalt oluliseks internetipanga ja teiste elektrooniliste teenuste arendamist

  19. Anti-scaling agents in kraft pulping

    Directory of Open Access Journals (Sweden)

    Felissia, F. E.

    2007-05-01

    Full Text Available Scale formation in the digester during kraft pulping represents a great problem in pulp mills. Scaling reduces pulping control and efficiency, increasing energy costs and leading to cleaning breakdowns, with subsequent losses in productivity. The kraft process promotes CaCO3 scaling due to high calcium ion and carbonate concentrations, as well as high alkalinity and temperature levels, which increase the speed with which liquors reach a state of supersaturation. This work examines the action of diethylene triamine penta(methylene phosphonic acid (DTPMPA, either alone or combined with commercial anti-scaling agents, as an inhibitor of calcium carbonate precipitation in the kraft pulping of Pinus taeda. The theoretical amount of calcium deposited in the digester was obtained by mass balance. Soluble calcium was stable throughout cooking when using the phosphonates alone or combined with anti-scaling agents. When adding only DTPMPA, calcium stays in the pulp, rather than forming deposits.

  20. Survey of receiving-water environmental impacts associated with discharges from pulp mills; 2: Gonad size, liver size, hepatic erod activity and plasma sex steroid levels in white sucker

    Energy Technology Data Exchange (ETDEWEB)

    Munkittrick, K.R.; Servos, M.R. (Department of Fisheries and Oceans, Burlington, Ontario (Canada). Great Lakes Lab. for Fisheries and Aquatic Sciences); Van Der Kraak, G.J.; McMaster, M.E. (Univ. of Guelph, Ontario (Canada). Dept. of Zoology); Portt, C.B. (C. Portt and Associates, Guelph, Ontario (Canada)); Heuvel, M.R. van den (Univ. of Waterloo, Ontario (Canada). Dept. of Biology)

    1994-07-01

    Fish collected from the receiving areas of 12 Canadian pulp mills were examined, including sites receiving effluent from kraft mills using chlorine as well as sulfite mills. Field collections included sampling of receiving water for chemistry and toxicity testing, and sampling of local fish for organ weights, hepatic MFO (ethoxyresorufin-O-deethylase, EROD) activity, plasma steroid levels, and levels of liver dioxins. The main objectives of this study were to determine whether the discharge of effluent from pulp mills to sites other than Jackfish Bay was associated with physiological or biochemical disruptions in wild fish, whether there was any correlation between waste treatment and the presence of biological responses in wild fish, and whether there was any association between the use of chlorine as a bleaching agent and these responses. Although white sucker collected near bleached-kraft mills exhibited the highest EROD induction and dioxin levels, elevated enzyme activity was observed in fish from sites that did not use chlorine, and depressions in plasma sex steroid levels was not correlated with the level of EROD activity. The absence of chlorine bleaching or the presence of secondary treatment did not eliminate responses in fish, including decreased circulating levels of sex steroids, decreased gonadal size, and increase liver size. This survey has shown that (a) induction of hepatic EROD enzymes and depressions of plasma sex steroid levels during gonadal growth are found downstream of several pulp mills; (b) these changes are seen at some mills without chlorine bleaching and at mills that have secondary treatment; (c) substantial dilutions of nontoxic effluent do not appear to remove these responses; (d) the dominant factor determining the presence or absence of responses appeared to be dilution level; and (e) lab toxicity tests on invertebrates, rainbow trout, and fat-head minnows could not predict the presence of these responses in wild fish.

  1. OZONE BLEACHING AT NEUTRAL PH – A NEW CONCEPT

    Directory of Open Access Journals (Sweden)

    Fernando de Carvalho

    2010-08-01

    Full Text Available The effect of medium consistency ozone stage pH was evaluated for brown and oxygen delignified eucalyptus kraft pulp samples obtained from VCP - Luiz Antônio pulp mill. These samples were used as such or previously treated with the hot acid stage (A. The main objective of this study was to determine the viability of increasing the ozone stage pH aiming at decreasing bleaching variable costs. The ozone stage was studied in the pH range of 2.5-9.0, taking into account some important variables which affect ozone bleaching: (1 pulp kappa number entering the ozone stage, (2 reactivity of ozone towards lignin versus hexenuronic acids (HexA´s, (3 pulp treatments prior to ozone stage (acid hydrolysis, and (4 pulp treatments after the ozone stage (extraction or a chlorine dioxide stage.  Therefore, the impact of ozone stage pH was investigated in bleaching process such as Z/DEop vs AZ/DEop, Z/DEopD vs AZ/DEopD, Z/E vs AZ/E. The results were interpreted based on ozone stage efficiency and selectivity, and overall bleaching performance measured by the total bleaching chemical consumption required to achieve full brightness, pulp quality and environmental impact. It was concluded that the increase of ozone stage pH from 2.5 to 7.0 has a slightly negative impact on the efficiency and selectivity, measured after Z/DEop sequence, but this effect is not expressive in the end of Z/DEopD bleaching sequence. The increase of ozone stage pH from 2.5 to 7.0 in the sequence Z/DEopD is cost-effective at industrial level because it represents expressive reduction of sulphuric acid and caustic soda demand for pH control in the bleaching plant. These gain areas achieved without any significant changes in pulp quality and effluent load discharge. Nevertheless, the increase of ozone stage pH from 2.5 to 7.0 has a very high negative impact on the efficiency and selectivity for the Z/E and AZ/E processes and it is not recommended in such cases.

  2. Understanding the Nature and Reactivity of Residual Lignin for Improved Pulping and Bleaching Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Yuan-Zong Lai

    2001-11-30

    One of the most formidable challenges in kraft pulping to produce bleached chemical pulps is how to effectively remove the last 5-10% of lignin while maintaining the fiber quality. To avoid a severe fiber degradation, kraft pulping is usually terminated in the 25-30 kappa number range and then followed by an elementally chlorine free (ECF) or a totally chlorine free (TCF) bleaching sequence to reduce the environmental impacts.

  3. Waste fatty acid addition to black liquor to decrease tall oil soap solubility and increase skimming efficiency in kraft mills pulping mountain pine beetle-infested wood

    Energy Technology Data Exchange (ETDEWEB)

    Uloth, V.; Guy, E. [FPInnovations, Prince George, BC (Canada). PAPRICAN Div.; Shewchuk, D. [Cariboo Pulp and Paper, Quesnel, BC (Canada); Van Heek, R. [Aker Kvaerner, Vancouver, BC (Canada)

    2009-07-01

    This paper presented the results of tests conducted to determine if the addition of waste fatty acids from vegetable oil processing might decrease tall oil soap solubility in pine-beetle impacted wood from British Columbia (BC). The soap recovery and tall oil production at BC mills has fallen by 30 to 40 percent in recent years due to the pulping of high proportions of grey-stage beetle-impacted wood. Full-scale mill tests were conducted over a 4-day period. The study showed that the addition of tall oil fatty acids or waste fatty acids from vegetable oil processing could decrease tall oil soap solubility and increase the soup skimming efficiency in mills pulping a large percentage of grey stage beetle-infested wood. The addition of fatty acids increased tall oil soap skimming efficiency from 50.2 percent in the baseline tests to 71.8 percent based on the total soap available, and from 76.7 percent in the baseline tests to 87.5 percent based on insoluble soap only. The economic analyses indicated that waste fatty acid addition could be economical when natural gas and oil prices are high. 4 tabs., 9 figs.

  4. Coral Bleaching

    OpenAIRE

    Brinch, Anna; Hemmingsen, Sofie K. Møhlenfeldt; Rosenquist, Camilla; Tangaa, Stine Rosendal

    2010-01-01

    This review scrutinises the different cellular mechanisms and environmental stressors that lead to bleaching and discuss the numerous effects of these. Coral bleaching is characterized by corals losing their symbiotic zooxanthellae. Different environmental stressors, e.g. elevated sea temperatures, irradiance, changing salinity and increasing atmospheric CO2 induce damage in multiple sites of the photosynthetic apparatus of the zooxanthellae, leading to bleaching. Reactive oxygen species ...

  5. Influence of xilanase treatment on Pinus pinaster kraft pulp

    OpenAIRE

    Spiridon, Iuliana; Duarte, Ana Paula; Curto, Joana

    2010-01-01

    In Portugal, pulp and paper industry uses especially two wood species, Eucalyptus globules and Pinus pinaster. The second species gives pulps with low bleachability (compared with other common softwood species, like Pinus silvester), utilised for packaging papers. It is known that treatments with different hydrolytic enzymes could improve the bleaching capacity of softwood pulp. That is why, xylanases were used to improve Pinus pinaster kraft pulp characteristics. The enzymatic hydrolysis imp...

  6. DESORPTION OF METAL IONS FROM KRAFT PULPS. PART 1. CHELATION OF HARDWOOD AND SOFTWOOD KRAFT PULP WITH EDTA

    OpenAIRE

    Kim Granholm; Leo Harju; Ari Ivaska

    2010-01-01

    Chelation of unbleached and oxygen bleached hardwood and softwood kraft pulps with EDTA was studied. The main focus was on the desorption of magnesium, manganese, and iron due to their impact in TCF-bleaching. Desorption of other metal ions present were also studied in order to get an over-all estimation of the metal ion concentrations and their desorption during chelation. By using the concept of side reaction coefficients, an estimation of the chelating strength of EDTA at different pH can ...

  7. Yield Improvement and Energy Savings Uing Phosphonates as Additives in Kraft pulping

    Energy Technology Data Exchange (ETDEWEB)

    Ulrike W. Tschirner; Timothy Smith

    2007-03-31

    Project Objective: Develop a commercially viable modification to the Kraft process resulting in energy savings, increased yield and improved bleachability. Evaluate the feasibility of this technology across a spectrum of wood species used in North America. Develop detailed fundamental understanding of the mechanism by which phosphonates improve KAPPA number and yield. Evaluate the North American market potential for the use of phosphonates in the Kraft pulping process. Examine determinants of customer perceived value and explore organizational and operational factors influencing attitudes and behaviors. Provide an economic feasibility assessment for the supply chain, both suppliers (chemical supply companies) and buyers (Kraft mills). Provide background to most effectively transfer this new technology to commercial mills.

  8. Enzymes improve ECF bleaching of pulp

    OpenAIRE

    Lachenal, D.; Bajpai, P. K.; S P Mishra; Sharma, N.; Anand, A; Bajpai, P.

    2006-01-01

    The delignification efficiency of different laccase enzymes was examined on the eucalyptus Kraft pulp. The laccase enzyme from Trametes versicolor showing the highest delignification efficiency was selected and used in the elemental chlorine-free bleaching sequence for improving the pulp bleachability. An appreciable reduction in chlorine dioxide consumption was also obtained. Further reduction in chlorine dioxide consumption was obtained when the same laccase treated pulp was subjected to an...

  9. Peroxy bleaches

    Energy Technology Data Exchange (ETDEWEB)

    Carson, P.A. [Unilever Research, Port Sunlight Laboratory (United States) and Chemistry Department, University of Manchester, Institute of Science and Technology (United States)]. E-mail: pcarson2005@aol.com; Fairclough, C.S. [Unilever Research, Port Sunlight Laboratory (United States); Mauduit, C. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States); Colsell, M. [Chemistry Department, University of Manchester, Institute of Science and Technology (United States)

    2006-08-25

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing.

  10. Peroxy bleaches

    International Nuclear Information System (INIS)

    Fabric laundering is now a sophisticated chemical process involving a variety of operations including bleaching. The chemistry of peroxy bleaches is described including the use of novel organic compounds to provide effective bleaching at the lower temperatures of modern wash cycles. The instability of peroxy compounds is illustrated using cameo case histories to relate theory and practice. Techniques available for determining their thermochemistry are summarised. A model is provided for hazard and risk assessment of development projects in general (particularly those involving new molecules, processes or formulations) from ideas phase through exploratory laboratory investigations to pilot plant scale-up and eventual manufacture and commercial exploitation. This paper is a prelude to Part 2, which describes the determination of thermodynamic and kinetic properties of peroxy bleaches and discusses the implication of the results in terms of precautions for their safe storage and incorporation into detergent formulations during processing

  11. Combustion properties of kraft black liquors; Mustalipeaen koostumuksen vaikutus lipeaen poltto-ominaisuuksiin

    Energy Technology Data Exchange (ETDEWEB)

    Alen, R.; Siistonen, H.; Heikkinen, T.; Malkavaara, P. [Jyvaeskylae Univ. (Finland)

    1996-12-01

    The aim of this work is to study the combustion properties of kraft black liquors from modified cooking. Both the industrial and laboratory-made black liquors are included. In addition, changes in the combustion properties of the spent liquors obtained by mixing prior to combustion different chlorine-free bleach liquors with black liquor are studied. (author)

  12. BLEACHING EUCALYPTUS PULPS WITH SHORT SEQUENCES

    Directory of Open Access Journals (Sweden)

    Flaviana Reis Milagres

    2011-03-01

    Full Text Available Eucalyptus spp kraft pulp, due to its high content of hexenuronic acids, is quite easy to bleach. Therefore, investigations have been made attempting to decrease the number of stages in the bleaching process in order to minimize capital costs. This study focused on the evaluation of short ECF (Elemental Chlorine Free and TCF (Totally Chlorine Free sequences for bleaching oxygen delignified Eucalyptus spp kraft pulp to 90% ISO brightness: PMoDP (Molybdenum catalyzed acid peroxide, chlorine dioxide and hydrogen peroxide, PMoD/P (Molybdenum catalyzed acid peroxide, chlorine dioxide and hydrogen peroxide, without washing PMoD(PO (Molybdenum catalyzed acid peroxide, chlorine dioxide and pressurized peroxide, D(EPODP (chlorine dioxide, extraction oxidative with oxygen and peroxide, chlorine dioxide and hydrogen peroxide, PMoQ(PO (Molybdenum catalyzed acid peroxide, DTPA and pressurized peroxide, and XPMoQ(PO (Enzyme, molybdenum catalyzed acid peroxide, DTPA and pressurized peroxide. Uncommon pulp treatments, such as molybdenum catalyzed acid peroxide (PMo and xylanase (X bleaching stages, were used. Among the ECF alternatives, the two-stage PMoD/P sequence proved highly cost-effective without affecting pulp quality in relation to the traditional D(EPODP sequence and produced better quality effluent in relation to the reference. However, a four stage sequence, XPMoQ(PO, was required to achieve full brightness using the TCF technology. This sequence was highly cost-effective although it only produced pulp of acceptable quality.

  13. Anaerobic treatment of pulp and paper mill effluents--status quo and new developments.

    Science.gov (United States)

    Habets, Leo; Driessen, Willie

    2007-01-01

    Since the early 1980s, anaerobic treatment of industrial effluents has found widespread application in the pulp and paper industry. Over 200 installations are treating a large variety of different pulp and paper mill effluents. Amongst various anaerobic systems the UASB and IC are the most applied anaerobic reactor systems. Anaerobic treatment is well feasible for effluents originated from recycle paper mills, mechanical pulping (peroxide bleached), semi-chemical pulping and sulphite and kraft evaporator condensates. The advantages of anaerobic pre-treatment are (1) net production of renewable energy (biogas), (2) minimized bio-solids production, (3) minimal footprint and (4) reduced emission of greenhouse gases. Via in-line application of anaerobic treatment in closed circuits (paper kidney technology) further savings on cost of fresh water intake and effluent discharge levies are generated. PMID:17486855

  14. The effect of introducing ozone in elemental chlorine free bleaching of eucalyptus kraft pulp%桉木硫酸盐浆ECF漂白引入臭氧漂白的效果

    Institute of Scientific and Technical Information of China (English)

    刘红峰

    2015-01-01

    ZDED and DEDD sequences were applied on an oxygen-delignified eucalyptus (mixture of E.grandisand E.saligna) kraft pulp from Brazil. When ZDED and DEDD were compared, the displacement ratio calculated as the quantity of pure chlorine dioxide replaced by 1 kg ozone was found between 2.5 and 3.5 kg, as compared to 1.7 kg in theory—indicating that less wasting reactions occur in the ZDED sequence. The cellulose viscosity decreased substantially with the increase in the ozone charge (down to 50% at 0.8% ozone). Other typical characteristics of the ZDED pulps were easier beating, lower water retention value, higher proportion of kinked fibers, and lower wet zerospan breaking length (seen only at 0.8% ozone charge), as compared to DEDD. The viscosity loss due to the introduction of ozone in an elemental chlorine free sequence did not translate into a similar loss in strength. A comparison with the depolymerizing effect of cellulase suggests that the determining factoris not the extent of the drop in viscosity but rather the heterogeneity of the attack along the fibers. It is concluded that ozone oxidation of cellulose in the fibers would be rather homogeneous. Moreover, the appearance of morecurls and kinks would not be necessarily related to the viscosity loss. For example, a (2,2,6,6-tetramethylpiperidin-1-yl) oxidanyl (TEMPO) treated DEDD pulp, enriched in carboxyl groups, had more straight fibers than the original DEDD pulp, despite its lower viscosity. The presence of ionic groups would be a more important factor; the lower content in carboxyl groups in the ZDED pulps, compared to the DEDD pulps, could promote the easier formation of curl and kinks during the ZDED sequence.%巴西桉木浆(巨桉和柳桉)氧脱木素采用了ZDED和DEDD漂白工序.对比ZDED和DEDD漂白工序,计算出的置换率(1kg臭氧可代替的纯二氧化氯量)为2.5~3.5kg,而理论值为1.7kg,表明ZDED漂白工序中无效反应较少.随着臭氧用量的增加,纤维

  15. PROCESS FOR THE PRODUCTION OF DISSOLVING PULP FROM TREMA ORIENTALIS (NALITA BY PREHYDROLYSIS KRAFT AND SODA-ETHYLENEDIAMINE (EDA PROCESS

    Directory of Open Access Journals (Sweden)

    M. A. Quaiyyum

    2008-08-01

    Full Text Available This paper presents a preliminary study for the production of dissolving pulp from Trema orientalis (Nalita. Water prehydrolysis kraft and soda-ethylenediamine (EDA pulping for the production of dissolving pulp from T. orientalis was investigated. Prehydrolysis at 150 and 170 oC did not produce pulp with high α-cellulose content when using the kraft process. But addition of 0.25 % H2SO4 in prehydrolysis liquor increased the purity of the pulp with the sacrifice of pulp yield and viscosity. The soda-EDA process produced better pulp yield, kappa number, viscosity, and α-cellulose content as compared to the kraft process. Increasing EDA charge in the soda liquor increased pulping selectivity and α-cellulose content. Degraded cellulose (R18-R10 in soda-EDA pulp was lower than kraft pulp. But the bleachability of soda-EDA pulp was inferior as compared to kraft pulp in DED bleaching.

  16. The decontamination of bleaching effluent by pilot-scale solar Fenton process.

    Science.gov (United States)

    Wang, Zhaojiang; Chen, Kefu; Li, Jun; Mo, Lihuan

    2011-01-01

    A solar Fenton process was applied as post-treatment to selectively eliminate organic pollutants and toxicants in bleaching effluents of kraft pulp mills. Experiments were conducted to study the effect of system parameters (pH, initial concentration of H2O2, molar ratio of Fe2+/H2O2 and solar-UV irradiance) on the removals of chemical oxygen demand and colour. The results showed 92.8% of COD and 99.6% of colour were removed at pH 3.5, H2O2 30 mM/ L, Fe2+/H2O2 1:100, solar-UV irradiance 11070 mW/m2, reaction time 120 min. The first-order kinetic model was used to study the dependence of the reaction rate on solar-UV irradiance: a linear relationship was shown to exist between reaction rate constants and solar-UV irradiance. The results of gas chromatography mass spectrometry analysis showed that the toxicity of the bleaching effluents was mainly derived from the presence of mononuclear aromatics, polycyclic aromatic hydrocarbons and organochlorides, which were all degraded into harmless organic acids under the attack of hydroxyl radicals generated from the solar Fenton reaction. PMID:21879547

  17. Efeito do conteúdo e da natureza da lignina residual na eficiência e na seletividade do branqueamento com ozônio Effect of residual lignin content and nature on the efficiency and selectivity of ozone bleaching

    Directory of Open Access Journals (Sweden)

    Elenice Pereira Maia

    2003-04-01

    Full Text Available Neste estudo foram avaliados os efeitos do conteúdo e da natureza da lignina residual na eficiência e na seletividade do branqueamento com ozônio de polpa kraft convencional (kraft e pré-deslignificada com oxigênio (kraft-O. Constatou-se que a eficiência do branqueamento com ozônio se eleva com o aumento do conteúdo de lignina residual da polpa. O tratamento com ozônio é mais seletivo para polpas kraft-O, mas para um mesmo tipo de polpa a seletividade de branqueamento com ozônio se eleva com o aumento de lignina residual. A eficiência do branqueamento com ozônio aumenta com o teor de lignina fenólica na polpa, entretanto a seletividade é negativamente afetada pela presença destas estruturas.This study aimed to evaluate the effect of residual lignin content and nature on the efficiency and selectivity of ozone bleaching of conventional (kraft and oxygen delignified (kraft-O pulps. Ozone bleaching efficiency was found to be enhanced by increasing pulp residual lignin content. Ozone treatment is more selective for kraft-O pulps, but for a given type of pulp (kraft or kraft-O, ozone bleaching selectivity increases with increasing pulp lignin content. Ozone bleaching efficiency increases with increasing pulp lignin phenolic hydroxyl content whereas selectivity is negatively affected by these structures.

  18. The effects of pulp mill effluent on the sex steroid binding protein in white sucker (Catostomus commersoni) and longnose sucker (C catostomus).

    Science.gov (United States)

    Pryce-Hobby, A C; McMaster, M E; Hewitt, L M; Van Der Kraak, G

    2003-02-01

    The objective of this study was to characterize the effects of pulp mill effluent on the properties of the sex steroid binding protein (SBP) in the plasma of white sucker (Catostomus commersoni) and longnose sucker (C. catostomus). SBPs which specifically bind estradiol and testosterone with high affinity (k(D) approximately 3 nM) and low capacity (B(max) approximately 73-81 nM) were identified in both species. Subsequent studies determined if the properties of the SBP in white sucker exposed to bleached kraft mill effluent (BKME) at Terrace Bay, ON, and in longnose sucker exposed to BKME at Grande Prairie, AB. differed from appropriate reference fish. There were no effects of BKME exposure on the binding affinity (k(D)) of the SBP in either species, but there was a significant increase in the binding capacity (B(max)) of longnose sucker SBP exposed to BKME. The livers of nai;ve white sucker exposed to effluent at Terrace Bay or a bleached sulfite/groundwood mill in Edmundston, NB, rapidly accumulated compounds of differing hydrophobicity that bound to both the white sucker and goldfish (Carassius auratus) SBP. Conversely, there was reduced accumulation of SBP ligands in the bile of effluent-exposed fish. We have demonstrated that constituents present within pulp mill effluent bind to both the white sucker and goldfish SBP, and that native species residing downstream of pulp mill effluents may experience modifications in the properties of their SBP. PMID:12600684

  19. INVESTIGATION ON THE CAUSES OF EUCALYPTUS KRAFT PULP BRIGHTNESS REVERSION

    OpenAIRE

    Kátia M. M. Eiras; Jorge Luiz Colodette; Ana Márcia M. L. Carvalho

    2005-01-01

    Some high brightness eucalyptus Kraft pulps have shown poor brightness stability. In most cases, the causes have notbeen identified and permanent solutions have not been found. This work focused on evaluating the brightness stability profile of pulpsbleached by in sequences such as O(DC)(PO)DD, O(DC)(PO)DP, OD(PO)DD, OD(PO)DP, ODHT(PO)DD, ODHT(PO)DP, OA/D(PO)DD, OA/D(PO)DP, OAD(PO)DD and O(Ze)D(PO). Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to...

  20. Eucalyptus kraft pulp production: Thermogravimetry monitoring

    International Nuclear Information System (INIS)

    Highlights: → Thermogravimetric analysis can be used to monitor the pulping process in a pulp mill. → ECF bleaching process affects the crystalline cellulose volatilization. → The fibre size has an influence on composition and thermal behavior of pulp. - Abstract: Under oxidative environment the thermal degradation of lignocellulosic materials like wood or pulp is sensitive to slight composition changes. For this, in order to complement the chemical and X-ray diffraction results, thermogravimetric analyses (TGA) were used to monitor pulp production in a modern pulp mill. Runs were carried out on crude, oxygen delignified and bleached pulps from three eucalyptus woods from different species and geographical origins. Moreover, with the modeling of thermogravimetric data, it was possible to obtain an approximate composition of samples which includes crystalline and amorphous cellulose. TGA results show that pulping has an intensive effect on bulk lignin and hemicellulose, but it has limited influence on the removal of these substances when they are linked to cellulose microfibril. The stages of oxygen delignification and bleaching, based in chlorine dioxide and hydrogen peroxide, increase the crystalline cellulose volatilization rate. These changes are compatible with a more crystalline microfibril. The influence of the fibre size on pulp composition, crystallinity and thermal degradation behavior was observed.

  1. Influence of the chemical composition on the combustion properties of kraft black liquor; Mustalipeaen koostumuksen vaikutus lipeaen poltto-ominaisuuksiin

    Energy Technology Data Exchange (ETDEWEB)

    Alen, R.; Siistonen, H.; Malkavaara, P. [Jyvaeskylae Univ. (Finland). Inst. of Chemistry

    1997-10-01

    The aim of this work is to study the combustion properties of kraft black liquors from modified cooking. Both the industrial and laboratory-made black liquors are included. In addition, changes in the combustion properties of the spent liquors obtained by mixing prior to combustion different chlorine-free bleach liquors with black liquor are studied. (orig.)

  2. Kraft black liquor delivery systems

    Energy Technology Data Exchange (ETDEWEB)

    Adams, T.N.; Empie, H.L.; Obuskovic, N.; Spielbauer, T.M.

    1990-02-01

    Improvement of spray nozzles for black liquor injection into kraft recovery furnaces is expected to result from obtaining a controlled, well-defined droplet size distribution. Work this year has centered on defining the capabilities of commercial black liquor nozzles currently in use. Considerations of the observed mechanism of droplet formation suggest a major revision is needed in the theory of how droplets form from these nozzles. High resolution, high sensitivity video has been shown to be superior to flash x-ray as a technique for measuring the droplet size distribution as well as the formation history. An environmentally sound spray facility capable of spraying black liquor at temperatures up to normal firing conditions is being constructed before data acquisition continues. Preliminary correlations have been developed between liquor properties, nozzle design, and droplet size. Three aspects of nozzle design have been investigated: droplet size distribution, fluid sheet thickness, and flow and pressure drop characteristics. The standard deviation about the median droplet size for black liquor is nearly the same as the for a wide variety of other fluids and nozzle types. Preliminary correlation for fluid sheet thickness on the plate of a splashplate nozzle show the strong similarities of black liquor to other fluids. The flow and pressure drop characteristic of black liquor nozzle, follow a simple two-term relationship similar to other flow devices. This means that in routine mill operation of black liquor nozzles only the fluid acceleration in the nozzle is important, viscous losses are quiet small. 21 refs., 53 figs., 10 tabs.

  3. DETERMINATION OF KRAFT LIGNIN CONCENTRATIONS BY FTIR

    Institute of Scientific and Technical Information of China (English)

    VietHoang; K.LoiNguyen

    2004-01-01

    A fast and accurate method based on FTIR is developed for determining the lignin content and its characteristic bands in alkali solutions. The work consisted of two main parts: 1) establishing a predictive model and 2) determination of the accuracy of the model. The model was derived by applying the partial least squares algorithm for multivariate analyses to a set of spectrum data obtained from selected IR absorption regions in the range of 1600-900 cm-1. The model was tested with spent liquors obtained from commercial pulp mills. The accuracy of the predictive model is extremely high suitable for commercial applications, particularly for monitoring the dynamic response of modem kraft pulping processes.

  4. DETERMINATION OF KRAFT LIGNIN CONCENTRATIONS BY FTIR

    Institute of Scientific and Technical Information of China (English)

    Viet Hoang; K. Loi Nguyen

    2004-01-01

    A fast and accurate method based on FTIR is developed for determining the lignin content and its characteristic bands in alkali solutions. The work consisted of two main parts: 1) establishing a predictive model and 2) determination of the accuracy of the model. The model was derived by applying the partial least squares algorithm for multivariate analyses to a set of spectrum data obtained from selected IR absorption regions in the range of 1600 - 900 cm-1. The model was tested with spent liquors obtained from commercial pulp mills.The accuracy of the predictive model is extremely high suitable for commercial applications,particularly for monitoring the dynamic response of modern kraft pulping processes.

  5. Enzymes improve ECF bleaching of pulp

    Directory of Open Access Journals (Sweden)

    Lachenal, D.

    2006-07-01

    Full Text Available The delignification efficiency of different laccase enzymes was examined on the eucalyptus Kraft pulp. The laccase enzyme from Trametes versicolor showing the highest delignification efficiency was selected and used in the elemental chlorine-free bleaching sequence for improving the pulp bleachability. An appreciable reduction in chlorine dioxide consumption was also obtained. Further reduction in chlorine dioxide consumption was obtained when the same laccase treated pulp was subjected to an acid treatment after the extraction stage followed by the DEPD sequence. Elemental-chlorine free bleaching was also performed using the xylanase-laccase treated pulp. Xylanase treatment was incorporated to the laccase mediator system in the elemental-chlorine free bleaching both sequentially and simultaneously. The bleaching sequence DEPD followed and in both the cases, the reduction in chlorine dioxide consumption was greater in comparison to the control. The chlorine dioxide consumption was reduced further when xylanase-laccase treated pulp was given an additional acid treatment. The final pulp properties of the treated pulps were comparable to the control pulp.

  6. The impact of kappa number composition on eucalyptus kraft pulp bleachability

    OpenAIRE

    Costa, M. M.; Colodette, J.L.

    2007-01-01

    Consumption of chemicals during ECF bleaching of kraft pulp correlates reasonably well with kappa number, which measures with KMnO4 the total amount of oxidizable material in the pulp. However, the method does not distinguish between the oxidizable material in residual lignin and other structures susceptible to oxidation, such as hexenuronic acids (HexAs), extractives and carbonyl groups in the pulp. In this study an attempt is made to separate the main contributors to the kappa number in oxy...

  7. Alternative technique for evaluating yield loss in modern bleach plants

    Directory of Open Access Journals (Sweden)

    Dalton Longue Júnior

    2009-12-01

    Full Text Available In this study an alternative technique is presented and discussed for measuring yield loss based on the analysis of total organic carbon (TOC in bleaching filtrates. Oxygen predelignified eucalyptus kraft pulp was subjected to the DHT(EPD, D(EPDD and D(EPDP bleaching sequences and the gravimetric yield of each stage was determined, with 10 replicates. Then the filtrates were analyzed for TOC and COD. Correlations were established among the three measurement methods (gravimetric, COD and TOC. Yield losses in the DHT stage were more accentuated than in the D0 stage, these losses being recovered in subsequent stages of the bleaching sequence. Yield loss decreased with each advancing stage of the bleaching sequences (D0,DHT>(EP>D1>P>D2. Yield loss increased with higher kappa factors in the first bleaching stage and with higher temperature in the (EP stage. The final P stage resulted in greater yield losses than the final D stage. Yield loss intensifies with gain in brightness from bleaching. Yield losses as measured by the TOC method revealed a narrower range of variation in relation to the gravimetric and COD methods, and the linear equation derived for the TOC vs. gravimetric yield relationship provided the best fit (R2=97.27%. Overall yield losses throughout were in the range of 4-5%, depending on the bleaching sequence and operating conditions.

  8. Removal of TOC and Color in Bleaching Effluents from Straw Pulp and Paper Mill by Fe0- H2O2 Process

    Institute of Scientific and Technical Information of China (English)

    YU Shui-li; LIU Ru-peng; LIU Ya-nan

    2006-01-01

    TOC and color in the bleaching effluent from straw pulp paper process could not reach draining standard after its treatment by a biochemical process. In this study, advanced treatment by integrated micro-electrolysis (Fe0) method and Fenton-like process was investigated under various conditions, i.e. pH, Fe/C ratio, initial H2O2 concentration and carrier gas. Results showed that Fe/C ratio(V/V =1.5), larger H2O2 dosage around 50 mg/L, lower pH(pH=3) turned out to be particularly efficient. Temperature was a key parameter, remarkably increasing reaction rates.Carrier air not only improved reaction efficiency, but also saved H2O2 dosage. Chlorinated organic compounds could be reductive dechlorinated by Fe0 reaction and oxidated by · OH produced from Fenton process. The combination of Fe0 and H2O2 reactions had been proved to be highly effective for the advanced treatment of such a type of wastewaters, and important advantages concerning the application in the study.

  9. Historical decline and altered congener patterns of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish and sediment in response to process changes at a pulp mill discharging into Jackfish Bay, Lake Superior.

    Science.gov (United States)

    Dahmer, Shari C; Tetreault, Gerald R; Hall, Roland I; Munkittrick, Kelly R; McMaster, Mark E; Servos, Mark R

    2015-11-01

    Improved regulations for pulp and paper mill effluents and an industry shift away from elemental chlorine bleaching in the 1990s greatly reduced the release of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into the environment. However, the high potential of these contaminants to persist in sediment and bioaccumulate in biota means that they have remained a concern. To document current contamination from bleached kraft pulp mill effluent, PCDD/Fs were measured in white sucker (Catostomus commersoni) collected from Jackfish Bay, Lake Superior. These values were contrasted to historically reported fish data as well as PCDD/F patterns from dated sediment cores. Patterns of PCDD/Fs in sediment cores from Jackfish Bay and reference sites demonstrated a relationship between contamination and mill process changes. During the peak PCDD/F contamination period (1991), when the mill was still using elemental chlorine, the contamination patterns in fish and sediment were distinct and dominated by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Following the reduction in the use of elemental chlorine during the early 1990s, a rapid decline was observed in PCDD/F contamination of fish tissue, and levels are now approaching background conditions with congener patterns more reflective of atmospheric sources. Although surface sediments from Jackfish Bay continue to have elevated PCDD/Fs, with some locations exceeding sediment quality guidelines, they do not appear to be highly bioavailable to benthic fish. PMID:26468966

  10. Vahur Kraft soovitab elektritootmise erastada / Vahur Kraft ; interv. Vallo Toomet

    Index Scriptorium Estoniae

    Kraft, Vahur, 1961-

    2003-01-01

    Eesti Panga president Vahur Kraft soovitab seoses Iraagi sõja ja ebakindlusega maailmas suhtuda ettevaatlikult majanduskasvu prognoosi ning näeb maksureformi läbiviimiseks vajaliku kokkuhoiu võimalusi hariduse, tervishoiu ja sotsiaalkindlustuse reformimisel. Diagramm. Tabel. Vt. samas: Andrus Säälik. Tulude alla jõuavad ka toetused

  11. Anaerobic treatment of cellulose bleach plant wastewater: chlorinated organics and genotoxicity removal

    Directory of Open Access Journals (Sweden)

    T. R. Chaparro

    2011-12-01

    Full Text Available This study assessed the removal efficiency of organic matter and how it relates to the decrease of toxic and mutagenic effects when an anaerobic reactor is used to treat the bleaching effluent from two kraft pulp mills. Parameters such as COD (chemical oxygen demand, DOC (dissolved organic carbon, AOX (adsorbable organic halogen, ASL (acid soluble lignin, color, chlorides, total phenols and absorbance values in the UV-VIS spectral region were measured. The acute and chronic toxicity and genetic toxicity assessments were performed with Daphnia similis, Ceriodaphnia sp. and Allium cepa L, respectively. The removal efficiency of organic matter measured as COD, ranged from 45% to 55%, while AOX removal ranged from 40% to 45%. The acute toxic and chronic effects, as well as the cytotoxic, genotoxic and mutagenic effects, decrease as the biodegradable fraction of the organics is removed. These results, together with the organic load measurement of the effluents of the anaerobic treatment, indicate that these effluents are recalcitrant but not toxic. As expected, color increased when the anaerobic treatment was applied. However, the colored compounds are of microbial origin and do not cause an increase in genotoxic effects. To discharge the wastewater, it is necessary to apply a physico-chemical or aerobic biological post-treatment to the effluents of the anaerobic reactor.

  12. The impact of kappa number composition on eucalyptus kraft pulp bleachability

    Directory of Open Access Journals (Sweden)

    M. M. Costa

    2007-03-01

    Full Text Available Consumption of chemicals during ECF bleaching of kraft pulp correlates reasonably well with kappa number, which measures with KMnO4 the total amount of oxidizable material in the pulp. However, the method does not distinguish between the oxidizable material in residual lignin and other structures susceptible to oxidation, such as hexenuronic acids (HexAs, extractives and carbonyl groups in the pulp. In this study an attempt is made to separate the main contributors to the kappa number in oxygen - delignified eucalyptus Kraft pulps and evaluate how these fractions behave during ECF bleaching using chlorine dioxide as the sole oxidant (DEDD sequence. Residual lignin and HexAs proved to be the main fractions contributing to the kappa number and chlorine dioxide consumption in ECF bleaching. Pulp bleachability with chlorine dioxide increases with increasing HexAs content of the pulp but chlorine dioxide per se does not react with HexAs. Reduction of pulp with sodium borohydride under conditions for removing carbonyl groups has no impact on bleachability. No correlation was found between the pulp of the extractive content and pulp bleachability. The removal of HexAs prior to ECF bleaching significantly decreases the formation of chlorinated organics in the pulp (OX and filtrates (AOX as well as of oxalic acids in the filtrates.

  13. Chemical characteristics and Kraft pulping of tension wood from Eucalyptus globulus labill Características químicas e polpação Kraft de madeira de tração de Eucalyptus globulus labill

    Directory of Open Access Journals (Sweden)

    María Graciela Aguayo

    2012-12-01

    Full Text Available Tension (TW and opposite wood (OW of Eucalyptus globulus trees were analyzed for its chemical characteristics and Kraft pulp production. Lignin content was 16% lower and contained 32% more syringyl units in TW than in OW. The increase in syringyl units favoured the formation of β-O-4 bonds that was also higher in TW than in OW (84% vs. 64%, respectively. The effect of these wood features was evaluated in the production of Kraft pulps from both types of wood. At kappa number 16, Kraft pulps obtained from TW demanded less active alkali in delignification and presented slightly higher or similar pulp yield than pulps made with OW. Fiber length, coarseness and intrinsic viscosity were also higher in tension than in opposite pulps. When pulps where refined to 30°SR, TW pulps needed 18% more revolutions in the PFI mill to achieve the same beating degree than OW pulps. Strength properties (tensile, tear and burst indexes were slightly higher or similar in tension as compared with opposite wood pulps. After an OD0(EOD1 bleaching sequence, both pulps achieved up to 89% ISO brightness. Bleached pulps from TW presented higher viscosity and low amount of hexenuronic acids than pulps from OW. Results showed that TW presented high xylans and low lignin content that caused a decrease in alkali consumption, increase pulp strength properties and similar bleaching performance as compared with pulps from OW.Madeira de tração e oposta de árvores de Eucalyptus globulus foram analisadas quanto a suas características químicas e produção de polpa Kraft. A caracterização química da madeira de tração (TW de Eucalyptus globulus Labill. mostrou um conteúdo similar de celulose, alto conteúdo de xilanas e baixo conteúdo de lignina quando comparada com a madeira oposta (OW de uma mesma árvore. O conteúdo de lignina foi 16% menor e contém 32% mais unidades siringila em TW que em OW. O aumento das unidades siringila favoreceu a formação de ligações

  14. ABSORBENT MATERIALS BASED ON KRAFT PULP: PREPARATION AND MATERIAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Fredrik Wernersson Brodin,

    2012-02-01

    Full Text Available Today, petroleum-based superabsorbents are widely used, but interest in renewable alternatives is on the rise. This study presents two wood-based absorbent materials suitable for various absorption applications as an alternative to petroleum-based products. Never-dried bleached kraft pulp was treated with TEMPO-oxidation, and new carboxylate and aldehyde groups were introduced. It was found that the aldehyde groups contributed to the wet integrity of the absorbent materials, possibly by the formation of hemiacetal bonds. After oxidation, the pulp fibers were gradually disintegrated, and size analysis showed that the disintegration rate was enhanced by an increase in the charge of the oxidant. Freeze drying produced a porous foam with a large surface area that enabled a rapid absorption rate as well as a reasonably high absorption capacity even for absorption under load. Air drying formed a compact film with a slow absorption rate but with a high final capacity for absorption.

  15. TECHNOLOGICAL CHARACTERIZATION OF Eucalyptus benthamii WOOD FOR KRAFT PULP PRODUCTION

    Directory of Open Access Journals (Sweden)

    Isabel Cristina Nogueira Alves

    2011-03-01

    Full Text Available The purpose of this study was to evaluate the quality of Eucalyptus benthamii wood for kraft pulp production. A hybrid of Eucalyptus urophylla x Eucalyptus grandis, probably the most planted Eucalyptus clone in Brazil, was also analyzed for comparison purposes. Basic density, chemical composition and fiber dimensions were determined for the two species. The Eucalyptus benthamii wood presented an anatomical structure, basic density and fiber dimensions quite similar to those of other species planted by the Brazilian pulp industry. However, it presented poorer wood quality characteristics when compared to the hybrid urograndis species, with higher amounts of extractives and lignin, lower amount of glucans, more galactans and lower S/G ratio, characteristics leading to lower pulping yield. Additional studies should be carried out to establish its pulping, bleaching and paper strength properties.

  16. Detection of Chlorophenolic Compounds in Bleaching Effluents of Chemical Pulps

    Institute of Scientific and Technical Information of China (English)

    Chhaya Sharma; S.Mohanty; S.Kumar; N.J.Rao; li qian

    2008-01-01

    Laboratory bleaching effluents from the chlorination and caustic extraction stages of mixed wood kraft pulp processing have been analysed both qualitatively and quantitatively for various chlorophenolics by using GC.A number of chlorinated derivaties of phenols,catechols,guaiacols and syringaldehydes have been detected and their concentrations are estimated.The results are compared with that of different agriculture residue / hardwood pulps,which were reported in literature.The concentrations of various compounds detected have also been compared with their reported 96LC50 values.

  17. Papermaking fibers from giant reed (Arundo donax L. by advanced ecologically friendly pulping and bleaching technologies

    Directory of Open Access Journals (Sweden)

    Pereira, H.

    2006-07-01

    Full Text Available The anatomical structure and chemical composition of the stem-wall material of giant reed is considered from the viewpoint of raw material characterization for industrial fiber production. The effect of stem morphology (nodes and internodes on pulping results and general pulp properties is discussed. The advantages of application of modern organic solvent based (organosolv pulping technologies to giant reed are shown in comparison with the conventional (kraft method. The conditions optimization for Ethanol-Alkali pulping (a selected organosolv pulping process is given, and the chemical kinetics of the principal macromolecular components during ethanol-alkali pulping is described. The bleachability of organosolv pulps by short totally chlorine free (TCF bleaching sequences using hydrogen peroxide and ozone as the active bleaching chemicals without pulp pre-delignification is examined and compared with kraft pulps. The enzymatic pre-treatment of reed organosolv pulps by commercial xylanase preparation is considered as a possibility toward the improvement of pulp bleachability.

  18. Nova tecnologia de branqueamento de celulose adaptada ao fechamento do circuito de água A novel bleaching technology adapted to partial bleach plant closure

    Directory of Open Access Journals (Sweden)

    Marcelo Moreira Costa

    2006-02-01

    Full Text Available A Celulose Nipo-Brasileira é uma das maiores produtoras de celulose kraft branqueada de eucalipto no Brasil. Produz 860.000 tsa/ano em duas linhas, que são equipadas com digestores contínuos. Ambas as linhas fabricam polpa ECF (Elemental Chlorine Free com as seqüências Dhot(EOPD(EPD e D(EOPDP, respectivamente, na linha 1 e 2. A fábrica tem tratamento do efluente com lodo ativado com dois tanques de aeração com capacidade para 20.000 m³, equipados com aeradores superficiais seguidos por quatro clarificadores secundários (dois para cada reator. Nas últimas décadas, a fábrica tem otimizado e vem mudando seus processos, a fim de melhorar a preservação ambiental. Com o objetivo de reduzir o volume de efluente, DQO e carga de AOX, a seqüência Ahot(EOPD(PO proposta foi avaliada em testes laboratoriais, com reciclagem de filtrado parcial. Este artigo propôs a reciclagem de filtrado, que reduz o volume de efluente da fábrica em 9 m³/tsa (tonelada secada ao ar, isto é, mais ou menos 50% do total. O filtrado recuperado é parcialmente desviado para o ciclo de recuperação e para o estágio de deslignificação oxigênio. A reutilização do filtrado Ahot no ciclo de recuperação é para substituir os filtrados, atualmente usados para lavar lama de cal e "dregs". O impacto dos NPEs no ciclo de cálcio não foi significante. Essa estratégia permitiu uma recuperação de carga alcalina de 12 kg NaOH/tsa de polpa, que, do contrário, seria perdida. A branqueabilidade da polpa e a sua qualidade não foram afetadas significativamente. O efluente descartado, proveniente das etapas D(PO, mostrou-se com baixas cargas de cor, de DQO, de AOX e de uma boa biodegradabilidade (DBO5/DQO.Celulose Nipo-Brasileira is one of the largest eucalyptus bleached kraft pulp mills in Brazil. It produces 860,000 tpy in two lines that are equipped with continuous digesters. Line 1 and line 2 produces ECF (Elemental Chlorine Free pulp with the sequences: Dhot

  19. White sucker (Catostomus commersoni) growth and sexual maturation in pulp mill-contaminated and reference rivers

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, M.M.; Bussieres, D.; Dodson, J.J. (Univ. Laval, Sainte-Foy, Quebec (Canada)); Hodson, P.V. (Canada Center for Inland Waters, Burlington, Ontario (Canada))

    1995-02-01

    Induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity and accumulation of chlorophenolic compounds typical of bleached-kraft mill effluent (BKME) in fish sampled downstream of a pulp mill on the St. Maurice River, Quebec, Canada, provided evidence of chemical exposure to BKME. In comparison, fish sampled over the same distances and in similar habitats in a noncontaminated reference river, the Gatineau River, demonstrated low EROD activity and contamination levels. Accelerated growth of white suckers occurred between 2 and 10 years of age in both rivers at downstream stations relative to upstream stations, suggesting the existence of gradients of nutrient enrichment independent of BKME contamination. The impact of BKME exposure was expressed as reduced investment in reproduction, as revealed by greater length at maturity, reduced gonad size, and more variable fecundity. These effects were not obvious in simple upstream-downstream comparisons, but became evident when fish from the uncontaminated Gatineau River showed increased gonadal development and reduced age and size at maturity in response to enhanced growth rates.

  20. Bleach vs. Bacteria

    Science.gov (United States)

    ... Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds Posted April 2, 2014 Your ... hypochlorous acid to help kill invading microbes, including bacteria. Researchers funded by the National Institutes of Health ...

  1. Superheater corrosion in kraft recovery boilers; Korrosion hos oeverhettare i sodapannor. En oeversikt och diskussion

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, F. [AaF-IPK, Stockholm (Sweden)

    1997-02-01

    Corrosion seems to be the most essential factor limiting the life and the availability of kraft recovery boilers. The steam temperature from the kraft recovery boiler has, seen from the view of electricity production and steam turbine operation, traditionally been kept moderate, especially in comparison with steam data from normal utility power plants. So the corrosion of the superheaters has been more a limitation for the temperature of the steam produced by the boiler than a life length limitation. Both the pressure and the temperature of the steam are limited by corrosion. The temperature of the boiling water, and hence the pressure, is limited by the corrosion in the lower furnace. The temperature of the steam is limited by the corrosion in the superheater. Kraft boiler superheater corrosion is here governed not only by the boiler design, but more by the mill chemistry and boiler operation practice. This report discusses the formation and the properties of the deposits and their relation to boiler operation and the corrosion of the superheater tube material. We have tried to understand the corrosion in the kraft boiler superheaters better by comparing with the experience from the utility boilers. 86 refs, 79 figs

  2. Preventing Strength Loss of Unbleached Kraft Pulp

    Energy Technology Data Exchange (ETDEWEB)

    Martin Hubbe; Richard Venditti; John Heitmann

    2003-04-16

    Kraft pulp fibers lose inter-fiber bonding ability when they are dried during the manufacture of paper. Adverse environmental consequences of this loss include (a) limitations on the number of times that kraft fibers can be recycled, (b) reduced paper strength, sometimes making it necessary to use heavier paper or paperboard to meet product strength requirements, increasing the usage of raw materials, (c) decreased rates of paper production in cases where the fiber furnish has been over-refined in an attempt to regain inter-fiber bonding ability. The present study is the first of its type to focus on unbleached kraft fibers, which are a main ingredient of linerboard for corrugated containers. About 90 million tons of unbleached kraft fiber are used worldwide every year for this purpose.

  3. Survey of receiving-water environmental impacts associated with discharges from pulp mills; 4: Bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentration in white sucker (Catostomus commersoni) in relation to biochemical indicators of impact

    Energy Technology Data Exchange (ETDEWEB)

    Heuvel, M.R. van den; Dixon, D.G. (Univ. of Waterloo, Ontario (Canada). Dept. of Biology); Munkittrick, K.R.; Servos, M.R. (Department of Fisheries and Oceans, Burlington, Ontario (Canada). Great Lakes Lab. for Fisheries and Aquatic Sciences); Van Der Kraak, G.J.; McMaster, M.E. (Univ. of Guelph, Ontario (Canada). Dept. of Zoology); Portt, C.B. (C. Portt and Associates, Guelph, Ontario (Canada))

    1994-07-01

    The H411E rat hepatoma bioassay was used to measure 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent concentrations (TECs) in livers of white sucker (Catostomus commersoni) collected downstream from eight Ontario pulp mills and five reference sites. Subsamples of liver were also chemically analyzed for dioxins and furans. Bioassay-derived TECs were compared with TECs calculated from chemical residues using toxic equivalency factors (TEFs) specifically generated for the H411E cell line. This indicated that the bioassay-derived TECs could be accounted for largely by the additive effect of the dioxin and furan congeners. Seven of the eight examined mills had significantly higher TECs than the corresponding reference locations. The bioassay-derived TECs were highest at mills that used kraft pulping and chlorine bleaching. Although lower than the kraft mills, the thermomechanical (TMP) and sulfite mills also had higher TECs than the adjacent preference locations. The TECs were compared with hepatic 7-ethoxyresorufin-O-deethylase activity (EROD), as well as with concentrations of the plasma steroid hormones 17[beta]-estradiol, 11-ketotestosterone, and testosterone. Significant correlations were found between EROD activity and TECs in both male and female white sucker. The correlation for males was stronger than that for females. Some of the variability in this relationship for females could be explained by a multivariate regression that added 17[beta]-estradiol to the analysis; a strongly negative relationship between 17[beta]-estradiol and EROD activity was superimposed on the positive EROD-TEC relationship. No significant correlations were found between TECs and 11-ketotestosterone in males, 17[beta]-estradiol in females, and gonadosomatic indexes in either sex. There were significant negative correlations between TECs and testosterone in both sexes.

  4. A method for detecting MFO induction by Japanese pulp mill effluents with chick embryo

    Energy Technology Data Exchange (ETDEWEB)

    Tatarazako, Norihisa; Kamaya, Yasushi [Japan Pulp and Paper Research Inst. Inc., Tokodai, Tsukuba (Japan)

    1995-12-31

    As a biomarker of physiological responses in fish exposed to pulp and paper mill effluents, mixed function oxygenase (MFO) induction has been investigated by many researchers. The induction and/or inhibition of MFOs is generally affected by various factors of fish such as species, maturity, sex, size and spawning status, and by other environmental variables. Therefore, the method demands technical skills to get a constant result. In addition, the test is costly and also time consuming. In this paper, the authors propose a MFOs induction method using chick embryo, instead of fish, for the assessment of pulp mill effluent. The merits of this method are as follows; inexpensive and commercially available test organisms, easy maintenance of the organisms, no feeding, high uniformity of the developing stage, sensitive responses to xenobiotics, low sample volume requirements, easy testing of various samples at one time and minimal training. P450 1A1 has been found in the microsome of chick embryo. Metabolic function of the P450 1A1 can be regarded basically the same as that of fish. Small amount of xenobiotics, about 100 {micro}l, were injected into the air chamber of 16-day-old chick embryos. Liver microsomes were isolated 48 h after administration. Ethoxyresorufin-O-deethylase (EROD) activity was determined by the direct fluorimetric method. Using the chick embryo method, the authors analyzed various chloro-organics, model bleached kraft pulp mill effluents, model black liquor and several total effluents of Japanese pulp mills. Methylcholanthrene and 2,3,7,8-TCDD were used as positive controls. In this paper, the authors will report the details of the chick embryo method and also some results of the assessment using the method.

  5. EVALUATION OF A NEW LACCASE PRODUCED BY STREPTOMYCES IPOMOEA ON BIOBLEACHING AND AGEING OF KRAFT PULPS

    Directory of Open Access Journals (Sweden)

    M. Enriqueta Arias

    2011-06-01

    Full Text Available The aim of this work is to prove the suitability of a new alkaline and halo-tolerant bacterial laccase (SilA produced by Streptomyces ipomoea CECT 3341 to enhance the conventional chemical bleaching process of an industrial eucalyptus kraft pulp. The laccase used for this study was a recombinant laccase obtained from cultures of E. coli BL21 (DE3 grown in LB liquid medium. The biobleaching experiment was carried out on Eucalyptus globulus kraft pulps using the above mentioned laccase and acetosyringone as natural mediator. Then, an alkaline extraction and further hydrogen peroxide steps were applied to evaluate the efficiency of the laccase-mediator system as a pretreatment in the bleaching sequences. Biobleached pulps showed a kappa number decrease and a brightness increase without decreasing the viscosity values significantly. Also, a reduction in the consumption of hydrogen peroxide was observed when the enzymatic treatment was applied to the pulp. CIE L*a*b* and CIE L*C* color coordinates measured in pulps demonstrated that among all treatments applied to pulps, the laccase-acetosyringone system presented the best optical properties even after an accelerated ageing process. Finally, it is also remarkable that during this treatment 64% of the laccase activity remained unaltered.

  6. Comparative bacterial degradation and detoxification of model and kraft lignin from pulp paper wastewater and its metabolites

    Science.gov (United States)

    Abhishek, Amar; Dwivedi, Ashish; Tandan, Neeraj; Kumar, Urwashi

    2015-05-01

    Continuous discharge of lignin containing colored wastewater from pulp paper mill into the environment has resulted in building up their high level in various aquatic systems. In this study, the chemical texture of kraft lignin in terms of pollution parameters (COD, TOC, BOD, etc.) was quite different and approximately twofold higher as compared to model lignin at same optical density (OD 3.7 at 465 nm) and lignin content (2000 mg/L). For comparative bacterial degradation and detoxification of model and kraft lignin two bacteria Citrobacter freundii and Serratia marcescens were isolated, screened and applied in axenic and mixed condition. Bacterial mixed culture was found to decolorize 87 and 70 % model and kraft lignin (2000 mg/L), respectively; whereas, axenic culture Citrobacter freundii and Serratia marcescens decolorized 64, 60 % model and 50, 55 % kraft lignin, respectively, at optimized condition (34 °C, pH 8.2, 140 rpm). In addition, the mixed bacterial culture also showed the removal of 76, 61 % TOC; 80, 67 % COD and 87, 65 % lignin from model and kraft lignin, respectively. High pollution parameters (like TOC, COD, BOD, sulphate) and toxic chemicals slow down the degradation of kraft lignin as compared to model lignin. The comparative GC-MS analysis has suggested that the interspecies collaboration, i.e., each bacterial strain in culture medium has cumulative enhancing effect on growth, and degradation of lignin rather than inhibition. Furthermore, toxicity evaluation on human keratinocyte cell line after bacterial treatment has supported the degradation and detoxification of model and kraft lignin.

  7. Survey of receiving-water environmental impacts associated with discharges from pulp mills; 3: Polychlorinated dioxins and furans in muscle and liver of white sucker (Catostomus commersoni)

    Energy Technology Data Exchange (ETDEWEB)

    Servos, M.R.; Huestis, S.Y.; Whittle, D.M.; Munkittrick, K.R. (Department of Fisheries and Oceans, Burlington, Ontario (Canada). Great Lakes Lab. for Fisheries and Aquatic Sciences); Van Der Kraak, G.J. (Univ. of Guelph, Ontario (Canada). Dept. of Zoology)

    1994-07-01

    Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured in white sucker liver samples from seven pulp and paper mill sites, and three reference sites in Ontario. The mills included five bleached-kraft mills, with and without secondary treatment, and two sulfite-mechanical mills. 2,3,7,8-T[sub 4]CDD and 2,3,7,8-T[sub 4]CDF were the dominant congeners detected in both liver and fillet samples at all of the pulp and paper mill sites, with mean 2,3,7,8-T[sub 4]CDD toxic equivalent concentrations (TEQs) as high as 124 pg g[sup [minus]1] in liver tissue. concentrations of PCDDs/PCDFs in liver tissues were severalfold higher than in fillet tissue, but this difference can be accounted for by lipid normalization. Biological information, including liver weight, gonad weight, MFO activity (ethoxyresorufin-O-deethylase, EROD), and plasma sex steroids, was measured on individual fish. There was no relationship between TEQs and condition factor, gonadosomatic index, liver somatic index, or circulating plasma 11-ketotestosterone. A weak negative correlation was observed between circulating plasma testosterone and TEQs. Although there was a positive correlation between MFO activity (EROD) and TEQ, one site with very low chlorine used and low TEQs and EROD activity similar to levels observed at more contaminated sites. This finding, along with recent observations that MFO activity is rapidly cleared in pulp-mill-exposed fish, casts doubt on an exclusive causal relationship between MFO activity and PCDDs/PCDFs in these sites.

  8. Composite tube cracking in kraft recovery boilers: A state-of-the-art review

    Energy Technology Data Exchange (ETDEWEB)

    Singbeil, D.L.; Prescott, R. [Pulp and Paper Research Inst. of Canada, Vancouver, British Columbia (Canada); Keiser, J.R.; Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

    1997-07-01

    Beginning in the mid-1960s, increasing energy costs in Finland and Sweden made energy recovery more critical to the cost-effective operation of a kraft pulp mill. Boiler designers responded to this need by raising the steam operating pressure, but almost immediately the wall tubes in these new boilers began to corrode rapidly. Test panels installed in the walls of the most severely corroding boiler identified austenitic stainless steel as sufficiently resistant to the new corrosive conditions, and discussions with Sandvik AB, a Swedish tube manufacturer, led to the suggestion that coextruded tubes be used for water wall service in kraft recovery boilers. Replacement of carbon steel by coextruded tubes has solved most of the corrosion problems experienced by carbon steel wall tubes, however, these tubes have not been problem-free. Beginning in early 1995, a multidisciplinary research program funded by the US Department of Energy was established to investigate the cause of cracking in coextruded tubes and to develop improved materials for use in water walls and floors of kraft recovery boilers. One portion of that program, a state-of-the-art review of public- and private-domain documents related to coextruded tube cracking in kraft recovery boilers is reported here. Sources of information that were consulted for this review include the following: tube manufacturers, boiler manufacturers, public-domain literature, companies operating kraft recovery boilers, consultants and failure analysis laboratories, and failure analyses conducted specifically for this project. Much of the information contained in this report involves cracking problems experienced in recovery boiler floors and those aspects of spout and air-port-opening cracking not readily attributable to thermal fatigue. 61 refs.

  9. Patterns of coral bleaching: Modeling the adaptive bleaching hypothesis

    Science.gov (United States)

    Ware, J.R.; Fautin, D.G.; Buddemeier, R.W.

    1996-01-01

    Bleaching - the loss of symbiotic dinoflagellates (zooxanthellae) from animals normally possessing them - can be induced by a variety of stresses, of which temperature has received the most attention. Bleaching is generally considered detrimental, but Buddemeier and Fautin have proposed that bleaching is also adaptive, providing an opportunity for recombining hosts with alternative algal types to form symbioses that might be better adapted to altered circumstances. Our mathematical model of this "adaptive bleaching hypothesis" provides insight into how animal-algae symbioses might react under various circumstances. It emulates many aspects of the coral bleaching phenomenon including: corals bleaching in response to a temperature only slightly greater than their average local maximum temperature; background bleaching; bleaching events being followed by bleaching of lesser magnitude in the subsequent one to several years; higher thermal tolerance of corals subject to environmental variability compared with those living under more constant conditions; patchiness in bleaching; and bleaching at temperatures that had not previously resulted in bleaching. ?? 1996 Elsevier Science B.V. All rights reserved.

  10. Selectivity Studies of Oxygen and Chlorine Dioxide in the Pre-Delignification Stages of a Hardwood Pulp Bleaching Plant

    OpenAIRE

    Barroca, Maria J. M. C.; Marques, Pedro J. T. S.; Seco, Isabel M.; Castro, José Almiro A. M.

    2001-01-01

    This work is concerned with the role of oxygen on the selectivity of chlorine dioxide in the pre-delignification stage of a E. globulus pulp bleaching plant. Its main purpose is to study the selectivity of chlorine dioxide when applied to an oxygen pre-delignified hardwood kraft pulp and to compare it to that of a conventional pre-delignification with chlorine dioxide (D). The intrinsic viscosity and kappa number were used to follow the polysaccharides degradation and the delignification rate...

  11. 78 FR 31315 - Kraft Pulp Mills NSPS Review

    Science.gov (United States)

    2013-05-23

    ... Performance Standards and National Emission Standards for Hazardous Air Pollutants Reviews; Final rules, 77 FR... Stationary Sources and Emission guidelines for Existing Sources; Commercial and Industrial Solid Waste... dry standard cubic foot HAP Hazardous air pollutant H 2 S Hydrogen Sulfide HVLC High volume...

  12. Bleach Neutralizes Mold Allergens

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Researchers at National Jewish Medical and Research Center have demonstrated that dilute bleach not only kills common household mold, but may also neutralize the mold allergens that cause most mold-related health complaints. The study, published in the Journal of Allergy and Clinical Immunology, is the first to test the effect on allergic…

  13. BLEACHING NEPTUNE BALLS

    Directory of Open Access Journals (Sweden)

    BONET Maria Angeles

    2014-05-01

    Full Text Available Posidonia Oceanic is a seaweed from Mediterranean Sea and it is more concentrated at the Balerian SEA. This implies the Valencian Community also. It forms vaste underwater meadows in the sea and are part of the Mediterranean ecosystem. It is a sea-grass specie with fruits and flowers. Leaves are ribbon-like and they grow in winter and at the end of summer some of them are separated and arrive to some sea line. Fuit is separated and can floate, it is known as “the olive of the sea” mainly in Italy, or as the Neptune Balls. As it can be used in different fields, it is is being studied in order ro have the precitice tests. Some authors have reported the manufacturing of fully bio-based comites with a gluten matrix by hot-press molding. And it has been considered as an effective insulator for building industry or even though to determine the presence of mercure in the Mediterranean sea some years ago. As many applications can be designed from that fibers, it has been considered to be bleached in order to used them in fashionable products. Consequently, its original brown color is not the most suitable one and it should be bleached as many other cellulosic fibers. The aim of this paper is to bleache neptune balls however, the inner fibers were not accessible at all and it implied not to bleach the inner fibers in the neptune ball. Further studiesd will consider bleaching the individualized fibers.

  14. Utilización de Eucalyptus spp. Alternativas de plantaciones uruguayas para pulpa Kraft

    Directory of Open Access Journals (Sweden)

    Javier Doldán

    2011-05-01

    Full Text Available Las plantaciones de Eucalyptus globulus han mostrado desiguales tasas de crecimiento en diferentes regiones de Uruguay. Esto ha motivado la búsqueda de otros orígenes de semilla y especies para la producción de pulpa de celulosa. Propiedades papeleras de las pulpas blanqueadas (ECF de especies alternativas llevan a intuir que podrían ser atractivas para mercados de pulpa de fibra corta. En este trabajo se realiza un comparativo del E. grandis, E. dunnii, E. maidenii y E. globulus (procedencia de semilla “Jeeralang” con el E. globulus predominante en Uruguay. Se discute el potencial de estas maderas como base para una mezcla en cocción, basándose en el análisis de propiedades físicas (densidad aparente básica, propiedades pulpables (rendimiento, carga de álcali activo en cocción Kraft y consumo de madera y propiedades papeleras. En trabajos previos se han encontrado diferencias significativas entre el comportamiento pulpable del Eucalyptus globulus y Eucalyptus maidenii, sugiriendo que nosería recomendable mezclar estas especies. La misma conclusión se podría extender a las especies de Eucalyptus estudiadas. Sin embargo, teniendo en cuenta los similares requerimientos en las cargas de álcali activo, la mezcla entre especies alternativas podría ser aplicada.AbstractEucalyptus globulus plantations have shown different growth rates in different sites in Uruguay. This fact has triggered the search for other pulp wood species and seed provenance. Paper making properties of ECF bleached pulps of alternative speciessuggest that these species could be perfectly used as hardwood bleached pulp raw materials. This study intends to compare alternativeUruguayan pulpwood species E. grandis, E. dunnii, E. maidenii and “Jeeralang” a seed provenance of E. globulus to the E. globulus most widely cultivated in the country. Physical properties of wood (Basic Density, Kraft pulping performance (pulp yield, active alkali and wood consumption

  15. EXTRACELLULAR PROTEINS PRODUCED BY DIFFERENT SPECIES OF THE FUNGUS TRICHODERMA ON SECONDARY PAPER MILL SLUDGE SUBSTRATE

    Directory of Open Access Journals (Sweden)

    Ida Vaskova,

    2012-01-01

    Full Text Available Kraft pulping is the most commonly used pulping process in the pulp and paper industry. In this process wood chips are chemically delignified using sodium sulfide and sodium hydroxide. Delignification is usually followed by mechanical fiberization and a bleaching process of the resulting wood pulp. In addition to lignin-free wood pulp, this process also produces waste that contains residues of used chemicals, lignin, cellulose, hemicelluloses, and small amounts of other wood components. Because of the worldwide large-scale production of paper, the sludge from paper mills contributes significantly to environmental pollution. Although there have been great efforts being made to utilize this lignin-rich material, sludge is mostly disposed in landfills or incinerated in a boiler. This research project used secondary sludge as a substrate for 7 wood-decay fungi taxonomically belonging to the genus Trichoderma. The examined fungi expressed the capability of consuming sludge components as a carbon source to produce extracellular proteins. The proteins were separated by gel electrophoresis. Before and after fungi cultivation, the sludge was analyzed by Fourier transform infrared spectroscopy (FTIR.

  16. Energy efficiency improvement of a Kraft process through practical stack gases heat recovery

    International Nuclear Information System (INIS)

    A process scheme for the optimal recovery of heat from stack gases considering energy and technical constraints has been developed and applied to an existing Kraft pulping mill. A system based on a closed loop recirculation of hot oil is used to recover the heat from stack gases and distribute it to the appropriate cold streams. The recovery of heat from stack gases is part of an overall optimization of the Kraft mill. Tools such as Pinch Analysis and exergy analysis are used to evaluate the process streams. The results indicate that 10.8 MW of heat from stack gases can be reused to heat process streams such as the deaerator water, hot water, drying filtrates, and black liquor. A simulation model of the recirculation loop has been developed to determine the specifications of the recovery system. The total heat exchanger surface area required by the system is 3460 m2, with a hot oil recirculation temperature of 137 oC. The anticipated total investment is $10.3 M, with a payback time of 1.8 years. - Highlights: → We developed a process design for recovering heat from stack gases in a Kraft mill. → The recovered heat is optimally distributed to the process cold streams. → Heat recovery system has a total surface area of 3500 m2 without gases condensation. → A reduction of 7 percent in total process steam demand is anticipated. → A total investment of 10.3 M$ is needed with a payback time of less than two years

  17. AN IMPROVED METHOD FOR ISOLATING RESIDUAL KRAFT LIGNIN IN HIGH YIELD AND PURITY

    Institute of Scientific and Technical Information of China (English)

    Shubin Wu; Dimitris S.Argyropoulos

    2004-01-01

    When washed pulps is milled and ground to a fine powder, the resulting material may easily be degraded by cellulolytic enzymes. The klason and UV lignin content of the solid residuals obtained in this step were 49.9% lignin for spruce KP, and 21.4% for poplar KP. The solid residuals from enzymatic treatment contained about 93.3% and 90.7% of the lignin originally presented in the spruce KP and poplar KP respectively. The enzymatic treated residual was then subjected to mild acidolysis, which caused the cleavage of lignin-carbohydrate linkages.The resulting Ground Enzymatic/Acidolysis Kraft Lignin (GEA-KL) is of significantly higher yield than our previous two-step (enzymatic/acidolysis) residual kraft lignin (EA-KL). The improved method offers kraft lignin preparations in higher yield and purity than any other known method with minimal work up and solvent requirements. DFRC/quantitative 31p NMR protocol and quantitative DEPT edited 13C RMR were used for characterizing of RKLs.

  18. AN IMPROVED METHOD FOR ISOLATING RESIDUAL KRAFT LIGNIN IN HIGH YIELD AND PURITY

    Institute of Scientific and Technical Information of China (English)

    ShubinWu; DimitrisS.Argyropoulos

    2004-01-01

    When washed pulps is milled and ground to a fine powder, the resulting material may easily be degraded by cellulolytic enzymes. The klason and UV lignin content of the solid residuals obtained in this step were 49.9% lignin for spruce KP, and 21.4% for poplar KP. The solid residuals from enzymatic treatment contained about 93.3% and 90.7% of the lignin originally presented in the spruce KP and poplar KP respectively. The enzymatic treated residual was then subjected to mild acidolysis, which caused the cleavage of lignin-carbohydrate linkages. The resulting Ground Enzymatic/Acidolysis KraftLignin (GEA-KL) is of significantly higher yield than our previous two-step (enzymatic/acidolysis) residual kraft lignin (EA-KL). The improved method offers kraft lignin preparations in higher yield and purity than any other known method with minimal work up and solvent requirements. DFRC/quantitative P NMR protocol and quantitative DEPT edited C RMR were used for characterizing of RKLs.

  19. Strength enhancement of fiber network by carboxymethyl cellulose during oxygen delignification of kraft pulp

    Directory of Open Access Journals (Sweden)

    Eero Kontturi

    2008-02-01

    Full Text Available Sorption of carboxymethyl cellulose (CMC on the fiber surface was applied during oxygen delignification to enhance the strength properties of softwood kraft pulp. Unlike many previous efforts, the focus was not set on the improvement of selectivity of oxygen delignification, i.e. retaining stable viscosity vs. decreasing kappa number. Instead, without an improved selectivity, handsheets from CMC-treated fibers exhibited a 15% improvement in tensile index and 25% improvement in tear index after a full bleaching sequence in comparison to the untreated reference pulp. Since it is demonstrated that the CMC addition can be incorporated as an integral step in the fiberline process, the method offers an effortless and viable option to produce pulp resulting in stronger paper products.

  20. THE EFFECT OF HEMICELLULOSE EXTRACTION ON FIBER CHARGE PROPERTIES AND RETENTION BEHAVIOR OF KRAFT PULP FIBERS

    Directory of Open Access Journals (Sweden)

    Katja Lyytikäinen

    2011-02-01

    Full Text Available The integrated forest biorefinery (IFBR concept provides a promising opportunity for the development of the pulp and paper industry. One proposed next generation technology for an integrated forest biorefinery is the extraction of hemicelluloses, allowing the co-production of pulp and different hemicellulose-based chemicals. In addition to paper properties, hemicelluloses are known to be important for the function of cationic papermaking additives, because they are the main source of charged groups in fibers. This paper shows that the alkaline extraction of hemicelluloses from bleached kraft pulp decreases both the total and surface charge of the pulps. It was found that the decreased fiber charge leads to increased filler retention with fixed retention aid dosage. The reduction observed in the fiber surface charge for alkali-extracted pulp was mainly attributed to the decrease in the amount of anionic groups located in fines.

  1. Gas Chromatography Analysis of Resin and Fatty Acids from Laboratory Generated Bleach Plant Effluents

    Institute of Scientific and Technical Information of China (English)

    Chhaya Sharma; S. Mohanty; S. Kumar; N.J. Rao

    2007-01-01

    Laboratory generated spent bleached liquor from the chlorination, caustic extraction stage of mixed wood kraft pulp processing has been analyzed both qualitatively and quantitatively for various resin & fatty acids by using GC. A number of resin acids,saturated and unsaturated fatty acids, chloro fatty and resin acid have been detected and their concentrations are estimated. The results are compared with results on different agriculture residue/hardwood pulps, which were reported earlier. The concentrations of various compounds detected have also been compared with their reported LC50 values.

  2. Cellulose kraft pulp reinforced polylactic acid (PLA composites: effect of fibre moisture content

    Directory of Open Access Journals (Sweden)

    Sanna Virtanen

    2016-06-01

    Full Text Available PLA offers a competitive and CO2 neutral matrix to commonly used polyolefin polymer based composites. Moreover, the use of PLA reduces dependency on oil when producing composite materials. However, PLA has a tendency of hydrolytic degradation under melt processing conditions in the presence of moisture, which remains a challenge when processing PLA reinforced natural fibre composites. Natural fibres such as cellulose fibres are hygroscopic with 6–10 wt% moisture content at 50–70% relative humidity conditions. These fibres are sensitive to melt processing conditions and fibre breakage (cutting also occur during processing. The degradation of PLA, moisture absorption of natural fibres together with fibre cutting and uneven dispersion of fibres in polymer matrix, deteriorates the overall properties of the composite. In the given research paper, bleached softwood kraft pulp (BSKP reinforced PLA compounds were successfully melt processed using BSKP with relatively high moisture contents. The effect of moist BSKP on the molecular weight of PLA, fibre length and the mechanical properties of the composites were investigated. By using moist never-dried kraft pulp fibres for feeding, the fibre cutting was decreased during the melt compounding. Even though PLA degradation occurred during the melt processing, the final damage to the PLA was moderate and thus did not deteriorate the mechanical properties of the composites. However, comprehensive moisture removal is required during the compounding in order to achieve optimal overall performance of the PLA/BSKP composites. The economic benefit gained from using moist BSKP is that the expensive and time consuming drying process steps of the kraft pulp fibres prior to processing can be minimized.

  3. Development of a strategy for energy efficiency improvement in a Kraft process based on systems interactions analysis

    Science.gov (United States)

    Mateos-Espejel, Enrique

    The objective of this thesis is to develop, validate, and apply a unified methodology for the energy efficiency improvement of a Kraft process that addresses globally the interactions of the various process systems that affect its energy performance. An implementation strategy is the final result. An operating Kraft pulping mill situated in Eastern Canada with a production of 700 adt/d of high-grade bleached pulp was the case study. The Pulp and Paper industry is Canada's premier industry. It is characterized by large thermal energy and water consumption. Rising energy costs and more stringent environmental regulations have led the industry to refocus its efforts toward identifying ways to improve energy and water conservation. Energy and water aspects are usually analyzed independently, but in reality they are strongly interconnected. Therefore, there is a need for an integrated methodology, which considers energy and water aspects, as well as the optimal utilization and production of the utilities. The methodology consists of four successive stages. The first stage is the base case definition. The development of a focused, reliable and representative model of an operating process is a prerequisite to the optimization and fine tuning of its energy performance. A four-pronged procedure has been developed: data gathering, master diagram, utilities systems analysis, and simulation. The computer simulation has been focused on the energy and water systems. The second stage corresponds to the benchmarking analysis. The benchmarking of the base case has the objectives of identifying the process inefficiencies and to establish guidelines for the development of effective enhancement measures. The studied process is evaluated by a comparison of its efficiency to the current practice of the industry and by the application of new energy and exergy content indicators. The minimum energy and water requirements of the process are also determined in this step. The third stage is

  4. Synthesis and characterization of kraft lignin-based epoxy resins

    OpenAIRE

    El Mansouri, Nour-Eddine; Yuan, Qiaolong; Huang, Farong

    2011-01-01

    Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectro...

  5. SYNTHESIS AND CHARACTERIZATION OF KRAFT LIGNIN-BASED EPOXY RESINS

    OpenAIRE

    Nour Eddine El Mansouri,; Qiaolong Yuan; Farong Huang Mail

    2011-01-01

    Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectro...

  6. Elimination of the calcium cycle: direct electrolytic causticizing of Kraft smelt. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pfromm, P.; Winnick, J.

    1999-01-19

    An electrochemical molten salt alternative to the classic Kraft causticizing process has been investigated and the feasibility of the process was successfully shown. The experiments include (A) the determination of background thermal decomposition gases, (B) the electrolysis of a sodium carbonate only smelt to show that sodium oxide can be electrochemically produced, and (C) electrolysis of a synthetic smelt containing 80 mole % Na{sub 2}CO{sub 3} and 20 mole % Na{sub 2}S. The experiments show, that sodium hydroxide (NaOH) was produced by the electrochemical reduction of sodium carbonate to sodium oxide in the molten state. In the experiment containing sodium sulfide, there was formation of less than 5 mole % of polysulfide. Energy savings on the order of 500,000 BTU per ton of kraft pulp produced are estimated, based on the energy used by the mill. Operating costs are estimated to be currently similar to conventional processing. However, price increases of fossil fuels and increased co-generation of electricity in the mill will give the electrolytical process significant cost advantages.

  7. Elimination of the Calcium Cycle: Direct Electrolytic Causticizing of Kraft Smelt, Final report

    Energy Technology Data Exchange (ETDEWEB)

    P. Pfromm, J. Winnick

    1999-01-31

    An electrochemical molten salt alternative to the classic kraft causticizing process has been investigated and the feasibility of the process was successfully shown. The experiments included (a) determination of background thermal decomposition gases, (b) the electrolysis of a sodium-carbonate-only smelt to show that sodium oxide can be electrochemically produced, and (c) electrolysis of a synthetic smelt containing 80 mole% Na2-CO3 and 20 mole% Na2-S. The experiments show that sodium hydroxide (NaOH) was produced by the electrochemical reduction of sodium carbonate to sodium oxide in the molten state. In the experiment containing sodium sulfide, there was formation of less than 5 mole% of polysulfide. Energy savings on the order of 500,000 BTU per ton of kraft pulp produced are estimated, based on the energy used by the mill. Operating costs are estimated to be currently similar to conventional processing. However, price increases of fossil fuels and increased co-generation of electricity in the mill will give the electrolytical process significant cost advantages.

  8. Kraft cooking of gamma irradiated wood, (2)

    International Nuclear Information System (INIS)

    Pre-irradiation of wood in alkaline aqueous ethanol increases kraft pulp yield by up to 1.2%, as already reported. In order to clarify the mechanism of the pulp yield gain, the behaviors of lignin and carbohydrates during pre-irradiation and cooking were investigated. The results are summarized as follows: 1) γ-Irradiation of guaiacylethane in alkaline aqueous ethanol produced 5-(1-hydroxyethyl)-guaicylethane, which is formed by radical coupling between α-hydroxyethyl radical from ethanol and guaiacylethane radical having an unpaired electron at C-5. 5,5'-Dehydrodiguaiacylethane, which may be a predominant product produced by γ-irradiation in the absence of ethanol, was also detected. 2) The yield of vanillin obtained by nitrobenzene oxidation of MWL decreased with an increase of γ-ray dosage. The presence of ethanol during γ-irradiation lessened the extent of this decrease and also the degradation of cellobiose. 3) Gel filtration of the products obtained by γ-irradiation of MWL and cellobiose in the presence of 14C-ethanol showed the possible combination between ethanol and MWL or cellobiose. 4) Molecular weight distributions of kraft lignin obtained from pre-irradiated beech chips were compared with those obtained from unirradiated chips. This result shows that γ-irradiation in the presence of ethanol decreases the ability of lignin to condense during kraft cooking. (author)

  9. Structural characterization of Kraft lignins from different spent cooking liquors by 1D and 2D Nuclear Magnetic Resonance spectroscopy

    International Nuclear Information System (INIS)

    Three Kraft lignins isolated from black liquors of several paper pulp mills of the North of Spain and Portugal were structurally characterized by using monodimensional (1H and 13C) and bidimensional Nuclear Magnetic Resonance (NMR) spectrometry. From the latter, 13C–1H heteronuclear single quantum correlation (HSQC) and heteronuclear multiple bond correlation (HMBC) were employed. Lignins from black liquors are usually burned for power generation. Nevertheless, they could become high value added products within a biorefinery context. In that case, a good understanding of their structure is a prior step to transform them. From all the NMR techniques studied, HSQC has risen as the most powerful tool in lignin characterization. Kraft cooking conditions and the type of wood seem to be the main factors that determine the differences observed in the lignins. All the samples have shown an important decrease in the number of β–O–4′ linkages, due to the Kraft process, and resinol has become the most resistant linkage to the process. Moreover, all samples seem to be mainly linked to a one polysaccharide: xylan. Several parameters like S/G ratio, portion of phenolic and aliphatic hydroxyls, amount of aromatic protons and other structural aspects were also estimated. - Highlights: • Lignins from three Kraft spent liquors were obtained by acid precipitation. • Structural characterization of the dissolved lignins was performed by NMR. • Wood source and pulping conditions determine the lignin characteristics. • Kraft process implies cleavage of β–O–4 linkages and survival of resinol linkages. • Comparison of the samples would aid decisions on its future revalorization

  10. Reactions of chlorine (III) and their kinetics in the chlorine dioxide bleaching of kraft pulps

    OpenAIRE

    Lehtimaa, Tuula

    2010-01-01

    The reactions of Cl(III) were investigated utilizing iodometric titration in combination with DMSO and EDTA to prevent undesired side reactions. Among a large group of suggested Cl(III) decomposition reactions, two reactions were found to be adequate to describe the Cl(III) decomposition in the absence of metals and HOCl. The rate parameters (k - rate coefficient, Ea - activation energy) were determined for these reactions. The reaction between Cl(III) and HOCl is known to start with the...

  11. CRITERIA SELECTION FOR BLEACHED EUCALYPT KRAFT PULP SPECIFICATION ORIENTED TO THE MANUFACTURE OF OFFSET PAPERS

    Directory of Open Access Journals (Sweden)

    Edison da Silva Campos

    2009-09-01

    Full Text Available The purpose of this work was to analyze the characteristics of some eucalypts pulps available in the market, aiming to understand their influence in the properties of the offset papers. Another objective of this work was to show alternatives to reduce the number of laboratory tests in the pulp specifications. Thirteen (13 market pulps (Brazilian and international pulps were analyzed and the tests applied were as follows: intrinsic viscosity, alkali solubility at 5%, coarseness, numbers of fibers per gram of pulp, average length of fibers, fine fraction by the Dynamic Paper Chemistry Jar (DPCJ, drainability by Schopper Riegler, before refining. Other tests, such as: tensile index, stretch, burst index, tear index, bulk, air resistance, opacity and absorption of water by cappilarity (Klemm were performed for each type of pulp before refining and for refining levels of 25 ºSR, 30 ºSR, 40 ºSR and 55 ºSR. No evidence of the influence of S5 and intrinsic viscosity was observed at the range of the market pulp properties variation. The Brazilian pulps presented higher initial drainability and required lower PFI revolutions to the same level of refining in comparison to the international pulps. The initial average values of strength indexes: tensile, stretch, burst and tear were higher to the Brazilian pulps. However, this situation was changed at 25 ºSR and other levels of drainability. Due to the higher number of correlations at 30 ºSR, this level of drainability was chosen to determine the pulp characteristics profile. At this level, international pulps showed better values of tensile and tear index, but a higher energy consumption and a lower opacity in comparison to the Brazilian pulps. In addition, this paper  suggested the concentration of the lab technical evaluation of pulps on the analysis of opacity, tensile and tear indexes. Such procedure should reduce the number of lab tests as well.

  12. Humidity testing of bleached holograms.

    Science.gov (United States)

    Chenoweth, A J

    1971-04-01

    One of the proposed storage media for semipermanent optical stores is an array of bleached holograms fabricated on photographic plates. If a store utilizing this medium is to be operated in a field environment, the effect of humidity variation requires consideration. In this study holograms were made using either Burckhardt's potassium ferricyanide or Russo and Sottini's modified R-10 type bleach on Kodak 649F and Agfa 10E70 plates. Diffraction efficiency was measured as a function of relative humidity over the range 30-98%. For holograms fabricated and tested as described above it was found that relative humidity values above 75% caused a permanent loss in diffraction efficiency for potassium ferricyanide bleached plates; humidity above 90% produced a temporary loss in R-10 bleached plates. PMID:20094561

  13. Optical dating: insufficiently bleached sediments

    International Nuclear Information System (INIS)

    Although infrared-stimulated luminescence (IRSL) signals in feldspars can be bleached rapidly by sunlight, there could still be a small amount of IRSL signal remaining in sediment grains if they have experienced only relatively short sunlight exposure before deposition. This remaining signal results in a ''remnant dose'' stored in the grain and is important for young samples but negligible for old samples. Several methods have been introduced to detect insufficient bleaching, and some of them can provide information on the extent of the bleaching. Others can only distinguish between samples bleached for a very long time and for a short time. Empirical methods are introduced to evaluate the possible values of equivalent dose accumulated since the grains were deposited. These methods involve the analysis of the equivalent doses and the natural IRSL signals obtained using single-disc dose determination methods. (author)

  14. Was meinem Auge diese Kraft gegeben

    OpenAIRE

    Fichte, Johann Gottlieb

    2014-01-01

    Was meinem Auge diese Kraft gegeben,Daß alle Mißgestalt ihm ist zerronnen,Dass ihm die Nächte werden heitre Sonnen,Unordnung Ordnung, und Verwesung Leben? – Was durch der Zeit des Rams verworrnes WebenMich sicher leitet hin zum ew´gen Bronnen,Des Wahren, Guten, Schönen und der WonnenUnd ihm vernichtend eintaucht all mein Streben? Das ist´s: seit in Uraniens Auge die tiefeSich selber klare, blaue, stille, reineLichtflamm’, ich selber still, hineingesehen; Seitdem blieb dieses Aug´ mir in der T...

  15. VISCOSITY MODELING OF CONVENTIONAL KRAFT COOKS

    Institute of Scientific and Technical Information of China (English)

    DONGBO YAN; GOPAL A. KRISHNAGOPALAN

    2004-01-01

    Static and dynamic models were studied for both softwood and hardwood viscosity loss during Kraft pulping process. G-factor and initial EA charge in the style of Hatton equation can predicate final pulp viscosity. Dynamic models generated by effective alkaline (EA) and temperature profile information can be used to predicate pulp viscosity at any time during pulping process. Viscosity online real-time prediction is made possible by this model through an online NIR sensor, which has been well calibrated to measure black liquor EA and temperature.

  16. Krafting an agreement: Negotiations to reduce pollution from the Nordic pulp industry, 1985--1989

    Energy Technology Data Exchange (ETDEWEB)

    Auer, M.R.

    1996-05-01

    International environmental accords frequently contain obligations that may be easily satisfied by their signatories. Observers have speculated why it is in a state`s interests to sign agreements that lack strict conditions, but policy analysts lack a coherent model explaining how such agreements are formalized. Knowledge, values, and authority are key forces that elucidate how environmental accords are developed with provisions that are easily executable. This dissertation examines the formulation of Helsinki Commission recommendations to reduce emissions of organochlorines from Nordic kraft pulp mills. The kraft pulp industry, the largest industrial pollution emitter to the Baltic Sea, is also a crucial foreign exchange earner for both Sweden and Finland. Hence, Swedes and Finns were the most active participants in regional negotiations to reduce organochlorine emissions. Key variable analysis explains how obstacles in various regional negotiations were overcome, and how parties constructed a recommendation with obligations that could be easily accommodated. The two sides never agreed about the level of risk posed by organochlorines in the marine environment. This problem influenced the strictness of pollution limits specified in the final agreement. But, the parties overcame formidable obstacles in the negotiations, including: (1) concerns about costs to industry and competitive disadvantages in the pulp and paper sector; (2) disagreement about technologies to combat the problem; and (3) domestic rule-making schedules that were out of sync.

  17. THE EFFECT OF Eucalyptus APMP FIBERS REINFORCEMENT ON Pinus radiata KRAFT PULP PROPERTIES

    Directory of Open Access Journals (Sweden)

    Mauro Manfredi

    2008-06-01

    Full Text Available Kraft pulps derived from pine species are largely used for high strength paper products. The quality of such pulps hasbeen improved significantly in the last decades through advances in wood quality and adequate choice of pine species. The quality ofpine fibers can be further improved by incorporating other fibers to them. In fact, the mixture of pine fibers with hardwood fibers iscommon practice around the world. An alternative to further improve the quality of pine fibers is by mixing them with wood fibersproduced by modern techniques. This study evaluated the impact of mixing 10-40% of eucalyptus wood fibers produced by the P-RCAPMP process on the Pinus radiata fiber properties. The pulp mixes were beat in a PFI mill and evaluated for the main physicalproperties. It was observed that the eucalyptus wood fibers improve the bonding capacity of the Pinus radiata fibers. At a given tensilestrength, the properties of tear index and opacity of the pulp mix increase with increasing proportion of eucalyptus wood fibers. It isconcluded that addition of up to 30% eucalyptus wood fibers to Pinus radiata kraft pulp is viable alternative to improve some of itsproperties.

  18. Avaliação do emprego de microfiltração para remoção de fibras do efluente de branqueamento de polpa celulósica Evaluation of the use of microfiltration for removal of fiber from bleaching pulp mill effluent

    Directory of Open Access Journals (Sweden)

    Míriam Cristina Santos Amaral

    2013-03-01

    Full Text Available O processo de branqueamento é o estágio em que ocorre a maior perda de fibras durante a fabricação de polpa celulósica. Além de ser uma perda de produto, estas fibras aumentam a concentração de matéria orgânica do efluente dificultando seu tratamento. O objetivo deste trabalho foi avaliar o emprego de microfiltração (MF na remoção de fibras de efluente de branqueamento alcalino de polpa celulósica. Foi empregada membrana de poli(éter imida com tamanho médio de poros de 0,5 µm e área de filtração de 0,05 m². O efeito das condições operacionais no fluxo permeado foi avaliado através do monitoramento do perfil de fluxo durante a operação em diferentes condições de velocidade de escoamento (Reynolds de 1.226, 1.653 e 2.043, pH da alimentação (7, 10 e 10,6, temperatura (28, 43 e 48°C e pressão de operação através da avaliação da pressão crítica. Os resultados mostraram que a MF é um processo eficiente para remoção de fibras, apresentado 99% eficiência de remoção de sólidos suspensos. O melhor desempenho da operação de MF foi obtido empregando pH 7, pressão de 1 bar e Re de 1.653. Os resultados mostram que a redução do fluxo se deve principalmente à formação de torta.The bleaching process is the stage where there is the greatest loss of fibers during the pulp production. Besides being a waste of product, these fibers increase the concentration of organic matter in the effluent and make the treatment of effluent more difficult. The aim of this study was to evaluate the use of microfiltration (MF in the removal of fiber of effluent of alkaline bleaching pulp mill. The membrane employed was hollow fiber poly (ether imide, with average pore size of 0.5 µm and filtration area of 0.05 m². The effect of operating conditions on the permeate flux was evaluated by monitoring the flux profile during operation in different conditions of flow velocity (Reynolds 1,226, 1,653 and 2,043, pH of feeding (7, 10

  19. Cellulose Depolymerisation and Paper Properties in E. Globulus Kraft Pulps

    OpenAIRE

    Carvalho, M. G.; Ferreira, P. J.; Figueiredo, M.M.

    2000-01-01

    The aim of this work was to study the impact of cellulose depolymerisation on the beating potential and handsheet properties of the portuguese E. globulus kraft pulp. A homogeneous sample of eucalypt wood chips was cooked using different kraft pulping conditions (cooking temperatures and times, and sodium hydroxide and sodium sulphide concentrations) in order to obtain a wide variation for intrinsic viscosity of the pulps. In the range of industrial cooking conditions, this property was found...

  20. Phosphorylation of Kraft fibers with phosphate esters.

    Science.gov (United States)

    Shi, Ying; Belosinschi, Dan; Brouillette, François; Belfkira, Ahmed; Chabot, Bruno

    2014-06-15

    Phosphate esters, derived from two different long-chain aliphatic alcohols, were used as phosphorylating reagents for Kraft pulp fibers. High phosphorus contents and almost non-degraded fibers were obtained by following this pathway. The phosphorylation efficiency was influenced by the alkyl chain length of PEs since the phosphorus content in modified fibers was higher for the shorter chain reagent. Due to the heterogeneous reaction environment, the amount of grafted phosphorus was found to be almost three times higher at the surface than in the bulk of the fibers. Analyses also indicated that the phosphorus was bonded to fibers as a phosphate-like structure. Furthermore, the situation seemed to be different for the fiber surface where significant amounts of phosphorus were present in more complex structures like pyrophosphate or even oligo-phosphate. PMID:24721058

  1. Formation and emission of PCDD/Fs in Chinese non-wood pulp and paper mills.

    Science.gov (United States)

    Wang, Xueli; Ni, Yuwen; Zhang, Haijun; Zhang, Xueping; Chen, Jiping

    2012-11-01

    Chlorine bleaching is still practiced by non-wood pulp and paper mills in China, resulting in considerable formation and emission of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). We investigate the distribution of PCDD/Fs in different papermaking processes and dioxin emissions at six typical Chinese non-wood pulp and paper mills. Raw materials for papermaking included reed, wheat straw, bamboo, and sugar cane bagasse. The formation and emission of PCDD/Fs varied strikingly according to bleaching processes and raw materials. Elemental chlorine bleaching promoted the formation of tetra- to octa-CDDs and 2,3,7,8-TCDF, while hypochlorite bleaching only gave rise to a significant increase of 2,3,7,8-TCDF. Bleaching with elemental chlorine and hypochlorite increased 2,3,7,8-TCDF 0.9-42.5 and 0.3-4.1 times, respectively. Most of the 2,3,7,8-TCDF formed at hypochlorite bleaching stage was partitioned into the effluent, which indicated that hypochlorite bleaching was also an important emission source of dioxins. The removal of PCDD/Fs occurred visibly during alkaline digestion, alkaline extraction, and hydrogen peroxide bleaching. Furthermore, the annual emission of PCDD/Fs from Chinese non-wood pulp and paper mills was evaluated. PMID:23067332

  2. Coral Mortality and Bleaching Output

    Science.gov (United States)

    COMBO is a spreadsheet-based model for the use of managers, conservationists, and biologists for projecting the effects of climate change on coral reefs at local-to-regional scales. The COMBO (Coral Mortality and Bleaching Output) model calculates the impacts to coral reefs from...

  3. Fermentation and chemical treatment of pulp and paper mill sludge

    Science.gov (United States)

    Lee, Yoon Y; Wang, Wei; Kang, Li

    2014-12-02

    A method of chemically treating partially de-ashed pulp and/or paper mill sludge to obtain products of value comprising taking a sample of primary sludge from a Kraft paper mill process, partially de-ashing the primary sludge by physical means, and further treating the primary sludge to obtain the products of value, including further treating the resulting sludge and using the resulting sludge as a substrate to produce cellulase in an efficient manner using the resulting sludge as the only carbon source and mixtures of inorganic salts as the primary nitrogen source, and including further treating the resulting sludge and using the resulting sludge to produce ethanol.

  4. Delignification of Pinus radiata kraft pulp by treatment with a yeast genetically modified to produce laccases; Deslignificacion de pasta kraft de Pinus radiata con una levadura geneticamente modificada para producir lacasa

    Energy Technology Data Exchange (ETDEWEB)

    Arana-Cuenca, A.; Tellez-Jurado, A.; Yague, S.; Ferminan, E.; Carbajo, J. M.; Dominguez, A.; Gonzalez, T.; Villar, J. C.; Gonzalez, A. E.

    2010-07-01

    Cellulose pulp bleaching is one of the main biotechnological applications of fungal laccases due to their capacity to degrade lignin from unbleached pulp. This application requires low cost enzyme production and higher enzyme concentrations than those obtained from the natural fungal producers. Heterologous expression of laccase in yeasts is an option for producing these enzymes on an industrial scale. In this work, we have demonstrated the heterologous expression of the cglcc1 gene, responsible for laccase production in the basidiomicetous fungus Coriolopsis gallica, in the yeast Kluyveromyces lactis. In order to know if the transformed yeast has delignificant capability, a Pinus radiata kraft pulp has been incubated with it. After the treatment, a significant decrease in kappa number (13%) and in lignin content (22%) was observed. These results showed the delignificant capability of this transformed yeast. It can be concluded that the use of genetically modified microorganisms that do not demonstrate cellulolitic activity can produce high laccase levels and delignify cellulose pulps with a potential applications in cellulose pulp bleaching. (Author) 25 refs.

  5. SYNTHESIS AND CHARACTERIZATION OF KRAFT LIGNIN-BASED EPOXY RESINS

    Directory of Open Access Journals (Sweden)

    Nour Eddine El Mansouri

    2011-05-01

    Full Text Available Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.

  6. Optical bleaching studies of quartz

    International Nuclear Information System (INIS)

    The bleaching properties of a hydrothermal, Arkansas quartz are studied in detail. The thermoluminescence (TL) and phototransferred TL (PTTL) signals are examined as a function of wavelength, illumination time and temperature at which the sample is illuminated. We have also briefly studied the effects of pre-irradiation annealing on the sample. The results of these experiments are described and their relevance to the models for TL is discussed. (Author)

  7. Study on Bleaching Technology of Cotton Fabric with Sodium Percarbonate

    Directory of Open Access Journals (Sweden)

    Li Zhi

    2016-01-01

    Full Text Available Bleach cotton fabric with sodium percarbonate solution. Analyse of the effect of the concentration of sodium percarbonate solution, bleaching time, bleaching temperature and the light radiation on the bleaching effect of fabric.The result shows that increasing concentrations of percarbonate,increasing the bleaching time , raising the bleaching temperature and the UV irradiation may whiten the cotton fabric.The most suitable conditions for the bleaching process is concentration of sodium percarbonate solution 6 g/ L, bleaching temperature 80°C and bleaching time 60 min.

  8. CHARACTERIZATION OF STRUCTURAL CHANGES IN LIGNIN DURING CONTINUOUS BATCH KRAFT COOKING OF EUCALYPTUS GLOBULUS

    Directory of Open Access Journals (Sweden)

    Ewa W. Rutkowska

    2009-02-01

    Full Text Available Eucalyptus globulus wood originating from plantations in Uruguay was subjected to continuous batch kraft cooking (CBC, applying mill-like conditions. Pulp samples were taken at different stages of CBC cooking being representative for all three cooking phases. The residual lignin was successfully isolated in a reasonable yield by a new method, the dissolved wood lignin (DWL protocol, which is based on the total dissolution of ball milled wood and pulp samples in dimethylsulfoxide and N-methylimidazole (DMSO/NMI followed by precipitation in dioxane/ water to separate lignin and carbohydrate fractions. For comparative reasons, the lignin was also isolated by a conventional mild acidolysis (AL method. Extensive structural lignin characterization using 1D and 2D NMR revealed that the DWL protocol allows the isolation of less altered lignin than the AL method. During bulk and residual delignification, the S/G ratio of lignin remaining in the fibers continuously decreased, while the content of -O-4 units and phenolic OH groups remained almost unaffected, suggesting that the CBC process permits enhanced delignification efficiency and good bleachability.

  9. Molekulardynamik-Simulationen supramolekularer Komplexe unter Einfluss einer externen Kraft

    OpenAIRE

    Schlesier, Thomas

    2013-01-01

    Supramolekulare Komplexe werden durch nichtkovalente Bindungen stabilisiert. Legt man eine externe Kraft an einen solchen Komplex an, ist es möglich, diese Bindungen zu öffnen. Anhand der dafür benötigten Kraft läßt sich die Stabilität des Komplexes bestimmen. Im Rahmen dieser Arbeit wurden zwei supramolekulare Komplexe, die unterschiedliche Arten von nichtkovalenten Bindungen enthalten, mit Hilfe von Molekulardynamik (MD) Simulationen untersucht. In beiden Fällen wurden die relevanten Bindun...

  10. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

    Science.gov (United States)

    Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

    2015-01-01

    Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (plaser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

  11. Life cycle greenhouse gases and non-renewable energy benefits of kraft black liquor recovery

    International Nuclear Information System (INIS)

    The life cycle greenhouse gas (GHG) and fossil fuel benefits of black liquor recovery are analyzed. These benefits are due to the production of energy that can be used in the pulping process or sold, and the recovery of the pulping chemicals that would otherwise need to be produced from other resources. The fossil GHG emissions and non-renewable energy consumption of using black liquor in the kraft recovery system are approximately 90% lower than those for a comparable fossil fuel-based system. Across all scenarios, the systems relying on black liquor solids achieve a median reduction of approximately 140 kg CO2 eq./GJ of energy produced, compared to the systems relying on fossil fuels to provide the same energy and pulping chemical production functions. The benefits attributable to the recovery of pulping chemicals vary from 44% to 75% of the total benefit. Applied to the total production of kraft pulp in the U.S., the avoided emissions are equivalent to the total Scopes 1 and 2 emissions from the entire U.S. forest products industry. These results do not depend on the accounting method for biogenic carbon (because biogenic CO2 emissions are the same for the systems compared) and the results are valid across a range of assumptions about the displaced fossil fuel, the GHG-intensity of the electricity grid, the fossil fuels used in the lime kiln, and the level of cogeneration at pulp and paper mills. The benefits occur without affecting the amount of wood harvested or the amount of chemical pulp produced. -- Highlights: ► Black liquor, a by-product of kraft pulping, represents about half of the energy used in the paper industry. ► The greenhouse gases (GHG) benefits of black liquor recovery compared to an equivalent fossil fuel system were analyzed. ► The GHG emissions of the black liquor system are approximately 90% lower than those for the fossil fuel system. ► The benefits from the recovery of the chemicals vary from 44% to 75% of the total benefit.

  12. Improved Materials for Use as Components in Kraft Black Liquor Recovery Boilers; TOPICAL

    International Nuclear Information System (INIS)

    This Cooperative Research and Development Agreement (CRADA) was undertaken to evaluate current and improved materials and materials processing conditions for use as components in kraft black liquor recovery boilers and other unit processes. The main areas addressed were: (1) Improved Black Liquor Nozzles, (2) Weld Overlay of Composite Floor Tubes, and (3) Materials for Lime Kilns. Iron aluminide was evaluated as an alternate material for the nozzles used to inject an aqueous solution known as black liquor into recovery boilers as well for the uncooled lining in the ports used for the nozzles. Although iron aluminide is known to have much better sulfidation resistance in gases than low alloy and stainless steels, it did not perform adequately in the environment where it came into contact with molten carbonate, sulfide and sulfate salts. Weld overlaying carbon steel tubes with a layer of stainless weld metal was a proposed method of extending the life of recovery boiler floor tubes that have experienced considerable fireside corrosion. After exposure under service conditions, sections of weld overlaid floor tubes were removed from a boiler floor and examined metallographically. Examination results indicated satisfactory performance of the tubes. Refractory-lined lime kilns are a critical component of the recovery process in kraft pulp mills, and the integrity of the lining is essential to the successful operation of the kiln. A modeling study was performed to determine the cause of, and possible solutions for, the repeated loss of the refractory lining from the cooled end of a particular kiln. The evaluation showed that the temperature, the brick shape and the coefficient of friction between the bricks were the most important parameters influencing the behavior of the refractory lining

  13. Subchronic metabolic effects and toxicity of a simulated pulp mill effluent on juvenile lake trout, Salmo trutta m. lacustris.

    Science.gov (United States)

    Oikari, A; Linström-Seppä, P; Kukkonen, J

    1988-12-01

    Juvenile lake trout (Salmo trutta m. lacustris) were exposed for 7 weeks to 0.05X and 0.2X 96-hr LC50 concentrations of simulated bleached kraft pulp mill effluent (KME - Sa + CP). A sulfate soap preparation, composed mainly of resin and fatty acids, with added chlorophenols (CP, tri-, tetra-, and penta-CP) was used as the toxicant mixture. Concentrations of free CP in plasma and free and conjugated CP in bile were proportional to their concentrations in the water. The greatest total gradient between bile and water CP was 5.2 X 10(4) for pentachlorophenol. The activity of a liver polysubstrate monooxygenase (PSMO) system, assayed with three model substrates, increased 40 to 67% due to KME - Sa + CP. However, the increase was not directly dependent on the exposure concentration. In contrast to PSMO, activities of conjugating enzymes (p-nitrophenol UDP-glucuronosyl and glutathione transferases) were decreased in the liver. Increased concentration of glutathione was noted in the liver and kidney. In addition, a small (9%) but significant decrease in blood hemoglobin concentration was observed at the higher exposure concentration. Although growth rate of lake trout was markedly decreased due to KME - Sa + CP, hydromineral balance and carbohydrate metabolism in fish were unaffected, indicating possible physiological compensation. On the other hand, lethality tests with lake trout preexposed to KME - Sa + CP at 0.2 X LC50 revealed decreased tolerance, whereas at the lower exposure concentration it was unchanged. We therefore conclude that various physiological adjustments in trout during subchronic exposures were not adaptive in terms of short-term tolerance. PMID:3265913

  14. In vitro penetration of bleaching agents into the pulp chamber

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Valera, M C; Mancini, M N G;

    2004-01-01

    To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures.......To investigate pulp chamber penetration of bleaching agents in teeth following restorative procedures....

  15. A Cost-Benefit Assessment of Gasification-Based Biorefining in the Kraft Pulp and Paper Industry

    Energy Technology Data Exchange (ETDEWEB)

    Eric D. Larson; Stefano Consonni; Ryan E. Katofsky; Kristiina Iisa; W. James Frederick

    2007-03-31

    Production of liquid fuels and chemicals via gasification of kraft black liquor and woody residues (''biorefining'') has the potential to provide significant economic returns for kraft pulp and paper mills replacing Tomlinson boilers beginning in the 2010-2015 timeframe. Commercialization of gasification technologies is anticipated in this period, and synthesis gas from gasifiers can be converted into liquid fuels using catalytic synthesis technologies that are in most cases already commercially established today in the ''gas-to-liquids'' industry. These conclusions are supported by detailed analysis carried out in a two-year project co-funded by the American Forest and Paper Association and the Biomass Program of the U.S. Department of Energy. This work assessed the energy, environment, and economic costs and benefits of biorefineries at kraft pulp and paper mills in the United States. Seven detailed biorefinery process designs were developed for a reference freesheet pulp/paper mill in the Southeastern U.S., together with the associated mass/energy balances, air emissions estimates, and capital investment requirements. Commercial (''Nth'') plant levels of technology performance and cost were assumed. The biorefineries provide chemical recovery services and co-produce process steam for the mill, some electricity, and one of three liquid fuels: a Fischer-Tropsch synthetic crude oil (which would be refined to vehicle fuels at existing petroleum refineries), dimethyl ether (a diesel engine fuel or LPG substitute), or an ethanol-rich mixed-alcohol product. Compared to installing a new Tomlinson power/recovery system, a biorefinery would require larger capital investment. However, because the biorefinery would have higher energy efficiencies, lower air emissions, and a more diverse product slate (including transportation fuel), the internal rates of return (IRR) on the incremental capital investments would be

  16. AFM investigation of kraft pulp ber swelling in controlled humidity

    International Nuclear Information System (INIS)

    Full text: Kraft pulp fibers are wood fibers from softwood, typically spruce and pine, which are the main constituent for so called kraft paper. Kraft paper is used mainly for packaging applications, where a high strength is required. In this work, the swelling behavior of spruce kraft pulp fibers is investigated by atomic force microscopy (AFM). To perform this task, the AFM was equipped with a fluid cell and a setup where the relative humidity inside the fluid cell can be controlled. The setup enables to select any humidity value between approximately 5% and 80% relative humidity. With this setup, a change in surface morphology of the scanned area could be observed. Furthermore, the evolution of the characteristic surface wrinkles of dried pulp fibers with increasing humidity was quantified in two different ways. One way is to measure the distance between the surface wrinkles, the other to determine their height. It could be shown that the distance between the wrinkles is increasing, whereas the height is decreasing. This means that the surface is becoming smoother when the ber is swelling, which is best observed on a completely wet fiber. (author)

  17. Võlakoorem tuhmistab Eesti võimalusi / Vahur Kraft

    Index Scriptorium Estoniae

    Kraft, Vahur, 1961-

    2003-01-01

    Eesti Panga president Vahur Kraft hoiatab liiga kergekäelise laenuvõtmise eest. Tema sõnul on Eesti Pank valmis vajaduse korral kasutama võimalusi nii laenuandjate kui ka -võtjate mõjutamiseks. Riigi stabiliseerimisreservist

  18. Rehe ja Kraft napsasid hiidudelt turuosa / Piret Reiljan

    Index Scriptorium Estoniae

    Reiljan, Piret, 1983-

    2007-01-01

    Nordea ja Sampo Pank on viimase aastaga uute ärilaenude mahtu kasvatanud 100 protsenti. Diagramm: Uute ärilaenudega esirinnas Nordea ja Sampo. Kommenteerivad: Priit Põldoja, Ahti Asmann, Aivar Rehe, Vahur Kraft ja Alo Lillepea. Vt. samas: Kodulaenude andmisel näpistab Sampo Ühispangalt turgu

  19. THERMOPLASTIC STARCH-KRAFT LIGNIN-GLYCEROL BLENDS

    Science.gov (United States)

    Starch-kraft lignin-glycerol blends were extruded in a twin-screw extruder to produce non-brittle films. One week after extrusion, films with a mid-range composition of 52% starch, 20% lignin, and 28% glycerol showed a tensile strength at break of 2.8 MPa, Young's modulus of 48 MPa, and elongation ...

  20. REEF MANAGER'S GUIDE TO CORAL BLEACHING

    Science.gov (United States)

    A Reef Manager's Guide to Coral Bleaching is the result of a collaborative effort by over 50 scientists and managers to: (1) engage in information-sharing in the areas of coral reef science and management for climate change and coral bleaching; and (2) compile a management tool ...

  1. On luminescence bleaching of tidal channel sediments

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Pejrup, Morten; Murray, Andrew S.;

    2015-01-01

    We investigate the processes responsible for bleaching of the quartz OSL signal from tidal channel sediment. Tidal dynamics are expected to play an important role for complete bleaching of tidal sediments. However, no studies have examined the amount of reworking occurring in tidal channels and o...

  2. Bleaching in vital teeth: a literary review

    Directory of Open Access Journals (Sweden)

    Felipe Fagundes Soares

    2008-01-01

    Full Text Available Tooth bleaching technique has presented a significant evolution, promoting higher satisfaction and comfort to the patients. Therefore, the aim of this study was to present the bleaching agents and the techniques, discussing advantages and disadvantages of each one, and the effect of these agents in the oral environment. The main agents used in the bleaching technique are the hydrogen peroxide and the carbamide peroxide, promoting the bleaching effect through oxidation of organic compounds. The application of these agents can be made at home or at a doctor office. During treatment, it may occur some adverse effects, such as tooth sensibility, increasing of dental porosity, and some interactions with the restorative material. However, these adverse effects can be eliminated or controlled when the treatment is executed under professional orientation. When the bleaching technique is well indicated and correctly conducted, it is associated with significantly positive results.

  3. [Gingival bleaching: teaching and ethnocentrism].

    Science.gov (United States)

    Bolla, Edson Daruich; Goldenberg, Paulete

    2010-06-01

    The aim of this study was to identify buccal/gingival cosmetic dentistry patterns subjacent to formation and professional practice of the dental surgeon from the ethnocentrism point of view. This is an exploratory study with a qualitative approach based on the thematic analysis. Initially a documental analysis was carried out. Thereafter, dental surgeons were interviewed and semi-structured questions were applied. In the Periodontal teaching field, this study showed that the presence of racial melanosis is omitted or treated as an alteration in the normality patterns and it is considered anti-aesthetic. All the interviewers learnt how to practice gingival bleaching in the post-graduation courses, they were all encouraged to offer this cosmetic dentistry procedure with the opportunity of obtaining a beautiful and healthy smile, thus assuring the belief of the Caucasian racial aesthetic superiority. This study make us think that the offer of gingival bleaching is oriented by the Caucasian pattern of beauty evidencing the ethnocentric character of this procedure. PMID:20640340

  4. Jüri Kraft : Eesti eksport nõuab Euroopa Liitu minekut / Jüri Kraft ; interv. Sulev Oll

    Index Scriptorium Estoniae

    Kraft, Jüri, 1935-

    2003-01-01

    Kahe kergetööstusettevõtte, Sangari ja Mivari nõukogu esimees, endine ENSV kergetööstusminister Jüri Kraft leiab, et kui Eesti ei astu EL-i ja loobub soodsast ekspordivõimalusest, kordub Eestis 1990. aastate alguse olukord

  5. Integrated chemical plants at the pulp mill

    Energy Technology Data Exchange (ETDEWEB)

    Ehtonen, P.; Hurme, M.; Jaervelaeinen, M.

    1995-12-31

    The goal of this paper is to present how the chemical plants can be integrated to the pulp mill. The integration renders possible to balance the chemical consumptions. The total mass balance of a pulp mill with the incoming fuel material and the outgoing waste and flue gases are discussed. The balance figures are presented for the chemicals of the modern fibre line, which will produce fully bleached softwood pulp with an improved effluent quality. The main benefits are lower chemical and transportation costs. The principal over-all plant process block diagrams and process descriptions are presented. The presented info system provides real time information on process and production status at overall mill and department levels. (author)

  6. A survey of present levels of radiocesium in Swedish pulp mill liquors and the implications for wood radiocesium transfer factors

    International Nuclear Information System (INIS)

    Assessments of the impact from radioactive fallout on the pulp industry and the accumulation processes for radionuclides in such industries, using wood and water as primary raw materials, have been conducted in previous studies. Hitherto, there is a general lack of data on present levels of radioactivity in pulp mill liquors apart from the few mills studied by [NILSSON (1992)] [RAVILA AND HOLM (1992)] [MANJON ET AL. (1996) and [KROSSHAVN ET AL. (1997)]. A survey was therefore initiated to describe and compare the present activity levels in pulp mill liquors from various mill locations in Sweden. The 137Cs activity in pulp mill liquors were compared with the mill location and the deposition pattern of the Chernobyl fallout and nuclear weapons fallout. The large input of wood (approx. 2500 m3 day-1) to an average Nordic Kraft mill and the relatively long-term retention time for radiocesium in the Kraft mill recovery cycle enables representative sampling of substances directly related to the activity concentration in wood

  7. Extended impregnation kraft cooking of softwood : Effects on reject, yield, pulping uniformity, and physical properties

    OpenAIRE

    Karlström, Katarina

    2009-01-01

    Converting wood into paper is a complex process involving many different stages, one of which is pulping. Pulping involves liberating the wood fibres from each other, which can be done either chemically or mechanically. This thesis focuses on the most common chemical pulping method, the kraft cooking process, and especially on a recently developed improvement of the impregnation phase, which is the first part of a kraft cook. Extended impregnation kraft cooking (EIC) technique is demonstrated...

  8. PROTEIN EXTRACTION FROM SECONDARY SLUDGE OF PAPER MILL WASTEWATER AND ITS UTILIZATION AS A WOOD ADHESIVE

    OpenAIRE

    Muhammad Pervaiz; Mohini Sain

    2011-01-01

    In this study, secondary sludge (SS) from a kraft paper mill was used as a source of biomass to recover protein and investigate its potential use as a wood adhesive. The process of protein recovery involved disruption of the floc structure in alkaline medium to disintegrate and release intercellular contents into the aqueous phase followed by separation of soluble protein. Finally, the soluble protein was subjected to low pH precipitation and the pelletized sludge protein, referred to as reco...

  9. Improved Usage of Wood Raw Material through Modification of the Kraft Process

    OpenAIRE

    Tavast, Daniel

    2015-01-01

       The kraft process is a complex system with many variables, and though the process is fairly well understood, there is still much we do not know.      This thesis examines some aspects of the kraft process that could prove to be of interest for the pulp and paper industry, specifically, the impact of wood chip impregnation and of the chemical structure of xylan on spruce kraft pulp. The intent is to suggest modifications to the kraft process as it is used today.      The effect of wood chip...

  10. Mergers and acquisitions : the case of Kraft Foods and Cadbury

    OpenAIRE

    Ribeiro, Sara Isabel de Paula

    2013-01-01

    The aim of this dissertation is to focus on a determinant aspect of Corporate Finance that is Mergers and Acquisitions (M&A). This dissertation not only provides a practical analysis of main issued regarding a process of M&A, but also provides a theoretical framework about M&A. Specifically, this dissertation explores the real case of Kraft Foods - world’s second largest manufacturer and packager food products – and Cadbury - the world’s second largest confectionery firm. ...

  11. Modeling Reef Hydrodynamics to Predict Coral Bleaching

    Science.gov (United States)

    Bird, James; Steinberg, Craig; Hardy, Tom

    2005-11-01

    The aim of this study is to use environmental physics to predict water temperatures around and within coral reefs. Anomalously warm water is the leading cause for mass coral bleaching; thus a clearer understanding of the oceanographic mechanisms that control reef water temperatures will enable better reef management. In March 1998 a major coral bleaching event occurred at Scott Reef, a 40 km-wide lagoon 300 km off the northwest coast of Australia. Meteorological and coral cover observations were collected before, during, and after the event. In this study, two hydrodynamic models are applied to Scott Reef and validated against oceanographic data collected between March and June 2003. The models are then used to hindcast the reef hydrodynamics that led up to the 1998 bleaching event. Results show a positive correlation between poorly mixed regions and bleaching severity.

  12. Thermoluminescence dating of partially bleached sediments

    International Nuclear Information System (INIS)

    A major problem in TL dating of sediments is the lack of knowledge concerning the degree of bleaching that took place during transport of the material prior to deposition. A method is proposed that may enable partially bleached sediments to be dated by determining the correct residual value to be used with the build-up curve. The method uses a combination of results for quartz and feldspar, presuming that these two minerals have the same age. Samples are bleached by sunlight for different periods, and the correct bleaching time is taken as that producing residual values which yield identical ages for the minerals. Preliminary results for a number of aeolian sediments from Jutland are presented. In most cases the TL ages were in acceptable agreement with expected ages. (author)

  13. Kraft lignin behavior during reaction in an alkaline medium

    International Nuclear Information System (INIS)

    The reaction of kraft lignin in an alkaline medium was studied using a microreactor set. Chemical changes in reacted kraft lignins that include ash content, Klason lignin, acid-soluble lignin and sugars were studied. Structural characteristics of these lignins were also determined in terms of phenolic-hydroxyl, aliphatic-hydroxyl, methoxyl, Mw, Mn and polydispersity. The techniques employed were HPLC, UV spectroscopy, FTIR spectroscopy, proton nuclear magnetic resonance spectroscopy and organic gel permeation chromatography (GPC). The effects of temperature and reaction time on lignin properties were studied using response surface methodology. The reaction temperature ranged from 116 to 180 oC and the reaction time ranged from 18 to 103 min. The obtained response surfaces show that both factors affected lignin properties within these ranges. The phenolic and aliphatic-hydroxyl content and the number of active sites increased when the treatment severity was increased. Weight-average molecular weight (Mw), number-average molecular weight (Mn) and solid-yield percentage decreased when the treatment severity was increased. -- Highlights: → We studied the chemical and structural changes of Kraft lignin during its reaction in alkaline medium. → The phenolic and aliphatic hydroxyl content and the number of active sites increased when the treatment severity was increased. → Weight-average MW, number-average MW and solid-yield percentage decreased when the treatment severity was increased.

  14. Producing a True Lignin Depolymerase for Biobleaching Softwood Kraft Pulp

    Energy Technology Data Exchange (ETDEWEB)

    Simo Sarkanen

    2002-02-04

    This project constituted an intensive effort devoted to producing, from the white-rot fungus Tramets Cingulata, a lignin degrading enzyme (lignin depolymerase) that is directly able to biobleach or delignify softwood kraft pulp brownstock. To this end, the solutions in which T. cingulata was grown contained dissolved kraft lignin which fulfilled two functions; it behaved as a lignin deploymerase substrate and it also appeared to act as an inducer of enzyme expression. However, the lignin depolymerase isoenzymes (and other extracellular T. cingulata enzymes) interacted very strongly with both the kraft lignin components and the fungal hypae, so the isolating these proteins from the culture solutions proved to be unexpectedly difficult. Even after extensive experimentation with a variety of protein purification techniques, only one approach appeared to be capable of purifying lignin depolymerases to homogeneity. Unfortunately the procedure was extremely laborious; it involved the iso electric focusing of concentrated buffer-exchanged culture solutions followed by electro-elution of the desired protein bands from the appropriate polyacrylamide gel segments

  15. Internationalisation; KonKraft-rapport 4; Internasjonalisering

    Energy Technology Data Exchange (ETDEWEB)

    2008-07-01

    disintegrate. The obvious strategy to pursuit is to strengthen Norway's position as a dynamic and leading competence center for oil- and gas activities. Recruitment and development of sufficient competencies is generally a major challenge for the oil- and gas trade. Shortage of human capital leads to increased wage pressure which in the long run may weaken profits and competitiveness. In some of the petroleum clusters the companies try to find solutions to counteract the negative effects of the battle for the best brains. Through the project KonKraft INTSOK has unveiled high ambitions concerning increased internationalisation throughout the Norwegian petroleum cluster, except for Northern Norway. Here there is still an opposition against activities in the region, as well as in the Barents sea. INTSOK's intention with the project has been to describe its multitude. Therefore eight very different environments where selected to make a closer study on the development in different regions. The environments represent a variety of sizes, geography and trades. Some of the clusters are new or under establishment, others are already in full operation. Together the eight environments cover a major part of the value chain in the Norwegian offshore sector. The project has clearly demonstrated that cluster development contributes both to internationalisation as well as keeping the companies in Norway. Some main findings: The positive development in the drilling cluster of Southern Norway - the Node cluster - has created strong impact: The cluster ranks among the world's leading on drilling equipment and barely any oil or gas environment has had a similar expansion. The Kongsberg environment is not an offshore cluster, but an overall technology cluster where offshore applications is one of several technology areas. The companies develop and produce a broad range of advanced products and systems. The turnover among the offshore companies amounts to 65% of the total turnover for

  16. HOME BLEACHING TECHNIQUE USING CARBAMIDE PEROXIDE

    Directory of Open Access Journals (Sweden)

    Rahmi Alma Farah Adang

    2015-06-01

    Full Text Available There are two basic kinds of tooth whitening agents. The first is over the counter materials and the other is material used by the dentist or under dentist control. Home bleaching is a technique using 10% carbamide peroxide on a tray applied by patient under dentist supervision. This paper is a review of the effect of 10% carbamide peroxide home bleaching technique. It is revealed that this method is simple, safe, economic, and has short chairside time.

  17. Local Stressors Reduce Coral Resilience to Bleaching

    OpenAIRE

    Carilli, Jessica E; Norris, Richard D.; Black, Bryan A.; Walsh, Sheila M.; McField, Melanie

    2009-01-01

    Coral bleaching, during which corals lose their symbiotic dinoflagellates, typically corresponds with periods of intense heat stress, and appears to be increasing in frequency and geographic extent as the climate warms. A fundamental question in coral reef ecology is whether chronic local stress reduces coral resistance and resilience from episodic stress such as bleaching, or alternatively promotes acclimatization, potentially increasing resistance and resilience. Here we show that following...

  18. OVERVIEW OF IN-OFFICE BLEACHING OF VITAL TEETH

    Directory of Open Access Journals (Sweden)

    Hegde Mithra N.

    2012-11-01

    Full Text Available The importance of tooth whitening for patients has shown a dramatic increase in the number of products and procedures over recent years. Vital tooth bleaching refers to chair-side clinical application of a chemical solution to a tooth surface in order to achieve whitening effect of the teeth. Vital bleaching have found to be very effective but they also have their the drawbacks. The current article gives knowledge of vital tooth whitening with respect to external bleaching methods. the external bleaching of vital teeth focuses on patient selection, mechanisms, bleaching procedure and various in-office bleaching systems and techniques and their disadvantages.

  19. Local stressors reduce coral resilience to bleaching.

    Directory of Open Access Journals (Sweden)

    Jessica E Carilli

    Full Text Available Coral bleaching, during which corals lose their symbiotic dinoflagellates, typically corresponds with periods of intense heat stress, and appears to be increasing in frequency and geographic extent as the climate warms. A fundamental question in coral reef ecology is whether chronic local stress reduces coral resistance and resilience from episodic stress such as bleaching, or alternatively promotes acclimatization, potentially increasing resistance and resilience. Here we show that following a major bleaching event, Montastraea faveolata coral growth rates at sites with higher local anthropogenic stressors remained suppressed for at least 8 years, while coral growth rates at sites with lower stress recovered in 2-3 years. Instead of promoting acclimatization, our data indicate that background stress reduces coral fitness and resilience to episodic events. We also suggest that reducing chronic stress through local coral reef management efforts may increase coral resilience to global climate change.

  20. Cone photopigment bleaching abnormalities in diabetes.

    Science.gov (United States)

    Elsner, A E; Burns, S A; Lobes, L A; Doft, B H

    1987-04-01

    We have used a color-matching technique to obtain estimates of the optical density of cone photopigments as a function of retinal illuminance in patients with insulin-dependent diabetes mellitus (IDDM). We found that the half-bleach illuminance of some patients is abnormally high. That is, it takes more light to bleach an equivalent amount of photopigment in these patients. Since low illuminance color matches for these patients are normal, this implies that these patients have normal amounts of photopigment, but the photopigment is not bleaching normally. This result clearly points to abnormalities in the outer retina of these diabetic patients. The most likely causes of this abnormality are either decreases in the ability of the cones to absorb light, or an increased rate of regeneration of the cone photopigments. PMID:3557875

  1. Production of biofuels from lignocellulosic biomass in pulp and paper mill effluents for low carbon society

    OpenAIRE

    Thakur, Indu Shekhar; Nakagoshi, Nobukazu

    2011-01-01

    Carbon Dioxide (CO2) is the most prominent Green House Gas (GHGs) in the Earth's atmosphere is responsible for climate change and other environmental problems. However, CO2 may be converted into organic compounds and lignocellulosic biomass. The pulp and paper mill is a major industrial sector utilizing huge amount of natural product (woody and non-woody plants), inorganic and organic materials along with large volume of water in different stages of the paper manufacturing. In kraft pulping, ...

  2. Use of Carbonized Seed Hulls as Alternative to Bleaching Clay During Miscella Bleaching of Oils

    OpenAIRE

    Mona El- Hamidi; Taha, F. S.; Safinaz M. El- Shami; Hassanein, Minar M. M.

    2016-01-01

    Soybean oil (SBO) was miscella bleached in hexane using carbonized hulls of Jojoba (Jo), Jatrova (Ja), Peanuts (PN) and Pistachios (P) as alternatives to bleaching clays. Evaluation of bleached crude SBO with carbonized hulls was based on their delta-Free Fatty Acids (ΔFFA), reduction in Peroxide Value (PV), carotenoid content, color index and bleachability. Fuller’s Earth (FE) and Tonsil N (TN) were used for comparison with the carbonized hulls. Three oil: hexane ratios, 1: 0.5, 1:1 and 1:1....

  3. The Effects of Habitat on Coral Bleaching Responses in Kenya

    OpenAIRE

    Grimsditch, Gabriel; Mwaura, Jelvas M.; Kilonzo, Joseph; Amiyo, Nassir

    2010-01-01

    This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching incidence was monitored for the whole coral community, while zooxanthellae densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea, and Porites cylindrica) during a non-bleaching year (2006) and a year of mild-bleaching (200...

  4. Photo-bleaching response in chlorophyll solutions

    International Nuclear Information System (INIS)

    Photo-excitation processes were investigated in chlorophyll solutions by irradiation with UV light sources. Photo-excited bulk effects during the bleaching experiments were diagnosed. The optical diagnostic was expressed by a Beer-Lambert matrix formulation and applied to the experimental results. The chromophores evaluated optical cross-section was 10-15 cm2 and the optical absorption coefficient dynamic variation was fitted to a simple reaction rate model. The bleaching rates were expressed by this model and fitted to the experimental data

  5. The corrosion of titanium and some other construction materials during hydrogen peroxide bleaching according to the field measurements

    International Nuclear Information System (INIS)

    In a Finnish pulp mill, the field measurements of different materials were performed in different stages of peroxide bleaching: P1 and P2. The field measurements were performed with three different sensors. The sensors were designed in co-operation with Valmet Automation Kajaani Oy. Each sensor measured the corrosion potential, the redox potential and the weight losses of three different materials. Simultaneously, the data of the most important parameters of bleaching, i.e. temperature, pH, peroxide flow rate and concentration, mass flow, consistency, residuals, flow rate and concentration of alkaline, were collected in the data logger by a dedicated program. The results proved that the corrosion of different materials (stainless steel S31654, nickel-based alloy N10276 and titanium Gr. 5) could be estimated with field experiments. The uniform corrosion of titanium occurred in a certain bleaching situation. The field measurements gave a good estimation of whether the material dissolved during process operation or process disorders. Our results clearly show that the mixing of the chemicals can be reliably estimated, and thus advantageous for a pulp mill. The materials studied withstood the bleaching significantly better if the chemicals were mixed directly with a pulp. Usually the chemicals are mixed with alkaline and then added to the pulp. The field measurements could also be applied in ozone and in the peracetic acid bleaching stage. The sensors can be utilized as tools during process monitoring or diagnostics. With the aid of monitoring it is possible to clarify how the different process operation models affect the corrosion of materials. (author)

  6. 21 CFR 872.6475 - Heat source for bleaching teeth.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of...

  7. Bleaching and diffusion dynamics in optofluidic dye lasers

    DEFF Research Database (Denmark)

    Gersborg-Hansen, Morten; Balslev, Søren; Mortensen, Asger;

    2007-01-01

    The authors have investigated the bleaching dynamics that occur in optofluidic dye lasers where the liquid laser dye in a microfluidic channel is locally bleached due to optical pumping. They find that for microfluidic devices, the dye bleaching may be compensated through diffusion of dye molecules...... pumping devices. ©2007 American Institute of Physics....

  8. High-solids black liquor firing in pulp and paper industry kraft recovery boilers: Phase Ia - Low-temperature gasifier evaluation. Final report, November 1, 1995--October 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Southards, W.T.; Blude, J.D.; Dickinson, J.A. [and others

    1997-06-01

    This project, conducted under The United States Department of Energy (DOE) Cooperative Agreement DE-FC36-94GO10002/A002, was part of a multiple-phase effort to develop technologies that improve the energy efficiency and economics of chemical process recovery in the pulp and paper industry. The approach taken was to consider two major alternatives in two phases. Phase I, conducted previously, considered means to improve pulp mill recovery boilers using high-solids advanced combustion of black liquor; while this project, Phase la, considered means to recover kraft pulping mill process chemicals by low-temperature black liquor gasification. The principal steps previously proposed in this program were: (1) Evaluate these two technologies, high-solids advanced combustion and gasification, and then select a path forward using the more promising of these two options for future work. (2) Design and construct a pilot-scale unit based on the selected technology, and using that unit, develop the precompetitive data necessary to make commercialization attractive. (3) Develop and deploy a first-of-a-kind (FOAK) commercial unit in a kraft pulp mill. Phase I, which evaluated the high-solids advanced combustion option, was concluded in 1995. Results of that project phase were reported previously. This report describes the work conducted in Phase Ia. The work is described in Sections 1 through 4 and six appendices provide additional detail.

  9. Fenomena Bleaching Karang Tahun 2009 di Pulau Badi Selat Makassar (Coral Bleaching Event on 2009 in Badi Island Makassar Strait)

    OpenAIRE

    Yusuf, Syafyudin; Rani, Chair; Jompa, Jamaluddin

    2010-01-01

    Bleaching event is loss of zooxanthella from the marine organisms tissue, as a caused by enviromental stress. Coral bleaching fenomenom was observed on May and June 2009 in Badi Island on Makassar Strait, Indonesia . The method used in this study is identified the photos coral colonies which bleaching infected were photographed with a Ixus Digital Canon 75 camera in an underwater housing. The results showed that the bleaching corals are caused by temperature anomaly above 1,24oC higher...

  10. Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals

    DEFF Research Database (Denmark)

    Murray, A.S.; Thomsen, Kristina Jørkov; Masuda, N.; Buylaert, Jan-Pieter; Jain, Mayank

    2012-01-01

    relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar luminescence stimulated at 50 °C by infrared light (IR50) and feldspar luminescence stimulated at 290 °C by infrared light after a stimulation at 50 °C (pIRIR290), and use recently deposited samples to determine the......When dating older sedimentary deposits using quartz, there are no unambiguous methods for identifying the presence of incomplete bleaching. Current statistical analysis of dose distributions depends entirely on the assumption that incomplete bleaching and mixing are the main causes of any excess...... dispersion in the distribution; the only existing way to test this assumption is using independent age control. Here we suggest a new approach to this question, based on the differential bleaching rates of quartz and feldspar luminescence signals. We first present data that confirm the differences in...

  11. Thermal and spectroscopic analyses on the molecular interaction between eucalyptus kraft pulp components and offset printing inks

    Directory of Open Access Journals (Sweden)

    Ericka Figueiredo Alves

    2009-06-01

    Full Text Available Thermal and infrared spectroscopic analyzes were carried out in order to study the kind of interaction between the anatomical components of the bleached eucalyptus kraft pulp with offset inks. A Bauer-McNett fiber classifier was used in order to obtain the anatomical components of the pulp, separately. The determinations of the enthalpy of the processes occurring in the samples of inks and pulp, as well as the enthalpy of these components interactions were obtained by Differential Scanning Calorimetry. In the interaction between pulp and offset ink, the reduced enthalpy values of the endothermic peak were interpreted as due to the released energy for adhesion of the ink pigment to the substratum. The low enthalpy value, 58 to 121 cal.g -, ¹indicated that the settling of the ink occurs by physical interactions. The pulp fraction enriched with vessel elements caused a higher energy release during the adherence of the pigment into the pulp.O conhecimento técnico-científico das interações que ocorrem no processo de impressão offset é escasso, embora várias observações mostrem sua importância. O objetivo deste trabalho foi estudar por análises térmicas e espectroscópicas, na região 1do infravermelho, o tipo de interação dos componentes anatômicos da polpa branqueada kraft de eucalipto com tintas de impressão offset. Foi utilizado um classificador de fibras Bauer-McNett com o intuito de se obter os componentes anatômicos da polpa separadamente. As determinações da entalpia dos processos que ocorrem com as amostras de tintas, polpa e também a entalpia de interação destes componentes foram obtidas por Calorimetria Diferencial de Varredura. Na interação entre polpa e tinta offset, a redução dos valores de entalpia do pico endotérmico foi interpretada como sendo devida à liberação de energia para a adesão do pigmento da tinta ao substrato. Os baixos valores de entalpia (58 a 121 cal.g-1 indicam que o assentamento da tinta

  12. Modelling the optical bleaching of a complex TL signal

    International Nuclear Information System (INIS)

    Thermoluminescence (TL) intensity decrease is observed in many materials after optical stimulation and is called optical bleaching of TL. The optical bleaching of a TL peak does not always mean that the traps responsible for this peak are emptied by stimulating light. The McKeever model explains TL bleaching by the emptying of deep thermally disconnected traps. The modification of this model is used for simulating the optical bleaching of complex TL curves in the case of complex TL spectrum. Some characteristic outcomes important for interpreting the results of TL optical bleaching measurements are reported

  13. Enamel alteration following tooth bleaching and remineralization.

    Science.gov (United States)

    Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

    2016-06-01

    The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. PMID:27197087

  14. Biological and advanced treatment of sulfate pulp bleaching effluents

    International Nuclear Information System (INIS)

    Spent bleaching effluents (from chlorination (C) and extraction (E) stages) of a sulfate pulp mill were subjected to bench-scale biological and advanced treatment. Although > 90 % of the influent BOD5 could be removed in an activated sludge process, the effluent still contained high amounts of resistant substances. The maximum COD removal was about 50 %; the removal rates achieved in the parameters TOC, DOC, AOX, SAK (254 nm) were even lower. The biological treatment led to an increase in color (436 nm) up to 40 %. The biologically pretreated effluent was further treated by ozone or ozone/irradiation. The DOC, COD, color (436 nm), SAK (254 nm) and AOX removal rates amounted to 61 %, 81 %, 98 %, 92 % and 92 %, respectively. These methods led simultaneously to an increase in biological biodegradability as reflected by an increase in BOD5. A comparison of the results obtained for raw and biologically pretreated wastewaters showed that biodegradable substances should first be removed from the wastewater since otherwise the effectiveness of these methods decreased. The coagulation/flocculation of biologically pretreated effluent showed that FeCl3 was the most effective coagulant and that removal rates > 90 % could be achieved. The treatment with various powder activated carbons showed that a dosage of 10 g/l was required to achieve elimination rates > 90 % in the parameters DOC, COD, color (436 nm) and SAK (254 nm). Adsorption isotherms were developed for every activated carbon and adsorption constants were calculated. (author)

  15. Oxidant reduction and biodegradability improvement of paper mill effluent by irradiation

    International Nuclear Information System (INIS)

    Paper mill bleach processing wastewaters represent a large input of hazardous compounds to the environment and these compounds are usually non-biodegradable. A preliminary study using a 5000 Ci 60Co gamma radiation source as a surrogate for electron beam irradiation, potentially an emerging technology for wastewater treatment, to treat a paper mill bleach effluent showed that for an absorbed dose of 800 krads, chemical oxygen demand (COD) was reduced by 13.5% and 5 day biochemical oxygen demand (BOD5) was increased 58.6%. These changes altered the value of COD/BOD5 from 14 to 5. For the same dose, the absorbable organic halogen (AOX) was reduced 76.2%. These results suggested the possibility of using the electron beam process to detoxify paper mill effluent thereby generating a more biodegradable wastewater. (author)

  16. Jens Kraft og "De vilde Folk" (1760) - manden, forfatterskbet, værket

    DEFF Research Database (Denmark)

    Langkjær, Michael Alexander

    2000-01-01

    Jens Kraft and his Brief Account of the Principal Institutions, Customs and Ideas of the Savage Peoples, to Inform about the General Origins and Development of Humanity, Sorø, 1760 - The man, his writings, his book. The present dissertation presents some results of my research on Jens Kraft...... Norse peoples, thus offering an explanation of the general development of human culture: how it originates, and, more importantly, why, in some cases it did not progress beyond a certain level. Kraft shows that man's natural mode of development is a slow, uncertain process, quickened only...... concerned with theology, philology and antiquities, building up a comprehensive knowledge within the field of human studies. That knowledge found cumulative expression in 1760 when Kraft published his Brief Account of the Savage Peoples.Brief Account of the Savage Peoples seems an anomaly in the body...

  17. Application of thermoalkalophilic xylanase from Arthrobacter sp. MTCC 5214 in biobleaching of kraft pulp

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Bhosle, N.B.

    released by enzyme treatment showed a characteristic peak at 280 nm indicating the presence of lignin in the released coloring matter. Enzymatic prebleaching of kraft pulp showed 20 % reduction in kappa number of the pulp without much change in viscosity...

  18. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    Directory of Open Access Journals (Sweden)

    G. Dishon

    2015-06-01

    Full Text Available Coral reefs occupy only ~0.1% of the oceans habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced significant global declines due to a variety of causes, one of the major being widespread coral bleaching events. During bleaching the coral expels its symbiotic algae losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS to demonstrate a distinct biologically-induced decline of boron (B isotopic composition (δ11B as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded "vital effect" of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure.

  19. Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event.

    Science.gov (United States)

    Mydlarz, Laura D; Couch, Courtney S; Weil, Ernesto; Smith, Garriet; Harvell, C Drew

    2009-11-16

    One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function. PMID:20095242

  20. Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

    Science.gov (United States)

    Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

    2016-07-01

    As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel

  1. Investigation of catalyst and solvent systems for the catalytic oxidation of Kraft lignin

    OpenAIRE

    Mora Mir, Joan

    2010-01-01

    Lignin is one of the main constituents of wood together with cellulose and hemicellulose and can be used as a renewable feedstock for the production of chemicals. Lignin is an amorphous polymer which is separated from cellulose during the pulping processes in the paper industry. The Kraft process is the most extended pulping process and the so called Kraft lignin is one of the most promising sources for the obtaining of value-added products from its degradation. The catalytic oxidation of ...

  2. Antioxidant Activity of Lignin Phenolic Compounds Extracted from Kraft and Sulphite Black Liquors

    OpenAIRE

    Ana Paula Duarte; Cecília Baptista; Nuno Gil; Hélio Faustino

    2010-01-01

    The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in ter...

  3. Changes in bleaching susceptibility among corals subject to ocean warming and recurrent bleaching in Moorea, French Polynesia.

    Directory of Open Access Journals (Sweden)

    Morgan S Pratchett

    Full Text Available BACKGROUND: Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. METHODOLOGY/PRINCIPAL FINDINGS: This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites, during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98% than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. CONCLUSIONS/SIGNIFICANCE: Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species is producing a coral assemblage that is

  4. Caracterização de compostos reduzidos de enxofre gerados na produção de celulose kraft e pré-hidrólise kraft.

    Directory of Open Access Journals (Sweden)

    Afonso Moraes de Moura

    2010-08-01

    Full Text Available Um problema ambiental da indústria de celulose kraft é o odor causado pela emissão dos compostos reduzidos de enxofre gerados pela deslignificação de madeiras de um modo em geral. Para monitorar essas emissões, existem equipamentos simples, desenvolvidos para a medição contínua do "total reduced sulphur" (TRS, tal como o analisador coulométrico. Neste trabalho, foram analisados sulfeto de hidrogênio (H2S, metil mercaptana (CH3SH, dimetil sulfeto [(CH32S] e dimetil dissulfeto [(CH32S2], gerados em deslignificações laboratoriais kraft e pré-hidrólise kraft de dois grupos de madeiras de folhosas. Um dos grupos de madeiras continha 25% e o outro 20% de lignina, base peso seco. Foi observado que as madeiras com menores teores de lignina geraram significativamente menores quantidades de compostos reduzidos de enxofre de TRS. Não foram notadas diferenças significativas nas quantidades totais geradas entre os processos de deslignificação estudados. O processo pré-hidrólise kraft foi mais sensível aos teores de lignina da madeira que o processo kraft. Recomenda-se, por isso, trabalhar com madeiras com menores teores de lignina quando do uso do processo pré-hidrólise kraft para produção de celulose. As principais formas geradas de TRS foram dimetil sulfeto e metil mercaptana.

  5. Side effects of external tooth bleaching

    DEFF Research Database (Denmark)

    E.M., Bruzell; Pallesen, Ulla; Thoresen, N.R.;

    2013-01-01

    -office = 39.3% [n = 28]; p >0.05; 95% CI [OR]: 0.198‑1.102) whereas prevalence of gingival irritation was higher after in-office treatment (at-home = 14.0%; in-office = 35.7%; p <0.05) (mean age: 37.3 years; 73.7% women; n = 171). At the second follow-up, two and three patients reported side effects...... attributed to the bleaching treatment in the at-home and in-office groups, respectively. Predictors for side effects were tooth sensitivity, surface loss and gingivitis when observed at inclusion. Treatment-related predictors were bleaching concentration and contact between tray and gingiva. Conclusions...

  6. Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection.

    Science.gov (United States)

    Scott, Anna; Dixson, Danielle L

    2016-05-25

    Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. PMID:27226472

  7. Bleached dissolving pulps applying laccase treatments

    OpenAIRE

    Quintana, Elisabet; Valls Vidal, Cristina; Roncero Vivero, María Blanca

    2012-01-01

    A biobleaching sequence, using a laccase enzyme (Trametes Villosa) in combination with different mediators, was applied to softwood dissolving cellulose in order to study its bleaching efficiency and its potential in terms of kappa number, ISO brightness and viscosity. The tested mediators were classified as synthetic compounds such as HBT (1-hydroxybenzotriazole) and VA (violuric acid), and as natural compounds such as SA (syringaldehyde) and pCA (p-coumaric acid). The influence of the enzym...

  8. PULPING PROPERTIES OF KRAFT PULP OF NIGERIAN-GROWN KENAF (HIBISCUS CANNABINUS L.

    Directory of Open Access Journals (Sweden)

    Abiodun Oluwafemi Oluwadare

    2011-02-01

    Full Text Available This study was centered on finding a locally sourced alternative to imported long-fibre pulp for Nigerian pulp and paper mills. Fibre characteristics, chemical composition, and paper properties of pulp handsheets at different levels of kappa number and freeness in the range of 10 oSR and 62 oSR were evaluated using air-dried bast fibre obtained from decorticated kenaf plants grown in southern guinea savanna near Jebba, Nigeria. Kenaf bast fibre compared well with softwood, with an average fibre length of 2.90 mm, a flexibility ratio of 57%, and a Runkel ratio of 0.76. Ash, lignin, and pentosan contents were 0.6%, 12.5%, and 10.6%, respectively, while the cellulose content was 55.5%. Under alkali charge of 15.0 and, sulphidity of 17.5 with constant temperature, cooking time, and liquor-to-fibre ratio of 4.5:1, the screen yield was between 48.8 to 52.8 % with kappa number 12.04 to 20.5. Unbleached pulpsheets at kappa number between 15 and18.5 and pulp freeness 55 oSR and bleached pulp freeness between 148 and 336 mLs had better quality paper in terms of overall pulpsheet strength properties.

  9. A New Freeze Concentration Process for Minimum Effluent Process in Bleached Pulp

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Ru-Ying; Botsaris, Gregory D.

    2001-03-06

    This project researches freeze concentration as a primary volume reduction technology for bleaching plant effluents from paper-pulp mills before they are treated by expensive technologies, such as incineration, for the destruction of the adsorbable organic halogens. Previous laboratory studies show that freeze concentration has a greater than 99.5% purification efficiency for volatile, semivolatile, and nonprocess elements, or any other solute, thus producing pure ice that can be reused in the mill as water. The first section evaluates the anticipated regulatory and public pressures associated with implementing the technology; the remaining sections deal with the experimental results from a scaled-up freeze concentration process in a 100-liter pilot-plant at Tufts University. The results of laboratory scale experiments confirmed that the freeze concentration technology could be an efficient volume reduction technology for the above elements and for removing adsorbable organic hologens and or nonprocess elements from recycled water. They also provide the necessary data for designing and operating a larger pilot plant, and identify the technical problems encountered in the scale-up and the way they could be addressed in the larger scale plants. This project was originally planned to include the operation of a large pilot plant in the facilities of Swenson Process Equipment Inc., and a field test at a pulp mill, but the paper company withdrew its financial support for the field test. In place of a final economic evaluation after the field test, a preliminary evaluation based on the small pilot plant data predicts an economically reasonable freeze concentration process in the case of reduction of the bleaching-effluent flow to less than 5 m3/kkg pulp, a target anticipated in the near future.

  10. Thermoluminescence emission spectra and optical bleaching of oligoclase

    International Nuclear Information System (INIS)

    Thermoluminescence (TL) spectra of oligoclase samples have been recorded in the temperature range from 300 to 700 K and the wavelength range from 300 to 850 nm. Like other feldspars, oligoclase produces blue (peaking at 460 nm) and red (peaking at 765 nm) emission bands. The maximum of the red emission occurs 20 K lower than that of the blue band. Optical bleaching was performed at wavelengths varying from 360 to 800 nm. Bleaching of artificially irradiated oligoclase causes a decrease of the TL signal. The bleaching efficiency increases with decreasing wavelength. Bleaching does not only influence the height of the glow curve but also the shape. An interesting observation is that the ratio of the blue and red band intensities is not affected by a bleaching procedure. No evidence has been found that bleaching influences the shape of the emission spectra. The correlation between the blue and red bands is discussed. (Author)

  11. Water Mills in Israel

    OpenAIRE

    Frankel, Rafael

    2015-01-01

    The most fundamental questions regarding the history of water mills are when and where was the water mill invented and the relationship historically between the horizontal water mill, that with a horizontal water wheel and the vertical water mill that with a vertical water wheel as described by Vitruvius (De Architectura X, 5, 2). In both cases they are operated by a spindle that goes through a hole in the lower mill stone and turns the upper stone. In the horizontal mill this spindle is conn...

  12. Biorefinery pulp mill - BiSe

    Energy Technology Data Exchange (ETDEWEB)

    Henricson, K.; Saukkonen, E.; Nokkanen, T. (and others) (Lappeenranta Univ. of Technology (Finland). Lab. of Fiber and Paper Technology). Email: kaj.henricson@lut.fi

    2010-10-15

    A need to utilize woody material in a more efficient way to produce pulp, biofuels and energy is seen as a key factor in the development of new pulp mill biorefineries. There are many alternatives to execute the biorefinery concept. In the Biorefinery Pulp Mill (Biojalostamo Sellutehdas), BiSe project approach, prehydrolysis of wood chips and acid hydrolysis of logging residue for the production of bioethanol as well as the separation of lignin for the production of biodiesel are studied. The main goal of the project is to examine these new biofuel production methods and processes for the improvement of the competitiveness, energy effectiveness and economic profitability of domestic pulp mills, while keeping in mind the main product, chemical pulp. In the project, laboratory experiments on wood chip prehydrolysis prior to cooking, hydrolysis liquor treatment, cooking of prehydrolyzed chips, low power pulp bleaching and lignin separation are carried out. Based on these laboratory data, a simulation model of the biorefinery is created. The model is then used to assess the profitability of the BiSe biorefinery approach. (orig.)

  13. A comprehensive program to develop correlations for the physical properties of Kraft black liquor. Interim report No. 3

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, A.L.; Dong, D.J.; Schmidl, G.W.; Stoy, M.A.; Zaman, A.A.

    1993-09-01

    The black liquor properties program has been conducted over this last period so as to systematically collect data on properties, liquor composition, and lignin characteristics very carefully by methods that have developed during this program. Complete data has been collected for Slash Pine black liquors made by experimental pulping at different pulping conditions. In addition, data has been collected for mill liquors and partial properties or composition data has been collected on Slash Pine black liquors. Data reduction methods have been developed or extended for correlation of viscosity, heat capacity, heat of dilution, and density. Correlation of properties to pulping conditions and of composition to. pulping conditions has begun. In most cases, data reduction methods have been developed that are fundamentally based and that have been shown to be generally applicable to all black liquors. In the near future, we fully expect to accomplish our goal of developing generalized correlations relating physical properties of Slash Pine kraft black liquors to liquor composition. This interim report reviews the methods used, describes examples of data reduction methods that have been developed, and presents some preliminary results for correlation of liquor composition and properties to pulping conditions for Slash Pine black liquors.

  14. Replacing chemicals in recycle mills with mechanical alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Institute of Paper Science Technology

    2002-07-01

    A high-intensity spark fired underwater decomposes a small amount of the water into hydroxyl radicals, which are strong oxidants. These are able to oxidize contaminants such as glue and wood pitch that enter paper recycling mills as a part of the incoming furnish and cost the industry several hundred million dollars. The sparking technique is safe, inexpensive, and is capable of treating large volumes of water, which makes it attractive for mill applications. Several mill trials were run. Sparking caused a decrease in the tack of the deposits in one case. Lower bleach use occurred in two other mills; sparking reduced the degree of ink reattachment to fiber. The payback for either application is attractive. Sparking induced deposition of contaminants in another mill, which is a positive development--if it can be controlled. The technique is also able to degas water and to oxidize odor-causing sulfur compounds. Although one unit has been purchased by a mill, second-order effects caused by the technology needs to be defined further before the technology can be broadly applied.

  15. Effectiveness of bleaching agent on composite resin discoloration

    OpenAIRE

    Galih Sampoerno

    2012-01-01

    Background: The discoloration of teeth, especially anterior teeth, is one of aesthetic problems. The use of tooth bleaching agents for discolored natural teeth is becoming increasingly popular. Many dentists, however, get many problems when they conduct bleaching process since there is much composite filling on patient’s anterior teeth. Although many research have focused on the discoloration of composite resin after bleaching process, the problem still becomes debatable. Purpose: The purpose...

  16. Mass Coral Bleaching in 2010 in the Southern Caribbean

    OpenAIRE

    Alemu I, Jahson Berhane; Clement, Ysharda

    2014-01-01

    Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision mak...

  17. Dental pulp vascular permeability changes induced by dental bleaching

    OpenAIRE

    Cristiane da Costa; Sueli Patricia Harumi Miyagi; Marcelo dos Santos; Manoel Eduardo de Lima Machado; Márcia Martins Marques

    2012-01-01

    Aiming to compare the effect of different light sources for dental bleaching on vascular permeability of dental pulps, forty-eight incisors were used. The bleaching agent (35 % hydrogen peroxide) was activated by halogen light; LED (Light Emitting Diode) or LED, followed by laser phototherapy (LPT) (λ = 780 nm; 3 J/cm²). After the bleaching procedures, the animals received an intra-arterial dye injection and one hour later were sacrificed. The teeth were diaphanized and photographed. The...

  18. Evaluation of peanut hulls as an alternative to bleaching clays

    OpenAIRE

    Hassanein, M. M.M.; El- Shami, S. M.; Taha, F. S.

    2011-01-01

    Peanut hulls (PNH) were carbonized at different temperatures, times, and evaluated at different concentrations as an alternative to bleaching clays. Evaluation of bleached crude soybean oil with PNH was based on their delta free fatty acids, reduction in peroxide value (PV), reduction in phospholipids (PL) and bleachability. The performance of several commercially used bleaching clays was evaluated, for comparison. Mixtures were formulated including: PNH and Tonsil -N (TN), PNH and Fuller’s e...

  19. Coral community response to bleaching on a highly disturbed reef

    OpenAIRE

    Guest, J R; Low, J.; Tun, K.; Wilson, B.; Ng, C.; D. Raingeard; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P.A.; Toh, T. C.; McDougald, D; Chou, L. M.; Steinberg, P D

    2016-01-01

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on:...

  20. A global protocol for monitoring of coral bleaching

    OpenAIRE

    Oliver, J.; Setiasih, N.; Marshall, P.; Hansen, L.

    2004-01-01

    Coral bleaching and subsequent mortality represent a major threat to the future health and productivity of coral reefs. However a lack of reliable data on occurrence, severity and other characteristics of bleaching events hampers research on the causes and consequences of this important phenomenon. This article describes a global protocol for monitoring coral bleaching events, which addresses this problem and can be used by people with different levels of expertise and resources.

  1. Regeneration of irradiated optical fibres by photo-bleaching?

    International Nuclear Information System (INIS)

    It is known that a light power between 0,1 and 20 μW caused bleaching of colour centres, which implies a reduction of induced loss. Older fibres especially those with a core made of undoped, low OH silica, experience tremendous photo-bleaching. Light of shorter wavelengths has a higher bleaching efficiency than that of longer wavelengths and same light intensity. The investigations have demonstrated that the injection of photo-bleaching light of shorter wavelength and higher intensity can distinctly decrease the radiation-induced loss of Ge-doped fibres, especially at low temperatures. Another possibility to apply photo-bleaching by short wavelength is to regenerate fibres that are permanently installed in radiation environments. Modern undoped multi-mode (MM) step index (Si), Ge-doped MM graded index (Gi) and Ge-doped single-mode (SM) fibres that had been irradiated were submitted to bleaching light. In this article it is shown how loss reduction and necessary bleaching time depend on wavelength and intensity of the bleaching light, on fibre length (bleaching time) and on radiation dose. These results are promising for the regeneration of optical fibres in facilities where the fibres cannot be replaced easily by new ones. (A.C.)

  2. Coral community response to bleaching on a highly disturbed reef.

    Science.gov (United States)

    Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

    2016-01-01

    While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress. PMID:26876092

  3. Mass coral bleaching in 2010 in the southern Caribbean.

    Directory of Open Access Journals (Sweden)

    Jahson Berhane Alemu I

    Full Text Available Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching.

  4. Cuban mill set to produce quality bagasse newsprint

    Energy Technology Data Exchange (ETDEWEB)

    Matics, D.

    1981-10-01

    It is reported that a pilot plant has been constructed at Quivican, Cuba which is capable of producing up to 35 tons of mechanical pulp and approximately 35 tons of newsprint daily from bagasse. In addition to the experimental bagasse newspaper plant, the Cuban government is constructing a large bleached bagasse pulp and paper mill for production of 250 tons of bleached bagasse pulp and paper daily. The installation is scheduled to go into operation in early 1982. The United Nations Development Programme hopes that newsprint and other products which can be produced from the sugar cane stalk will lessen third world nations dependecy on an uncertain world sugar market and help stabilize their economy.

  5. Biomass torrefaction mill

    Science.gov (United States)

    Sprouse, Kenneth M.

    2016-05-17

    A biomass torrefaction system includes a mill which receives a raw biomass feedstock and operates at temperatures above 400 F (204 C) to generate a dusty flue gas which contains a milled biomass product.

  6. Changes in Bleaching Susceptibility among Corals Subject to Ocean Warming and Recurrent Bleaching in Moorea, French Polynesia

    OpenAIRE

    Pratchett, Morgan S.; McCowan, Dominique; Maynard, Jeffrey A; Heron, Scott F.

    2013-01-01

    Background Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-bu...

  7. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    Science.gov (United States)

    Dishon, G.; Fisch, J.; Horn, I.; Kaczmarek, K.; Bijma, J.; Gruber, D. F.; Nir, O.; Popovich, Y.; Tchernov, D.

    2015-10-01

    Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded vital effect of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure. Understanding the frequency of bleaching events is also critical for determining the relationship between natural and anthropogenic causes of these events.

  8. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    OpenAIRE

    Dishon, G.; Fisch, J.; Horn, I.; K. Kaczmarek; Bijma, J.; D. F. Gruber; O. Nir; Y. Popovich; D. Tchernov

    2015-01-01

    Coral reefs occupy only ~0.1% of the oceans habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced significant global declines due to a variety of causes, one of the major being widespread coral bleaching events. During bleaching the coral expels its symbiotic algae losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events hav...

  9. A novel paleo-bleaching proxy using boron isotopes and high-resolution laser ablation to reconstruct coral bleaching events

    OpenAIRE

    Dishon, G.; Fisch, J.; Horn, I.; K. Kaczmarek; Bijma, J.; D. F. Gruber; O. Nir; Y. Popovich; D. Tchernov

    2015-01-01

    Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been ex...

  10. In Situ Biodiesel Production from Residual Oil Recovered from Spent Bleaching Earth

    Directory of Open Access Journals (Sweden)

    Ramli Mat

    2011-05-01

    Full Text Available Currently, semi-refined and refined vegetable oils are used as a feedstock in biodiesel production. However, due to competition with conventional fossil fuel, economic reasons, shortage supply of food and its social impact on the global scale has somewhat slowed the development of biodiesel industry. Studies have been conducted to recover oil from mill palm oil operation especially from the spent bleaching earth. Hence, the study was to investigate the potential recovery of oil from spent bleaching earth to be used as a feedstock for biodiesel production. The effect of different types of catalysts (sodium hydroxide alkali and sulfuric acid catalysts on biodiesel yield was studied. In addition, the effect of volume addition of methanol to the weight of spent bleaching earth on the product yield was also studied. Furthermore, the effect of ratio of hexane to methanol was also carried out to determine its product yield. The studies were carried out in an in-situ biodiesel reactor system and the biodiesel product was analyzed using gas chromatography mass spectrometry. Result shows that the use of alkali catalyst produced the highest yield of biodiesel and the most optimum biodiesel yield was obtained when the methanol to spent bleaching earth ratio was 3.2:1 (gram of methanol: gram of SBE and hexane to methanol ratio of 0.6:1 (volume of hexane: volume of methanol. © 2011 BCREC UNDIP. All rights reserved(Received: 19th December 2010, Revised: 10th May 2011; Accepted: 18th May 2011[How to Cite: R. Mat, O.S. Ling, A. Johari, M. Mohamed. (2011. In Situ Biodiesel Production from Residual Oil Recovered from Spent Bleaching Earth. Bulletin of Chemical Reaction Engineering & Catalysis, 6(1: 53-57. doi:10.9767/bcrec.6.1.678.53-57][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.678.53-57 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/678 ] | View in 

  11. PROCESS OPTIMIZATION OF TETRA ACETYL ETHYLENE DIAMINE ACTIVATED HYDROGEN PEROXIDE BLEACHING OF POPULUS NIGRA CTMP

    OpenAIRE

    Qiang Zhao; Junwen Pu; Shulei Mao; Guibo Qi

    2010-01-01

    To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp con...

  12. IMPACT OF FURFURAL ON THE SUGAR ANALYSIS OF PRE-HYDROLYSIS LIQUOR OF KRAFT-BASED DISSOLVING PULP PRODUCTION PROCESS USING THE HPAEC TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Abrar Saeed

    2011-03-01

    Full Text Available High performance anion-exchange chromatography with pulse ampero-metric detector (HPAEC-PAD is a reliable method to systematically determine the sugar contents in pulp and paper waste streams, including bleaching and extraction liquors. We used the same method to determine the sugar content of industrially produced pre-hydrolysis liquor (PHL from a kraft-based dissolving pulp production process. The analysis showed that the traditional method cannot be applied for sugar analysis, and an improvement on the method was required. In fact, the presence of furfural in the PHL sample was the reason for the required modification. It was noted that the removal of furfural via evaporation could improve the reliability of the HPAEC technique for sugar assessments. If the concentration of furfural was higher than 0.045% (wt. in the PHL, the error introduced in the sugar analysis was profound. Also, the industrially produced PHL contained more furfural than the laboratory produced PHL under the same hydrolysis conditions. Consequently, the concentration of furfural in the PHL should be taken into account for sugar analysis using the HPAEC technique.

  13. Hot Corrosion at Air-Ports in Kraft Recovery Boilers

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Russell, James H.

    2003-01-01

    Hot corrosion can occur on the cold-side of airports in Kraft recovery boilers. The primary corrosion mechanism involves the migration of sodium hydroxide and potassium hydroxide vapors through leaks in the furnace wall at the airports and their subsequent condensation. It has been reported that stainless steel is attacked much faster than carbon steel in composite tubes, and that carbon steel tubing, when used with a low-chromium refractory, does not exhibit this type of corrosion. For hot corrosion fluxing of metal oxides, either acidic or basic fluxing takes place, with a solubility minimum at the basicity of transition between the two reactions. For stainless steel, if the basicity of the fused salt is between the iron and chromium oxide solubility minima, then a synergistic effect can occur that leads to rapid corrosion. The products of one reaction are the reactants of the other, which eliminates the need for rate-controlling diffusion. This effect can explain why stainless steel is attacked more readily than carbon steel.

  14. Toxic by-products from the combustion of Kraft lignin.

    Science.gov (United States)

    Font, Rafael; Esperanza, Mar; García, Angela Nuria

    2003-08-01

    Lignin samples, sub-product in the Kraft process of cellulose from eucalyptus wood, were burnt in a laboratory scale furnace at different residence temperatures and with distinct fuel-rich atmospheres. The yields of CO, CO(2), eight light hydrocarbons (methane, ethylene, ethane, propylene, acetylene, butane, etc.) and 60 semi-volatile+volatile compounds (benzene, toluene, ethylbenzene, styrene, indene, naphthalene, dibenzofuran, phenanthrene, chrysene, etc.) were determined, with nominal reactor temperatures between 800 and 1100 degrees C and residence times of the volatiles evolved and formed between 4 and 7 s. The collection of the gases and volatiles evolved was carried out with a Tedlar bag and by XAD-4 resin respectively, comparing the data obtained in both cases. The emission factor (mg/kg) of the CO was between 2500 and 90000, and under the poor-oxygen atmosphere, the emission factors of many by-toxic products were greater than 100 mg/kg. A pyrolysis run was also performed, obtaining emission factors between 30 and 3000 mg/kg, facilitating its identification. The behaviour of different compounds in the combustion runs was discussed considering three groups in accordance with their stability vs. oxygen, and two groups vs. temperature. PMID:12781238

  15. The Green Integrated Forest Biorefinery: An innovative concept for the pulp and paper mills

    International Nuclear Information System (INIS)

    The Green Integrated Forest Biorefinery (GIFBR), a new concept suitable for implementation in pulp and paper mills is characterized by low greenhouse gases emissions, reduced water consumption and production of effluents. Its fossil fuel consumption must be nil. Several challenges have to be addressed to develop a sustainable GIFBR facility. An implementation strategy by phase is proposed to schedule the total capital investment over several years and to mitigate the economic risks associated with the transformation of an existing pulp and paper mill into a GIFBR. In the first phase of the methodology, the receptor mill and the biorefinery plant are selected. An intensive energy and material integration of the two plants is performed in the second phase, then a gasification unit is implemented and, finally a polygeneration unit is installed. The methodology is illustrated by application to a case study based on a reference Canadian Kraft mill. Each phase of the implementation strategy of the GIFBR is described. - Highlights: • The Green Integrated Forest Biorefinery (GIFBR) is a new biorefinery concept. • A GIFBR includes a pulp mill, a biorefinery, a gasification and a polygeneration units. • An implementation strategy by phase is proposed to successfully develop a GIFBR. • To determine achievable level of integration between the GIFBR constituents is crucial. • GIFBR concept technically and economically feasibility for pulp and paper mills

  16. Effect of effluent from a nitrogen fertilizer factory and a pulp mill on the distribution and abundance of Aeromonas hydrophila in Albemarle Sound, North Carolina.

    OpenAIRE

    Hazen, T C; Esch, G W

    1983-01-01

    The density of Aeromonas hydrophila, standard count bacteria, fecal coliform bacteria, and 18 physical and chemical parameters were measured simultaneously at six sites for 12 months in Albemarle Sound, N.C. One site was above and two sites were below the discharge plume of a Kraft pulping process paper mill. The fourth site was above and the remaining two sites were below the discharge point of a nitrogen fertilizer factory. The impact of the pulp mill on water quality was acute, whereas tha...

  17. The effect of light-activation sources on tooth bleaching

    Directory of Open Access Journals (Sweden)

    Kusai Baroudi

    2014-01-01

    Full Text Available Vital bleaching is one of the most requested cosmetic dental procedures asked by patients who seek a more pleasing smile. This procedure consists of carbamide or hydrogen peroxide gel applications that can be applied in-office or by the patient (at-home/overnight bleaching system. Some in-office treatments utilise whitening light with the objective of speeding up the whitening process. The objective of this article is to review and summarise the current literature with regard to the effect of light-activation sources on in-office tooth bleaching. A literature search was conducted using Medline, accessed via the National Library of Medicine Pub Med from 2003 to 2013 searching for articles relating to effectiveness of light activation sources on in-office tooth bleaching. This study found conflicting evidence on whether light truly improve tooth whitening. Other factors such as, type of stain, initial tooth colour and subject age which can influence tooth bleaching outcome were discussed. Conclusions: The use of light activator sources with in-office bleaching treatment of vital teeth did not increase the efficacy of bleaching or accelerate the bleaching.

  18. Investigating Motivations for Women's Skin Bleaching in Tanzania

    Science.gov (United States)

    Lewis, Kelly M.; Robkin, Navit; Gaska, Karie; Njoki, Lillian Carol

    2011-01-01

    Why do many African women continue to use damaging skin-bleaching cosmetics that contain dangerous chemicals (e.g., mercury) that may increase their rates of infertility, skin cancer, and serious skin/brain/kidney disease? To address this question, our study investigated motivations driving the preservation of skin-bleaching practices in Tanzania.…

  19. Does deposition depth control the OSL bleaching of fluvial sediment?

    Science.gov (United States)

    Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

    2014-07-01

    The Optically Stimulated Luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could potentially provide insights into geomorphic processes. However, comparison of bleaching between samples is complicated by sample-to-sample variation in aliquot size and luminescence sensitivity. Here we develop an age model to account for these effects. With measurement data from multi-grain aliquots, we use Bayesian computational statistics to estimate the burial dose and bleaching parameters of the single-grain dose distribution. We apply the model to 46 samples taken from fluvial sediment of Rhine branches in the Netherlands, and compare the results with environmental predictor variables (depositional energy and environment, sample depth, depth relative to mean water level, dose rate). We find no significant correlations between any predictor variable and the bleaching parameters, although large uncertainties may be obscuring relationships. However, the best bleached samples are found close to the mean water level. Based on these results, we hypothesize that bleaching occurs mainly during fluvial transport rather than upon deposition, with extra bleaching possible for sediments near the transition of channel to overbank deposits due to local reworking after deposition either by wind or water.

  20. Vital tooth bleaching: biologic adverse effects-a review.

    Science.gov (United States)

    Minoux, Maryline; Serfaty, Rene

    2008-09-01

    Depending on etiology, the esthetic treatment of dyschromia may involve vital tooth- bleaching techniques. Hydrogen peroxide is the active molecule used for such procedures; however, its action mechanism is not clearly understood. Moreover, a variety of contradictory studies make difficult the evaluation of the safety of bleaching techniques. The purpose of this article is therefore to review the available literature (1) to describe the physicochemical properties of hydrogen peroxide and (2) to assess the safety of its use as a vital tooth-bleaching agent. Indeed, based on hydrogen peroxide's capacity to generate free radicals that diffuse throughout the dental hard tissues, concerns have been addressed regarding the adverse effects that bleaching products can induce on the enamel and dentin structures, pulp, and bonding to a composite resin system. Moreover, during self-application of home bleaching products, hydrogen peroxide is released into the oral cavity and ingested. Some questions have therefore arisen concerning its toxicity and its possible carcinogenicity. PMID:19107251

  1. Dental pulp vascular permeability changes induced by dental bleaching

    Directory of Open Access Journals (Sweden)

    Cristiane da Costa

    2012-02-01

    Full Text Available Aiming to compare the effect of different light sources for dental bleaching on vascular permeability of dental pulps, forty-eight incisors were used. The bleaching agent (35 % hydrogen peroxide was activated by halogen light; LED (Light Emitting Diode or LED, followed by laser phototherapy (LPT (λ = 780 nm; 3 J/cm². After the bleaching procedures, the animals received an intra-arterial dye injection and one hour later were sacrificed. The teeth were diaphanized and photographed. The amount of blue stain content of each dental pulp was quantified using a computer imaging program. The data was statistically compared (p < 0.05. The results showed a significant higher (p < 0.01 dye content in the groups bleached with halogen light, compared with the control, LED and LED plus LPT groups. Thus, tooth bleaching activated by LED or LED plus LPT induces lesser resulted in increased vascular permeability than halogen light.

  2. ESR studies on bleached sedimentary quartz

    Science.gov (United States)

    Walther, R.; Zilles, D.

    Some ESR signals in quartz are reported to be bleachable by sunlight and so they promise to be useful for dating sediments (Grün, 1989). The Ge signal in quartz is the only one that shows bleaching effects with UV light in short time scales (hours). Therefore we used quartz samples from the sites of Mauer ( 'Homo erectus heidelbergensis'), samples from a borehole in the Neckar valley ('Entensee', Ladenburg near Heidelberg) and samples from a pegmatite for basic studies on the Ge signal. The results show that with our standard sample preparation procedure for quartz separation (using red light as for TL samples), the natural Ge signal is not detectable, but rises clearly with gamma irradiation. Several experiments for examination of the stability and sensitivity of the Ge centre in quartz were carried out. For comparison with the behaviour of the Ge signal we measured the Al signal as well. Our experiments show that the Al signal is bleachable in long time scales (weeks). The behaviour on bleaching, irradiation and thermal annealing is very complicated, as the Al centre is a hole centre (it possibly interacts with several electron centres in the quartz and so the processes are of higher order).

  3. Simultaneous and rapid determination of multiple component concentrations in a Kraft liquor process stream

    Science.gov (United States)

    Li, Jian; Chai, Xin Sheng; Zhu, Junyoung

    2008-06-24

    The present invention is a rapid method of determining the concentration of the major components in a chemical stream. The present invention is also a simple, low cost, device of determining the in-situ concentration of the major components in a chemical stream. In particular, the present invention provides a useful method for simultaneously determining the concentrations of sodium hydroxide, sodium sulfide and sodium carbonate in aqueous kraft pulping liquors through use of an attenuated total reflectance (ATR) tunnel flow cell or optical probe capable of producing a ultraviolet absorbency spectrum over a wavelength of 190 to 300 nm. In addition, the present invention eliminates the need for manual sampling and dilution previously required to generate analyzable samples. The inventive method can be used in Kraft pulping operations to control white liquor causticizing efficiency, sulfate reduction efficiency in green liquor, oxidation efficiency for oxidized white liquor and the active and effective alkali charge to kraft pulping operations.

  4. Effect of the Purple Corn Beverage “Chicha Morada” in Composite Resin during Dental Bleaching

    Science.gov (United States)

    Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio

    2016-01-01

    During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p 3.3). PMID:27034897

  5. DECOLORIZATION OF PROCESS WATERS IN DEINKING MILLS AND SIMILAR APPLICATIONS: A REVIEW

    Directory of Open Access Journals (Sweden)

    Patrick Huber,

    2012-01-01

    Full Text Available Process waters in deinking mills often feature a strong coloration, due to dyes and pigments released from the recovered paper. This can usually be remediated by pulp bleaching treatment with appropriate chemicals. However, the red shade (from rhodamine dye is resistant to conventional bleaching treatments. This largely limits the use of deinked pulp in white paper grades. In this review, the available technologies for process water decolorization are discussed (chemical methods, physico-chemical methods and biological treatments. Ozonation of the process water appears to be the most promising technique for decolorization of process water in deinking mills. Other emerging technologies such as photo-catalytic treatment or mineralization by white-rot fungi (after adsorption on low-cost agricultural residues should be considered as well.

  6. Effect of raw material and Kraft Pulping Conditions on Characteristics of Dissolved Lignin

    OpenAIRE

    Svärd, Antonia

    2014-01-01

    Lignin is one of the main components in wood and during the chemical pulping processes it is degraded and dissolved into the cooking liquor. The current challenge is to meet the need for energy and raw materials, and reform to a more environmentally sustainable society, so there is a great interest in using kraft lignin as a raw material for energy, materials and as source of chemicals. ) To meet this goal, it is essential to obtain kraft lignin with desirable properties. The overall goal of ...

  7. Dry Kraft Pulping at Ambient Pressure for Cost Effective Energy Saving and Pollution Deduction

    Energy Technology Data Exchange (ETDEWEB)

    Yulin Deng; Art Ragauskas

    2012-08-28

    Sponsored by the DOE Industrial Energy Efficiency Grand Challenge program, our research team at the Georgia Institute of Technology conducted laboratory studies and confirmed the concept of making wood pulp using a dry pulping technology. This technology is a new process different from any prior pulping technology used in Kraft and CTMP pulping. Three different kinds of dry pulping methods were investigated. (a) Dry Pulping at Atmospheric Pressure: The first one is to dry and bake the pretreated woodchips in a conventional oven at atmospheric pressure without the use of a catalyst. (b) Dry Pulping at Reduced Pressure: The second method is to dry the pretreated woodchips first in a vacuum oven in the presence of anthraquinone (AQ) as a pulping catalyst, followed by baking at elevated temperature. (c) Liquid Free Chemical Pulping, LFCP. The third method is to first remove the free water of pretreated woodchips, followed by dry pulping using a conventional Kraft pulping digester with AQ and triton as additives. Method one: Experimental results indicated that Dry Pulping at Atmospheric Pressure could produce pulp with higher brightness and lower bulk than conventional Kraft pulp. However, tensile strength of the acquired pulp is much lower than traditional Kraft pulp, and their Kappa number and energy consumption are higher than conventional Kraft pulp. By fully analyzing the results, we concluded that wood fibers might be damaged during the drying process at elevated temperature. The main reason for wood fiber damage is that a long drying time was used during evaporation of water from the woodchips. This resulted in an un-uniform reaction condition on the woodchips: the outside layer of the woodchips was over reacted while inside the woodchips did not reacted at all. To solve this problem, dry pulping at reduced pressure was investigated. Method two: To achieve uniform reaction throughout the entire reaction system, the water inside the pretreated woodchips was

  8. Evaluation of peanut hulls as an alternative to bleaching clays

    Energy Technology Data Exchange (ETDEWEB)

    Hassanein, M. M.; El-Shami, S. M.; Taha, F. S.

    2011-07-01

    Peanut hulls (PNH) were carbonized at different temperatures, times, and evaluated at different concentrations as an alternative to bleaching clays. Evaluation of bleached crude soybean oil with PNH was based on their delta free fatty acids, reduction in peroxide value (PV), reduction in phospholipids (PL) and bleachability. The performance of several commercially used bleaching clays was evaluated, for comparison. Mixtures were formulated including: PNH and Tonsil -N (TN), PNH and Fuller's earth (FE) and PNH and O-passive (OP) and examined. The oxidative stability of oils was determined. Results for the investigated commercial bleaching clays revealed: TN > FE > F > TF > OP. Highest reduction in PV and PL, and highest bleachability were achieved for soybean oil bleached with 2% PNH carbonized at 500 degree centigrade for 30 min (PNH). Mixtures of PNH with the three chosen bleaching clays indicated that 1PNH : 2TN gave the highest bleachability. CSO was miscella bleached in hexane using PNH and resulted in an appreciable improvement in all oil characteristics, especially in bleachability. Oxidative stability of oils was in the following order: TN > control > FE > PNH with Induction period values of 23.1 > 6.43 > 5.73 > 2.85 h, respectively. (Author) 20 refs.

  9. ECF AND TCF BLEACHING OF SECONDARY FIBER PULP

    Directory of Open Access Journals (Sweden)

    Gustavo Ventorim

    2009-09-01

    Full Text Available In this study, ECF and TCF bleaching processes were evaluated for the bleaching of a deinked mixed office waste (MOW pulp sample produced in a pilot plant. The sample was bleached by all processes to a target brightness of 78 % ISO minimum. The results were interpreted on the basis of chemical cost to reach the target brightness, bleaching yield and bleached pulp quality as measured by viscosity, fluorescence and b* color coordinate. Among the ECF sequences, the mosattractive was the DEDD which showed the lowest chemical cost and produced bleached pulp of high quality as measured by viscosity, fluorescence and b* coordinate. The best TCF sequence with ozone was the Q(PO(ZQ(PO which resulted in very high brightness ceiling. This sequence decreased moderately the pulp b* coordinate and viscosity and slightly its fluorescence. Among the TCF sequences without ozone the Q(POQ(PO was the most effective but showed poor flexibility with regard to brightness ceiling. This sequence had little effect on pulp viscosity, fluorescence and b* coordinate. For all three  bleaching processes, it was determined that process yield is negatively affected by hot alkaline stages such as O, P and (PO.

  10. FM Interviews: Stephanie Mills

    OpenAIRE

    Valauskas, Edward

    2002-01-01

    Stephanie Mills is an author, editor, lecturer and ecological activist who has concerned herself with the fate of the earth and humanity since 1969, when her commencement address at Mills College in Oakland, Calif., drew the attention of a nation. Her speech, which the New York Times called "perhaps the most anguished statement" of the year's crop of valedictory speeches, predicted a bleak future. According to Mills, humanity was destined for suicide, the result of overpopulation and overuse ...

  11. A bleaching earth from egyptian local deposits

    Directory of Open Access Journals (Sweden)

    El Kinawy, Omayma S.

    2001-10-01

    Full Text Available The present investigation deals with the bleaching of vegetable oils using activated clays collected from some deposits in Egypt as compared to Tonsil FF currently used by local oil industry. The comparison was made; not only on the basis of the decolourising power of the earth, but also on the basis of its effects on the oil acidity, formation of the oil peroxides and the decomposition rate of the formed peroxides to aldehydes and ketones during the bleaching process. The activation of the collected earth samples was made using 4N HCl, 6N HCl and 30 % H2SO4. The bleaching tests of the activated samples were performed using the major four oil types processed in Egypt being cottonseed, sunflower, soybean and palm oils. In addition to the laboratory-evaluation tests, the performance of the activated samples, which showed promise on the lab-scale have been also tested on an industrial scale. The industrial application has proved that the activated local earth's can be successfully used as bleaching earth of local oils. Thus it can be used as a substitute of the varieties currently imported and used by the local oil sector.La presente investigación trata de la decoloración de aceites vegetales usando tierras activadas obtenidas de yacimientos egipcios, comparándola con el Tonsil FF usado normalmente en la industria oleícola local. La comparación se realizó, no sólo sobre la base del poder decolorante de la tierra, sino también sobre la base de sus efectos en la acidez del aceite, la formación de peróxidos y la velocidad de descomposición de los peróxidos formados en aldehidos y cetonas durante el proceso de decoloración. La activación de las muestras de tierras recogidas se hizo utilizando ClH 4N, ClH 6N y H2SO4 30 %. Los tests de decoloración de las muestras activadas se llevaron a cabo usando los cuatro tipos mayoritarios de aceites procesados en Egipto: aceite de semilla de algodón, de girasol, de soja y de palma. Además de los

  12. Intrapulpal temperature variation during bleaching with various activation mechanisms

    Directory of Open Access Journals (Sweden)

    Sílvia Masae de Araujo Michida

    2009-10-01

    Full Text Available OBJECTIVES: The aim of this study was to evaluate the intrapulpal temperature variation after bleaching treatment with 35% hydrogen peroxide using different sources of activation. MATERIAL AND METHODS: Twenty-four human teeth were sectioned in the mesiodistal direction providing 48 specimens, and were divided into 4 groups (n=12: (G1 Control - Bleaching gel without light activation, (G2 Bleaching gel + halogen light, (G3 Bleaching gel + LED, (G4 Bleaching gel + Nd:YAG Laser. The temperatures were recorded using a digital thermometer at 4 time points: before bleaching gel application, 1 min after bleaching gel application, during activation of the bleaching gel, and after the bleaching agent turned from a dark-red into a clear gel. Data were analyzed statistically by the Dunnet's test, ANOVA and Tukey's test (a=0.05. RESULTS: The mean intrapulpal temperature values (ºC in the groups were: G1: 0.617 ± 0.41; G2: 1.800 ± 0.68; G3: 0.975 ± 0.51; and G4: 4.325 ± 1.09. The mean maximum temperature variation (MTV values were: 1.5ºC (G1, 2.9ºC (G2, 1.7ºC (G3 and 6.9ºC (G4. When comparing the experimental groups to the control group, G3 was not statistically different from G1 (p>0.05, but G2 and G4 presented significantly higher (p<0.05 intrapulpal temperatures and MTV. The three experimental groups differed significantly (p<0.05 from each other. CONCLUSIONS: The Nd:YAG laser was the activation method that presented the highest values of intrapulpal temperature variation when compared with LED and halogen light. The group activated by LED light presented the lowest values of temperature variation, which were similar to that of the control group.

  13. FRAP analysis: accounting for bleaching during image capture.

    Directory of Open Access Journals (Sweden)

    Jun Wu

    Full Text Available The analysis of Fluorescence Recovery After Photobleaching (FRAP experiments involves mathematical modeling of the fluorescence recovery process. An important feature of FRAP experiments that tends to be ignored in the modeling is that there can be a significant loss of fluorescence due to bleaching during image capture. In this paper, we explicitly include the effects of bleaching during image capture in the model for the recovery process, instead of correcting for the effects of bleaching using reference measurements. Using experimental examples, we demonstrate the usefulness of such an approach in FRAP analysis.

  14. Bleaching and diffusion dynamics in optofluidic dye lasers

    CERN Document Server

    Gersborg-Hansen, M; Kristensen, A; Mortensen, N A

    2007-01-01

    We have investigated the bleaching dynamics that occur in optofluidic dye lasers where the liquid laser dye in a microfluidic channel is locally bleached due to optical pumping. We find that for microfluidic devices, the dye bleaching may be compensated through diffusion of dye molecules alone. By relying on diffusion rather than convection to generate the necessary dye replenishment, our observation potentially allows for a significant simplification of optofluidic dye laser device layouts, omitting the need for cumbersome and costly external fluidic handling or on-chip microfluidic pumping devices.

  15. The optical bleaching of thermoluminescence in K-feldspar

    International Nuclear Information System (INIS)

    The thermoluminescence (TL) of K-feldspar extracted from sediment was bleached by means of a sunlight simulator. The differences in the TL bleaching efficiency of different trap groups are correlated with significant differences between trap parameters. The fractional glow technique applied for the investigation of optically bleached samples reveals the coexistence of various trap groups which are active in the same temperature region over 300 deg. C. This gives rise to a growth curve (i.e. the TL intensity dependence on dose) with linear and nonlinear regions. (author)

  16. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars; Kinahan, J.

    2007-01-01

    We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between...... well-bleached and poorly bleached grains. It is especially important to investigate if the uncertainties assigned to individual estimates of dose adequately describe the observed variability in well-bleached dose distributions. We investigate this by quantifying the overdispersion in laboratory-bleached...

  17. Reuse of discarded deactivated bleaching earth in the bleaching of oils

    Directory of Open Access Journals (Sweden)

    Girgis, Adel Y.

    2005-03-01

    Full Text Available Discarded bleaching earth was used after its reactivation for the bleaching of sunflower, soybean and corn oils. The efficiency of reactivated bleaching earth was compared to the efficiency of virgin activated bleaching earth. Acid reactivated earth (pH 2.5-3 had a slightly higher content in silicone than virgin activated or neutralized reactivated earths. The best results in the color of sunflower and corn oils were obtained when neutralized earth (pH 6–7 was used at 1 and 2 % levels. Acid reactivated earth used at 2 % achieved a higher reduction in soybean oil color than virgin earth (pH 3 at the same dosage. Both reactivated earths reduced peroxide value, iron, conjugated dienes and soap, while they increased acidity and conjugated trienes. Furthermore, these reactivated earths determined higher decrements in the oil induction period than virgin earth. Reactivated earth could be used for 5 cycles for the bleaching of soybean or corn oils and for more than 6 cycles for sunflower oil.Tierra decolorante desechada, fue empleada, tras su reactivación para decolorar aceites de girasol, soja y maíz. La eficiencia de la tierra decolorante reactivada fue comparada con la de la virgen activada. La tierra reactivada ácida (pH 2,5–3 tuvo ligeramente mayor contenido en silicona que la tierra virgen o la reactivada neutra. Los mejores resultados en el color de los aceites de girasol y maíz fueron obtenidos cuando se emplearon niveles del 1 y 2 % de tierra reactivada neutra (pH 6-7. La tierra ácida reactivada, usada al 2 % consiguió una mayor reducción del color del aceite de soja, que una misma dosis de tierra virgen (pH 3. Ambas tierras reactivadas redujeron el índice de peróxidos, hierro, dienos conjugados y jabón de los aceites, mientras que hicieron aumentar la acidez y los trienos conjugados. Además, estas tierras reactivadas determinaron mayores descensos en los periodos de inducción del aceite que la tierra virgen. Las tierras

  18. Influence of Vegetable Oil on the Thermal Aging Rate of Kraft Paper and its Mechanism

    Institute of Scientific and Technical Information of China (English)

    YANG Lijun; DENG Bangfei; LIAO Ruijin; SUN Caixin; ZHU Mengzhao

    2012-01-01

    With the development of new insulation materials,vegetable oil—the best substitute for mineral oil—has gradually been widely used in the liquid insulation of transformers.To investigate the influence of vegetable oil on the thermal aging rate of oil paper,Kraft paper impregnated with mineral oil and vegetable oil have been underwent thermally accelerated aging at three different temperatures.The degree of polymerization(DP) of Kraft paper was measured to indicate the aging degree of insulation paper.The aging rate of Kraft paper in mineral oil and vegetable oil was compared quantitatively,and results showed that vegetable oil retarded paper's degradation rate and extended its useful lifetime.The reasons contributing to such phenomena were analyzed using X-ray Photoelectron Spectroscopy(XPS) and molecular simulation software.Kraft paper in vegetable oil had larger activation energy.Due to the larger interaction force between water and natural ester molecules,water molecules were easily bonded with natural ester,weakening the hydrolysis process of cellulose.Cellulose was chemically modified by natural ester during the thermal aging process,and the reactive-OH(hydroxyl) groups on the cellulose became esterified with fatty acid esters.Water molecules were firmly bounded to the ester groups on glucose produced by esterification.The long-chain fatty acid esterified to cellulose was parallel with cellulose chains and acted as a "water barrier" to further weaken the hydrolysis process.

  19. ON-SITE PRODUCTION OF ACTIVATED CARBON FROM KRAFT BLACK LIQUOR

    Science.gov (United States)

    A pilot plant was designed and constructed to produce char via the St. Regis hydropyrolysis kraft chemical recovery process and to produce activated carbon from the char. This report includes discussion of laboratory and prepilot work, the pilot plant, and presents operating resu...

  20. Impact of lignin and carbohydrate chemical structures on degradation reactions during hardwood kraft pulping processes

    Directory of Open Access Journals (Sweden)

    Ricardo B. Santos

    2013-02-01

    Full Text Available Most studies aimed at determining rates of hardwood delignification and carbohydrate degradation have focused on understanding the behavior of a single wood species. Such studies tend to determine either the delignification rate or the rate of carbohydrate degradation without examining the potential interactions resulting from related variables. The current study provides a comprehensive evaluation on both lignin and carbohydrate degradation during kraft pulping of multiple hardwood species. The kraft delignification rates of E. urograndis, E. nitens, E. globulus, sweet gum, maple, red oak, red alder, cottonwood, and acacia were obtained. Furthermore, the kinetics of glucan, xylan, and total carbohydrate dissolution during the bulk phase of the kraft pulping process for the above species were also investigated. The wide ranges of delignification and carbohydrate degradation rates were correlated to wood chemical characteristics. It appears that the S/G ratio and lignin-carbohydrate-complexes (LCCs are the main characteristics responsible for the differences in kraft pulping performance among the hardwoods studied.

  1. The effect of temperature on the catalytic conversion of Kraft lignin using near-critical water

    DEFF Research Database (Denmark)

    Nguyen, Thi Dieu Huyen; Maschietti, Marco; Åmand, Lars-Erik;

    2014-01-01

    The catalytic conversion of suspended LignoBoost Kraft lignin was performed in near-critical water using ZrO2/K2CO3 as the catalytic system and phenol as the co-solvent and char suppressing agent. The reaction temperature was varied from 290 to 370 C and its effect on the process was investigated...

  2. An environmental systems analysis of the Kraft pulp industry in Thailand

    NARCIS (Netherlands)

    Warit, J.

    2006-01-01

    The pulp industry inThailandis of economic and social importance because of its production value, the revenues from export and the employment in this sector. The eucalyptus-based Kraft pulp industry plays an importan

  3. Post-bleaching application of an antioxidant on dentin bond strength of three dental adhesives

    OpenAIRE

    Maryam Khoroushi; Tahereh Saneie

    2012-01-01

    Background: Antioxidizing agents have recently been suggested to compensate decreased bond strength of resin materials to bleached tooth tissues. This study compared the shear bond strength (SBS) of three different adhesives on bleached dentin immediately after bleaching, bleached/delayed for 1 week, and bleached/applied antioxidizing agent. Materials and Methods: The dentinal surfaces of 132 intact extracted molars were prepared and divided into 12 groups. The following adhesives were in...

  4. Study of Melanin Bleaching After Immunohistochemistry of Melanin-containing Tissues

    OpenAIRE

    Shen, Hongwu; Wu, Wenqiao

    2015-01-01

    Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3′-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium perman...

  5. Contrasting Patterns of Coral Bleaching Susceptibility in 2010 Suggest an Adaptive Response to Thermal Stress

    OpenAIRE

    James R Guest; Baird, Andrew H.; Maynard, Jeffrey A; Efin Muttaqin; Alasdair J Edwards; Stuart J Campbell; Katie Yewdall; Yang Amri Affendi; Loke Ming Chou

    2012-01-01

    BACKGROUND: Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. METHODOLOGY/PRINCIPAL FINDINGS: Surveys to estimate the bleaching ...

  6. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel;

    2005-01-01

    : 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted...... for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities......Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning...

  7. Ecology: Deep and complex ways to survive bleaching

    Science.gov (United States)

    Pandolfi, John M.

    2015-02-01

    Mass coral bleaching events can drive reefs from being the domains of corals to becoming dominated by seaweed. But longitudinal data show that more than half of the reefs studied rebound to their former glory. See Letter p.94

  8. New Parameter for In-Office Dental Bleaching

    Science.gov (United States)

    Bortolatto, Janaina Freitas; de Carvalho, Priscila Petrucelli Freire; Trevisan, Tamara Carolina; Floros, Michael Christopher; Junior, Osmir Batista de Oliveira

    2016-01-01

    Dental bleaching is considered a conservative and biologically safe treatment for discolored teeth. Despite this, one of the major undesirable effects of bleaching is dentin sensitivity which may occur during and after treatment. To address these sensitivity issues, new dental bleaching preparations with lower concentrations of hydrogen peroxide (H2O2) have recently been introduced to the market. This paper presents a clinical case report of a 20-year-old female patient admitted to the Araraquara Dental School, UNESP, Brazil. The patient underwent dental bleaching using one of the new products with reduced hydrogen peroxide concentration, Lase Peroxide Lite 6%, a 6% H2O2 gel containing titanium oxide nanoparticles doped with nitrogen (6% H2O2/N-doped TiO2).

  9. Sludge disinfection by combined treatment of bleaching powder and irradiation

    International Nuclear Information System (INIS)

    Sludge disinfection by combined treatment of bleaching powder and irradiation. Disinfection of sludge by combined treatment of bleaching powder and irradiation has been investigated. Sludge were obtained from water and waste sanitation department (Dinas Kebersihan) DKI located at Kebon Nanas, Jakarta. Sludge were mixed with bleaching powder at the concentration of 0, 10 and 20 mg/l and then irradiated in multipurpose panoramic batch irradiator (PANBIT) with doses of 2, 4, 6, 8, and 10 kGy and a dose rate 9 kGy/h. The reducing colony form unit caused by the combined treatment depend on type bacteria observed in sludge. Pathogenic bacteria as Clostridium still survive at a dose of 10 kGy on sludge containing 20 mg/l bleaching powder, but Salmonella, Shigella, and Vibrio were not detected in this experiment, neither in the control nor in the irradiated samples. (author). 14 refs.; 4 figs

  10. Through bleaching and tsunami: Coral reef recovery in the Maldives.

    Science.gov (United States)

    Morri, Carla; Montefalcone, Monica; Lasagna, Roberta; Gatti, Giulia; Rovere, Alessio; Parravicini, Valeriano; Baldelli, Giuseppe; Colantoni, Paolo; Bianchi, Carlo Nike

    2015-09-15

    Coral reefs are degrading worldwide, but little information exists on their previous conditions for most regions of the world. Since 1989, we have been studying the Maldives, collecting data before, during and after the bleaching and mass mortality event of 1998. As early as 1999, many newly settled colonies were recorded. Recruits shifted from a dominance of massive and encrusting corals in the early stages of recolonisation towards a dominance of Acropora and Pocillopora by 2009. Coral cover, which dropped to less than 10% after the bleaching, returned to pre-bleaching values of around 50% by 2013. The 2004 tsunami had comparatively little effect. In 2014, the coral community was similar to that existing before the bleaching. According to descriptors and metrics adopted, recovery of Maldivian coral reefs took between 6 and 15years, or may even be considered unachieved, as there are species that had not come back yet. PMID:26228070

  11. Evaluation of temperature increase during in-office bleaching

    Directory of Open Access Journals (Sweden)

    Rafael Francisco Lia MONDELLI

    2016-04-01

    Full Text Available ABSTRACT The use of light sources in the bleaching process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature. Objective The purpose of the present study was to measure the increase in intrapulpal temperature induced by different light-activated bleaching procedures with and without the use of a bleaching gel. Material and Methods A human maxillary central incisor was sectioned 2 mm below the cementoenamel junction. A K-type thermocouple probe was introduced into the pulp chamber. A 35% hydrogen peroxide bleaching gel was applied to the vestibular tooth surface. The light units used were a conventional halogen, a hybrid light (only LED and LED/Laser, a high intensity LED, and a green LED light. Temperature increase values were compared by two-way ANOVA and Tukey´s tests (p<0.05. Results There were statistically significant differences in temperature increases between the different light sources used and between the same light sources with and without the use of a bleaching gel. The presence of a bleaching gel generated an increase in intra-pulpal temperature in groups activated with halogen light, hybrid light, and high intensity LED. Compared to the other light sources, the conventional halogen lamp applied over the bleaching gel induced a significant increase in temperature (3.83±0.41°C. The green LED unit with and without gel application did not produce any significant intrapulpal temperature variations. Conclusion In the present study, the conventional halogen lamp caused the highest increase in intrapulpal temperature, and the green LED caused the least. There was an increase in temperature with all lights tested and the maximum temperature remained below the critical level (5.5°C. The addition of a bleaching gel led to a higher increase in intrapulpal temperatures.

  12. Evaluation of temperature increase during in-office bleaching

    Science.gov (United States)

    MONDELLI, Rafael Francisco Lia; SOARES, Ana Flávia; PANGRAZIO, Eugenio Gabriel Kegler; WANG, Linda; ISHIKIRIAMA, Sergio Kiyoshi; BOMBONATTI, Juliana Fraga Soares

    2016-01-01

    ABSTRACT The use of light sources in the bleaching process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature. Objective The purpose of the present study was to measure the increase in intrapulpal temperature induced by different light-activated bleaching procedures with and without the use of a bleaching gel. Material and Methods A human maxillary central incisor was sectioned 2 mm below the cementoenamel junction. A K-type thermocouple probe was introduced into the pulp chamber. A 35% hydrogen peroxide bleaching gel was applied to the vestibular tooth surface. The light units used were a conventional halogen, a hybrid light (only LED and LED/Laser), a high intensity LED, and a green LED light. Temperature increase values were compared by two-way ANOVA and Tukey´s tests (p<0.05). Results There were statistically significant differences in temperature increases between the different light sources used and between the same light sources with and without the use of a bleaching gel. The presence of a bleaching gel generated an increase in intra-pulpal temperature in groups activated with halogen light, hybrid light, and high intensity LED. Compared to the other light sources, the conventional halogen lamp applied over the bleaching gel induced a significant increase in temperature (3.83±0.41°C). The green LED unit with and without gel application did not produce any significant intrapulpal temperature variations. Conclusion In the present study, the conventional halogen lamp caused the highest increase in intrapulpal temperature, and the green LED caused the least. There was an increase in temperature with all lights tested and the maximum temperature remained below the critical level (5.5°C). The addition of a bleaching gel led to a higher increase in intrapulpal temperatures. PMID:27119761

  13. Conservation of Coral Reefs after the 1998 Global Bleaching Event

    OpenAIRE

    Hayes, R.L.; Goreau, T.J.; Mcclanahan, T.R.

    2000-01-01

    Large-scale coral bleaching has happened repeatedly in the Pacific and Indian oceans and the Caribbean since 1982. Previously it was observed only on a small scale (Williams and Bunkley- Williams 1990;Jokiel & Coles 1990; Glynn 1988, 1991; Goreau et al. 1993; Goreau & Hayes 1994, 1995). The 1998 bleaching event was globally the most extensive such event recorded except in the Caribbean and Central Pacific where a comparison of year-byyear temperature and bl...

  14. Endolithic algae: an alternative source of photoassimilates during coral bleaching.

    OpenAIRE

    Fine, Maoz; Loya, Yossi

    2002-01-01

    Recent reports of worldwide coral bleaching events leading to devastating coral mortality have caused alarm among scientists and resource managers. Differential survival of coral species through bleaching events has been widely documented. We suggest that among the possible factors contributing to survival of coral species during such events are endolithic algae harboured in their skeleton, providing an alternative source of energy. We studied the dynamics of photosynthetic pigment concentrat...

  15. BLEACHING OF SULFONATED CMP FROM BIO-TREATED WHEAT STRAW

    Institute of Scientific and Technical Information of China (English)

    HongYu; MenghuaQin; XuemeiLu; YinboQu; PeijiGao

    2004-01-01

    Wheat straw chemi-mechanical pulp was pretreated with a crude xylanase which was secreted by white rot fungus Phanerochaete Chrysosporium prior to hydrogen peroxide bleaching. The process of xylanase pretreatment and hydrogen peroxide bleaching was optimized. The xylanase treated pulp achieved a brightness gain of 5.8% ISO over the untreated pulp. The xylanase treatment was found to liberate reducing sugars and facilitating lignin removal. Fiber morphology of pulp treated with xylanase was also studied by SEM.

  16. Degradation of lignin and decolorization of paper mill bleach plant effluent (BPE) by marine fungi

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C; Chandramohan, D.; Michel, F.C; Reddy, C

    stream_size 2 stream_content_type text/plain stream_name Biotechnol_Lett_18_105.pdf.txt stream_source_info Biotechnol_Lett_18_105.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  17. 'Ethnic cleansing' bleaches the atrocities of genocide.

    Science.gov (United States)

    Blum, Rony; Stanton, Gregory H; Sagi, Shira; Richter, Elihu D

    2008-04-01

    Genocide has been the leading cause of preventable violent death in the 20th-21st century, taking even more lives than war. The term 'ethnic cleansing' is used as a euphemism for genocide despite it having no legal status. Like 'Judenrein' and 'racial hygiene' in Nazi medicine, it expropriates pseudo-medical terminology to justify massacre. Use of the term reifies a dehumanized view of the victims as sources of filth and disease, and propagates the reversed social ethics of the perpetrators. Timelines for recent genocides (Bosnia, 1991-1996, 200,000; Kosovo 1998-2000, 10,000-20,000; Rwanda, 1994, 800,000; Darfur 2002-2006, >400,000) show that its use bears no relationship to death tolls or the scale of atrocity. Bystanders' use of the term 'ethnic cleansing' signals the lack of will to stop genocide, resulting in huge increases in deaths, and undermines international legal obligations to acknowledge genocide. The term 'ethnic cleansing' corrupts observation, interpretation, ethical judgment and decision-making, thereby undermining the aim of public health. Public health should lead the way in expunging the term 'ethnic cleansing' from official use. 'Ethnic cleansing' bleaches the atrocities of genocide, leading to inaction in preventing current and future genocides. PMID:17513346

  18. PROCESS OPTIMIZATION OF TETRA ACETYL ETHYLENE DIAMINE ACTIVATED HYDROGEN PEROXIDE BLEACHING OF POPULUS NIGRA CTMP

    Directory of Open Access Journals (Sweden)

    Qiang Zhao

    2010-02-01

    Full Text Available To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching.

  19. Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

    International Nuclear Information System (INIS)

    To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoom activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.

  20. Selective Enrichment of a Methanol-Utilizing Consortium Using Pulp and Paper Mill Waste Streams

    Science.gov (United States)

    Mockos, Gregory R.; Smith, William A.; Loge, Frank J.; Thompson, David N.

    Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater. Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Wasteactivated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensate system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25°C with a hydraulic residence time and a solids retention time of 4 days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24-h feed/ decant cycles ranged from 79 to 89%, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste-activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen-limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen-limited conditions. This indicates that selectively enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.

  1. Selective enrichment of a methanol-utilizing consortium using pulp & paper mill waste streams

    Energy Technology Data Exchange (ETDEWEB)

    Gregory R. Mockos; William A. Smith; Frank J. Loge; David N. Thompson

    2007-04-01

    Efficient utilization of carbon inputs is critical to the economic viability of the current forest products sector. Input carbon losses occur in various locations within a pulp mill, including losses as volatile organics and wastewater . Opportunities exist to capture this carbon in the form of value-added products such as biodegradable polymers. Waste activated sludge from a pulp mill wastewater facility was enriched for 80 days for a methanol-utilizing consortium with the goal of using this consortium to produce biopolymers from methanol-rich pulp mill waste streams. Five enrichment conditions were utilized: three high-methanol streams from the kraft mill foul condensate system, one methanol-amended stream from the mill wastewater plant, and one methanol-only enrichment. Enrichment reactors were operated aerobically in sequencing batch mode at neutral pH and 25°C with a hydraulic residence time and a solids retention time of four days. Non-enriched waste activated sludge did not consume methanol or reduce chemical oxygen demand. With enrichment, however, the chemical oxygen demand reduction over 24 hour feed/decant cycles ranged from 79 to 89 %, and methanol concentrations dropped below method detection limits. Neither the non-enriched waste activated sludge nor any of the enrichment cultures accumulated polyhydroxyalkanoates (PHAs) under conditions of nitrogen sufficiency. Similarly, the non-enriched waste activated sludge did not accumulate PHAs under nitrogen limited conditions. By contrast, enriched cultures accumulated PHAs to nearly 14% on a dry weight basis under nitrogen limited conditions. This indicates that selectively-enriched pulp mill waste activated sludge can serve as an inoculum for PHA production from methanol-rich pulp mill effluents.

  2. Extreme mill make over

    OpenAIRE

    Ruberg, Toomas

    2006-01-01

    This paper examines the operation and performance of a lumber mill. Generating positive cash flow and remaining profitable at coincident low points of the economic and seasonal cycle are major challenges. Mill metrics were benchmarked using industry data which revealed performance gaps in costs, production rate, quality and lumber recovery. Economies of scale were investigated for lumber manufacturing. Capacity utilization for the site empirically determined that the unit was operating at clo...

  3. Pitt Mill Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Oder, R.R.; Borzone, L.A.

    1990-05-01

    Results of a technical and economic evaluation of application of the Pitt Mill to fine coal grinding are presented. The Pitt Mill is a vertically oriented, batch operated, intermediate energy density (0. 025 kW/lb media), stirred ball mill. The mill grinds coal from coarse sizes (typically 3/16 inch or 4 mesh topsize) to the 10 micron to 20 micron mean particle diameter size range in a single step using a shallow grinding bed containing inexpensive, readily available, course grinding media. Size reduction is efficient because of rapid product circulation through the grinding bed caused by action of a novel circulation screw mounted on the agitator shaft. When a dispersant is employed, the grinding can be carried out to 50% to 60% solids concentration. Use of coarse grinding media offers the possibility of enhanced mineral liberation because size reduction is achieved more by impact shattering than by attrition. The batch method offers the possibility of very close control over product particle size distribution without overproduction of fines. A two- phase program was carried out. In the first phase, Grinding Studies, tests were run to determine a suitable configuration of the Pitt Mill. Machine design parameters which were studied included screw configuration, media type, agitator RPM, time, media size, and slurry chamber aspect ratio. During the last part of this phase of the program, tests were carried out to compare the results of grinding Pocahontas seam, Pittsburgh {number sign}8, and East Kentucky Mingo County coals by the Pitt Mill and by a two-stage grinding process employing a Netzsch John mill to feed a high energy density (0.05 kW/Lb media) disc mill. 22 refs., 25 tabs.

  4. AFM analysis of bleaching effects on dental enamel microtopography

    International Nuclear Information System (INIS)

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm x 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  5. Antioxidant therapy enhances pulpal healing in bleached teeth

    Science.gov (United States)

    Lima, Adriano Fonseca; Marques, Marcelo Rocha; Soares, Diana Gabriela; Hebling, Josimeri; Marchi, Giselle Maria

    2016-01-01

    Objectives The purpose of this study was to evaluate the histopathological effects of an antioxidant therapy on the pulp tissue of rat teeth exposed to a bleaching gel with 35% hydrogen peroxide. Materials and Methods Forty rats were subjected to oral ingestion by gavage of distilled water (DW) or ascorbic acid (AA) 90 min before the bleaching therapy. For the bleaching treatment, the agent was applied twice for 5 min each to buccal surfaces of the first right mandibular molars. Then, the animals were sacrificed at 6 hr, 24 hr, 3 day, or 7 day post-bleaching, and the teeth were processed for microscopic evaluation of the pulp tissue. Results At 6 hr, the pulp tissue showed moderate inflammatory reactions in all teeth of both groups. In the DW and AA groups, 100% and 80% of teeth exhibited pulp tissue with significant necrosis and intense tissue disorganization, respectively. At 24 hr, the AA-treated group demonstrated a greater regenerative capability than the DW group, with less intense inflammatory reaction and new odontoblast layer formation in 60% of the teeth. For up to the 7 day period, the areas of pulpal necrosis were replaced by viable connective tissue, and the dentin was underlined by differentiated odontoblast-like cells in most teeth of both groups. Conclusions A slight reduction in initial pulpal damage during post-bleaching was promoted by AA therapy. However, the pulp tissue of AA-treated animals featured faster regenerative potential over time. PMID:26877990

  6. AFM analysis of bleaching effects on dental enamel microtopography

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira de Freitas, Ana Carolina, E-mail: anacarolfreitas@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Cardoso Espejo, Luciana, E-mail: luespejo@hotmail.com [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Brossi Botta, Sergio, E-mail: sbbotta@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Sa Teixeira, Fernanda de, E-mail: nandast@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil); Cerqueira, Luz Maria Aparecida A., E-mail: maacluz@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Garone-Netto, Narciso, E-mail: ngarone@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Bona Matos, Adriana, E-mail: bona@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Barbosa da Silveira Salvadori, Maria Cecilia, E-mail: mcsalva@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil)

    2010-02-15

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 {mu}m x 15 {mu}m area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  7. Analysis of optical bleaching of OSL signal in sediment quartz

    International Nuclear Information System (INIS)

    The aim of this work was to study the effect of the quality of optical bleaching on the results of OSL (Optically Stimulated Luminescence) dating method. The large aliquots of coarse quartz grains extracted from fluvial deposit were used in the study. The poor, medium and good bleaching were simulated in laboratory with help of Blue LED light source in series of experiments. Then the samples were irradiated with a common laboratory dose. The equivalent doses (DE) were measured by the help of standard Single Aliquot Regeneration (SAR) technique, but obtained DE distributions are analyzed in a new way. The method for recognizing and compensating for partial bleaching is proposed. The conclusions for dating sediment quartz samples are presented and discussed. -- Highlights: ► Bleaching experiments on sediment quartz are performed. ► Blue LED light source incorporated in luminescence reader is used. ► New analysis of data measured by standard SAR OSL technique is proposed. ► The results are promising for recognizing and compensating for partial bleaching

  8. Optical bleaching of radiation-induced colour centres in fluorapatite

    International Nuclear Information System (INIS)

    One of the important steps in thermoluminescence (TL) dating studies is the assessment of the total natural radiation dose that a sample has received and retained. This, in turn, depends on the thermal and temporal stabilities as well as the optical bleaching of the radiation-induced colour centres. In this paper, we report the effect of selective optical bleaching, after X-irradiation, on the TL glow curves of synthetic fluorapatite. X-irradiated fluorapatite exhibits three unresolved TL peaks around 150, 250 and 345 C. Diffuse reflectance studies of the polycrystalline fluorapatite show that X-irradiation induces absorption bands at 370 and 450 nm. Furthermore, exposure to light through 320 to 400 nm and 400 to 480 nm band filters effectively bleaches the TL glow from the first two peaks at around 150 and 250 C. By correlating the wavelength of light used for bleaching the TL with the radiation-induced absorption bands, the type of centres involved in the approx. 150 C TL glow peak in fluorapatite has been identified as E(II) or A centres, i.e. halogen ion vacancies with trapped electrons. Although the approx. 250 C TL glow peak is also bleached along with the 150 C TL peak, its temperature stability does not agree with that of the A centres. (author)

  9. Coral Reef Bleaching at Agatti Island of Lakshadweep Atolls, India

    Institute of Scientific and Technical Information of China (English)

    Ramar Vinoth; Mohan Gopi; Thipramalai Thankappanpillai Ajith Kumar; Thirunavukarassu Thangaradjou; Thangavel Balasubramanian

    2012-01-01

    A survey on coral bleaching was carried out at Agatti Island of Lakshadweep from May to June 2010.Elevated sea surface temperatures (SSTs) of the region exceeded the seasonal average and delayed the onset of monsoon,which triggered widespread bleaching of corals.The Agatti reefs showed an average of 73% bleached corals with apparent bleaching-related mortality of sea anemones (87%) and giant clams (83%).The SST increased up to 34 ℃ with an average maximum SST of 32.5℃ during the study period between May and June 2010.Coral reefs on the southern side of the island are fully or partially exposed to sun light during low tide in contrast to the other side.This suggests that the mortality is more likely due to the low tide exposure than exclusively due to the elevated SST.Observations indicated a clear increase in coral bleaching during April 2010,at levels higher than that in normal summer.

  10. Influence of H2SO4 as Activator to ClO2 on the Bleaching Effects

    OpenAIRE

    Xingxiang Ji; Jiachuan Chen; Guihua Yang,; Zhong Jian Tian

    2012-01-01

    In this study, we show that chlorine dioxide activated by 4% Hydrochloric Acid Solution (HCl) has the same bleaching effects as that by sulfuric acid (H2SO4). Chlorine dioxide is an important bleaching agent in ECF bleaching. Stable chlorine dioxide in conjunction with Hydrochloric Acid Solution (HCl) activation in a certain proportion can be applied in the process of pulp bleach with a bleaching result of environment friendly, positive brightness stability, low pollutant bleach and pulp brig...

  11. Modeling of chip bed packing in a continuous kraft cooking digester

    OpenAIRE

    Laakso, Sampsa

    2008-01-01

    This work focused on modeling of the chip bed packing phenomena in a continuous kraft cooking digester. A better understanding of chip bed packing would make it possible to optimize chip flow conditions in the digester, thereby ensuring uniform fiber quality and production efficiency. Chips are fed continuously into the digester, with the chip flow forming a solid bed. As the solid chip bed moves slowly downwards, cooking reactions proceed, which leads to softening of the chips. The soft...

  12. Effects of Penicillium chrysogenum var. halophenolicum on kraft lignin: color stabilization and cytotoxicity evaluation

    OpenAIRE

    Remédios, Marlene; Carvalho, Filomena A.; Enguita, Francisco J.; Cardoso, Carlos; Martins, Ivo C.; Santos, Nuno C.; Leitão, Ana Lúcia

    2016-01-01

    Wood industries and agricultural crops generate an inexhaustible supply of by-products like lignin, which constitutes an environmental problem. Increasing efforts have been done to find new applications for lignin. One of them is as a food additive, but its chemical nature makes it sensitive to browning which constitutes a major drawback for this type of lignin application. In the present study we are documenting how color stabilization of a commercial kraft lignin was achieved after the trea...

  13. Xylan reactions in kraft cooking and their influence on paper sheet properties

    OpenAIRE

    Danielsson, Sverker

    2006-01-01

    Xylan is the main hemicellulose in birch, eucalyptus, and most other hardwood species. During kraft pulping a series of chemical reactions and physical processes involving xylan take place. The processes studied in this thesis are the following: dissolution, degradation, redeposition onto the fibres, side group conversion, and cleavage of side groups off the xylan back bone. The side group in native xylan consists of methylglucuronic acid, which is mainly converted into hexenuronic acid durin...

  14. THE EFFECT OF Eucalyptus APMP FIBERS REINFORCEMENT ON Pinus radiata KRAFT PULP PROPERTIES

    OpenAIRE

    Mauro Manfredi; Jorge Luiz Colodette; Flaviana Reis Milagres; Rubens Chaves de Oliveira; Eric Chao Xu

    2008-01-01

    Kraft pulps derived from pine species are largely used for high strength paper products. The quality of such pulps hasbeen improved significantly in the last decades through advances in wood quality and adequate choice of pine species. The quality ofpine fibers can be further improved by incorporating other fibers to them. In fact, the mixture of pine fibers with hardwood fibers iscommon practice around the world. An alternative to further improve the quality of pine fibers is by mixing them ...

  15. Kinetics of liquid-solid reactions in naphthenic acid conversion and Kraft pulping

    Science.gov (United States)

    Yang, Ling

    Two liquid-solid reactions, in which the morphology of the solid changes as the reactions proceeds, were examined. One is the NA conversion in oil by decarboxylation on metal oxides and carbonates, and the other is the Kraft pulping in which lignin removal by delignification reaction. In the study of the NA conversion, CaO was chosen as the catalyst for the kinetic study from the tested catalysts based on NA conversion. Two reaction mixtures, carrier oil plus commercial naphthenic acids and heavy vacuum gas oil (HVGO) from Athabasca bitumen, were applied in the kinetic study. The influence of TAN, temperature, and catalyst loading on the NA conversion and decarboxylation were studied systematically. The results showed that the removal rate of TAN and the decarboxylation of NA were both independent of the concentration of NA over the range studied, and significantly dependent on reaction temperature. The data from analyzing the spent catalyst demonstrated that calcium naphthenate was an intermediate of the decarboxylation reaction of NA, and the decomposition of calcium naphthenate was a rate-determining step. In the study on the delignification of the Kraft pulping, a new mechanism was proposed for the heterogeneous delignification reaction during the Kraft pulping process. In particular, the chemical reaction mechanism took into account the heterogeneous nature of Kraft pulping. Lignin reacted in parallel with sodium hydroxide and sodium sulfide. The mechanism consists of three key kinetic steps: (1) adsorption of hydroxide and hydrosulfide ions on lignin; (2) surface reaction on the solid surface to produce degraded lignin products; and (3) desorption of degradation products from the solid surface. The most important step for the delignification process is the surface reaction, rather than the reactions occurring in the liquid phase. A kinetic model has, thus, been developed based on the proposed mechanism. The derived kinetic model showed that the mechanism

  16. INTEGRATION OF KRAFT PULPING ON A FOREST BIOREFINERY BY THE ADDITION OF A STEAM EXPLOSION PRETREATMENT

    OpenAIRE

    Raquel Martin-Sampedro; Maria E. Eugenio; Esteban Revilla; Juan A. Martin; J. Carlos Villar

    2011-01-01

    Steam explosion has been proposed for a wide range of lignocellulosic applications, including fractionation of biomass, pre-treatment of biomass for ethanol production, or as an alternative to conventional mechanical pulping. Nevertheless, a steam explosion process could also be used as pretreatment before chemical pulping, expecting a reduction in cooking time due to the open structure of the exploded chips. Thus, to evaluate the effect of steam explosion as a pretreatment in the kraft pulpi...

  17. Use of polymers and a surfactant in the treatment of Kraft process wastewater

    OpenAIRE

    Seyffert, Hans J.

    1988-01-01

    This study-investigated the use of cationic polymers, and a surfactant, EHDABr, in the color removal treatment of Kraft pulp and paper wastewater. Four polymers were evaluated for their color removal performance by jar test procedures. The polymers removed between 77 and 87% of the wastewater color. The affect of pH upon polymer performance varied with the polymer tested. Powdered activated carbon addition improved the performance of the polymers. The color removal abili...

  18. Use of Kraft Pine Lignin in Controlled-Release Fertilizer Formulations

    OpenAIRE

    García, M C.; Díez López, José Antonio; Vallejo, A.; García, L.; Cartagena, Maria C.

    1996-01-01

    Lignin was used as a majority component in a controlled-release fertilizer coating, since this waste product displays properties that make it an ideal substance for application in soil together with conventional mineral fertilizers. Pine lignin marketed under the name of Indulin AT and obtained by the Kraft process was used. Insoluble in water for all pH values that may occur in soil, this product was employed for coating pelleted urea. Seven series of fertilizer were obtained, which also con...

  19. Combustion properties of kraft black liquors; Ligniinifraktion vaikutus mustalipeaen poltto-ominaisuuksiin

    Energy Technology Data Exchange (ETDEWEB)

    Alen, R.; Rantanen, K.; Ekman, J.; Malkavaara, P. [Jyvaeskylae Univ. (Finland)

    1996-12-01

    The aim of this investigation was to find relationships between the structure of the dissolved lignin and the combustion properties (pyrolysis time, char burning time, and swelling) of softwood and hardwood kraft black liquors. In this conjunction, pine and birch chips, as well as their two mixtures (the mass ratios of pine chips to birch chips were 80:20 and 60:40), were delignified by conventional kraft pulping. In each cook series, a liquor sample was withdrawn at certain time intervals to obtain liquor samples with different chemical composition. The black liquors obtained were analyzed with respect to the content of lignin and `lignin monomers`, but also the molecular-mass distribution and the mass average molecular mass of lignin were made. In addition, the dissolved lignin was characterized by NMR spectroscopy and elemental analysis. Further data on the chemical structures of lignin in black liquors were obtained by identifying various degradation products formed from this material during oxidative (CuO oxidation) and pyrolytic treatments. Several correlations between the `structural parameters` of the dissolved lignin and the combustion properties of black liquor were found. These correlations were significant especially in the case of pine cook. The results revealed many findings which are, together with the earlier data, useful for a better understanding of the thermochemical behavior of different kraft black liquors during combustion in a recovery furnace. (author)

  20. Producing a True Lignin Depolymerase for Biobleaching Softwood Kraft Pulp; FINAL

    International Nuclear Information System (INIS)

    This project constituted an intensive effort devoted to producing, from the white-rot fungus Tramets Cingulata, a lignin degrading enzyme (lignin depolymerase) that is directly able to biobleach or delignify softwood kraft pulp brownstock. To this end, the solutions in which T. cingulata was grown contained dissolved kraft lignin which fulfilled two functions; it behaved as a lignin deploymerase substrate and it also appeared to act as an inducer of enzyme expression. However, the lignin depolymerase isoenzymes (and other extracellular T. cingulata enzymes) interacted very strongly with both the kraft lignin components and the fungal hypae, so the isolating these proteins from the culture solutions proved to be unexpectedly difficult. Even after extensive experimentation with a variety of protein purification techniques, only one approach appeared to be capable of purifying lignin depolymerases to homogeneity. Unfortunately the procedure was extremely laborious; it involved the iso electric focusing of concentrated buffer-exchanged culture solutions followed by electro-elution of the desired protein bands from the appropriate polyacrylamide gel segments

  1. The energy efficiency partnership - Kraft General Foods and Boston Edison Company

    International Nuclear Information System (INIS)

    During the past twenty years, inordinate shifts in the supply and demand of energy have forced both electric utility companies and their customers to investigate new and innovative ways to satisfy the ever increasing demand for electricity. The Energy Efficiency Partnership, developed between Kraft General Foods and Boston Edison Company, presents an exemplary study of how two corporate giants creatively solved the problem of uncontrolled energy costs and its positive effect on the overall operations of Kraft General Foods, Framingham. But the Energy Efficiency Partnership did more than reduce energy costs, it provided benefits to all parties on the playing field. To understand its significance, a review of the partnership's history is paramount. The first official announcement of the Energy Efficiency Partnership was made on April 9, 1990. Framingham, MA, The Commonwealth of Massachusetts Kraft General Foods Framingham, and Boston Edison Company have joined forces in a $3.6 million dollar energy partnership that will help keep 250 industrial jobs in Massachusetts and could lead to the future expansion of the international food company's Framingham facility

  2. SUGARCANE BAGASSE PULPING AND BLEACHING: THERMAL AND CHEMICAL CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Paulo Henrique Fernandes Pereira

    2011-05-01

    Full Text Available Cellulose fibers were isolated from sugarcane bagasse in three stages. Initially sugarcane bagasse was subjected to a pre-treatment process with hydrolyzed acid to eliminate hemicellulose. Whole cellulosic fibers thus obtained were then subjected to a two-stage delignification process and finally to a bleaching process. The chemical structure of the resulting cellulose fibers was studied by Fourier Transform Infrared (FTIR spectroscopy. Scanning Electron Microscopy (SEM and X-ray diffraction (XRD were used to analyze the effects of hydrolysis, delignification, and bleaching on the structure of the fibers. Two different thermal analysis techniques were used to study the bleaching cellulose fibers. These techniques confirmed that cellulose fibers were isolated from sugarcane bagasse. A future goal is to use these fibers as reinforcement elements in composites, organic-inorganic hybrid, and membranes for nanofiltration.

  3. Deoiling and Regeneration Efficiencies of Spent Bleaching Clay

    Directory of Open Access Journals (Sweden)

    A. W. Nursulihatimarsyila

    2010-01-01

    Full Text Available Problem statement: Disposal and reuse of Spent Bleaching Clay (SBC from palm oil processing industry is a problem of growing importance. The residual oil in the SBC can be recovered using hexane as solvent.Approach: In this study, the effect of different solid to solvent ratio on the deoiling efficiency of SBC samples from palm oil refinery and palm kernel refinery were studied. The amount of extracted oil and deoiling efficiency for both types of SBC increases as the solid to solvent ratio is decreased. Results: All the extracted oils, irrespective of the amount of solvent used, have poorer quality than crude oil and may be difficult to be refined to good quality and stability.Conclusion: The deoiled SBC treated using different solid to solvent ratio gave almost similar regeneration efficiency i.e., about 80% for bleaching of CPO and not more than 30% for bleaching of CPKO.

  4. Quantification of cross-bleaching during infrared (IR) light stimulation

    DEFF Research Database (Denmark)

    Kreutzer, Sebastian; Hülle, Daniela; Thomsen, Kristina Jørkov; Hilgers, Alexandra; Kadereit, Annette; Fuchs, Markus

    2013-01-01

    1 at the time” option can result in significant dose underestimation (1) if the sequence is not split into different sets, or (2) if samples are not placed on every 2nd position. In addition, a newly designed flange for the optical unit of the TL/OSL reader is presented which appears to reduce cross-bleaching......The cross-bleaching behaviour of automated Risø TL/OSL (DA-12, DA-15, DA-20) luminescence readers is investigated. By design, up to 24 or 48 aliquots can be stored on a carousel in a single measurement chamber. Due to this construction, irradiation or illumination on one sample may affect the...... adjacent position resulting in systematic errors. Previously reported for blue LEDs, such cross-talk (cross-bleaching/illumination) has never been quantified explicitly for the infrared (IR) LEDs, although they are intensively used in IRSL measurements of e.g. feldspar and polymineral samples. In IRSL...

  5. Ocean Acidification: A Major Driver of Coral Bleaching in the 21st Century?

    Science.gov (United States)

    Anthony, K.; Eakin, M. C.; Cao, L.; Caldeira, K.; Hoegh-Guldberg, O.

    2009-05-01

    Heat stress long been known to drive patterns of coral bleaching. Recently, however, it was discovered that ocean acidification can drive coral bleaching independently of temperature. This raises the question: how important will acidification be in driving coral bleaching under climate change? Here, we develop and apply a model that accounts for both thermal stress and ocean acidification in the coral bleaching response. Our analyses, which combine experimental bleaching data under manipulated ocean chemistry and warming with projections of CO2 and SST based on global circulation models, show that ocean acidification will become a key driver of future mass bleaching events within a few decades. Our findings, based on highly conservative assumptions, reveal that coral bleaching alert systems based on warming alone could underestimate coral bleaching by up to 50% during the 21st century. This is a striking result that will affect coral reef management strategies worldwide and has policy implications relating to global efforts to reduce greenhouse gas emissions.

  6. Evaluation of temperature increase during in-office bleaching.

    Science.gov (United States)

    Mondelli, Rafael Francisco Lia; Soares, Ana Flávia; Pangrazio, Eugenio Gabriel Kegler; Wang, Linda; Ishikiriama, Sergio Kiyoshi; Bombonatti, Juliana Fraga Soares

    2016-04-01

    The use of light sources in the bleaching process reduces the time required and promotes satisfactory results. However, these light sources can cause an increase in the pulp temperature. Objective The purpose of the present study was to measure the increase in intrapulpal temperature induced by different light-activated bleaching procedures with and without the use of a bleaching gel. Material and Methods A human maxillary central incisor was sectioned 2 mm below the cementoenamel junction. A K-type thermocouple probe was introduced into the pulp chamber. A 35% hydrogen peroxide bleaching gel was applied to the vestibular tooth surface. The light units used were a conventional halogen, a hybrid light (only LED and LED/Laser), a high intensity LED, and a green LED light. Temperature increase values were compared by two-way ANOVA and Tukey´s tests (phybrid light, and high intensity LED. Compared to the other light sources, the conventional halogen lamp applied over the bleaching gel induced a significant increase in temperature (3.83±0.41°C). The green LED unit with and without gel application did not produce any significant intrapulpal temperature variations. Conclusion In the present study, the conventional halogen lamp caused the highest increase in intrapulpal temperature, and the green LED caused the least. There was an increase in temperature with all lights tested and the maximum temperature remained below the critical level (5.5°C). The addition of a bleaching gel led to a higher increase in intrapulpal temperatures. PMID:27119761

  7. Effect of bleaching on the microhardness of tooth-colored restorative materials

    Directory of Open Access Journals (Sweden)

    Abdolrahim Davari

    2013-08-01

    Full Text Available   Background and Aims: Bleaching agents not only affect the tooth structure, but also may alter the properties of restorative materials. The aim of this in vitro study was to evaluate the effect of different bleaching regimens on the microhardness of four tooth-colored restorative materials.   Materials and Methods: Eighty specimens of four restorative materials (Microhybrid resin composite (Z250 (3M, ESPE, nanohybrid composite Z350 (3M, ESPE, packable composite P60 (3M, ESPE, and resin modified glass ionomer Vitremer (3M, ESPE were fabricated and were polished after 24 h with Soflex discs (3M,ESPE. Then the specimens were divided into two groups: In office bleach group, 40 specimens (10 of each restorative material were bleached with hydrogen peroxide 37.5% for 30 min in two sessions with 7 days interval. In home bleaching group, 40 specimens were bleached with carbamid peroxide 22%, 6 h a day for 14 days. Vickers microhardness test were done before and after bleaching (baseline. Finally data were evaluated using analysis of Variance.   Results: Two bleaching regimens were significantly decreased the microhardness values. In Z250 resin composite, the microhardness values before and after bleaching were 95.30 and 92.67 kg/mm2, respectively. for office bleaching (P=0.011 and 95.38 and 92.39 kg/mm2 for home bleaching (P<0.001. In Z350 resin composite, the microhardness values before and after bleaching were 98.29 and 92.41 kg/mm2, for office bleaching (P<0.001 and 97.35 and 93.44 kg/mm2 for home bleaching (P<0.001 respectively. In P60 resin composite, the microhardness values before and after bleaching were 103.10 and 96.16 kg/mm2, respectively. for office bleaching (P=0.045 and 102.61 and 98.16 kg/mm2 for home bleaching (P=0.001. In resin modified glass ionomer (Vitremer, the microhardness values before and after bleaching were 56.79 and 49.41 kg/mm2, respectively. for office bleaching (P=0.004 and 54.17 and 46.50 kg/mm2 for home bleaching (P

  8. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    OpenAIRE

    Hobbs, Jean-Paul A.; Frisch, Ashley J.; Ford, Benjamin M.; Thums, Michele; Saenz-Agudelo, Pablo; Furby, Kathryn A.; Berumen, Michael L.

    2013-01-01

    Background Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. Methodology/Principal Findings This study used underwater visual surveys to investigate bleaching in the 10 species of a...

  9. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    OpenAIRE

    Hobbs, Jean-Paul A; Ashley J Frisch; Ford, Benjamin M.; Michele Thums; Pablo Saenz-Agudelo; Kathryn A Furby; Berumen, Michael L.

    2013-01-01

    BACKGROUND: Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. METHODOLOGY/PRINCIPAL FINDINGS: This study used underwater visual surveys to investigate bleaching in the 10 species of...

  10. Coral bleaching, rise in sea temperature, and the population of Acanthaster planci in Okinawa

    OpenAIRE

    Arakaki, Yuji; Yamazato, Kiyoshi; 新垣, 裕治; 山里, 清; 名桜大学・国際・観光

    2001-01-01

    Large scale coral bleaching in Japanese waters, extending from the Ryukyus to southern Kyushyu, occurred in 1998 owing to high seawater temperature. In this study, the authors show population fluctuations of Acanthaster planci before and after this bleaching event, and try to explain the reason for these fluctuations in relation to this event. A. planci, a strong coral predator, prefers to prey on acroporid corals. These corals are easily bleached, and most of them died from the bleaching dur...

  11. Influence of bleaching and desensitizing gel on bond strength of orthodontic brackets

    OpenAIRE

    Fernanda Alves Rodrigues Britto; Adriana Simoni Lucato; Heloisa Cristina Valdrighi; Sílvia Amélia Scudeler Vedovello

    2015-01-01

    OBJECTIVE: The objective of this study was to assess, in vitro, the influence of bleaching gel and the use of desensitizing agent over bond strength of ceramic brackets bonded to bovine enamel. METHODS: One hundred bovine incisors were selected and randomly divided into five groups (n = 20): Group 1, control group (without bleaching); Group 2, bleached with 35% hydrogen peroxide; Group 3, bleached with 35% hydrogen peroxide (three applications, 15 minutes each) and desensitizing agent applied...

  12. Bleaching absorption fronts and beam propagation in laser-heated solenoids

    International Nuclear Information System (INIS)

    It is shown that the propagation velocity of bleaching laser-driven heating waves in the supersonic mode is governed by the requirement that the bleached plasma maintains an optical thickness of unity. It is proposed that in the case where the bleached plasma is confined by very large magnetic fields, the diameter of the plasma column may self-regulate so that the bleaching wave propagates at the Alfven velocity

  13. Modified Technique for Nonvital Tooth Bleaching: A Case Report

    OpenAIRE

    Abdelkader, Naglaa Nabil

    2015-01-01

    The aim of this study is to report a case of a nonvital, discolored, maxillary central incisor bleached by 35% hydrogen peroxide gel with the use of glass ionomer cement as a mechanical barrier in an attempt to minimize the undesirable side effects of intracoronal bleaching. The patient was a 13-year-old boy complaining of a discolored nonvital upper-right central incisor and was selected for this study from the pedodontic clinic in the Shibin Elkom teaching hospital in June 2013. After succe...

  14. Optical dating: bleaching experiment on IRSL signals from loess samples

    International Nuclear Information System (INIS)

    A kind of red LEDs (Light emitting Diode) with a wavelength of 655 nm provides light illumination of loess samples while pretreatment the samples with minimal effect on the latent IRSL. The IRSL signal is decreased to two percent after 20 minutes bleaching by sun light. It implies that the residual signals may be neglected even when dating very young loess samples, and that IRSL dating has significant potential in dating very poorly-bleached sediments. The recuperation of IRSL in loess is negligible, so the measurable age limit for IRSL is much lower than that for GLSL (Gree Light Stimulate Luminescence)

  15. Climatological context for large-scale coral bleaching

    Science.gov (United States)

    Barton, A. D.; Casey, K. S.

    2005-12-01

    Large-scale coral bleaching was first observed in 1979 and has occurred throughout virtually all of the tropics since that time. Severe bleaching may result in the loss of live coral and in a decline of the integrity of the impacted coral reef ecosystem. Despite the extensive scientific research and increased public awareness of coral bleaching, uncertainties remain about the past and future of large-scale coral bleaching. In order to reduce these uncertainties and place large-scale coral bleaching in the longer-term climatological context, specific criteria and methods for using historical sea surface temperature (SST) data to examine coral bleaching-related thermal conditions are proposed by analyzing three, 132 year SST reconstructions: ERSST, HadISST1, and GISST2.3b. These methodologies are applied to case studies at Discovery Bay, Jamaica (77.27°W, 18.45°N), Sombrero Reef, Florida, USA (81.11°W, 24.63°N), Academy Bay, Galápagos, Ecuador (90.31°W, 0.74°S), Pearl and Hermes Reef, Northwest Hawaiian Islands, USA (175.83°W, 27.83°N), Midway Island, Northwest Hawaiian Islands, USA (177.37°W, 28.25°N), Davies Reef, Australia (147.68°E, 18.83°S), and North Male Atoll, Maldives (73.35°E, 4.70°N). The results of this study show that (1) The historical SST data provide a useful long-term record of thermal conditions in reef ecosystems, giving important insight into the thermal history of coral reefs and (2) While coral bleaching and anomalously warm SSTs have occurred over much of the world in recent decades, case studies in the Caribbean, Northwest Hawaiian Islands, and parts of other regions such as the Great Barrier Reef exhibited SST conditions and cumulative thermal stress prior to 1979 that were comparable to those conditions observed during the strong, frequent coral bleaching events since 1979. This climatological context and knowledge of past environmental conditions in reef ecosystems may foster a better understanding of how coral reefs will

  16. Expression profiling and gene ontology analysis in fathead minnow (Pimephales promelas) liver following exposure to pulp and paper mill effluents.

    Science.gov (United States)

    Costigan, Shannon L; Werner, Julieta; Ouellet, Jacob D; Hill, Lauren G; Law, R David

    2012-10-15

    Many studies link pulp and paper mill effluent (PPME) exposure to adverse effects in fish populations present in the mill receiving environments. These impacts are often characteristic of endocrine disruption and may include impaired reproduction, development and survival. While these physiological endpoints are well-characterized, the molecular mechanisms causing them are not yet understood. To investigate changes in gene transcription induced by exposure to a PPME at several stages of treatment, male and female fathead minnows (FHMs) were exposed for 6 days to 25% (v/v) secondary (biologically) treated kraft effluent (TK) or 100% (v/v) combined mill outfall (CMO) from a mill producing both kraft pulp and newsprint. The gene expression changes in the livers of these fish were analyzed using a 22K oligonucleotide microarray. Exposure to TK or CMO resulted in significant changes in the expression levels of 105 and 238 targets in male FHMs and 296 and 133 targets in females, respectively. Targets were then functionally analyzed using gene ontology tools to identify the biological processes in fish hepatocytes that were affected by exposure to PPME after its secondary treatment. Proteolysis was affected in female FHMs exposed to both TK and CMO. In male FHMs, no processes were affected by TK exposure, while sterol, isoprenoid, steroid and cholesterol biosynthesis and electron transport were up-regulated by CMO exposure. The results presented in this study indicate that short-term exposure to PPMEs affects the expression of reproduction-related genes in the livers of both male and female FHMs, and that secondary treatment of PPMEs may not neutralize all of their metabolic effects in fish. Gene ontology analysis of microarray data may enable identification of biological processes altered by toxicant exposure and thus provide an additional tool for monitoring the impact of PPMEs on fish populations. PMID:22728206

  17. Expression profiling and gene ontology analysis in fathead minnow (Pimephales promelas) liver following exposure to pulp and paper mill effluents

    Energy Technology Data Exchange (ETDEWEB)

    Costigan, Shannon L.; Werner, Julieta; Ouellet, Jacob D.; Hill, Lauren G. [Department of Biology, Lakehead University, 955 Oliver Road, Ontario P7B 5E1, (Canada); Law, R. David, E-mail: dlaw@lakeheadu.ca [Department of Biology, Lakehead University, 955 Oliver Road, Ontario P7B 5E1, (Canada)

    2012-10-15

    Many studies link pulp and paper mill effluent (PPME) exposure to adverse effects in fish populations present in the mill receiving environments. These impacts are often characteristic of endocrine disruption and may include impaired reproduction, development and survival. While these physiological endpoints are well-characterized, the molecular mechanisms causing them are not yet understood. To investigate changes in gene transcription induced by exposure to a PPME at several stages of treatment, male and female fathead minnows (FHMs) were exposed for 6 days to 25% (v/v) secondary (biologically) treated kraft effluent (TK) or 100% (v/v) combined mill outfall (CMO) from a mill producing both kraft pulp and newsprint. The gene expression changes in the livers of these fish were analyzed using a 22 K oligonucleotide microarray. Exposure to TK or CMO resulted in significant changes in the expression levels of 105 and 238 targets in male FHMs and 296 and 133 targets in females, respectively. Targets were then functionally analyzed using gene ontology tools to identify the biological processes in fish hepatocytes that were affected by exposure to PPME after its secondary treatment. Proteolysis was affected in female FHMs exposed to both TK and CMO. In male FHMs, no processes were affected by TK exposure, while sterol, isoprenoid, steroid and cholesterol biosynthesis and electron transport were up-regulated by CMO exposure. The results presented in this study indicate that short-term exposure to PPMEs affects the expression of reproduction-related genes in the livers of both male and female FHMs, and that secondary treatment of PPMEs may not neutralize all of their metabolic effects in fish. Gene ontology analysis of microarray data may enable identification of biological processes altered by toxicant exposure and thus provide an additional tool for monitoring the impact of PPMEs on fish populations.

  18. Expression profiling and gene ontology analysis in fathead minnow (Pimephales promelas) liver following exposure to pulp and paper mill effluents

    International Nuclear Information System (INIS)

    Many studies link pulp and paper mill effluent (PPME) exposure to adverse effects in fish populations present in the mill receiving environments. These impacts are often characteristic of endocrine disruption and may include impaired reproduction, development and survival. While these physiological endpoints are well-characterized, the molecular mechanisms causing them are not yet understood. To investigate changes in gene transcription induced by exposure to a PPME at several stages of treatment, male and female fathead minnows (FHMs) were exposed for 6 days to 25% (v/v) secondary (biologically) treated kraft effluent (TK) or 100% (v/v) combined mill outfall (CMO) from a mill producing both kraft pulp and newsprint. The gene expression changes in the livers of these fish were analyzed using a 22 K oligonucleotide microarray. Exposure to TK or CMO resulted in significant changes in the expression levels of 105 and 238 targets in male FHMs and 296 and 133 targets in females, respectively. Targets were then functionally analyzed using gene ontology tools to identify the biological processes in fish hepatocytes that were affected by exposure to PPME after its secondary treatment. Proteolysis was affected in female FHMs exposed to both TK and CMO. In male FHMs, no processes were affected by TK exposure, while sterol, isoprenoid, steroid and cholesterol biosynthesis and electron transport were up-regulated by CMO exposure. The results presented in this study indicate that short-term exposure to PPMEs affects the expression of reproduction-related genes in the livers of both male and female FHMs, and that secondary treatment of PPMEs may not neutralize all of their metabolic effects in fish. Gene ontology analysis of microarray data may enable identification of biological processes altered by toxicant exposure and thus provide an additional tool for monitoring the impact of PPMEs on fish populations.

  19. Effectiveness of bleaching agent on composite resin discoloration

    Directory of Open Access Journals (Sweden)

    Galih Sampoerno

    2012-03-01

    Full Text Available Background: The discoloration of teeth, especially anterior teeth, is one of aesthetic problems. The use of tooth bleaching agents for discolored natural teeth is becoming increasingly popular. Many dentists, however, get many problems when they conduct bleaching process since there is much composite filling on patient’s anterior teeth. Although many research have focused on the discoloration of composite resin after bleaching process, the problem still becomes debatable. Purpose: The purpose of this study was to investigate the difference of the discoloration between hybrid composite and nano composite before and after the application of tooth bleaching agent, 38% hydrogen peroxide. Methods: Eighteen disk-shaped specimens (5 mm of each of two composite resins, hybrid and nano filler, were prepared. The each group was treated 3 times and the specimens were divided into two groups consisted of 9 specimens for each, and then immersed in black tea solutions for 72 hours. Next, after having staining and bleaching processes, the color of the specimens was measured with a optic spectrophotometer by using photo with type BPY-47 and digital microvolt. The differences of the light intensity among three measurements were then calculated. Afterwards, GLM MANOVA Repeated Measure and parametric analysis (Independent t-test and Paired t-test were then used to analyze the data. Results: After staining process, it is then known that the nano composite had more discoloration and more affected by the black tea solution than the hybrid one. Conclusion: After bleaching, the discoloration was finally removed completely from both hybride and nano filler composite resins and became brighter from the baseline color.Latar belakang: Salah satu problem estetik adalah adanya perubahan warna pada gigi anterior. Peningkatan pemakaian bahan bleaching semakin popular. Banyak dokter gigi mempunyai problem ketika mereka akan melakukan proses bleaching dan ditemukan banyak

  20. Uranium mining and milling

    International Nuclear Information System (INIS)

    In this report uranium mining and milling are reviewed. The fuel cycle, different types of uranium geological deposits, blending of ores, open cast and underground mining, the mining cost and radiation protection in mines are treated in the first part of this report. In the second part, the milling of uranium ores is treated, including process technology, acid and alkaline leaching, process design for physical and chemical treatment of the ores, and the cost. Each chapter is clarified by added figures, diagrams, tables, and flowsheets. (HK)

  1. Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

    KAUST Repository

    Hobbs, Jean-Paul A.

    2013-08-08

    Background:Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms.Methodology/Principal Findings:This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19-100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance.Conclusions/Significance:Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host

  2. Taxonomic, spatial and temporal patterns of bleaching in anemones inhabited by anemonefishes.

    Directory of Open Access Journals (Sweden)

    Jean-Paul A Hobbs

    Full Text Available BACKGROUND: Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments. Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. METHODOLOGY/PRINCIPAL FINDINGS: This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%; however, this percentage was much higher (19-100% during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance. CONCLUSIONS/SIGNIFICANCE: Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked

  3. Chlorine bleaches - A significant long term source of mercury pollution

    Science.gov (United States)

    Siegel, S. M.; Eshleman, A.

    1975-01-01

    Products of industrial electrolysis of brine - NaOCl-based bleaches and NaOH - yielded 17 to 1290 ppb of Hg upon flameless atomic absorption analysis. Compared with current U.S. rejection value of 5 ppb for potable waters, the above levels seem sufficiently high to be a matter of environmental concern.

  4. Bleached and unbleached MFC nanobarriers: properties and hydrophobisation with hexamethyldisilazane

    Energy Technology Data Exchange (ETDEWEB)

    Chinga-Carrasco, Gary, E-mail: gary.chinga.carrasco@pfi.no [Paper and Fibre Research Institute (PFI) (Norway); Kuznetsova, Nina; Garaeva, Milyausha [Kazan National Research Technological University (KNRTU) (Russian Federation); Leirset, Ingebjorg [Paper and Fibre Research Institute (PFI) (Norway); Galiullina, Guzaliya; Kostochko, Anatoly [Kazan National Research Technological University (KNRTU) (Russian Federation); Syverud, Kristin [Paper and Fibre Research Institute (PFI) (Norway)

    2012-12-15

    This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. The HMDS-modified films made of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m{sup -2} day{sup -1} atm{sup -1}, which is a good property for some packaging applications.

  5. Bleached and unbleached MFC nanobarriers: properties and hydrophobisation with hexamethyldisilazane

    International Nuclear Information System (INIS)

    This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. The HMDS-modified films made of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m−2 day−1 atm−1, which is a good property for some packaging applications.

  6. Bleaching in vital deciduous teeth – a clinical case

    Directory of Open Access Journals (Sweden)

    José Carlos Pettorossi Imparato

    2008-01-01

    Full Text Available There has been growing concern and search for esthetic beauty and harmony over the last few years. This concern does not form part ofadults’ lives only, but also of children’s. Among the substances used for bleaching dental structures, the most outstanding are those whoseactive principle is hydrogen peroxide-based . The present study reports a clinical case of a 4-year-old girl that suffered trauma of tooth 61 with consequent color alteration, but with no alteration in pulp vitality. The main complaint by the patient and her guardians concerned esthetics, therefore external dental bleaching was performed, using Opalescence Xtra® (Ultradent, in two sessions with an interval of one month between them. External in office bleaching was the treatment of choice, due to the tooth vitality, patient’s age and presence of only one darkened tooth. After the bleaching treatments an improvement in the darkening was observed, and both the child and her guardians were satisfied with the esthetic result.

  7. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    International Nuclear Information System (INIS)

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

  8. Studies on optical bleaching of x-ray irradiated KCL by thermoluminescence

    International Nuclear Information System (INIS)

    The optical bleaching characteristics of F-centres in X-ray irradiated KCl crystals have been studied by using thermoluminescence (TL) as the tool. It is found that the bleaching of F-centres takes place in two stages, a rapid stage initially, followed by a slow second age agreeing with reports of earlier workers based on photoconductivity and optical absorption measurements. SUDY OF THE BLEACHING CHARACTERISTICS OF THE INDIVIDUAL TL peaks shows that the individual TL peaks also follow a two-stage bleaching process. There is no correlation between the two stages of F-bleaching with those of formation of F-centres. (author)

  9. Bahan pemutih gigi dengan sertifikat ADA/ISO (Tooth bleaching material with ADA/ISO certificate

    Directory of Open Access Journals (Sweden)

    Asti Meizarini

    2005-06-01

    Full Text Available Bleaching of teeth for cosmetic reasons is a popular aspect of cosmetic dentistry because patients realize the aesthetical benefits of these products. The dentist as a clinician's practitioner must be knowledgeable of the products and their application techniques. Bleaching materials which are safe and effective are the ADA accepted or manufactured by those which have already haved ISO certificate. Dentist must have enough knowledge about in-office bleaching prescribed for home-use bleaching including their contra indication and side effects, to advise the patients and provide effective bleaching services.

  10. Surface discoloration of composite resins: Effects of staining and bleaching

    Directory of Open Access Journals (Sweden)

    Claudio Poggio

    2012-01-01

    Full Text Available Background: The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet·X HD, Clearfil AP-X, Gradia Direct and five nanohybrid composite resins (Ceram·X, GC Kalore, G-aenial, Grandio, GrandioSO, after staining and bleaching procedures. Materials and Methods: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h, for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco. The color of specimens was measured with a spectrophotometer according to the CIE LFNx01aFNx01bFNx01 system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DE abFNx01 between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA. Results: All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Conclusions: Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

  11. Monomer release from nanofilled and microhybrid dental composites after bleaching.

    Directory of Open Access Journals (Sweden)

    Masumeh Hasani Tabatabaee

    2014-02-01

    Full Text Available The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites.80 samples (5mm diameter and 3mm thickness of each composite were prepared. After curing, half of them were randomly polished. Each group was divided into 8 subgroups and immersed in water or 10%, 20% and 30% H2O2 for 3 or 8 hours. Eluted Bis-GMA (Bis-phenol A Glycidyl Dimethacrylate, TEGDMA (Triethyleneglycol Dimethacrylate, UDMA (Urethane Dimethacrylate and BisEMA (Bis-phenol A ethoxylate Dimethacrylate were quantified by high performance liquid chromatography and the results were analyzed by univariate ANOVA and t-test (P<0.05.Bleach significantly increased the overall release of monomers (P<0.001; TEGDMA was released more than Bis-GMA (P<0.001. Supreme released more TEGDMA compared to Z250 (P<0.001. Bleaching increased the release of this monomer (P<0.001. Increasing both the concentration of H2O2, and the immersion time, increased the release of TEGDMA (P<0.001. Polishing had no effect on release of this monomer (P=0.952. Supreme released more Bis-GMA than Z250 (P=0.000. The more concentrated H2O2 caused more elution of Bis-GMA (P= 0.003; while the effect of immersion time was not significant (P=0.824. Polishing increased the release of Bis-GMA (P=0.001. Neither the type of composite nor Bleaching had any effect on release of UDMA (P=0.972 and (P=0.811 respectively. Immersion duration increased the release of UDMA (P=0.002, as well as polishing (P=0.024.Bleaching increased the release of monomers. Nanofilled composites released more monomer than the microfilled.

  12. Tropical cyclone cooling combats region-wide coral bleaching.

    Science.gov (United States)

    Carrigan, Adam D; Puotinen, Marji

    2014-05-01

    Coral bleaching has become more frequent and widespread as a result of rising sea surface temperature (SST). During a regional scale SST anomaly, reef exposure to thermal stress is patchy in part due to physical factors that reduce SST to provide thermal refuge. Tropical cyclones (TCs - hurricanes, typhoons) can induce temperature drops at spatial scales comparable to that of the SST anomaly itself. Such cyclone cooling can mitigate bleaching across broad areas when well-timed and appropriately located, yet the spatial and temporal prevalence of this phenomenon has not been quantified. Here, satellite SST and historical TC data are used to reconstruct cool wakes (n=46) across the Caribbean during two active TC seasons (2005 and 2010) where high thermal stress was widespread. Upon comparison of these datasets with thermal stress data from Coral Reef Watch and published accounts of bleaching, it is evident that TC cooling reduced thermal stress at a region-wide scale. The results show that during a mass bleaching event, TC cooling reduced thermal stress below critical levels to potentially mitigate bleaching at some reefs, and interrupted natural warming cycles to slow the build-up of thermal stress at others. Furthermore, reconstructed TC wave damage zones suggest that it was rare for more reef area to be damaged by waves than was cooled (only 12% of TCs). Extending the time series back to 1985 (n = 314), we estimate that for the recent period of enhanced TC activity (1995-2010), the annual probability that cooling and thermal stress co-occur is as high as 31% at some reefs. Quantifying such probabilities across the other tropical regions where both coral reefs and TCs exist is vital for improving our understanding of how reef exposure to rising SSTs may vary, and contributes to a basis for targeting reef conservation. PMID:24474700

  13. Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

    Directory of Open Access Journals (Sweden)

    Andréa Abi Rached DANTAS

    2015-12-01

    Full Text Available ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home. Material and Methods Samples were randomly distributed into five experimental groups (n=15: C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE, luminosity (ΔL, green-red axis (Δa, and blue-yellow axis (Δb. The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments.

  14. Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

    Science.gov (United States)

    DANTAS, Andréa Abi Rached; BORTOLATTO, Janaina Freitas; RONCOLATO, Ávery; MERCHAN, Hugo; FLOROS, Michael Christopher; KUGA, Milton Carlos; de OLIVEIRA, Osmir Batista

    2015-01-01

    ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments. PMID:26814462

  15. In-office bleaching effects on the pulp flow and tooth sensitivity – case series

    Directory of Open Access Journals (Sweden)

    Andrés Felipe CARTAGENA

    2015-01-01

    Full Text Available Laser Doppler flowmetry (LDF is a noninvasive method capable of evaluating variations in pulp blood flow (PBF and pulp vitality. This method has thus far not been used to assess changes in blood flow after in-office bleaching. The aim of this case series report was to measure changes in PBF by LDF in the upper central incisor of three patients submitted to in-office bleaching. The buccal surfaces of the upper arch were bleached with a single session of 35% hydrogen peroxide gel with three 15-min applications. The color was recorded using a value-oriented Vita shade guide before in-office bleaching and one week after the procedure. The tooth sensitivity (TS in a verbal scale was reported, and PBF was assessed by LDF before, immediately, and one week after the bleaching session. The lower arch was submitted to dental bleaching but not used for data assessment. A whitening degree of 3 to 4 shade guide units was detected. All participants experienced moderate to considerable TS after the procedure. The PBF readings reduced 20% to 40% immediately after bleaching. One week post-bleaching, TS and PBF were shown to be equal to baseline values. A reversible decrease of PBF was detected immediately after bleaching, which recovered to the baseline values or showed a slight increase sooner than one week post-bleaching. The LDF method allows detection of pulp blood changes in teeth submitted to in-office bleaching, but further studies are still required.

  16. Influence of thermoluminescence signal for debris flow surface materials by sunlight bleaching

    International Nuclear Information System (INIS)

    Thermoluminescence was utilized for measuring the thermoluminescence signals of the standard debris flow samples which were bleached by simulated sunlight and debris flow samples after real sunlight bleaching. The experiment results demonstrate that light bleaching phenomenon of the debris flow occurs when it experiences a period of exposure. The thermoluminescence signal of the samples weakens gradually with the increase of depth. The optical bleaching phenomenon is obvious. Within a certain depth, light bleaching phenomenon is enhanced with the increase of light intensity. The annealing depth of simulated sunlight bleaching experiment is about 1 mm, and the actual annealing depth of sunlight bleaching is about 6 mm. According to the equivalent dose variation with depth, the mud of natural debris flow can be divided into two stages. It has fundamental significance in the application of thermoluminescence dating techniques to divide the stages of debris flow sediments. (authors)

  17. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    International Nuclear Information System (INIS)

    We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between well-bleached and poorly bleached grains. It is especially important to investigate if the uncertainties assigned to individual estimates of dose adequately describe the observed variability in well-bleached dose distributions. We investigate this by quantifying the over-dispersion in laboratory-bleached and gamma-irradiated samples. We show that there is a linear relationship between the over-dispersion and the mean dose. Knowing this uncertainty relationship enables us to estimate the burial dose by comparing the predicted uncertainty on the running mean with that calculated from actual dispersion

  18. Susceptibility to Coffee Staining during Enamel Remineralization Following the In-Office Bleaching Technique

    DEFF Research Database (Denmark)

    Mori, Aline Akemi; Lima, Fernanda Ferruzzi; Benetti, Ana Raquel;

    2016-01-01

    PURPOSE: To assess in situ the enamel mineralization level and susceptibility to coffee staining after in-office bleaching. MATERIALS AND METHODS: Thirty-six human dental fragments assembled into intraoral devices were bleached with 35% hydrogen peroxide and treated as follows: (group 1) no contact...... with coffee; (group 2) immersion in a coffee solution for 30 minutes daily for 7 days, starting 1 week after bleaching; and (group 3) immersion in a coffee solution for 30 minutes daily for 14 days, starting immediately after bleaching. Enamel mineralization and color were assessed before bleaching (T1......), immediately after bleaching (T2), and after 7 (T3) and 14 days (T4). The CIE whiteness index (W*) and closeness to white (ΔW*) following bleaching and/or immersion in coffee were calculated. Data were analyzed with Friedman and Wilcoxon tests or Kruskal-Wallis and Mann-Whitney U-tests (α = 0.05). RESULTS...

  19. Laccase-initiated cross-linking of lignocellulose fibres using a ultra-filtered lignin isolated from kraft black liquor.

    Science.gov (United States)

    Elegir, G; Bussini, D; Antonsson, S; Lindström, M E; Zoia, L

    2007-12-01

    In this work, the effect of Trametes pubescens laccase (TpL) used in combination with a low-molecular-weight ultra-filtered lignin (UFL) to improve mechanical properties of kraft liner pulp and chemi-thermo-mechanical pulp was studied. UFL was isolated by ultra-filtration from the kraft cooking black liquor obtained from softwood pulping. This by-product from the pulp industry contains an oligomeric lignin with almost twice the amount of free phenolic moieties than residual kraft pulp lignin. The reactivity of TpL on UFL and kraft pulp was studied by nuclear magnetic resonance spectroscopy and size exclusion chromatography. Laccase was shown to polymerise UFL and residual kraft pulp lignin in the fibres, seen by the increase in their average molecular weight and in the case of UFL as a decrease in the amount of phenolic hydroxyls. The laccase initiated cross-linking of lignin, mediated by UFL, which gives rise to more than a twofold increase in wet strength of kraft liner pulp handsheets without loosing other critical mechanical properties. Hence, this could be an interesting path to decrease mechano-sorptive creep that has been reported to lessen in extent as wet strength is given to papers. The laccase/2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) mediator system showed a greater increase in wet tensile strength of the resulting pulp sheets than the laccase/UFL system. However, other mechanical properties such as dry tensile strength, compression strength and Scott Bond internal strength were negatively affected by the laccase/ABTS system. PMID:17955195

  20. Comparison of Condensation Reactions of Lignin at Cα-Positionsin Kraft and Acid Sulfite Delignification of Western Hemlock

    OpenAIRE

    Funaoka, Masamitsu; Chiang, Vincent L.; Kolppo, Kari; Stokke, Douglas D.; 船岡, 正光

    1991-01-01

    Acid sulfite delignification of western hemlock(Tsuga heterophylla)was carried out from 90℃ to a final temperature of 145℃. Kraft pulping was also carried out from 90℃,but to a final temperature of 170℃. At various stages of delignification structual units condensed at Cα-positions in residual lignins weredetemined directly without isolating their lignins.In kraft pulping,the formation of structural units condensed at Cα-positions started at the point where about 50% of the lignin were remove...

  1. Reversão da brancura em pastas kraft de Eucalyptus globulus

    OpenAIRE

    Sêco, Isabel Maria Carvalho Lopes

    2006-01-01

    O trabalho proposto no âmbito da presente dissertação tem como objectivo último o estudo do fenómeno de reversão da brancura, induzida por via térmica, de uma pasta kraft de Eucalyptus globulus nacional branqueada segundo uma sequência D0E1D1D2. A concretização deste objectivo passou, em primeiro lugar, pelo estudo do efeito de algumas das principais variáveis processuais do branqueamento na estabilidade da brancura da pasta final. Das variáveis analisadas, verificou-se que ...

  2. Yield-increasing additives in kraft pulping: Effect on carbohydrate retention, composition and handsheet properties

    Energy Technology Data Exchange (ETDEWEB)

    Vaaler, David Andre Grimsoeen

    2008-07-01

    In this thesis, increased hemicellulose retention during kraft pulping has been studied. The work has been divided into three parts: i) Development of an accessible and reliable method for determination of carbohydrate composition of kraft pulps ii) Investigation of the composition and molecular mass distributions of the carbohydrates in kraft pulps with increased hemicellulose content iii) Investigation of the effect of increased hemicellulose content on the sheet properties of kraft pulps with increased hemicellulose content. A method for carbohydrate determination was developed. In this method, enzymes are used to hydrolyse the pulp into monosaccharides. A relatively mild acid hydrolysis is performed prior to detection on an HPLC with an RI-detector. The pulp is not derivatized and no pre-treatment (mechanical or chemical) is needed to determine the carbohydrate composition using the method developed here. Peak deconvolution software is used to improve the accuracy. Polysulphide and H2S primarily increase the glucomannan yield, which can be boosted by up to 7 % on o.d. wood. However, the cellulose yield is more affected by the cooking time and the maximum yield increase of cellulose is approximately 2 % on o.d. wood compared to an ordinary kraft pulp. The cooking time is influenced by sulphide ion concentration, AQ addition and the final Kappa number. The xylan yield is remarkably stable, however the alkali profile during the cook may influence the xylan yield. Surface xylan content of the fibres depends on residual alkali concentration in the black liquor. The molecular mass distributions of cellulose and hemicellulose were determined for pulps with increased hemicellulose content using size exclusion chromatography. Deconvolution by peak separation software is used to gain information about the degree of polymerization for cellulose and hemicellulose. The average DP of glucomannan in the kraft fibre was found to be 350 +- 30 and the average DP of xylan in the

  3. A comprehensive program to develop correlations for physical properties of kraft black liquor. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Fricke, A.L.; Zaman, A.A.

    1998-05-01

    The overall objective of the program was to develop correlations to predict physical properties within requirements of engineering precision from a knowledge of pulping conditions and of kraft black liquor composition, if possible. These correlations were to include those relating thermodynamic properties to pulping conditions and liquor composition. The basic premise upon which the research was based is the premise that black liquor behaves as a polymer solution. This premise has proven to be true, and has been used successfully in developing data reduction methods and in interpreting results. A three phase effort involving pulping, analysis of liquor composition, and measurement of liquor properties was conducted.

  4. Evaluation of End Mill Coatings

    Energy Technology Data Exchange (ETDEWEB)

    L. J. Lazarus; R. L. Hester,

    2005-08-01

    Milling tests were run on families of High Speed Steel (HSS) end mills to determine their lives while machining 304 Stainless Steel. The end mills tested were made from M7, M42 and T15-CPM High Speed Steels. The end mills were also evaluated with no coatings as well as with Titanium Nitride (TiN) and Titanium Carbo-Nitride (TiCN) coatings to determine which combination of HSS and coating provided the highest increase in end mill life while increasing the cost of the tool the least. We found end mill made from M42 gave us the largest increase in tool life with the least increase in cost. The results of this study will be used by Cutting Tool Engineering in determining which end mill descriptions will be dropped from our tool catalog.

  5. Bioluminescence inhibition assays for toxicity screening of wood extractives and biocides in paper mill process waters.

    Science.gov (United States)

    Rigol, Anna; Latorre, Anna; Lacorte, Sílvia; Barceló, Damià

    2004-02-01

    The risk associated with wood extractives, biocides, and other additives in pulp and paper mill effluents was evaluated by performing a characterization of process waters and effluents in terms of toxicity and chemical analysis. The individual toxicity of 10 resin acids, two unsaturated fatty acids, and three biocides was estimated by measuring the bioluminescence inhibition with a ToxAlert 100 system. Median effective concentration values (EC50) of 4.3 to 17.9, 1.2 to 1.5, and 0.022 to 0.50 mg/L were obtained, respectively. Mixtures of these three families of compounds showed antagonistic effects. Chemical analysis of process waters was performed by liquid chromatography- and gas chromatography-mass spectrometry. Biocides such as 2-(thiocyanomethylthio)-benzotiazole (TCMTB) (EC50 = 0.022 mg/L) and 2,2-dibromo-3-nitrilpropionamide (DBNPA) (EC50 = 0.50 mg/L) were the most toxic compounds tested and were detected at concentrations of 16 and 59 microg/L, respectively, in a closed-circuit recycling paper mill. Process waters from kraft pulp mills, printing paper mills, and packing board paper mills showed the highest concentration of resin acids (up to 400 microg/L) and accounted for inhibition percentages up to 100%. Detergent degradation products such as nonylphenol (NP) and octylphenol (OP) and the plasticizer bisphenol A (BPA) were also detected in the waters at levels of 0.6 to 10.6, 0.3 to 1.4, and 0.7 to 187 microg/L, respectively. However, once these waters were biologically treated, the concentration of detected organic compounds diminished and the toxicity decreased in most cases to values of inhibition lower than 20%. PMID:14982380

  6. Comparing the Effect of Different Bleaching Regims of Carbamide Peroxide on Microhardness of Z250 Composite

    Directory of Open Access Journals (Sweden)

    B Esmaeili

    2015-11-01

    Full Text Available Introduction: Bleaching products with oxidizing mechanism can exert side effects on the restorative materials existing in the oral cavity. Since bleaching agents are applied in different concentrations, the present study aimed to compare the effect of different bleaching regims of carbamide peroxide on microhardness of Z250 microhybride composite. Methods: In this in vitro study , 32 specimens of micro hybride composite (Z250 were made which were randomly divided into 4 subgroups (n=8: G1: bleached with10% carbamide peroxide 4 hours a day for 2 weeks G2: bleached with 16%carbamide peroxide 3 hours a day for 2 weeks G3: bleached with 22%carbamide peroxide 1hour a day for 2 weeks G4: the control subgroup stored in distilled water at 37◦c for 2 weeks. Microhardness of specimens was measured before and after bleaching using Vickers hardness testing machine. Moreover, the study data were analyzed statistically applying Anova and t-test (&alpha= 0.05. Results: This study findings revealed that using bleaching agent significantly decreased the  microhardness of composite resin in the bleaching groups compared to the control group, though the concentration of carbamide peroxide produced no significant effect on the microhardness value. (p>0.13 Conclusion: Bleaching therapy can cause a reduction in microhardness of Z250 composite and different concentrations of carbamide peroxide can reduce microhardness of Z250 to the same value.

  7. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

    Directory of Open Access Journals (Sweden)

    Loke Ming Chou

    Full Text Available Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached. The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change.

  8. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility

    Science.gov (United States)

    Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera–Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change. PMID:27438593

  9. Susceptibility of central Red Sea corals during a major bleaching event

    KAUST Repository

    Furby, Kathryn A.

    2013-01-04

    A major coral bleaching event occurred in the central Red Sea near Thuwal, Saudi Arabia, in the summer of 2010, when the region experienced up to 10-11 degree heating weeks. We documented the susceptibility of various coral taxa to bleaching at eight reefs during the peak of this thermal stress. Oculinids and agaricids were most susceptible to bleaching, with up to 100 and 80 % of colonies of these families, respectively, bleaching at some reefs. In contrast, some families, such as mussids, pocilloporids, and pectinids showed low levels of bleaching (<20 % on average). We resurveyed the reefs 7 months later to estimate subsequent mortality. Mortality was highly variable among taxa, with some taxa showing evidence of full recovery and some (e. g., acroporids) apparently suffering nearly complete mortality. The unequal mortality among families resulted in significant change in community composition following the bleaching. Significant factors in the likelihood of coral bleaching during this event were depth of the reef and distance of the reef from shore. Shallow reefs and inshore reefs had a higher prevalence of bleaching. This bleaching event shows that Red Sea reefs are subject to the same increasing pressures that reefs face worldwide. This study provides a quantitative, genus-level assessment of the vulnerability of various coral groups from within the Red Sea to bleaching and estimates subsequent mortality. As such, it can provide valuable insights into the future for reef communities in the Red Sea. © 2013 Springer-Verlag Berlin Heidelberg.

  10. Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

    Science.gov (United States)

    Chou, Loke Ming; Toh, Tai Chong; Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

    2016-01-01

    Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change. PMID:27438593

  11. Susceptibility of central Red Sea corals during a major bleaching event

    Science.gov (United States)

    Furby, K. A.; Bouwmeester, J.; Berumen, M. L.

    2013-06-01

    A major coral bleaching event occurred in the central Red Sea near Thuwal, Saudi Arabia, in the summer of 2010, when the region experienced up to 10-11 degree heating weeks. We documented the susceptibility of various coral taxa to bleaching at eight reefs during the peak of this thermal stress. Oculinids and agaricids were most susceptible to bleaching, with up to 100 and 80 % of colonies of these families, respectively, bleaching at some reefs. In contrast, some families, such as mussids, pocilloporids, and pectinids showed low levels of bleaching (bleaching. Significant factors in the likelihood of coral bleaching during this event were depth of the reef and distance of the reef from shore. Shallow reefs and inshore reefs had a higher prevalence of bleaching. This bleaching event shows that Red Sea reefs are subject to the same increasing pressures that reefs face worldwide. This study provides a quantitative, genus-level assessment of the vulnerability of various coral groups from within the Red Sea to bleaching and estimates subsequent mortality. As such, it can provide valuable insights into the future for reef communities in the Red Sea.

  12. Bacteria are not the primary cause of bleaching in the Mediterranean coral Oculina patagonica.

    Science.gov (United States)

    Ainsworth, T D; Fine, M; Roff, G; Hoegh-Guldberg, O

    2008-01-01

    Coral bleaching occurs when the endosymbiosis between corals and their symbionts disintegrates during stress. Mass coral bleaching events have increased over the past 20 years and are directly correlated with periods of warm sea temperatures. However, some hypotheses have suggested that reef-building corals bleach due to infection by bacterial pathogens. The 'Bacterial Bleaching' hypothesis is based on laboratory studies of the Mediterranean invading coral, Oculina patagonica, and has further generated conclusions such as the coral probiotic hypothesis and coral hologenome theory of evolution. We aimed to investigate the natural microbial ecology of O. patagonica during the annual bleaching using fluorescence in situ hybridization to map bacterial populations within the coral tissue layers, and found that the coral bleaches on the temperate rocky reefs of the Israeli coastline without the presence of Vibrio shiloi or bacterial penetration of its tissue layers. Bacterial communities were found associated with the endolithic layer of bleached coral regions, and a community dominance shift from an apparent cyanobacterial-dominated endolithic layer to an algal-dominated layer was found in bleached coral samples. While bacterial communities certainly play important roles in coral stasis and health, we suggest environmental stressors, such as those documented with reef-building corals, are the primary triggers leading to bleaching of O. patagonica and suggest that bacterial involvement in patterns of bleaching is that of opportunistic colonization. PMID:18059488

  13. Models for optical bleaching of thermoluminescence in sediments

    International Nuclear Information System (INIS)

    In this paper, we examine several models for the description of TL, focusing most attention on the properties of optical bleaching, in an effort to determine if realistic models can be devised which accurately describe the observed behavior. The models considered include multiple trapping and recombination levels, radiative and non-radiative processes, trap interaction effects, retrapping of released charge, and include transitions into and out of the recombination centers as well as the traps. All such phenomena are likely to occur in real materials and should be included in any model which purports to describe such materials. This paper concludes that models which account for the recombination of freed electrons with trapped holes during the bleaching period appear to be the most successful at describing the observed phenomena. (author)

  14. Optical bleaching, TSL and OSL features of CVD diamond

    International Nuclear Information System (INIS)

    Luminescence and optical features of chemical vapour deposition (CVD) diamond have been studied in view of the potential application of this material in ionising radiation dosimetry field. For this purpose, thermally stimulated luminescence (TSL) and optically stimulated luminescence (OSL) techniques have been used. A large amount of work has emphasised the excellent dosimetric properties of CVD diamond. Nevertheless, TSL measurements showed that after irradiation, this material is extremely sensitive to ambient light and the stored dose information is drastically affected by optical bleaching. From OSL analysis, it follows that both types of processes (TSL and OSL) were characterised by the same excitation and emission spectra and that optical bleaching originated from a broad stimulation band lying from visible to near infrared with a continuous character. (authors)

  15. Estimation of Acacia melanoxylon unbleached Kraft pulp brightness by NIR spectroscopy

    Directory of Open Access Journals (Sweden)

    António J. A. Santos

    2015-08-01

    Full Text Available Aim of the study: The ability of NIR spectroscopy for predicting the ISO brightness was studied on unbleached Kraft pulps of Acacia melanoxylon R. Br. Area of study: Sites covering littoral north, mid interior north and centre interior of Portugal. Materials and methods: The samples were Kraft pulped in standard identical conditions targeted to a kappa number of 15. A Near Infrared (NIR partial least squares regression (PLSR model was developed for the ISO brightness prediction using 75 pulp samples with a variation range of 18.9 to 47.9 %. Main results: Very good correlations between NIR spectra and ISO brightness were obtained. Ten methods were used for PLS analysis (cross validation with 48 samples, and a test set validation was made with 27 samples. The 1stDer pre-processed spectra coupling two wavenumber ranges from 9404 to 7498 cm-1 and 4605 to 4243 cm-1 allowed the best model with a root mean square error of ISO brightness prediction of 0.5 % (RMSEP, a r2 of 99.5 % with a RPD of 14.7. Research highlights: According to AACC Method 39-00, the present model is sufficiently accurate to be used for process control (RPD ≥ 8

  16. Growth of Pinus radiada in soil containing solid waste from the kraft pulp industry

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, M.; Vicuna, R.; Gonzalez, B.; Bronfman, M. [Pontificia Universidad Catolica de Chile, Facultad de Ciencias Biologicas, Santiago (Chile); Osses, M. [Celulosa Arauco y Constitucion, Arauco (Chile); Toro, J.; Balocchi, C.; Rodriguez, E. [Bioforest, S.A, Concepcion (Chile)

    2000-06-01

    The germination and growth of Pinus radials Don. plantlets in solid residues deriving from a Kraft pulp industry was evaluated. Plant conditions were monitored by histological studies of roots and shoot-tips, as well as by plant analyses of several essential and non essential elements. The solids employed consisted of ashes, fly-ashes, dregs, grits, primary sludge, brown stock screening rejects and various mixtures of them. Their addition, in a range of combinations to sandy/metamorphic or marine terrace/clay soils, resulted in effective and sustained growth under greenhouse conditions. Low proportions of wastes favored growth in most cases, indicating that they may act as fertilisers. In some experiments, especially in those where waste was added in proportions ranging from 50% to 60%, germination and/or development were slightly affected. Two-year old field experiments have confirmed that in spite of the high pH values, Na ion content or elevated water retention capacity exhibited by some of the solids tested, their use is beneficial for the growth of radiate pine. To date, we have not observed negative effects other than growth inhibition when some solids are present at concentrations above 60%. Our preliminary results suggest that an adequate use as fertiliser of solid waste from the Kraft pulp industry may constitute a profitable alternative in its management. (orig.)

  17. Antioxidant Activity of Lignin Phenolic Compounds Extracted from Kraft and Sulphite Black Liquors

    Directory of Open Access Journals (Sweden)

    Ana Paula Duarte

    2010-12-01

    Full Text Available The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in terms of gallic acid equivalents (Folin-Ciocalteu colorimetric method, and the antioxidant activity in the crude extracts at several pH values and in the separated fractions was measured using the DPPH test for radical scavenging capacity. The total phenolic content of crude extracts and separated fractions ranged from 92.7 to 181.6 and from 91.6 to 1,099.6 mg GAE/g, respectively, while the antioxidant activity index (AAI ranged from 2.20 to 3.41 and from 2.21 to 11.47 respectively, showing very strong antioxidant activity in all studied cases. The fractions separated by column chromatography were submitted to mass spectrometry analysis and the results were compared to others in the literature of natural products, mainly from Eucalyptus, and the characteristic bands of functional groups were identified by 1H-NMR and FTIR. These methods allowed the identification of 17 phenolic compounds.

  18. INTEGRATION OF KRAFT PULPING ON A FOREST BIOREFINERY BY THE ADDITION OF A STEAM EXPLOSION PRETREATMENT

    Directory of Open Access Journals (Sweden)

    Raquel Martin-Sampedro

    2011-02-01

    Full Text Available Steam explosion has been proposed for a wide range of lignocellulosic applications, including fractionation of biomass, pre-treatment of biomass for ethanol production, or as an alternative to conventional mechanical pulping. Nevertheless, a steam explosion process could also be used as pretreatment before chemical pulping, expecting a reduction in cooking time due to the open structure of the exploded chips. Thus, to evaluate the effect of steam explosion as a pretreatment in the kraft pulping of Eucalyptus globulus, steam exploded chips and control chips were subjected to kraft cookings. Steam exploded chips provided pulps with reductions of kappa number by up to 70% with no significant change in viscosity. Therefore, the cooking time could be shortened by 60%, increasing the productivity and obtaining pulps with similar delignification degree to those of the control pulp. Furthermore, not only the production rate could be increased, but also most of the hemicelluloses could be recovered before pulping and converted to a value-added product. Finally, although exploded pulp had inferior mechanical strength, the optical properties, which are more important in eucalyptus pulps, were found to be better.

  19. Is climate change triggering coral bleaching in tropical reef?

    Digital Repository Service at National Institute of Oceanography (India)

    Kalyan, De; Sautya, S.; Mote, S.; Tsering, L.; Patil, V.; Nagesh, R.; Ingole, B.S.

    & Marine Chemicals Research Institute, Mandpam Camp 623 519, India e-mail: vaibhav@csmcri.org Is climate change triggering coral bleaching in tropical reef? Elevated sea-surface temperatures (SST) caused by global warming is having seri- ous... and to also undertake complete digitiza- tion of its collection for database and Figure 1. View of compactors housing herbarium sheets. linking it to leading global biodiversity databases. We are in process of obtaining recognition from National...

  20. Bleached smear microscopy provides higher yield in diagnosing pulmonary tuberculosis

    OpenAIRE

    Jithendra Kandati; Suresh Kumar Boorsu; Ramamohan Pathalapati; Madhavulu Buchineni

    2016-01-01

    Background: Tuberculosis (TB) remains one of the major deadliest communicable diseases throughout the world. Worldwide, 9.6 million people are estimated to have fallen ill with TB in 2014, India accounts for 23% of total global cases. The study evaluated the performance of direct sputum smear versus bleach concentration smear in diagnosis of pulmonary tuberculosis. Methods: Patients more than 10 years of age who presented with history of cough for >2 weeks duration were included. One spot ...

  1. Comparison of pulping and bleaching behaviors of some agricultural residues

    OpenAIRE

    ATEŞ, Saim; DENİZ, İlhan; KIRCI, Hüseyin; ATİK, Celil; OKAN, Onur Tolga

    2015-01-01

    The present study determines the characteristics of bleaching and beating of annual plants and agricultural waste, which constitute important raw material potential for the pulp and paper industry in Turkey. It also examines the effects of this process on several paper properties. Firstly, chemical contents are determined for each raw material and then evaluated for use in the pulp and paper industry. All raw materials studied are found to be suitable for use in the pulp and paper industry, a...

  2. A Preliminary Assessment of Coral Bleaching in Mozambique

    OpenAIRE

    SCHLEYER, M.; Obura, D.; Rodrigues, M.J.

    1999-01-01

    The 1997-1998 El Nino southern oscillation (ENSO) caused elevated sea temperatures that resulted in global coral bleaching. Coral reefs constitute an important biological resource in terms of their complex biodiversity and are the basis for tropical reef fisheries and marine ecotourism. They represent one of Mozambique's main coastal assets and its coastal communities and growing tourism industry rely mainly on reef-based resources. Mozambican artisanal fisheries are largely centred on reefs ...

  3. Sunscreens Cause Coral Bleaching by Promoting Viral Infections

    OpenAIRE

    Danovaro, Roberto; Bongiorni, Lucia; Corinaldesi, Cinzia; Giovannelli, Donato; Damiani, Elisabetta; Astolfi, Paola; Greci, Lucedio; Pusceddu, Antonio

    2008-01-01

    Background Coral bleaching (i.e., the release of coral symbiotic zooxanthellae) has negative impacts on biodiversity and functioning of reef ecosystems and their production of goods and services. This increasing world-wide phenomenon is associated with temperature anomalies, high irradiance, pollution, and bacterial diseases. Recently, it has been demonstrated that personal care products, including sunscreens, have an impact on aquatic organisms similar to that of other contaminants. Objectiv...

  4. Habitat and Bleaching in the Foraminiferan Peneroplis Pertusus

    OpenAIRE

    Ellison, Aimee

    2006-01-01

    The effects of human activities on the earth’s environment have gained increasing attention in recent years. With coral reefs declining worldwide, efficient tools for assessing reef health are more important than ever. The species of larger foraminifera known as Peneroplis pertusus share key characteristics with reef building corals. By examining the populations’ natural distribution along with the abiotic factors affecting bleaching, a better understanding of reef systems as a whole is a...

  5. Through bleaching and tsunami : coral reef recovery in the Maldives

    OpenAIRE

    Morri, C.; M. MONTEFALCONE; Lasagna, R.; Gatti, G.; A. Rovere; Parravicini, Valeriano; Baldelli, G.; Colantoni, P.; C.N. BIANCHI

    2015-01-01

    Coral reefs are degrading worldwide, but little information exists on their previous conditions for most regions of the world. Since 1989, we have been studying the Maldives, collecting data before, during and after the bleaching and mass mortality event of 1998. As early as 1999, many newly settled colonies were recorded. Recruits shifted from a dominance of massive and encrusting corals in the early stages of recolonisation towards a dominance of Acropora and Pocillopora by 2009. Coral cove...

  6. Poling-assisted bleaching of metal-doped nanocomposite glass

    OpenAIRE

    Deparis, O.; Kazansky, P. G.; Abdolvand, A.; Podlipensky, A.; Seifert, G.; Graener, H

    2004-01-01

    Thermal poling of soda-lime glass which was doped with spherical or ellipsoidal silver nanoparticles has revealed what we believe to be a phenomenon of general interest in the physics of nanocomposite materials: The field-assisted dissolution of metal nanoparticles embedded in glass. Macroscopically, this phenomenon manifested itself as poling-assisted bleaching of the glass in the sense that the glass became more (or even completely) transparent under the anode. The phenomenon is physically ...

  7. ALKALINE PEROXIDE BLEACHING OF HOT WATER TREATED WHEAT STRAW

    Directory of Open Access Journals (Sweden)

    Suvi Mustajoki

    2010-05-01

    Full Text Available The aim of this study was to evaluate the possibilities for chemical consumption reduction in P-P-Paa-P bleaching (P alkaline peroxide stage, Paa peracetic stage of hot water treated straw and the effect of the wheat straw variability on the process. Papermaking fibre production from wheat straw using such a process could be implemented on a small scale if chemical consumption was low enough to eliminate the need for chemical recovery. The pulp properties obtained with this process are equal to or even superior to the properties of wheat straw soda pulp. The possibility of enhancing the first peroxide stage with oxygen and pressure was studied. The possibility for substitution of sodium hydroxide partially with sodium carbonate was also investigated. The objective was to achieve International Standardization Organization (ISO brightness of 75%, with minimal sodium hydroxide consumption, whilst maintaining the pulp properties. The optimization of the peroxide bleaching is challenging if the final brightness target cannot be reduced. Results indicate that up to 25% of the sodium hydroxide could be substituted with sodium carbonate without losing brightness or affecting pulp properties. Another possibility is a mild alkali treatment between the hot water treatment and the bleaching sequence.

  8. Optical bleaching of bismuth implanted silica glass: A threshold effect

    International Nuclear Information System (INIS)

    The near surface regions of high purity silica glass discs, Spectrosil A, were modified by implantation with bismuth ions at 160 keV and room temperature. The glasses implanted with a nominal dose of 6 x 1016 Bi/cm2 at ∼5 μA/cm2 were subsequently bleached with a 5.0 eV KrF pulsed excimer laser. The laser had an average pulse duration of ∼20 ns and repetition rate of 10 Hz, It was found that the bleaching was dependent upon the power density of the laser for a constant total integrated energy. Ion backscattering and optical absorption measurements were made before and after laser irradiation. Large changes in optical density and depth distribution of the implanted ions were observed at power densities of ≥45 mJ/cm2-pulse. On the basis of the experimental results, the onset of the threshold for bleaching of silica glass implanted with 6 x 1016 Bi/cm2 at 160 keV and at room temperature is between 30 and 45 mJ/cm2-pulse

  9. Assessment of the process of cottonseed oil bleaching in hexane

    Directory of Open Access Journals (Sweden)

    Megahed, Ola A.

    2002-12-01

    Full Text Available This work has been initiated to assess the feasibility of bleaching cottonseed oil in miscella as a processing step next to alkali refining in miscella. Alkali refining of cottonseed oil in miscella has several advantages over conventional refining technologies with respect to oil quality, oil losses and process cost. Therefore, the process efficiency of the bleaching of cottonseed oil in presence of hexane (at a volumetric ratio of 1:1, has been studied and compared to that without solvent. The process efficiency has been evaluated according to the decolourization capacity, the oil losses on spent earth, the filtration rate of the oil from the clay and the acidity of the bleached oil as well as its peroxide content. The bleaching in presence of hexane was carried out at 25ºC whereas that by conventional bleaching at 110ºC. Different clay loads were used in each of the two bleaching techniques and the colour indices of the oils before and after bleaching determined in each case. The results were used to predict Freundlich adsorption equations for the oil pigments in both cases. These equations were then used to predict the colour of the oils obtained by bleaching of refined oils of different grades. The results have shown that oil decolourization is more efficient in presence of solvent when the starting oil is of an acceptable grade and the reverse is true for low grade oils. Also, the possibility of oil oxidation during bleaching is less in presence of solvent. Moreover, the bleaching in miscella has proved two other additional advantages over conventional bleaching. The filtration of oil from clay is much faster in miscella bleaching and the oil losses on spent earth is lower. This will be reflected on the overall process economy.Este trabajo ha sido iniciado para evaluar la viabilidad de la decoloración del aceite de semilla de algodón en miscela como un paso de procesado próximo a la refinación alcalina en miscela. La refinaci

  10. Fracture resistance of bleached teeth restored with different procedures

    Directory of Open Access Journals (Sweden)

    Matheus Coelho Bandéca

    2012-08-01

    Full Text Available This study evaluated the fracture resistance of teeth submitted to internal bleaching and restored with different non-metallic post. Eighty mandibular incisors were endodontically treated and randomly divided in 10 groups (n = 8: G1- restored with composite resin (CR, G2- CR + fiber-reinforced composite post (FRC, Everstick post, Sticktech cemented with resin cement self-etch adhesive (RCS, Panavia F 2.0, Kuraray, G3- CR + FRC + self-adhesive resin cement (SRC, Breeze, Pentral Clinical, G4- CR+ glass fiber post (GF, Exacto Post, Angelus + RCS, G5- CR + GF + SRC. The G6 to G10 were bleached with hydrogen peroxide (HP and restored with the same restorative procedures used for G1 to G5, respectively. After 7 days storage in artificial saliva, the specimens were submitted to the compressive strength test (N at 0.5 mm/min cross-head speed and the failure pattern was identified as either reparable (failure showed until 2 mm below the cement-enamel junction or irreparable (the failure showed <2 mm or more below the cement-enamel. Data were analyzed by ANOVA and Tukey test (α = 0.05. No significant difference (p < 0.05 was found among G1 to G10. The results suggest that intracoronal bleaching did not significantly weaken the teeth and the failure patterns were predominately reparable for all groups. The non-metallic posts in these teeth did not improve fracture resistance.

  11. Optical bleaching of bismuth implanted silica glass: A threshold effect

    International Nuclear Information System (INIS)

    The near surface regions of high purity silica glass discs, Spectrosil A, were modified by implantation with bismuth ions at 160 key and room temperature. The glasses implanted with a nominal dose of 6x1016 Bi/cm2 at ∼5 μA/cm2 were subsequently bleached with a 5.0 eV KrF pulsed excimer laser. The laser had an average pulse duration of ∼20 ns and repetition rate of 10 Hz. It was found that the bleaching was dependent upon the power density of the laser for a constant total integrated energy. Ion backscattering and optical absorption measurements were made before and after laser irradiation. Large changes in optical density and depth distribution of the implanted ions were observed at power densities of ≥45 mJ/cm2-pulse. Onset of threshold for bleaching of silica glass implanted with 6x1016 Bi/cm2 at 160 key and at room temperature is between 30 and 45 mJ/cm2-pulse

  12. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    Energy Technology Data Exchange (ETDEWEB)

    Added, N. [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil)]. E-mail: nemitala@dfn.if.usp.br; Rizzutto, M.A. [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil); Curado, J.F. [GFAA, Depto de Fisica Nuclear, IFUSP, University of Sao Paulo, Travessa R da rua do Matao 187, Cidade Universitaria, Caixa Postal 66318, CEP 05508-970 Sao Paulo, SP (Brazil); Francci, C. [School of Dentistry, University of Sao Paulo (Brazil); Markarian, R. [School of Dentistry, University of Sao Paulo (Brazil); Mori, M. [School of Dentistry, University of Sao Paulo (Brazil)

    2006-08-15

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a {sup 35}Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy.

  13. RESPONSE SURFACE METHODOLOGY APPROACH FOR OPTIMIZATION OF FLAX SEED OIL BLEACHING PROCESS

    Directory of Open Access Journals (Sweden)

    Miroslav Ondrejovič

    2013-10-01

    Full Text Available Flax seed is an important source of omega-3 polyunsaturated fatty acids essential for human physiology. For low oxidation stability, specific taste and concomitant color compounds this oil is poorly applicable as nutraceutical additive. The aim of this study was optimization of flax seed oil bleaching. The optimal conditions for the bleaching process were determined using response surface methodology. A central composite design was used to investigate the effects of three independent variables, namely solid to liquid ratio, temperature and time, to output parameters of the bleaching process such as crude oil color expressed as optical density at 490 nm, acid and peroxide value. Calculated optimal conditions for the bleaching, expressed by the optical density of the oil were as follows: temperature 50°C, bleaching time 77 minutes and solid-liquid ratio 56 g of bleaching agent to 1 liter of oil.

  14. Comparative study of the effects of two bleaching agents on oral microbiota.

    Science.gov (United States)

    Alkmin, Yara Tardelli; Sartorelli, Renata; Flório, Flávia Martão; Basting, Roberta Tarkany

    2005-01-01

    This study evaluated the in vivo effects of bleaching agents containing 10% carbamide peroxide (Platinum/Colgate) or 7.5% hydrogen peroxide (Day White 2Z/Discus Dental) on mutans Streptococcus during dental bleaching. The products were applied on 30 volunteers who needed dental bleaching. In each volunteer, one of the two bleaching agents was used on both dental arches one hour a day for three weeks. Analysis of the bacterial counts was made by collecting saliva before (baseline values), during (7 and 21 days) bleaching treatments and 14 days posttreatment. The Friedman non-parametric analysis (alpha=0.05) found no differences in microorganism counts at different times for each group for both agents (p>0.05). The Mann Whitney nonparametric test (alpha=0.05) showed no differences in micro-organism counts for both agents (p>0.05). Different bleaching agents did not change the oral cavity mutans Streptococcus counts. PMID:16130860

  15. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    International Nuclear Information System (INIS)

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a 35Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy

  16. Etiology and prevention of external cervical root resorption associated to teeth bleaching

    Directory of Open Access Journals (Sweden)

    Eliane Mendes da SILVA

    2010-03-01

    Full Text Available Introduction and objective: Esthetic dentistry has been prioritizedand the desire for whiter teeth has been increasingly present in dental offices, since whiter teeth tend to indicate health, beauty, youth and a more attractive smile. Teeth bleaching is a conservative method widely used to restore the original color of darkened teeth. However, possible relations with the external cervical root resorption have concerned many researchers and clinicians. Literature review: There are many mechanisms that can activate the external cervical root resorption, such as: chemical and physical action of the bleaching materials used, morphology of the cementoenamel junction associated to the immune system, material concentration, traumas and bleaching technique used. Conclusion: Therefore, considering many factors that are still not conclusive, preventing deleterious effects on teeth and support structures, care must be taken when choosing bleaching agent and bleaching technique, as well as when selecting each case, beyond a proper restoration after teeth bleaching.

  17. Study of the hydrogen peroxide bleaching agent effects on bovine enamel using X-ray fluorescence

    International Nuclear Information System (INIS)

    Hydrogen Peroxide's a bleaching agent capable of oxidizing a wide range of colored organic, causing discoloration and hence bleaching of the substrate, but some authors related the occurrence of side effects related to bleaching of the tooth structure, such as changes in morphology superficial. It was used 6 bovine incisors, each tooth was initially evaluated six times in different areas to obtain the count of elements phosphorus and calcium using X-Ray Fluorescence. The teeth were randomly divided in two groups: both groups were submitted to bleaching in office with hydrogen peroxide 38%, once a week during three weeks. Group 1 was stored in distilled water and group 2 in artificial saliva, between the sessions. The measurements were repeated every seven days before the bleaching treatment. Besides that, changes in mineral levels were always assessed in the same area and using the same procedure. It was observed that the bleaching was not able to demineralize the tooth enamel studied. (author)

  18. Holographic gratings with different spatial frequencies recorded on BB-640 bleached silver halide emulsions using reversal bleaches

    OpenAIRE

    Álvarez López, Mariela Lázara; Camacho, Norma; Neipp López, Cristian; Márquez Ruiz, Andrés; Beléndez Vázquez, Augusto; Pascual Villalobos, Inmaculada

    2003-01-01

    The research made in the field of recording materials for holographic applications has yielded to materials of improving quality. Photographic emulsions have played an important role in this investigation, since although this is the first material used for recording purposes, there are a series of characteristics that convert the photographic emulsion in a very interesting material for holographic recording. In this work we will present the optimisation of a reversal bleaching process. This p...

  19. Uranium-mill appraisal program

    International Nuclear Information System (INIS)

    The results of special team appraisals at NRC-licensed uranium mills in the period May to November 1981 are reported. Since the Three Mile Island accident, NRC management has instituted a program of special team appraisals of radiation protection programs at certain NRC-licensed facilities. These appraisals were designed to identify weaknesses and strengths in NRC-licensed programs, including those areas not covered by explicit regulatory requirements. The regulatory requirements related to occupational radiation protection and environmental monitoring at uranium mills have been extensively upgraded in the past few years. In addition, there was some NRC staff concern with respect to the effectiveness of NRC licensing and inspection programs. In response to this concern and to changes in mill requirements, the NRC staff recommended that team appraisals be conducted at mills to determine the adequacy of mill programs, the effectiveness of the new requirements, and mill management implementation of programs and requirements. This report describes the appraisal scope and methodology as well as summary findings and conclusions. Significant weaknesses identified during the mill appraisals are discussed as well as recommendations for improvements in uranium mill programs and mill licensing and inspection

  20. Yang-Mills and Beyond

    CERN Document Server

    Marateck, Samuel

    2011-01-01

    In their 1954 paper, Yang and Mills invented the non-Abelian field strength to satisfy certain criteria but didn't explain how it could be derived. In the penultimate section we show how the Yang-Mills field strength derives from Yang's gauge transformation. The preceding sections place Yang-Mills theory in historical perspective and cover material relating to the field strength. The final section shows how Yang-Mills theory was combined with spontaneous symmetry breaking, the Goldstone theorem and subsequent work to contribute to the Standard Model of particle physics.

  1. Evaluation of peanut hulls as an alternative to bleaching clays

    Directory of Open Access Journals (Sweden)

    Hassanein, M. M. M.

    2011-09-01

    Full Text Available Peanut hulls (PNH were carbonized at different temperatures, times, and evaluated at different concentrations as an alternative to bleaching clays. Evaluation of bleached crude soybean oil with PNH was based on their delta free fatty acids, reduction in peroxide value (PV, reduction in phospholipids (PL and bleachability. The performance of several commercially used bleaching clays was evaluated, for comparison. Mixtures were formulated including: PNH and Tonsil -N (TN, PNH and Fuller’s earth (FE and PNH and O-passive (OP and examined. The oxidative stability of oils was determined. Results for the investigated commercial bleaching clays revealed: TN > FE > F > TF > OP. Highest reduction in PV and PL, and highest bleachability were achieved for soybean oil bleached with 2% PNH carbonized at 500°C for 30 min (PNH”. Mixtures of PNH” with the three chosen bleaching clays indicated that 1PNH”: 2TN gave the highest bleachability. CSO was miscella bleached in hexane using PNH” and resulted in an appreciable improvement in all oil characteristics, especially in bleachability. Oxidative stability of oils was in the following order: TN > control > FE > PNH” with Induction period values of 23,1 > 6,43 > 5,73 > 2,85 h, respectively.

    Las cáscaras de maní (PNH fueron carbonizadas a diferentes temperaturas y tiempos, y utilizadas a diferentes concentraciones como una alternativa a las tierras decolorantes. La evaluación de un aceite de soja decolorado con PNH se ha basado en sus ácidos grasos libres, reducción del índice de peróxidos (PV, reducción de los fosfolípidos (PL, y en la blanqueabilidad. El rendimiento de varias tierras decolorantes de uso comercial fue evaluado y comparado con el de PNH carbonizada. Las mezclas formuladas incluían: PNH y Tonsil-N (TN, PNH y tierras de Fuller (FE y PNH y O-pasivo (OP. La estabilidad oxidativa de los aceites resultantes fue determinada. Los resultados revelaron que la efectividad de la

  2. Corrosion Study of Stainless Steels in Peracetic Acid Bleach Media With and Without Chloride and Chelant

    OpenAIRE

    Rohtash; Ajay K Singh; Rajendra Kumar

    2014-01-01

    The paper industries are adopting non-chlorine containing chemicals e.g. peroxide, ozone, peracids etc. as alternate of chlorine based bleach chemicals e.g. chlorine and chlorine dioxide etc. with the aim of eco-friend atmospheres. Changeover to the new chemicals in the bleaching process is likely to affect the metallurgy of the existing bleach plants due to change in the corrosivity of the media. Accordingly, corrosion investigations were performed in a peracid namely peracetic a...

  3. Vital Bleaching of Tetracycline-Stained Teeth by Using KTP Laser: A Case Report

    OpenAIRE

    Kinoshita, Jun-Ichiro; Jafarzadeh, Hamid; Forghani, Maryam

    2009-01-01

    Bleaching of discolored teeth is one of the most important topics in aesthetic dentistry. A great challenge in this area is obtaining good results in tetracycline-stained teeth. The wavelength and features of KTP laser, which is a type of Nd:YAG laser, seem to be appropriate for bleaching of these teeth. This case report underlines the importance of knowledge about the photochemical bleaching by using the KTP laser and its side effects on soft tissues.

  4. THE EFFECTS OF HOME BLEACHING ON THE HARDNESS OF AMALGAM FILLING

    OpenAIRE

    Andi Soufyan; Niti Matram

    2015-01-01

    Dental bleaching has been considered as a feasible approach for dental esthetic, and many dental bleaching products can be seen in the market. Therefore, the side effect of such dental product should be studied. This study was aimed to determine the effect of carbamide peroxide-containing home bleaching agent on the hardness of dental amalgam surface structure. Forty amalgam filling specimens were divided into 4 groups, which consist of 3 treatment groups and 1 controu group. Each group was e...

  5. The effect of different drinks on tooth color after home bleaching

    OpenAIRE

    Karadas, Muhammet; Seven, Nilgun

    2014-01-01

    Objective: This study evaluated the influence of coffee, tea, cola, and red wine staining on the color of teeth after home bleaching. Materials and Methods: A total of 45 samples were obtained from 45 sound maxillary central incisors. The home bleaching procedure was performed using 10% carbamide peroxide gel applied to the sample surface for a period of 6 h each day, for 14 days. After bleaching, baseline color measurements were taken, and the samples were immersed in four staining solutions...

  6. Optical bleaching of BaFCl crystals X-irradiated at room temperature

    International Nuclear Information System (INIS)

    The optical bleaching behaviour of the optical absorption bands produced by X-irradiation is investigated by paying particular attention to the difference between the two types of F centers in the BaFCl crystals. The optical bleachings are performed using a Xe-lamp. The optical absorption spectra and changes in the absorption bands during bleaching with F(Cl-) and F(F-) light are given and discussed

  7. Status of the Coral Reefs of Maldives after the Bleaching Event in 1998

    OpenAIRE

    Zahir, H.

    2000-01-01

    A pilot reef monitoring study was conducted in 1998 to assess the extent of coral bleaching in the Maldives. The aims of this monitoring exercise were: 1. To quantitatively document the post-bleaching status of the shallow-water coral communities on the reefs of the north, central and southern regions of Maldives. 2. To estimate bleaching-induced coral mortality by comparing data yielded by the pilot survey with data from previous surveys, especially those sites for which historical dat...

  8. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    Science.gov (United States)

    Groppo, D. P.; Caldas, L. V. E.

    2016-07-01

    The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source (90Sr+90Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed.

  9. Evaluation of bleach-sedimentation for sterilising and concentrating Mycobacterium tuberculosis in sputum specimens

    Directory of Open Access Journals (Sweden)

    Valencia Teresa

    2011-10-01

    Full Text Available Abstract Background Bleach-sedimentation may improve microscopy for diagnosing tuberculosis by sterilising sputum and concentrating Mycobacterium tuberculosis. We studied gravity bleach-sedimentation effects on safety, sensitivity, speed and reliability of smear-microscopy. Methods This blinded, controlled study used sputum specimens (n = 72 from tuberculosis patients. Bleach concentrations and exposure times required to sterilise sputum (n = 31 were determined. In the light of these results, the performance of 5 gravity bleach-sedimentation techniques that sterilise sputum specimens (n = 16 were compared. The best-performing of these bleach-sedimentation techniques involved adding 1 volume of 5% bleach to 1 volume of sputum, shaking for 10-minutes, diluting in 8 volumes distilled water and sedimenting overnight before microscopy. This technique was further evaluated by comparing numbers of visible acid-fast bacilli, slide-reading speed and reliability for triplicate smears before versus after bleach-sedimentation of sputum specimens (n = 25. Triplicate smears were made to increase precision and were stained using the Ziehl-Neelsen method. Results M. tuberculosis in sputum was successfully sterilised by adding equal volumes of 15% bleach for 1-minute, 6% for 5-minutes or 3% for 20-minutes. Bleach-sedimentation significantly decreased the number of acid-fast bacilli visualised compared with conventional smears (geometric mean of acid-fast bacilli per 100 microscopy fields 166, 95%CI 68-406, versus 346, 95%CI 139-862, respectively; p = 0.02. Bleach-sedimentation diluted paucibacillary specimens less than specimens with higher concentrations of visible acid-fast bacilli (p = 0.02. Smears made from bleach-sedimented sputum were read more rapidly than conventional smears (9.6 versus 11.2 minutes, respectively, p = 0.03. Counting conventional acid-fast bacilli had high reliability (inter-observer agreement, r = 0.991 that was significantly reduced (p

  10. Influence of fluoride-containing adhesives and bleaching agents on enamel bond strength

    Directory of Open Access Journals (Sweden)

    Vanessa Cavalli

    2012-12-01

    Full Text Available This study evaluated the influence of fluoride-containing carbamide peroxide (CP bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL and Optibond Solo Plus (SP, respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10 with 10% CP (CP and 10% CP + fluoride (CPF or were left unbleached (control. Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (∝TBS testing. The enamel ∝TBS of the FL and SP groups (control, not bleached were higher (p FL + CPF = FL + CP and SP > SP + CPF = SP + CP. The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar ∝TBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength.

  11. Influence of fluoride-containing adhesives and bleaching agents on enamel bond strength.

    Science.gov (United States)

    Cavalli, Vanessa; Liporoni, Priscila Cristiane Suzy; Rego, Marcos Augusto do; Berger, Sandrine Bittencourt; Giannini, Marcelo

    2012-01-01

    This study evaluated the influence of fluoride-containing carbamide peroxide (CP) bleaching agents and adhesive systems on bonded enamel interfaces that are part of the dynamic pH cycling and thermal cycling models. The buccal surfaces of 60 bovine incisors were restored with a composite resin and bonded with three- and two-step, etch-and-rinse, fluoride-containing adhesives, Optibond FL (FL) and Optibond Solo Plus (SP), respectively. Restored teeth were subjected to thermal cycling to age the interface. Both SP and FL adhesive-restored teeth were bleached (n = 10) with 10% CP (CP) and 10% CP + fluoride (CPF) or were left unbleached (control). Bleaching was performed for 14 days simultaneously with pH cycling, which comprised of 14 h of remineralization, 2 h of demineralization and 8 h of bleaching. The control groups (FL and SP) were stored in remineralizing solution during their bleaching periods and were also subjected to carious lesion formation. Parallelepiped-shaped samples were obtained from the bonded interface for microtensile bond strength (μTBS) testing. The enamel μTBS of the FL and SP groups (control, not bleached) were higher (p FL > FL + CPF = FL + CP and SP > SP + CPF = SP + CP). The groups subjected to treatment with the fluoride-containing bleaching agents exhibited similar μTBS compared to regular bleaching agents. Bleaching agents, regardless of whether they contained fluoride, decreased enamel bond strength. PMID:23184165

  12. Impacts of the 1998 and 2010 mass coral bleaching events on the Western Gulf of Thailand

    Science.gov (United States)

    Sutthacheep, Makamas; Yucharoen, Mathinee; Klinthong, Wanlaya; Pengsakun, Sittiporn; Sangmanee, Kanwara; Yeemin, Thamasak

    2013-11-01

    A long-term study of coral reef ecology in the Gulf of Thailand provides a good opportunity to examine the temporal variation on the impact of mass coral bleaching at those reef sites. We compared the bleaching and mortality of corals between the mass bleaching events in 1998 and 2010 at a coral community in the Western Gulf of Thailand. The aim was to identify the coral species which were most likely to suffer from (and to be able to tolerate) changes in seawater temperature. Significant differences in the susceptibility of the coral taxa to bleaching events between the years 1998 and 2010 and among coral species were documented. Bleaching was significantly different between the most dominant corals. Diploastrea heliopora was the most resistant coral to bleaching in both years. Some coral species showed more resistance to bleaching in 2010. The coral mortality following the mass bleaching events in 1998 and 2010 varied significantly between the years and the coral taxa. Mortality of some dominant coral taxa was also lower in 2010. Seven coral species, i.e. Astreopora myriophthalma, Pachyseris rugosa, Turbinaria mesenterina, Goniastrea pectinata, Favia pallida, F. maritima, Favites halicora, Platygyra daedalea and Galaxea fascicularis, were tolerant to the coral bleaching events. An ecosystem-based approach to managing coral reefs in the Gulf of Thailand is needed to identify appropriate marine protected area networks and to strengthen marine and coastal resource policies in order to build coral reef resilience.

  13. Annual coral bleaching and the long-term recovery capacity of coral.

    Science.gov (United States)

    Schoepf, Verena; Grottoli, Andréa G; Levas, Stephen J; Aschaffenburg, Matthew D; Baumann, Justin H; Matsui, Yohei; Warner, Mark E

    2015-11-22

    Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. PMID:26582020

  14. Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

    Directory of Open Access Journals (Sweden)

    Rodrigo PIROLO

    2014-12-01

    Full Text Available There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E and lightness (∆L variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05. Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001. All specimens presented a decrease in brightness (negative ∆L. The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively. Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching.

  15. Japan steel mill perspective

    Energy Technology Data Exchange (ETDEWEB)

    Murase, K. [Kobe Steel Ltd., Tokyo (Japan)

    2004-07-01

    The international and Japan's steel industry, the coking coal market, and Japan's expectations from Canada's coal industry are discussed. Japan's steel mills are operating at full capacity. Crude steel production for the first half of 2004 was 55.8 million tons. The steel mills are profitable, but costs are high, and there are difficulties with procuring raw materials. Japan is trying to enhance the quality of coke, in order to achieve higher productivity in the production of pig iron. Economic growth is rising disproportionately in the BRICs (Brazil, Russia, India, and China), with a large increase in coking coal demand from China. On the supply side, there are several projects underway in Australia and Canada to increase production. These include new developments by Elk Valley Coal Corporation, Grande Cache Coal, Western Canadian Coal, and Northern Energy and Mining in Canada. The Elga Mine in the far eastern part of Russia is under development. But the market is expected to remain tight for some time. Japan envisions Canadian coal producers will provide a stable coal supply, expansion of production and infrastructure capabilities, and stabilization of price. 16 slides/overheads are included.

  16. Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf

    OpenAIRE

    Shuail, Dawood; Wiedenmann, Jörg; D'Angelo, Cecilia; Baird, Andrew H.; Pratchett, Morgan S.; Riegl, Bernhard; Burt, John A.; Petrov, Peter; Amos, Carl

    2016-01-01

    A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~ 40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48 °C, 34.55 °C, 35.05 °C)...

  17. Effect of pulping variables on enthalpy of kraft black liquors: Empirical predictive models

    Energy Technology Data Exchange (ETDEWEB)

    Zaman, A.A.; Fricke, A.L. [Univ. of Florida, Gainesville, FL (United States). Dept. of Chemical Engineering

    1996-07-01

    The effects of pulping variables on enthalpy of slash pine kraft black liquors from a 2{sup k} + 2k + 1 (k = 4) central composite design pulping experiments that were performed in a large pilot scale digester have been studied. The four cooling variables were effective alkali, sulfidity, cooking temperature, and time at temperature. In all cases, the white liquor was adjusted to a causticizing efficiency of 85% and a reduction of 93% with Na{sub 2}CO{sub 3} and Na{sub 2}SO{sub 4}. The enthalpy of these liquors was determined over wide ranges of temperature and solids concentrations using a Setaram C-80 calorimeter. In this work, previous models for enthalpy-concentration relations were used to perform a systematic study on the effects of pulping conditions on enthalpy and to develop statistically based quantitative models for enthalpy as a function of pulping variables. These results are presented, and their utility is discussed.

  18. Biobleaching chemistry of laccase-mediator systems on high-lignin-content kraft pulps

    International Nuclear Information System (INIS)

    A high-lignin-content softwood kraft pulp was reacted with laccase in the presence of 1-hydroxybenzotriazole (HBT), N-acetyl-N-phenylhydroxylamine (NHA), and violuric acid (VA). The biodelignification response with violuric acid was superior to both 1-hydroxybenzotriazole and N-acetyl-N-phenylhydroxylamine. NMR analysis of residual lignins isolated before and after the biobleaching treatments revealed that the latter material was highly oxidized and that the magnitude of structural changes was most pronounced with the laccase - violuric acid biobleaching system. An increase in the content of carboxylic acid groups and a decrease in methoxyl groups were noted with all three laccase-mediator systems. The oxidation biobleaching pathway is directed primarily towards noncondensed C5 phenolic lignin functional structures for all three laccase-mediated systems. The laccase - violuric acid system was also reactive towards C5-condensed phenolic lignin structures. (author)

  19. Hydro- and solvothermolysis of kraft lignin for maximizing production of monomeric aromatic chemicals.

    Science.gov (United States)

    Lee, Hong-shik; Jae, Jungho; Ha, Jeong-Myeong; Suh, Dong Jin

    2016-03-01

    The hydro-/solvothermolysis of kraft lignin using water and ethanol as a solvent were investigated in this study. The effect of the water-to-ethanol ratio on the yields of monomeric aromatic chemicals (MACs) and the kinetic behavior of MACs was studied in a series of batch experiments. The yields of MACs other than catechol increased as the ratio of ethanol increased, and the content of the total MACs in bio-crude oil (BCO) reached 35% when the ratio of ethanol was 100% at a reaction temperature of 300 °C. The formation of phenol, guaiacol, and alkylguaiacols was enhanced in ethanol, while the formation of catechol was dominant in water. The formation of more substituted MACs such as vanillin, acetoguaiacone, and homovanillic acid was not affected by the solvent. The role of reaction parameters on the yields of MACs was elucidated, and the main reaction pathways in water and in ethanol were proposed. PMID:26722814

  20. Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment

    Science.gov (United States)

    Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

    2015-12-01

    Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were not

  1. Effects of coral bleaching on the obligate coral-dwelling crab Trapezia cymodoce

    Science.gov (United States)

    Stella, J. S.; Munday, P. L.; Jones, G. P.

    2011-09-01

    Corals are an essential and threatened habitat for a diverse range of reef-associated animals. Episodes of coral bleaching are predicted to increase in frequency and intensity over coming decades, yet the effects of coral-host bleaching on the associated animal communities remain poorly understood. The present study investigated the effects of host-colony bleaching on the obligate coral-dwelling crab, Trapezia cymodoce, during a natural bleaching event in the lagoon of Lizard Island, Australia. Branching corals, which harbour the highest diversity of coral associates, comprised 13% of live coral cover at the study site, with 83% affected by bleaching. Crabs on healthy and bleached colonies of Pocillopora damicornis were monitored over a 5-week period to determine whether coral bleaching affected crab density and movement patterns. All coral colonies initially contained one breeding pair of crabs. There was a significant decline in crab density on bleached corals after 5 weeks, with many corals losing one or both crabs, yet all healthy colonies retained a mating pair. Fecundity of crabs collected from bleached and healthy colonies of P. damicornis was also compared. The size of egg clutches of crabs collected from bleached hosts was 40% smaller than those from healthy hosts, indicating a significant reduction in fecundity. A laboratory experiment on movement patterns found that host-colony bleaching also prompted crabs to emigrate in search of more suitable colonies. Emigrant crabs engaged in aggressive interactions with occupants of healthy hosts, with larger crabs always usurping occupants of a smaller size. Decreased densities and clutch sizes, along with increased competitive interactions, could potentially result in a population decline of these important coral associates with cascading effects on coral health.

  2. Contrasting patterns of coral bleaching susceptibility in 2010 suggest an adaptive response to thermal stress.

    Directory of Open Access Journals (Sweden)

    James R Guest

    Full Text Available BACKGROUND: Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. METHODOLOGY/PRINCIPAL FINDINGS: Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; p<0.001. Bleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. CONCLUSIONS/SIGNIFICANCE: The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments.

  3. Oxidative pyrolysis of kraft lignin in a bubbling fluidized bed reactor with air

    International Nuclear Information System (INIS)

    Fast pyrolysis of kraft lignin with partial (air) oxidation was studied in a bubbling fluidized bed reactor at reaction temperatures of 773 and 823 K. The bio-oil vapors were fractionated using a series of three condensers maintained at desired temperatures, providing a dry bio-oil with less than 1% water and over 96% of the total bio-oil energy. Oxygen feed was varied to study its effect on yield, composition, and energy recovery in the gas, char and oil products. The addition of oxygen to the pyrolysis process increased the production of gases such as CO and CO2. It also changed the dry bio-oil properties, reducing its heating value, increasing its oxygen content, reducing its average molecular weight and tar concentration, while increasing its phenolics concentration. The lower reaction temperature of 773 K was preferred for both dry bio-oil yield and quality. Autothermal operation of the pyrolysis process was achieved with an oxygen feed of 72 or 54 g per kg of biomass at the reaction temperatures of 773 and 823 K, respectively. Autothermal operation reduced both yield and total energy content of the dry bio-oil, with relative reductions of 24 and 20% for the yield, 28 and 23% for the energy content, at 773 and 823 K. - Highlights: • Autothermal pyrolysis of Kraft lignin is possible with introduction of air. • Under autothermal conditions, 24% of the dry bio-oil chemicals are lost at 773 K. • Partial oxidation helps produce more simple phenols and less pyrolytic lignin. • Bio-oil from lignin pyrolysis has a very high phenolics concentration

  4. Micro power/heat cogeneration incorporating a stirling engine; microKraft-Waerme-Kopplung mit Stirlingmotor

    Energy Technology Data Exchange (ETDEWEB)

    Luft, S. [Solo Kleinmotoren GmbH, Sindelfingen (Germany)

    2003-05-01

    The Stirling-engine for CHP-purpose developed by SOLO is a trend-setting technology. It represents the most suspicious perspective apart from the fuel-cell technology in order to become suitable to the requirements of the future power supply in the focus of the sustainability and the decentralized energy supply. The charm of the Stirling technology is based on the external combustion: a so far not known variability with the primary energy choice as well as a life span substantially extending, wear-free operation are possible thereby. The external combustion reduces also the maintenance and the emissions in a measure not known with conventional engine technologies. The development steps are finished. The result is the world-wide first concept for the commercial, stationary application of decentralized micro-CHP on Stirling technology basis, which goes into series. (orig.) [German] Das von SOLO entwickelte STIRLING-Motorenkonzept zur Kraft-Waerme-Kopplung ist eine Technologie, die neben der Brennstoffzellen-Technologie die vielversprechende Perspektive darstellt, um den Anforderungen der zukuenftigen Energieversorgung im Fokus der Nachhaltigkeit und der dezentralen Energiebereitstellung gerecht zu werden. Der Charme der Stirlingtechnologie liegt in der aeusseren Verbrennung. Eine bisher nicht gekannte Variabilitaet bei der Primaerenergiewahl und ein die Lebensdauer erheblich verlaengernder, verschleissfreier Betrieb werden dadurch ermoeglicht. Die externe Verbrennung verringert auch die Wartungsaufwendungen und reduziert die Emissionen in einem bei konventionellen Motorentechnologien nicht gekannten Mass. Die Entwicklungsschritte sind abgeschlossen und das Ergebnis ist das weltweit erste Konzept zur kommerziellen, stationaeren Anwendung dezentraler Kraft-Waerme-Kopplung, auf Stirling-Technologie-Basis, das in Serie geht. (orig.)

  5. Oil and gas activities in northern Norway. Summary; KonKraft rapport 6

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    KonKraft report 6 deals with oil and gas operations on the Norwegian continental shelf (NCS) from Nordland county and northwards. It aims to contribute to a broad factual base for decision processes related to opening new exploration areas in these waters. The Norwegian petroleum sector employs about 250 000 people directly and indirectly. It accounts for a third of government revenues, and 90 per cent of its profits accrue to the state. NOK 119 billion of the central government budget in 2009 comes directly from oil and gas revenues. These funds finance roads, nursery schools, hospitals and the Norwegian welfare state. In addition, they safeguard future pensions. This industry is at a crossroads today. Oil production has dropped by 30 per cent since 2000. Recent forecasts from the Norwegian Petroleum Directorate show that it may be reduced by 50 per cent from its peak by 2013. Overall oil and gas output is expected to begin falling from the middle of the next decade. To slow this decline in output and revenues, the oil companies need access to new and attractive exploration acreage. Half the production expected by the government in 2030 relates to resources which have yet to be proven. Opening further areas of the NCS to petroleum activities would contribute to maintaining substantial investment and revenues for the community, and to continuing the development of industry in the northernmost parts of the country. The report reviews unopened areas along the Norwegian coast from the Helgeland region and north-eastwards to the Russian border. Nordland VI and VII plus Troms II are regarded by the petroleum industry as the most promising regions for big discoveries which could slow the production decline. The KonKraft 2 report concerning production development on the NCS estimates remaining resources in these three areas at 3.4 billion barrels of oil equivalent (boe). (Author)

  6. Tooth bleaching--a critical review of the biological aspects

    DEFF Research Database (Denmark)

    Dahl, J E; Pallesen, Ulla

    2003-01-01

    addressing the risk of other adverse effects are lacking. Direct contact with hydrogen peroxide induced genotoxic effects in bacteria and cultured cells, whereas the effect was reduced or abolished in the presence of metabolizing enzymes. Several tumor-promoting studies, including the hamster cheek pouch......, and in the period of 1-8 years' observation time, from 10 to 40% of the initially successfully treated teeth needed re-treatment. Cervical root resorption is a possible consequence of internal bleaching and is more frequently observed in teeth treated with the thermo-catalytic procedure. When the external tooth...

  7. EFFECT BLEACHING REAGENT ON THE QUALITY OF FLAX CELLULOSE

    OpenAIRE

    Дейкун, Ірина Михайлівна

    2015-01-01

    The paper studies the impact of bleaching chemicals such as chlorine dioxide, hydrogen peroxide and chlorine on the product yield, residual lignin content, a-cellulose, viscosity, ash content and whiteness of flax natron cellulose for chemical processing.It was found that one-step processing of flax pulp with chlorine dioxide consumption rate 0,3…0,5 % and with hydrogen peroxide consumption rate 2…3 % by weight of abs. dry cellulose is more effective than treatment with chlorine water at chlo...

  8. Reducing bleaching effects in organic nanofibers by coating

    DEFF Research Database (Denmark)

    Tavares, Luciana; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter;

    Para-hexaphenylene (p-6P) organic nanofibers emit polarized, blue light upon UV excitation with a peak wavelength of the emitted light of 425 nm [1] and a spatially anisotropic distribution of the emitted light [2]. These features could enable future (opto-)electronic applications [3], since, for...... example, these molecules in the form of a thin film can function as an OLED [4]. However, the nanofibers exhibit a characteristic photoinduced reaction during illumination with UV light that causes a decrease in luminescence intensity (bleaching) and that is partly attributed to photooxidation [1]. Here...

  9. Fabrication of Polymer Nonlinear Directional Coupler by Photo-bleaching

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The preparation of a nonlinear directional coupler in polymer PMMA/DR1 film by photobleaching is studied. We find it easier to obtain a required coupling length by controlling photo-bleaching time than by controlling the dimension of the coupler. The transmittance of each arm is measured when the pulse input light energy changes in our experiment. The experimental results show that the coupling length will change with the intensity of input light due to optical nonlinearities of the polymer PMMA/DR1 at 1064nm.

  10. Mill Integration-Pulping, Stream Reforming and Direct Causticization for Black Liquor Recovery

    Energy Technology Data Exchange (ETDEWEB)

    Adriaan van Heiningen

    2007-06-30

    MTCI/StoneChem developed a steam reforming, fluidized bed gasification technology for biomass. DOE supported the demonstration of this technology for gasification of spent wood pulping liquor (or 'black liquor') at Georgia-Pacific's Big Island, Virginia mill. The present pre-commercial R&D project addressed the opportunities as well as identified negative aspects when the MTCI/StoneChem gasification technology is integrated in a pulp mill production facility. The opportunities arise because black liquor gasification produces sulfur (as H{sub 2}S) and sodium (as Na{sub 2}CO{sub 3}) in separate streams which may be used beneficially for improved pulp yield and properties. The negative aspect of kraft black liquor gasification is that the amount of Na{sub 2}CO{sub 3} which must be converted to NaOH (the so called causticizing requirement) is increased. This arises because sulfur is released as Na{sub 2}S during conventional kraft black liquor recovery, while during gasification the sodium associated Na{sub 2}S is partly or fully converted to Na{sub 2}CO{sub 3}. The causticizing requirement can be eliminated by including a TiO{sub 2} based cyclic process called direct causticization. In this process black liquor is gasified in the presence of (low sodium content) titanates which convert Na{sub 2}CO{sub 3} to (high sodium content) titanates. NaOH is formed when contacting the latter titanates with water, thereby eliminating the causticizing requirement entirely. The leached and low sodium titanates are returned to the gasification process. The project team comprised the University of Maine (UM), North Carolina State University (NCSU) and MTCI/ThermoChem. NCSU and MTCI are subcontractors to UM. The principal organization for the contract is UM. NCSU investigated the techno-economics of using advanced pulping techniques which fully utilize the unique cooking liquors produced by steam reforming of black liquor (Task 1). UM studied the kinetics and

  11. Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

    Science.gov (United States)

    Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

    2016-01-01

    The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching. PMID:27148662

  12. Occupational eczema and asthma in a hairdresser caused by hair-bleaching products

    DEFF Research Database (Denmark)

    Hougaard, Majken G; Menné, Torkil; Søsted, Heidi

    2012-01-01

    Occupational allergic contact eczema and asthma caused by bleaching agents is seen in hairdressers. Bleaching agents contain persulfate salts, which are known to induce immediate reactions such as rhinitis, asthma, contact urticaria, and anaphylaxis. The immunologic mechanism is not, however, ful...

  13. Effect of bleaching on the shear bond strength of the enamel

    Directory of Open Access Journals (Sweden)

    Thiago Arruda

    2008-01-01

    Full Text Available Objective: To evaluate the effect of dental bleaching on the shear bond strength of enamel. Methods: Fifty molars were selected and divided into five groups (n=10; G1-without bleaching (control; G2-bleached with 10% carbamide peroxide and restored 24h later; G3-bleached with 10% carbamide peroxide and restored seven days later; G4-bleached with 35% hydrogen peroxide and restored a 35% and restored 24h later; G5-bleached with 35% hydrogen peroxide and restored a 35% and restored seven days later. During the 24h and 7-day intervals the test specimens remained stored in artificial saliva, after which the restorative procedures were performed on the enamel. Results: The microshear bond strength test indicated the following results in MPa (ANOVA and Tukey post-hoc: G1-43.15 a (±5.19; G2-31.34 ab (± 4.41; G3-36.66 ab (± 3.11; G4-22.87 c (±3.76 and G5-35.67 ab (± 4.64. Conclusion: Groups G1, G2, G3 and G5 showed no statistical difference and Group G4 (bleached with 35% hydrogen peroxide and restored 24h later showed diminished bond strength between the bleached enamel and resin composite.

  14. Corals differential susceptibilities to bleaching along the Red Sea Coast, Egypt

    Directory of Open Access Journals (Sweden)

    MONTASER ALY MAHMOUD AL-HAMMADY

    2011-07-01

    Full Text Available Ammar MSA, Obuid-Allah AH, Al-Hammady MAM. 2011. Corals differential susceptibilities to bleaching along the Red Sea Coast, Egypt. Nusantara Bioscience 3: 73-81. Coral bleaching was studied at four sites in four widely geographically separated areas. Three of these sites are subjected to different human activities and the fourth one is considered as a control site. Data were collected by using SCUBA diving equipments and the line transects method. A total of 3940 coral colonies, representing 62 species in 21genera and 10 families, were recorded on transects on the reefs of four studied sites.20.11% of all corals were affected by bleaching: 5.4% were moderately affected; 2.7% severely affected and 12.007% were dead. Overall, there were differences in the proportion of colonies affected by bleaching between the studied sites. Ras El-Behar, the site impacted by petroleum oil, has the maximum average proportion of moderately, severely bleached and dead colonies. While, the lowest average proportions of severely bleached colonies and dead colonies were found at Kalawy bay. Surprisingly, coral reef taxa at El-Hamraween harbor showed high resistance to bleaching probably because of having a new different clade of Symbiodinium which can withstand sea water temperature. Species with highest susceptibilities to bleaching in areas of oil pollution, increased sedimentation and heavy load of phosphate are Stylophora pistillata, Acropora granulosa and Montipora meandrina, respectively while species with lowest susceptibilities are Fungia fungites, Alveopora daedalea and Millepora dichotoma, respectively.

  15. Coral reef bleaching and sea surface temperature anomalies: 1991-1996 global patterns

    Energy Technology Data Exchange (ETDEWEB)

    Goreau, T.J.; Hayes, R.L.; Strong, A.

    1997-12-31

    Global spatio-temporal patterns of mass coral reef bleaching during the first half of the 1990s continued to show the strong temperature correlations which first became established in the 1980s. Satellite sea surface temperature data and field observations were used to track thermal bleaching events in real time. Most bleaching events followed warm season sea surface temperature anomalies of around +1 degree celsius above historical means. Global bleaching patterns appear to have been strongly affected by worldwide cooling which followed eruption of Mount Pinatubo in June 1991. High water temperatures and mass coral reef bleaching took place in the Caribbean, Indian Ocean, and South Pacific in 1991, but there were few thermal anomalies or bleaching events in 1992 and 1993, years which were markedly cooler worldwide. Following the settling of Mount Pinatubo aerosols and resumption of global warming trends, extensive ocean thermal hot spots and bleaching events resumed in the South Pacific, South Atlantic, and Indian Oceans in 1994. Bleaching again took place in hot spots in the Indian Ocean and Caribbean in 1995, and in the South Atlantic, Caribbean, South Pacific, North Pacific, and Persian Gulf in 1996. Coral reefs worldwide are now very close to their upper temperature tolerance limits. This sensitivity, and the fact that the warmest ecosystems have no source of immigrant species pre-adapted to warmer conditions, may make coral reef ecosystems the first to be severely impacted if global temperatures and sea levels remain at current values or increase further.

  16. The effect of elapsed time following bleaching on enamel bond strength of resin composite.

    Science.gov (United States)

    Cavalli, V; Reis, A F; Giannini, M; Ambrosano, G M

    2001-01-01

    Recent studies have concluded that carbamide peroxide bleaching agents significantly affect the bond strength of composite to bleached enamel. This study evaluated the effects of bleaching regimen with different carbamide peroxide concentrations and post-treatment times on composite bond strength to enamel. Two hundred and four flat buccal and lingual enamel surfaces obtained from erupted sound third molars were randomly divided into 17 groups (n = 12). Sixteen experimental groups comprised the evaluation of four carbamide peroxide home bleaching agents (Opalescence 10%-20% and Whiteness 10%-16%) and four time intervals after bleaching (one day, one, two and three weeks). Specimens of control group were not submitted to bleaching and were stored in artificial saliva at 37 degrees C for 10 days. The specimens of experimental groups were exposed to one daily application of carbamide peroxide for six hours for 10 consecutive days. After each daily treatment and post-bleaching, the specimens were stored in artificial saliva solution. Bonds were formed with Scotchbond MP and Z-100 composite resin, and shear bond test was carried out 24 hours after adhesive-composite application. Two-way ANOVA showed that the bond strengths were significantly different (p < 0.05). For the first two weeks post-bleaching, the bond strengths of resin to enamel were low. After a lapse of three weeks, the bond strength returned to that of the untreated control group. Increased concentration did not prolong the time needed prior to bonding. PMID:11699184

  17. Assessment of acute phase proteins and oxidative stress status of Nigerians using bleaching agents

    International Nuclear Information System (INIS)

    The disruption of primary innate immune function of the epidermal layer of the skin accounts for the susceptibility of individuals using bleaching agents to localized or systemic infections. This subverted innate immunity in these people may lead to other pathological conditions. The resultant effects of skin bleaching and phagocytes activation in response to infections have not been studied in Nigerians using bleaching agents. The present study therefore assessed the levels of C-reactive protein (CRP), albumin, total antioxidant potential (TAP), total plasma peroxides (TPP), oxidative stress index (OSI) and malonaldehyde (MDA) in the users bleaching agents. Thirty (30) people who had used bleaching agents for average of 4.9 + 1.2 years participated in this study. They were recruited from various schools and markets within the city of Ibadan, Oyo State, Nigeria. Thirty apparently healthy staffs of University College Hospital Ibadan, Ibaadan, Nigeria, who had never used bleaching agents served as controls. All the subjects used for this study had no metabolic abnormality and tested negative to both HIV and hepatitis B infections. The mean value of TAP (p 0.20) when compared with the controls. Oxidative stress and chronic inflammation are possible consequences of skin bleaching. The users of skin bleaching agents may need antioxidant therapies to avert the risks of oxidative stress. (author)

  18. Re-evaluating luminescence burial doses and bleaching of fluvial deposits using Bayesian computational statistics

    Science.gov (United States)

    Cunningham, A. C.; Wallinga, J.; Hobo, N.; Versendaal, A. J.; Makaske, B.; Middelkoop, H.

    2015-01-01

    The optically stimulated luminescence (OSL) signal from fluvial sediment often contains a remnant from the previous deposition cycle, leading to a partially bleached equivalent-dose distribution. Although identification of the burial dose is of primary concern, the degree of bleaching could potentially provide insights into sediment transport processes. However, comparison of bleaching between samples is complicated by sample-to-sample variation in aliquot size and luminescence sensitivity. Here we begin development of an age model to account for these effects. With measurement data from multi-grain aliquots, we use Bayesian computational statistics to estimate the burial dose and bleaching parameters of the single-grain dose distribution. We apply the model to 46 samples taken from fluvial sediment of Rhine branches in the Netherlands, and compare the results with environmental predictor variables (depositional environment, texture, sample depth, depth relative to mean water level, dose rate). Although obvious correlations with predictor variables are absent, there is some suggestion that the best-bleached samples are found close to the modern mean water level, and that the extent of bleaching has changed over the recent past. We hypothesise that sediment deposited near the transition of channel to overbank deposits receives the most sunlight exposure, due to local reworking after deposition. However, nearly all samples are inferred to have at least some well-bleached grains, suggesting that bleaching also occurs during fluvial transport.

  19. MODIFIED OPAL:A NOVEL STABILIZER FOR HYDROGEN PEROXIDE BLEACHING OF PULPS

    Institute of Scientific and Technical Information of China (English)

    Xueren Qian; Xianhui An; Wenbo Liu; Gang Yu; Zhanqian Song

    2004-01-01

    The possibility of modified opal as the stabilizer of hydrogen peroxide bleaching was investigated. The results showed that the modified opal in place of sodium silicate as the stabilizer of hydrogen peroxide bleaching is feasible. At the same dosage, above 3% ISO can be increased for both wheat straw pulp and deinked pulp. The stabilizing ability of the modified opal to hydrogen peroxide bleaching of pulp is improved markedly. It is favorable for bleaching to increase temperature and time within a permissive extent. The suitable process conditions are 10% of pulp consistency, 3% of hydrogen peroxide, 1.5% of sodium hydroxide, 3% of the modified opal, 70℃ and 60 min when the modified opal is used as the stabilizer of hydrogen peroxide bleaching. At these conditions, the brightness gain can reach about 16% ISO for wheat straw pulp. In addition, it is favorable for bleaching to add a little magnesium sulfate when the modified opal is used as the stabilizer of hydrogen peroxide bleaching, the brightness of pulp can increase I%ISO if0.05% of magnesium sulfate is added. The cost analysis indicated that the modified opal is superior to sodium silicate as the stabilizer of hydrogen peroxide bleaching in economical aspect and has further the potential of market development.

  20. Comparing Environmental Influences on Coral Bleaching Across and within Species using Clustered Binomial Regression

    Science.gov (United States)

    Differential susceptibility among reef-building coral species can lead to community shifts and loss of diversity as a result of temperature-induced mass bleaching events. However, the influence of the local environment on species-specific bleaching susceptibilities has not been ...

  1. INDICATORS OF UV EXPOSURE IN CORALS AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

    Science.gov (United States)

    A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Through interactions with other factors such as sedimentation, pollution, and bacterial infection, bleaching can impact large areas of a reef with limited recovery, and it might be induc...

  2. Project Overview: A Reef Manager’s Guide to Coral Bleaching

    Science.gov (United States)

    The purpose of this report is to provide the latest scientific knowledge and discuss available management options to assist local and regional managers in responding effectively to mass coral bleaching events. Background A Reef Manager’s Guide to Coral Bleaching is...

  3. The Effects of Habitat on Coral Resistance and Resilience to Bleaching.

    OpenAIRE

    Grimsditch, G.; Kilonzo, J.; Amiyo, N.

    2008-01-01

    This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa Marine Park and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching responses were monitored for the general coral community and zooxanthella densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea and Porites cylindrica ) during a nonbleaching year (20...

  4. Post-bleaching application of an antioxidant on dentin bond strength of three dental adhesives

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2012-01-01

    Conclusions: The findings suggest that bond strength of resin to bleached dentin may be affected with the adhesive system. Reduced SBS to bleached dentin can be amended by the use of SA as an antioxidizing agent. However, the amount of reversed bond strength subsequent to applying antioxidant might be related to the kind of dental adhesive.

  5. Oxidative stress and bioindicators of reproductive function in pulp and paper mill effluent exposed white sucker.

    Science.gov (United States)

    Oakes, Ken D; McMaster, Mark E; Pryce, Andrea C; Munkittrick, Kelly R; Portt, Cam B; Hewitt, L Mark; MacLean, Dan D; Van Der Kraak, Glen J

    2003-07-01

    This study investigates oxidative stress and bioindicators of reproductive function in wild white sucker (Catostomus commersoni) collected from environments receiving pulp and paper mill effluent discharges in northern Ontario. Samples were collected over an eight-year period adjacent to three pulp and paper mills using a variety of processing and bleaching techniques. Fish collected downstream of pulp and paper mills within the Moose River basin exhibited elevated hepatic and gonadal 2-thiobarbituric acid reactive substances (TBARS), the presence of which is indicative of oxidative stress in these tissues. Within the Jackfish Bay system, exposure to pulp and paper mill effluent did not elevate hepatic or gonadal TBARS. Hepatic cytochrome P4501A activity (CYP1A) and fatty acyl-CoA oxidase (FAO) activities were frequently increased in livers of Moose River basin fish exposed to pulp and paper mill effluent, while lower activities of both enzymes were found within fish from the Jackfish Bay system. This suggests that oxidative stress may be related to CYP1A and FAO activities. Within the Moose River system, increases in measures of oxidative stress (TBARS, FAO) were generally coincident with decreased levels of 17 beta-estradiol; however, testosterone was often lower in Jackfish Bay system fish without any commensurate changes in oxidative stress. The suite of reproductive and oxidative stress parameters measured in this study varied between seasons and mills suggesting responses to effluent are dynamic and effects are complicated by different receiving environments. The relationship between gonad size, gonadal oxidative stress, and circulating plasma steroids remains unclear. PMID:12730610

  6. Temperature-Regulated Bleaching and Lysis of the Coral Pocillopora damicornis by the Novel Pathogen Vibrio coralliilyticus

    OpenAIRE

    Ben-Haim, Yael; Zicherman-Keren, Maya; Rosenberg, Eugene

    2003-01-01

    Coral bleaching is the disruption of symbioses between coral animals and their photosynthetic microalgal endosymbionts (zooxanthellae). It has been suggested that large-scale bleaching episodes are linked to global warming. The data presented here demonstrate that Vibrio coralliilyticus is an etiological agent of bleaching of the coral Pocillopora damicornis. This bacterium was present at high levels in bleached P. damicornis but absent from healthy corals. The bacterium was isolated in pure ...

  7. Relationship between anthropogenic impacts and bleaching-associated tissue mortality of corals in Curaçao (Netherlands Antilles)

    OpenAIRE

    Nagelkerken, I.

    2007-01-01

    Chronic anthropogenic impacts can have a negative effect on coral health and on coral energy budgets needed for regeneration of lesions. I therefore hypothesise that during massive bleaching events, the degree of corals showing bleaching-related tissue mortality is higher in areas subject to chronic anthropogenic impacts than in relatively pristine areas. In the present study, the degree of bleaching and bleaching-related tissue mortality was estimated for eight abundant coral species in Cura...

  8. Comparison of the bleaching efficacy of three different agents used for intracoronal bleaching of discolored primary teeth: An in vitro study

    Directory of Open Access Journals (Sweden)

    R Ganesh

    2013-01-01

    Full Text Available Everyone wants whiter teeth to make them feel younger and to provide beautiful smiles with the accompanying increase in self-esteem. Bleaching is an established, simple, cost-effective and conservative method for improving the color of the discolored teeth. Aim: The aim of this in vitro study was to compare the bleaching efficacy of 10% carbamide peroxide, 10% hydrogen peroxide and 2g sodium perborate as bleaching agents on the artificially discolored human primary maxillary central incisors. Materials and Methods: Forty extracted human primary central incisors with intact crowns were selected for the study. Pulpectomy was performed and each tooth was artificially stained with 2 ml of fresh human blood and centrifuged. --The teeth were randomly divided into four experimental groups of 10 teeth each and the baseline color evaluation was performed. 0.04 ml of the bleaching agent is syringed into the access cavity of the tooth and, in the control group, 0.04 ml of distilled water was syringed into the access cavity and it was sealed with IRM and placed at 37°C in an incubator throughout the experiment. The color of the bleached teeth was determined at 0, 7 and 14 days. The data obtained were analyzed using ANOVA and Turkey′s test. Results: There was statistical significance (P = 0.00 among the carbamide peroxide, sodium perborate, hydrogen peroxide and control groups after 7 and 14 days and a significance of P = 0.013 among the carbamide peroxide, sodium perborate and hydrogen peroxide after two bleaching sessions (day 14 was seen. Conclusions: The bleaching efficacy of 10% hydrogen peroxide gel was more effective than 10% carbamide peroxide and sodium perborate in bleaching the artificially discolored primary teeth.

  9. Enamel susceptibility to red wine staining after 35% hydrogen peroxide bleaching

    Directory of Open Access Journals (Sweden)

    Sandrine Bittencourt Berger

    2008-06-01

    Full Text Available Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10. Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments.

  10. Use of the LM-OSL technique for the detection of partial bleaching in quartz

    DEFF Research Database (Denmark)

    Larsen, N.A.; Bulur, E.; Bøtter-Jensen, L.; McKeever, S.W.S.

    We present a study of the sensitivity to light (ease-of-bleaching) of the trapped charge in sedimentary quartz grains using an optically stimulated luminescence (OSL) technique in which the intensity of the stimulation light is linearly increased during the measurement period. The technique is...... -irradiation, or (2) partially bleached, followed by the laboratory beta -dose. The ratio of the OSL signals due to the beta -dose from the partly and fully bleached aliquots is illustrated to be a potential indicator of the degree of optical resetting of the OSL signal in dating material. The key parameter...... known as linear modulation OSL (LM-OSL). In controlled laboratory conditions, this technique has been employed to study the ease-of-bleaching of the trapped charge in quartz by comparing the OSL curves of quartz aliquots which have been either: (1) fully bleached, followed by a laboratory dose of beta...

  11. Spring ``bleaching'' among Pocillopora in the Sea of Cortez, Eastern Pacific

    Science.gov (United States)

    Lajeunesse, T. C.; Reyes-Bonilla, H.; Warner, M. E.

    2007-06-01

    A mild bleaching event was observed among Pocillopora spp. in the southern Gulf of California in the spring of 2006. Uniform bleaching occurred in numerous colonies on the upper portions of their branches. Most (˜90%) colonies that exhibited bleaching contained a species of endosymbiotic dinoflagellate, Symbiodinium C1b-c, which differed from the Symbiodinium D1 found inhabiting most unbleached colonies. Analysis of chlorophyll fluorescence, indicated a decline in photosystem II photochemical activity, especially among colonies populated with C1b-c. By early August, most affected colonies had recovered their normal pigmentation and fluorescence values were once again high for all colonies. No mortality was observed among tagged bleached colonies nor did symbiont species composition change during recovery. This unusual episode of bleaching did not appear to be a response to thermal stress, but may have been triggered by high levels of solar radiation during a period of unseasonally high water clarity in the early spring.

  12. Seasonal Dynamical Prediction of Coral Bleaching in the Great Barrier Reef, Australia

    Science.gov (United States)

    Spillman, C. M.; Alves, O.

    2009-05-01

    Sea surface temperature (SST) is now recognised as the primary cause of mass coral bleaching events. Coral bleaching occurs during times of stress, particularly when SSTs exceed the coral colony's tolerance level. Global warming is potentially a serious threat to the future of the world's reef systems with predictions by the international community that bleaching will increase in both frequency and severity. Advance warning of anomalous sea surface temperatures, and thus potential bleaching events, would allow for the implementation of management strategies to minimise reef damage. Seasonal SST forecasts from the coupled ocean-atmosphere model POAMA (Bureau of Meteorology) have skill in the Great Barrier Reef (Australia) several months into the future. We will present model forecasts and probabilistic products for use in reef management, and assess model skill in the region. These products will revolutionise the way in which coral bleaching events are monitored and assessed in the Great Barrier Reef and Australian region.

  13. Climate change disables coral bleaching protection on the Great Barrier Reef.

    Science.gov (United States)

    Ainsworth, Tracy D; Heron, Scott F; Ortiz, Juan Carlos; Mumby, Peter J; Grech, Alana; Ogawa, Daisie; Eakin, C Mark; Leggat, William

    2016-04-15

    Coral bleaching events threaten the sustainability of the Great Barrier Reef (GBR). Here we show that bleaching events of the past three decades have been mitigated by induced thermal tolerance of reef-building corals, and this protective mechanism is likely to be lost under near-future climate change scenarios. We show that 75% of past thermal stress events have been characterized by a temperature trajectory that subjects corals to a protective, sub-bleaching stress, before reaching temperatures that cause bleaching. Such conditions confer thermal tolerance, decreasing coral cell mortality and symbiont loss during bleaching by over 50%. We find that near-future increases in local temperature of as little as 0.5°C result in this protective mechanism being lost, which may increase the rate of degradation of the GBR. PMID:27081069

  14. The combination of sodium perborate and water as intracoronal teeth bleaching agent

    Directory of Open Access Journals (Sweden)

    Ananta Tantri Budi

    2008-12-01

    Full Text Available Background: The color change on post-endodontic treated teeth can be overcome by intracoronal tooth bleaching using walking bleach. Some agents used in walking bleach are combination of sodium peroxide and hydrogen peroxide, and combination of sodium perborate and water. Purpose: The objective of this review is to provide information and consideration of using safe and effective bleaching agents in the field of dentistry. Reviews: On one side, the use of sodium perborate and water combination does not cause the reduction of dentin hardness, enamel decay, and root resorbtion. On the other side, the use of sodium perborate and 30% hydrogen peroxide combination indicates that it takes longer time in yielding the proper color of teeth. Conclusion: The use of sodium perborate and water combination as bleaching agents is effective and safe.

  15. Seychelles Lagoon Provides Corals with a Refuge from Bleaching

    Directory of Open Access Journals (Sweden)

    Zvy Dubinsky

    2008-06-01

    Full Text Available An extensive bleaching event in the summer of the year 1997-1998 affected most reefs along East Africa's shores. In the aftermath of that episode, the reefs of Île Alphonse in the Seychelles were examined and it was found that reefs along the seaward slopes of the island lost >95% of their branching coral colonies, with considerably higher survival of massive species. Île Alphonse features a nearly circular shallow lagoon, with steep seaward slopes. Contrary to our expectations, mortality in the warmer lagoon was far lower than of coral colonies on the surrounding slopes, bathed in deeper and cooler waters. We suggest that corals in the lagoon were protected from UV radiation by leachate stemming from seagrass leaves steeped in the lagoon. Our measurements in the lagoon showed a strong attenuation of ultraviolet radiation, not observed in the waters outside the lagoon, and laboratory examination confirmed that the strong UV absorption of substances leached into seawater from decomposing leaves of the seagrass Thalassodendron (=Cymodocea testudinaceum. Our findings demonstrate the synergism between elevated seawater temperature and UV radiation in triggering bleaching on shallow reefs.

  16. Seychelles Lagoon Provides Corals with a Refuge from Bleaching

    International Nuclear Information System (INIS)

    An extensive bleaching event in the summer of the year 1997-1998 affected most reefs along East Africa's shores. In the aftermath of that episode, the reefs of Ile Alphonse in the Seychelles were examined and it was found that reefs along the seaward slopes of the island lost >95% of their branching coral colonies, with considerably higher survival of massive species. Ile Alphonse features a nearly circular shallow lagoon, with steep seaward slopes. Contrary to our expectations, mortality in the warmer lagoon was far lower than of coral colonies on the surrounding slopes, bathed in deeper and cooler waters. We suggest that corals in the lagoon were protected from UV radiation by leachate stemming from sea grass leaves steeped in the lagoon. Our measurements in the lagoon showed a strong attenuation of ultraviolet radiation, no observed in the waters outside the lagoon, and laboratory examination confirmed that the strong UV absorption of substances leached into seawater from decomposing leaves of the sea grass Thalassodendron (=Cymodocea) testudinaceum. Our findings demonstrate the synergism between elevated seawater temperature and UV radiation in triggering bleaching on shallow reefs.

  17. INVESTIGATION ON HARDENED STEEL MILLING WITH MICRO-END MILL

    Institute of Scientific and Technical Information of China (English)

    HUYing-ning; WANGCheng-yong; WUXue-qi; QINZhe; ZENGBao-ping

    2004-01-01

    Tool wear and breakage of the micro-milling tool is an important problem for high speed machining of hardened steel die and mould. Dry milling of S136 hardened steel is carried out using TiA1N coated carbide micro-end mill (Ф2 mm). The effect of cutting speed, feed per tooth and radial depth of cut on cutting force is analyzed. Cutting parameters adapting to dry machining and strategy optimized for higher rate of material removal with lower cutting force are attained. Results of SEM observation show that the main failure patterns of micro-end mill are breakage of tool tip, wear and drop-off of surface coating, micro-chipping, and breakage of flank.

  18. Galilean Yang-Mills Theory

    OpenAIRE

    Bagchi, Arjun; Basu, Rudranil; Kakkar, Ashish; Mehra, Aditya

    2015-01-01

    We investigate the symmetry structure of the non-relativistic limit of Yang-Mills theories. Generalising previous results in the Galilean limit of electrodynamics, we discover that for Yang-Mills theories there are a variety of limits inside the Galilean regime. We first explicitly work with the $SU(2)$ theory and then generalise to $SU(N)$ for all $N$, systematising our notation and analysis. We discover that the whole family of limits lead to different sectors of Galilean Yang-Mills theorie...

  19. Influence of Bleaching on Flavor of 34% Whey Protein Concentrate and Residual Benzoic Acid Concentration in Dried Whey Proteins

    Science.gov (United States)

    Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

  20. Electron beam radiation treatment of pulp bleaching effluent

    International Nuclear Information System (INIS)

    There are very high values of the chemical oxidation demand (COD) in the effluent from pulp mills. The COD value of the effluent is still higher after traditional biological treatment. The biologically treated wastewater from pulp mill was irradiated using low energy EB. For the wastewater irradiated with a dose of less than 1 kGy, its COD value was reduced to 1/4 of the value for unirradiated wastewater. Chromaticity of the irradiated-wastewater was also greatly decreased. The UV-visible spectra of a significant constituent of the wastewater indicated that the contaminants were degraded well

  1. Response of millepora alcicornis (Milleporina: Milleporidae) to two bleaching enventgs at Puerto Morelos reef, Mexican Caribbean

    International Nuclear Information System (INIS)

    Two naturally occurring colonies of Millepora alcicornis were monitored during 1997 and 1998, both years in which this species bleached in the Mexican Caribbean. One colony (HL) was naturally exposed to a high light environment and another nearby colony (LL) was exposed to 5.9 times lower light levels due to shadowing by a pier. For 10 days in August 1997, seawater temperatures in the surrounding reef lagoon rose up to 1.5 degrees C above the 6-year August average. The HL colony bleached to white during this period, whereas, the LL colony remained dark-brown colored. The HL colony recovered its normal dark-brown coloration (reversible bleaching) within several weeks, during which time the seawater temperatures returned to average. The following year, for 10 days, seawater temperatures rose up to 3 degrees C above the 7-year August average and both colonies bleached to white and neither colony recovered (irreversible bleaching). Both colonies were rapidly overgrown by algae and hydroids and, as of June 2003, no recovery has taken place. Prior to the 1997 bleaching, experiments using solar radiation showed that the quantum yield of photosystem II charge separation of branches from HL and LL colonies were affected for several hours by exposure to ultraviolet radiation (UVR, 280 to 400 nm), but recovered by the same evening, suggesting that UVR does not have long-term effects on photochemistry in M. alcicornis. In situ effective quantum yield of photosystem II charge separation (ΔF/Fm') measurements before the 1998 bleaching event indicate that both colonies were healthy in terms of the physiological status of their endosymbionts. During and after the 1998 bleaching event, both colonies showed a reduction in ΔF/Fm' and consequently an increase in excitation pressure on photosystem II. The data suggest that temperature is not the only factor that causes bleaching and that solar radiation may play an important role in coral bleaching. (Author)

  2. The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness

    Science.gov (United States)

    Moosavi, Horieh; Darvishzadeh, Fatemeh

    2016-01-01

    Objectives: This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Methods: Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Results: Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel. PMID:27099635

  3. Understanding milling induced changes: Some results

    Indian Academy of Sciences (India)

    K Chattopadhyay; N Ravishankar; T A Abinandanan; Viji Varghese

    2003-10-01

    The effect of mechanical milling on materials has been studied using simple model systems. The results show that milling leads to enhancement in both thermodynamic driving force and transport kinetics. A study of some characteristic physical properties of the milled samples in comparison to the bulk shows how milling affects the properties.

  4. Chemical changes of kraft lignin and some enzymes produced by the white-rot fungus Coriolopsis Gallica

    OpenAIRE

    Gómez Alarcón, Gonzalo; Sáiz-Jiménez, Cesáreo; Lahoz, Rafael; O'Connor, A

    1987-01-01

    The excretion of extracellular enzymes and the degradation of indulin (pine kraft lignin) by the fungus Coriolopsis gallica were studied. By using a lignin-impregnated glass fibre disc which simulated natural conditions, the fungus excreted phenol oxidases during the log phase of growth and reached two activity maxima in the autolytic phase. However, in absence of indulin the fungus had a different behaviour with respect to phenol oxidases. It was concluded that in the ex...

  5. Corporate Image and Public Health: An Analysis of the Philip Morris, Kraft, and Nestlé Websites

    OpenAIRE

    Smith, Elizabeth

    2012-01-01

    Companies need to maintain a good reputation to do business; however, companies in the infant formula, tobacco, and processed food industries have been identified as promoting disease. Such companies use their websites as a means of promulgating a positive public image, thereby potentially reducing the effectiveness of public health campaigns against the problems they perpetuate. The author examined documents from the websites of Philip Morris, Kraft, and Nestlé for issue framing and analyzed...

  6. Experimental evaluation of the performances of cellulosic pads made out of Kraft and NSSC corrugated papers as evaporative media

    International Nuclear Information System (INIS)

    Highlights: ► We experimentally evaluated the performances of cellulosic pads. ► A number of experiments have been done in a wind tunnel. ► The results showed that cooling efficiency improves with decrease of air velocity and flute size. ► Water consumption increases with the increase of air velocity. ► Cooling efficiency of various pads was also compared. - Abstract: The purpose of this study was to evaluate the performances of cellulosic pads made out of Kraft and NSSC corrugated papers in three flute sizes, experimentally. A number of experiments have been done in a wind tunnel in order to evaluate the cooling efficiency and water consumption as a function of air velocity. The tests were carried out at three levels of air velocity (1.8, 2.25, and 2.67 ms−1) for three flute sizes of Kraft and NSSC corrugated papers (2.5, 3.5, and 4.5 mm). Analysis of the results indicated that cooling efficiency improves with decrease of air velocity and flute size of corrugated papers; however, water consumption increases with the increase of air velocity. The results were compared with each other and it was shown that the cellulosic pad made out of Kraft paper with 2.5 mm flute size has the highest performance (92%) at 1.8 ms−1 air velocity in comparison with the other cellulosic pads.

  7. KRAFT PULPING CHARACTERISTICS OF THREE MOROCCAN EUCALYPTI. PART 1. PHYSICAL AND CHEMICAL PROPERTIES OF WOODS AND PULPS

    Directory of Open Access Journals (Sweden)

    Mohammed El Moussaouiti,

    2012-02-01

    Full Text Available Two eucalyptus hybrids (EGC 39, EGC 241, resulting from crosses between Eucalyptus grandis and Eucalyptus camaldulensis, were investigated to see if they could produce kraft papermaking fibers with low lignin and adequate physical properties. The two hybrids were harvested at an age of 8 years along with 6-8 year old Eucalyptus camaldulensis (Rostrata. All three eucalypti were grown in the area of Gharb in the North-West of Morocco. The tracheids in the two hybrids had a very high Runkel ratio (2 x cell wall thickness/lumen diameter and produced kraft paper sheets with low tensile strength due to a low degree of fiber collapse thus a low relative bonded area. These fibers could be used to increase the stiffness of a papermaking furnish. The lignin in the EGC 39 chips was more reactive in kraft pulping as compared to the other two eucalypti. Methoxyl analyses and nitrobenzene oxidation (NBO of the in-situ lignin (wood meals were performed, and it was concluded that the syringyl content of the EGC 39 lignin was less than or equal to those in the other two eucalypti. Differences in the guaiacyl fraction of the three samples will be discussed in Part 2 of this series.

  8. Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

    Science.gov (United States)

    Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

    2016-06-01

    Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

  9. Effect of Temperature on Adhesion of Vibrio Strain AK-1 to Oculina patagonica and on Coral Bleaching

    OpenAIRE

    A. Toren; Landau, L; Kushmaro, A.; Y. Loya; Rosenberg, E

    1998-01-01

    Laboratory aquarium experiments demonstrated that Vibrio strain AK-1 caused rapid and extensive bleaching of the coral Oculina patagonica at 29°C, slower and less-complete bleaching at 23°C, and no bleaching at 16°C. At 29°C, the application of approximately 100 Vibrio strain AK-1 cells directly onto the coral caused 50 and 83% bleaching after 10 and 20 days, respectively. At 16°C, there was no bleaching, even with an initial inoculum of 1.2 × 108 bacteria. To begin to understand the effect o...

  10. Effect of different restorative procedures on the fracture resistance of teeth submitted to internal bleaching

    Directory of Open Access Journals (Sweden)

    Andiara Ribeiro Roberto

    2012-02-01

    Full Text Available The aim of this study was to evaluate the influence of different restorative procedures on the fracture resistance of endodontically treated teeth submitted to intracoronal bleaching. Fifty upper central incisors were distributed into 5 groups: GI - healthy teeth; GII - endodontically treated teeth sealed with Coltosol; GIII - endodontically treated teeth bleached and sealed with Coltosol; GIV - endodontically treated teeth bleached and restored with composite resin; and GV - endodontically treated teeth bleached and restored with a fiberglass post and composite resin. In the bleached specimens, a cervical seal was made prior to bleaching with 38% hydrogen peroxide. The gel was applied on the buccal surface and in the pulp chamber, and was then light-activated for 45 s. This procedure was repeated three times per session for four sessions, and each group was submitted to the restorative procedures described above. The specimens were submitted to fracture resistance testing in a universal testing machine. There were statistically significant differences among the groups (p 0.05. The restorative procedures using composite resin were found to successfully restore the fracture resistance of endodontically treated and bleached teeth.

  11. Excess algal symbionts increase the susceptibility of reef corals to bleaching

    Science.gov (United States)

    Cunning, Ross; Baker, Andrew C.

    2013-03-01

    Rising ocean temperatures associated with global climate change are causing mass coral bleaching and mortality worldwide. Understanding the genetic and environmental factors that mitigate coral bleaching susceptibility may aid local management efforts to help coral reefs survive climate change. Although bleaching susceptibility depends partly on the genetic identity of a coral's algal symbionts, the effect of symbiont density, and the factors controlling it, remain poorly understood. By applying a new metric of symbiont density to study the coral Pocillopora damicornis during seasonal warming and acute bleaching, we show that symbiont cell ratio density is a function of both symbiont type and environmental conditions, and that corals with high densities are more susceptible to bleaching. Higher vulnerability of corals with more symbionts establishes a quantitative mechanistic link between symbiont density and the molecular basis for coral bleaching, and indicates that high densities do not buffer corals from thermal stress, as has been previously suggested. These results indicate that environmental conditions that increase symbiont densities, such as nutrient pollution, will exacerbate climate-change-induced coral bleaching, providing a mechanistic explanation for why local management to reduce these stressors will help coral reefs survive future warming.

  12. Relationships between temperature, bleaching and white syndrome on the Great Barrier Reef

    Science.gov (United States)

    Ban, S. S.; Graham, N. A. J.; Connolly, S. R.

    2013-03-01

    Coral bleaching and disease have often been hypothesized to be mutually reinforcing or co-occurring, but much of the research supporting this has only drawn an implicit connection through common environmental predictors. In this study, we examine whether an explicit relationship between white syndrome and bleaching exists using assemblage-level monitoring data from up to 112 sites on reef slopes spread throughout the Great Barrier Reef over 11 years of monitoring. None of the temperature metrics commonly used to predict mass bleaching performed strongly when applied to these data. Furthermore, the inclusion of bleaching as a predictor did not improve model skill over baseline models for predicting white syndrome. Similarly, the inclusion of white syndrome as a predictor did not improve models of bleaching. Evidence for spatial co-occurrence of bleaching and white syndrome at the assemblage level in this data set was also very weak. These results suggest the hypothesized relationship between bleaching and disease events may be weaker than previously thought, and more likely to be driven by common responses to environmental stressors, rather than directly facilitating one another.

  13. Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

    Directory of Open Access Journals (Sweden)

    Renata Plá Rizzolo Bueno

    2012-06-01

    Full Text Available OBJECTIVE: This in vitro study evaluated the influence of two 10% carbamide peroxide bleaching agents - a commercial product (Opalescence PF; Ultradent Products, Inc. and a bleaching agent prepared in a compounding pharmacy - on the chemical degradation of a light-activated composite resin by determining its release of ions before and after exposure to the agents. MATERIAL AND METHODS: Thirty composite resin (Filtek Z250; 3M/ESPE samples were divided into three groups: group I (exposed to Opalescence PF commercial bleaching agent, group II (exposed to a compounded bleaching agent and group III (control - Milli-Q water. After 14 days of exposure, with a protocol of 8 h of daily exposure to the bleaching agents and 16 h of immersion in Milli-Q water, the analysis of ion release was carried out using a HP 8453 spectrophotometer. The values were analyzed statistically by ANOVA, Tukey's test and the paired t-tests. The significance level was set at 5%. RESULTS: After 14 days of the experiment, statistically significant difference was found between group II and groups I and III, with greater ion release from the composite resin in group II. CONCLUSIONS: The compounded bleaching agent had a more aggressive effect on the composite resin after 14 days of exposure than the commercial product and the control (no bleaching.

  14. Modelling the thermal bleaching of OSL signal in the case of a competition between recombination centres

    International Nuclear Information System (INIS)

    The thermal bleaching of the optically stimulated luminescence (OSL) has been investigated by computer simulations for a model including three traps and two luminescence centres. The deepest trap is active only during the OSL process. Two other traps are active only during the thermal bleaching. The thermal bleaching effects on the OSL intensity as well as on the OSL curve shape are presented for the wide range of trap and luminescence centre parameters and for the different settings of optical detection window. The conventional OSL curve analysis consisting in decomposition of the OSL curve into first order components is applied to the simulation results and the optical cross section spectra obtained as a result of this analysis are compared with the model assumptions. The simulations show that OSL signal can decrease to undetectable level even when the traps related to this signal are not emptied during thermal bleaching. The residual level of the OSL signal after bleaching process, however, depends strongly on centre parameters and concentrations. The modifications of optical detection spectral window lead to significant changes of bleaching effects. The thermal bleaching influences also the optical cross section spectra obtained as a result of the OSL curve decomposition.

  15. Influence of bleach activators on the fabric made from cotton (gossypium hamster l.)

    International Nuclear Information System (INIS)

    Raw cotton contains various type of trash and most of the impurities are removed during the spinning process but still the cotton fabric coming from the weaving or knitting process always contains some impurities. Some time cotton fabric gets the oil, stains and coloured materials which affect the quality of dyed fabric. Bleaching is a process that eliminates unwanted coloured matters from the fibres, yarn and fabrics. A bleaching agent is a material that lightens or whitens a substrate through chemical action. Hydrogen peroxide is by far the most commonly used oxidative bleaching agent for cotton and its blends, accounting for more than 90 percent of all the bleaching agents. The use of activators to enhance the bleaching performance of hydrogen peroxide for cellulosic materials has gained popularity now a day. In this context the main objectives of this paper are to study the influence of different bleaching activators on cotton fabric and to give implications for textile extension.The results indicate that the activators with different concentrations, along with different concentrations of hydrogen peroxide (H/sub 2/O/sub 2) have significant influence on the bleaching performance of cotton fabric. (author)

  16. Evaluation of cotton-fabric bleaching using hydrogen peroxide and Blue LED

    Science.gov (United States)

    de Oliveira, Bruno P.; Moriyama, Lilian T.; Bagnato, Vanderlei S.

    2015-06-01

    The raw cotton production requires multiple steps being one of them the removal of impurities acquired during previous processes. This procedure is widely used by textile industries around the world and is called bleaching. The raw cotton is composed by cellulosic and non-cellulosic materials like waxes, pectins and oils, which are responsible for its characteristic yellowish color. The bleaching process aims to remove the non-cellulosic materials concentration in the fabric, increasing its whiteness degree. The most used bleaching method utilizes a bath in an alkali solution of hydrogen peroxide, stabilizers and buffer solutions under high temperature. In the present study we evaluated the possibility of using a blue illumination for the bleaching process. We used blue LEDs (450 nm) to illuminate an acid hydrogen peroxide solution at room temperature. The samples treated by this method were compared with the conventional bleaching process through a colorimetric analysis and by a multiple comparison visual inspection by volunteers. The samples were also studied by a tensile test in order to verify the integrity of the cloth after bleaching. The results of fabric visual inspection and colorimetric analysis showed a small advantage for the sample treated by the standard method. The tensile test showed an increasing on the yield strength of the cloth after blue light bleaching. The presented method has great applicability potential due to the similar results compared to the standard method, with relative low cost and reduced production of chemical waste.

  17. Influence of hydrogen peroxide bleaching gels on color, opacity, and fluorescence of composite resins.

    Science.gov (United States)

    Torres, C R G; Ribeiro, C F; Bresciani, E; Borges, A B

    2012-01-01

    The aim of the present study was to evaluate the effect of 20% and 35% hydrogen peroxide bleaching gels on the color, opacity, and fluorescence of composite resins. Seven composite resin brands were tested and 30 specimens, 3-mm in diameter and 2-mm thick, of each material were fabricated, for a total of 210 specimens. The specimens of each tested material were divided into three subgroups (n=10) according to the bleaching therapy tested: 20% hydrogen peroxide gel, 35% hydroxide peroxide gel, and the control group. The baseline color, opacity, and fluorescence were assessed by spectrophotometry. Four 30-minute bleaching gel applications, two hours in total, were performed. The control group did not receive bleaching treatment and was stored in deionized water. Final assessments were performed, and data were analyzed by two-way analysis of variance and Tukey tests (pColor changes were significant for different tested bleaching therapies (pcolor change observed for 35% hydrogen peroxide gel. No difference in opacity was detected for all analyzed parameters. Fluorescence changes were influenced by composite resin brand (pbrand Z350. It was concluded that 35% hydrogen peroxide bleaching gel generated the greatest color change among all evaluated materials. No statistical opacity changes were detected for all tested variables, and significant fluorescence changes were dependent on the material and bleaching therapy, regardless of the gel concentration. PMID:22433032

  18. Effect of three nanobiomaterials on the surface roughness of bleached enamel

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2015-01-01

    Full Text Available Background: The ever-increasing demand for enhanced esthetic appearance has resulted in significant developments in bleaching products. However, the enamel surface roughness (SR might be negatively affected by bleaching agents. This in vitro study was undertaken to compare the effects of three nanobiomaterials on the enamel SR subsequent to bleaching. Materials and Methods: The crowns of six extracted intact nonerupted human third molars were sectioned. Five dental blocks measuring 2 mm × 3 mm × 4 mm were prepared from each tooth and placed in colorless translucent acrylic resin. The enamel areas from all the specimens were divided into five groups (n = 6: Group 1 did not undergo any bleaching procedures; Group 2 was bleached with a 40% hydrogen peroxide (HP gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by bioactive glass (BAG, amorphous calcium phosphate, and hydroxyapatite, respectively. The enamel SR was evaluated before and after treatment by atomic force microscopy. The data were analyzed by Kruskal–Wallis and Mann–Whitney tests. Results: SR increased significantly in the HP group. SR decreased significantly in the HP gel modified by BAG group as compared to other groups. Conclusions: Within the limitations of this study, incorporation of each one of the three test biomaterials proved effective in decreasing enamel SR subsequent to in-office bleaching technique.

  19. Mg(OH2-BASED HYDROGEN PEROXIDE BLEACHING OF CMP PULPS AT HIGH CONSISTENCY

    Directory of Open Access Journals (Sweden)

    Pedram Fatehi

    2011-11-01

    Full Text Available The objective of this study was to investigate the bleaching performance of a Mg(OH2-based hydrogen peroxide process at a high consistency. In this work, an industrially produced chemimechanical pulp (CMP was bleached via Mg(OH2- or NaOH-based hydrogen peroxide processes at 10% and 25% consistencies. The results showed that the pulp bleached under the conditions of 1.5% Mg(OH2 and 3% H2O2 at 25% consistency had a similar brightness to, a lower yellowness index, and a higher opacity than the pulp produced under the conditions of 2.1% NaOH, 3% Na2SiO3, and 3% H2O2 at the same consistency. The temperature (70 ºC and time (150 min of the bleaching were the same for both processes. Under the conditions stated above, the Mg(OH2-based process had a higher yield than the NaOH-based process did. The bleaching effluent of the Mg(OH2-based process had a higher residual H2O2, but a lower Chemical Oxygen Demand (COD load and turbidity, compared with that of the NaOH-based process. However, the strength properties and water retention value (WRV of the pulp bleached via the Mg(OH2-based process were lower, while its bulk was higher than those of the pulp bleached via the NaOH-based process.

  20. SUBAQUEOUS DISPOSAL OF MILL TAILINGS

    Energy Technology Data Exchange (ETDEWEB)

    Neeraj K. Mendiratta; Roe-Hoan Yoon; Paul Richardson

    1999-09-03

    A study of mill tailings and sulfide minerals was carried out in order to understand their behavior under subaqueous conditions. A series of electrochemical experiments, namely, cyclic voltammetry, electrochemical impedance spectroscopy and galvanic coupling tests were carried out in artificial seawater and in pH 6.8 buffer solutions with chloride and ferric salts. Two mill tailings samples, one from the Kensington Mine, Alaska, and the other from the Holden Mine, Washington, were studied along with pyrite, galena, chalcopyrite and copper-activated sphalerite. SEM analysis of mill tailings revealed absence of sulfide minerals from the Kensington Mine mill tailings, whereas the Holden Mine mill tailings contained approximately 8% pyrite and 1% sphalerite. In order to conduct electrochemical tests, carbon matrix composite (CMC) electrodes of mill tailings, pyrite and galena were prepared and their feasibility was established by conducting a series of cyclic voltammetry tests. The cyclic voltammetry experiments carried out in artificial seawater and pH 6.8 buffer with chloride salts showed that chloride ions play an important role in the redox processes of sulfide minerals. For pyrite and galena, peaks were observed for the formation of chloride complexes, whereas pitting behavior was observed for the CMC electrodes of the Kensington Mine mill tailings. The electrochemical impedance spectroscopy conducted in artificial seawater provided with the Nyquist plots of pyrite and galena. The Nyquist plots of pyrite and galena exhibited an inert range of potential indicating a slower rate of leaching of sulfide minerals in marine environments. The galvanic coupling experiments were carried out to study the oxidation of sulfide minerals in the absence of oxygen. It was shown that in the absence of oxygen, ferric (Fe3+) ions might oxidize the sulfide minerals, thereby releasing undesirable oxidation products in the marine environment. The source of Fe{sup 3{minus}} ions may be