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Sample records for bleached kraft mill

  1. 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

    and in combination: total bleaching effluent, alkaline bleaching effluent, kraft evaporator condensate, and chemithermomechanical pulping effluent. The total bleaching effluent, consisting of the chlorine dioxide bleaching and alkaline bleaching effluents, exhibited the highest potential for organic matter...

  2. 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.

  3. 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...

  4. Assessment of reproductive effects in largemouth bass (Micropterus salmoides) exposed to bleached/unbleached kraft mill effluents

    Science.gov (United States)

    Sepulveda, M.S.; Ruessler, D.S.; Denslow, N.D.; Holm, S.E.; Schoeb, T.R.; Gross, T.S.

    2001-01-01

    This study evaluated the potential effects of different concentrations of bleached/unbleached kraft mill effluent (B/UKME) on several reproductive endpoints in adult largemouth bass (Micropterus salmoides). The kraft mill studied produces a 50/50 mix of bleached/unbleached market pulp with an estimated release of 36 million gal of efffluent/day. Bleaching sequences were C90d10EopHDp and CEHD for softwood (pines) and hardwoods (mainly tupelo, gums, magnolia, and water oaks), respectively. Bass were exposed to different effluent concentrations (0 [controls, exposed to well water], 10, 20, 40, or 80%) for either 28 or 56 days. At the end of each exposure period, fish were euthanized, gonads collected for histological evaluation and determination of gonadosomatic index (GSI), and plasma was analyzed for 17??-estradiol, 11-ketotestosterone, and vitellogenin (VTG). Largemouth bass exposed to B/UKME responded with changes at the biochemical level (decline in sex steroids in both sexes and VTG in females) that were usually translated into tissue/organ-level responses (declines in GSI in both sexes and in ovarian development in females). Although most of these responses occurred after exposing fish to 40% B/UKME concentrations or greater, some were observed after exposures to 20% B/UKME. These threshold concentrations fall within the 60% average yearly concentration of effluent that exists in the stream near the point of discharge (Rice Creek), but are above the <10% effluent concentration present in the St. Johns River. The chemical(s) responsible for such changes as well as their mode(s) of action remain unknown at this time.

  5. 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

  6. 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.

  7. 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

  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. 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.

  10. 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.

  11. 漂白硫酸盐苇浆制浆废水的处理%Treatment of the Waste Water from a Mill Producing Bleached Kraft Reed Pulp

    Institute of Scientific and Technical Information of China (English)

    马乐凡; 李晓林; 王跃泉

    2001-01-01

    Laboratory results of the treatment of pulping black liquor,washing and bleaching waste wate of a mill producing bleached kraft reed pulp were presented. Process and installation of reed BKP pulping waste water treatment were designed, operation parameters and running results of treatment stages were discussed. Black liquor after anaerobic treatment and acid precipitating of lignin could be mixed with washing and bleaching waste water based on the discharged ratio of the mill to discharge, the pollution load of the mixed effluent will meet the national regulation requirement after further treatment by active sludge.%讨论了漂白硫酸盐苇浆厂制浆黑液和中段废水的实验室处理结果。设计了芦苇BKP制浆废水的处理工艺流程和装置,并重点讨论了各处理段的运行参数和运行结果。BKP苇浆蒸煮黑液首先经厌氧和酸析木素处理,然后再与制浆中段水按工厂排放比例混合,混合废水经活性污泥法处理后,可达到国家标准排放。

  12. 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.

  13. 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.

  14. 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...

  15. 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

  16. 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.

  17. Effects of ozone on kraft process pulp mill effluent

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, A. (Stanley Industrial Consultants, Edmonton, Alberta (Canada)); Smith, D.W. (Univ. of Alberta, Edmonton, (Canada))

    1992-12-01

    Effluent from a kraft process pulp mill was studied in a batch reactor for ozone doses between 50 and 200 mg O[sub 3]/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.

  18. 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 ...

  19. 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.

  20. 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.

  1. REINFORCEMENT POTENTIAL OF BLEACHED SAWDUST KRAFT PULP IN DIFFERENT MECHANICAL PULP FURNISHES

    Directory of Open Access Journals (Sweden)

    Risto I. Korpinen

    2009-11-01

    Full Text Available Bleached unrefined and refined sawdust kraft pulps were added to bleached Norway spruce thermomechanical (TMP and pressurised groundwood (PWG pulps in different proportions. Handsheets were prepared and tested for physical properties. In addition, economic calculations were done to estimate the production costs of different bleached pulps in Finland. It was found that the addition of unrefined and refined sawdust kraft pulp improved drainability of the mechanical pulps. Tear strength of PGW furnishes was increased when either unrefined or refined sawdust pulp was added. Tear strength of TMP furnishes was not influenced when different sawdust kraft pulps were added. Up to 30 % of unrefined sawdust kraft pulp could be added and no significant negative effect was observed in TMP and PGW furnishes. On the other hand, when refined sawdust kraft pulp was added into the mechanical pulp furnishes, a clear improvement in the tensile strength was observed. According to the economic calculation the production cost of bleached sawdust kraft pulp is almost as low as the production cost of bleached mechanical pulp. We suggest that economically viable sawdust kraft pulp can be used as a substituent for expensive long fibre reinforcement kraft pulp in the production of mechanical pulp based papers.

  2. 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)

  3. 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.

  4. 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...

  5. 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.

  6. Molecular analysis of bacterial isolates and total community DNA from kraft pulp mill effluent treatment systems.

    Science.gov (United States)

    Fortin, N; Fulthorpe, R R; Allen, D G; Greer, C W

    1998-06-01

    Chloroaliphatics are major components of bleached kraft mill effluents. Gene probes and oligonucleotide primers were developed to monitor kraft pulp mill effluent treatment systems for the presence of key genes (dehalogenases) responsible for the dehalogenation of chloroaliphatic organics. The primers were used for polymerase chain reaction (PCR) analysis of genomic DNA extracted from dehalogenating bacterial isolates and from total community DNA extracted from water and sediments of mill effluent treatment system. PCR amplification with oligonucleotide primers designed from dhlB, encoding the haloacid dehalogenase from Xanthobacter autotrophicus, revealed the presence of dehalogenase genes in both aerated lagoons and stabilization basins. Similarly, positive results were obtained with mmoX primers designed from the soluble methane monooxygenase gene of Methylococcus capsulatus Bath. The haloacetate dehalogenase encoding gene (dehH2) from Moraxella sp. was typically not detected in mill effluent treatment systems unless the biomass was selectively enriched. DNA sequence analysis of several PCR fragaments revealed significant similarity to known dehalogenase amd methane monooxygenase genes. The results indicated a broad distribution of known dehalogenation genes and bacteria with chloroorganic-degrading potential in the mill effluent treatment systems. PMID:9734304

  7. 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.

  8. TCF bleaching sequence in kraft pulping of olive tree pruning residues.

    Science.gov (United States)

    Requejo, A; Rodríguez, A; Colodette, J L; Gomide, J L; Jiménez, L

    2012-08-01

    The aim of the present work was to find a suitable Kraft cooking process for olive tree pruning (OTP), in order to produce pulp of kappa number about 17. The Kraft pulp produced under optimized conditions showed a viscosity of 31.5 mPa·s and good physical, mechanical, and optical properties, which are suitable for paper production. The physical-mechanical and optical properties were measured before and after bleaching. Although the OTP pulp was bleached to 90.9% ISO brightness (kappapulp showed a brightness reversion equal to 1.3%. Furthermore, this bleached pulp did not need a high intensity of beating due to high drainability degree in the unbeaten pulp. So that, OTP is suggested as an interesting raw material for cellulosic pulp production because its properties are comparable to those of other agricultural residues, currently used in the paper industry.

  9. Ecotoxicological assessment of a recipient lake sediment of bleached-kraft pulping discharges

    Energy Technology Data Exchange (ETDEWEB)

    Suominen, K.P.; Wittmann, C.; Liukkonen, M.; Kaehkoenen, M.A.; Salkinoja-Salonen, M.S.

    1999-10-01

    The authors assessed the biological status of age-dated sediments in Lake Saimaa, a recipient lake for wastewaters from pulp and paper industry for more than 100 years that has also received kraft pulp bleaching wastewater since 1954. Adenosine triphosphate content dropped in the recipient sediment from the top 1 cm to 4 to 6 cm below the sediment surface by a factor of 1,000 but increased again in deeper, older layers. The dominant species in the diatom community, Aulacoseira alpigena and Cyclotella kuetzingiana, disappeared and were replaced by Asterionella formosa in the 4- to 6-cm layer. This layer was three- to fivefold more toxic to Vibrio fischeri (as measured by the median effective concentration) and slightly genotoxic (as measured by the SOS-chromotest induction ratio, I{sub c}/I{sub o} for Esherichia coli PQ37) compared with the layers above and below it. The 4- to 6-cm layer also contained up to 4,900 mg of solvent-soluble organic halogen. Enzyme activity was detected at depths of 0 to 1 cm and 4 to 6 cm, and more than 90% of the enzymes were bound to the particulate matter. Ninety-seven percent of the organic halogen in the sediment was particle bound. Apparently, full ecological recovery occurred in the layer from 0 to 1 cm, which had accumulated in 1990s, after the discharging pulp mill discontinued use of Cl{sub 2} in the bleaching process and installed full-scale biological treatment for the wastewaters.

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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.

  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. 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

  3. Advanced Modeling and Materials in Kraft Pulp Mills

    Energy Technology Data Exchange (ETDEWEB)

    Keiser, J.R.; Gorog, J.P.

    2002-05-15

    This CRADA provided technical support to the Weyerhaeuser Company on a number of issues related to the performance and/or selection of materials at a number of locations in a pulp and paper mill. The studies related primarily to components for black liquor recovery boilers, but some effort was directed toward black liquor gasifiers and rolls for paper machines. The purpose of this CRADA was to assist Weyerhaeuser in the evaluation of materials exposed in various paper mill environments and to provide direction in the selection of alternate materials, when appropriate.

  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. 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...

  6. 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.

  7. 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.

  8. 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

  9. Characterization of kraft pulp mill particulate emissions—A summary of existing measurements and observations

    Science.gov (United States)

    Pinkerton, John E.; Blosser, Russell O.

    Particulate matter emission sources at a kraft pulp mill include kraft recovery furnaces, lime kilns, smelt dissolving tanks and power boilers. Chemical and physical characteristics of these paniculate emissions are reviewed. Measurements of particle size distributions for these sources made with cascade impactors and microscopic counting techniques both before and after paniculate control devices such as multiple cyclones, wet scrubbers, and electrostatic precipitalors are discussed. In general, particles with equivalent diameters less than 3 jim comprise the bulk of the controlled paniculate emissions from all sources. Sodium sulfate is the dominant paniculate emission from kraft recovery furnaces, smelt dissolving tanks and lime kilns. Results from a field investigation of the relationship between human observations of near-stack plume opacity and measured in-stack paniculate concentrations and opacities are summarized. Trained cenified panels of observers were used in the investigation to estimate plume opacities from two kraft recovery furnaces, a combination wood/coal-fired boiler, and a combination wood/oil-fired boiler at four different pulp mill locations. Plume opacities were varied from near-zero to 45 % by adjustment of the paniculate control equipment operation. The effects of different background viewing conditions, observer positions, observer experience levels, and plume characteristics are enumerated. It is concluded that there can be substantial variations between measured in-stack opacities and human perceptions of near-stack plume opacities. The degree of agreement between the human judgements and measured in-stack opacities is significantly affected by the background viewing conditions. It is further shown that even with a panel of six or seven trained observers with similar visual acuity, there can be significant departures of individual opacity readings from the panel mean opacity. Although this investigation deals with questions of human

  10. 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.

  11. Geração de finos no branqueamento de pasta kraft de eucalipto e seu efeito nas propriedades do papel Genarations of fines in eucalyptus kraft pulp bleaching and their effect on paper properties

    Directory of Open Access Journals (Sweden)

    Jaqueline Silveira Comelato

    2013-02-01

    Full Text Available Este trabalho teve por objetivo avaliar a quantidade de finos gerada por diferentes reagentes de branqueamento e seu efeito nas propriedades físicas e mecânicas da celulose kraft de eucalipto. A polpa foi branqueada por quatro sequências diferentes. Parte das amostras foi classificada em equipamento Bauer-McNett, sendo a parte não classificada (global refinada para 40 ºSR, em moinho laboratorial PFI. As duas maiores porções de cada amostra proveniente da classificação foram também refinadas com o mesmo número de revoluções que a sua amostra global. Realizaram-se ensaios físicos e mecânicos das amostras refinadas, e suas fibras foram analisadas em equipamento FQA (Fiber Quality Analyser, antes e depois do refino. A maior quantidade de finos foi observada nas polpas refinadas e na sequência-referência. Os resultados de tração foram mais elevados e significativos nas amostras globais; as polpas classificadas não apresentaram diferença entre si, sendo atribuída a maior resistência à tração na presença de finos. A resistência ao rasgo foi afetada pelo comprimento das fibras e não pelo teor de finos. Os maiores valores de ascensão capilar Klemm ocorreram nas amostras classificadas em razão da ausência de finos e do maior comprimento de fibras.The objective of this work was to evaluate the generation of fines by different bleaching reagents and its effect on physical and mechanical properties of eucalyptus kraft pulp. The pulp was bleached by four different sequences. Some of these samples was classified in Bauer-McNett equipment. The unclassified part of the pulp (global was refined to 40ºSR in a laboratory PFI mill. The two major classified portions of each sample were also refined at the same revolutions as its global sample. Physical and mechanical tests were performed for both classified and unclassified samples, and their fibers were analyzed in FQA (Fiber Quality Analyzer, before and after refining.The greater

  12. 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.

  13. 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.

  14. 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

  15. 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...

  16. 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

  17. 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

  18. 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

  19. 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...

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. 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 ...

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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...

  10. 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...

  11. 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.

  12. 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

  13. 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...

  14. 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.

  15. Electro-coagulation treatment efficiency of graphite, iron and aluminum electrodes using alum and wood ash electrolytes on a Kraft pulp and paper mill effluent.

    Science.gov (United States)

    Orori, O B; Etiégni, L; Senelwa, K; Mwamburi, M M; Balozi, K B; Barisa, G K; Omutange, E S

    2010-01-01

    Specific power consumption and reduction of BOD, COD, TS, pH, and chemical elements were used to determine the treatment efficiency of Fe, graphite and Al electrodes with alum and wood ash as supporting electrolytes on the effluent from a Kraft pulp and paper mill in Kenya. Five sampling points were selected along mill's effluent treatment system: primary settling tank (SP1), first aerated lagoon (SP2), second aerated lagoon (SP3), stabilization pond (SP4), and at discharge point (SP5). Operating costs were also compared between treatments. Graphite electrodes combined with alum showed the lowest power consumption (0.5 to 3.9 mWh/m³), followed by Al and Fe. All the electrodes reduced color from a maximum of 3,200°H to the minimum local standard of 15°H. However Al electrode with alum was the most effective method for BOD and COD reduction by over 60% and 58.8% respectively and generated less sludge at all sampling points. The cost of treatment was lowest with graphite electrode (US$0.006 to 0.0008 per m³ of effluent), but highest with Al electrodes combined with wood ash (US$31.74 to 8.34 per m³). Further study is required for the effectiveness of increasing the concentration of wood ash leachate at higher concentration and current density. PMID:20935369

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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

  3. 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...

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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 ...

  13. 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...

  14. Alkaline xylan extraction of bleached kraft pulp-effect of extraction time on pulp chemical composition and physical properties%漂白硫酸盐浆的碱性木聚糖抽提对纸浆化学组分和物理性质的影响

    Institute of Scientific and Technical Information of China (English)

    林庆旭; 夏新兴

    2013-01-01

    In this pilot scale study, we examined the effects of alkaline extraction time on xylan removal, pulp and paper properties, and the consequences that need to be addressed when scaling up and intensifying the process. Alkaline extraction of bleached birch kraft pulp yields two fractions:pure polymeric xylan and pulp with reduced xylan content. Our results indicate that a similar amount of xylan can be extracted in 5 min as the amount obtained in 60 min. We found, however, that the shorter extraction time is beneficial to maintain the fiber and paper properties at an acceptable level. This pilot trial demonstrated that the washing procedure of the alkali-treated fibers must be selected with care to avoid causing mechanical damage to fibers and to avoid the loss of fines.%  研究了扩大和强化过程时碱抽提时间对木聚糖去除、纸浆和纸张性能及结果的影响。漂白桦木硫酸盐浆的碱抽提产生了两部分产物:纯木聚糖和木聚糖含量降低的纸浆。研究结果表明:抽提5m in得到的木聚糖量与抽提60m in得到的木聚糖量是相近的;在合理的范围内,缩短提取时间有利于保持纤维和纸张的性能;碱处理纤维的洗涤必须小心进行,以避免造成对纤维的机械损伤,以及细小纤维的流失。

  15. 木聚糖酶诱导释放负电荷及其对漂白硫酸盐浆纤维胶体作用和留着的影响%Xylanase-induced liberation of negatively charged species and their effect on colloidal interactions and the retention of bleached kraft pulp ifbers

    Institute of Scientific and Technical Information of China (English)

    苗成; 刘忠

    2016-01-01

    The ability and specificity of various monocomponent endo-1,4-β-xylanases to release negatively charged species from never-dried, bleached, birch kraft pulp was studied. The effects of dissolution of these xylan-based components on pulp ifltrate properties and the subsmoluent chemical retention were determined. The results revealed that the amount of charged species released depended on the xylanase and that the ratio of charged species released to dissolved xylan is not linear. Chemical retention tests showed that high levels of dissolved xylan interfere with the ifxation of colloidal species, which was conifrmed by removing the dissolved hemicelluloses. The roles of residual hemicellulose and the properties of modified fibers on chemical retention and the level of internal sizing are discussed.%本文研究未干燥的漂白硫酸盐浆中各种内切-1,4-β-木聚糖酶组分释放负电荷的能力和特异性,同时分析木聚糖组分溶解液对浆料滤液性能和化学留着的影响。实验结果表明,电荷释放的数量和木聚糖酶相关,溶解木聚糖的质量和电荷释放量不成线性关系。化学留着实验表明,高含量溶解木聚糖能够影响胶体的固化作用,因为该过程能够移除溶解的半纤维素。本文探究残留的半纤维素和改性纤维性能对化学留着的作用和浆内施胶的影响。

  16. Pulping of the giant leucaena wood. I. Pulping by the kraft process

    Energy Technology Data Exchange (ETDEWEB)

    Usami, K.; Ogino, T.; Takano, I.; Shimada, K.; Nishida, A.

    1980-01-01

    Cooking of Leucaena latisiliqua with kraft liquor (30% sulfidity as Na/sub 2/O) at 160 degrees gave 59.1% pulp with Kappa number 59.0 and Hunter brightness 19.9. The strength properties of pulp were comparable to those of beech pulp. It was confirmed that the extractives remaining in the bleached pulp adversely affect the color reversion.

  17. 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)

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

    Directory of Open Access Journals (Sweden)

    Kátia M. M. Eiras

    2005-12-01

    Full Text Available 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(PODD, O(DC(PODP, OD(PODD, OD(PODP, ODHT(PODD, ODHT(PODP, OA/D(PODD, OA/D(PODP, OAD(PODD and O(ZeD(PO. Brightness stability tests induced by according to Tappi UM200 procedureon samples bleached to 90±0.5% ISO. Brightness stability was measured after each bleaching stage of the various sequences andexpressed as brightness loss in % ISO. The results indicate that pulps bleached with sequences ending with a peroxide stage havehigher brightness stability compared to those ending with a chlorine dioxide stage. Pulps bleached with a standard sequence, initiatingwith a (DC stage, show brightness stability similar to that of pulp bleached by an ECF (Elementary chlorine free sequence initiatingwith a regular D0 stage. ECF sequences, initiated with hot stages produce pulps with higher brightness stability than sequencesinitiating with a regular D0 stage. The profile across the bleaching sequences shows a tendency of increased brightness stability inalkaline stages containing peroxide and decreased stability in those stages containing chlorine and/or chlorine dioxide, parallelingpulp carbonyl group content.

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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...

  6. 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.

  7. 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.

  8. 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.)

  9. 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.

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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

  18. Control of the accumulation of non-process elements and organic compounds in pulp mills with bleach filtrate reuse. Quarterly report, October--December 1996

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, W.J.; Laver, M.L.; Rorrer, G.L.

    1996-12-31

    A portion of each filtrate sample was freeze-dried and the resulting solids were analyzed for ash content. Adsorption experiments with calcium and barium were carried at 70{degrees}C in a temperature controlled incubator under continuous mixing in order to simulate the environment experienced by brownstock as it moves through the Q stage. In the calcium experiments, it was difficult to accurately determine the calcium adsorbed on the pulp by measuring the depletion of calcium in the aqueous phase. Consequently, the technique was modified. In the modified technique, the calcium-adsorbed pulp is acid washed again to release the calcium. The calcium concentration in the washings is measured, and the calcium adsorbed on the pulp is estimated by material balance. Measurement of calcium adsorption on the brownstock pulp fibers from the L-P/Samoa mill have been obtained.

  19. Alternative Technologies for Biofuels Production in Kraft Pulp Mills—Potential and Prospects

    Directory of Open Access Journals (Sweden)

    Esa Vakkilainen

    2012-07-01

    Full Text Available The current global conditions provide the pulp mill new opportunities beyond the traditional production of cellulose. Due to stricter environmental regulations, volatility of oil price, energy policies and also the global competitiveness, the challenges for the pulp industry are many. They range from replacing fossil fuels with renewable energy sources to the export of biofuels, chemicals and biomaterials through the implementation of biorefineries. In spite of the enhanced maturity of various bio and thermo-chemical conversion processes, the economic viability becomes an impediment when considering the effective implementation on an industrial scale. In the case of kraft pulp mills, favorable conditions for biofuels production can be created due to the availability of wood residues and generation of black liquor. The objective of this article is to give an overview of the technologies related to the production of alternative biofuels in the kraft pulp mills and discuss their potential and prospects in the present and future scenario.

  20. 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.

  1. 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.

  2. Evaluation of bleachability on pine and eucalyptus kraft pulps

    Directory of Open Access Journals (Sweden)

    Marcela Freitas Andrade

    2013-09-01

    Full Text Available In recent decades, the pulp industry has been changing and improving its manufacturing processes in order to enhance production capacity, product quality and environmental performance. The aim of this study was to evaluate the bleachability effect on the efficient washing and alkaline leaching in eucalyptus and pine Kraft pulps using three different bleaching sequences: AD(EPD, A/D(EPDP and DHT(EPDP. This study was carried out in two stages. In the first part, the optimum conditions for pulp bleaching in order to achieve a brightness of 90% ISO were established. The second step was a comparative study between the pulps that received alkaline leaching and efficient washing with reference pulp (without treatment. The brightness, viscosity, kappa number and HexA in pulp were analyzed. The three sequences studied reached the desired brightness, but the sequence AD(EPD produced a lower reagent consumption for the same brightness. In the three sequences studied, the efficient washing of the pulp after oxygen delignification has contributed significantly to the removal of dissolved organic and inorganic materials in the pulp and the alkaline leaching decreased significantly the pulp kappa number due to a higher pulp delignification and bleachability.

  3. Nanocrystalline cellulose from aspen kraft pulp and its application in deinked pulp.

    Science.gov (United States)

    Xu, Qinghua; Gao, Yang; Qin, Menghua; Wu, Kaili; Fu, Yingjuan; Zhao, Jian

    2013-09-01

    Nanocrystalline cellulose (NCC) isolated from bleached aspen kraft pulp was characterized, and its application as pulp strengthening additive and retention aid was investigated. Results showed that NCC with high crystallinity of more than 80% can be obtained using 64 wt% sulfuric acid. The structure of nanocrystalline cellulose is parallelepiped rod-like, and their cross-sectional dimension is in the nanometer range with a high aspect ratio. The formation of microparticle retention systems during the application of NCC together with cationic polyacrylamide and cationic starch in deinked pulp was able to further improve pulp retention and strength properties without negative influence on the drainage.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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 ...

  17. 78 FR 31315 - Kraft Pulp Mills NSPS Review

    Science.gov (United States)

    2013-05-23

    ... Transfer and Advancement Act J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations I. Executive Summary A. Purpose of Regulatory Action... Sierra Club case, the D.C. Circuit vacated the SSM exemption provisions in the General Provisions of...

  18. Harvesting undelimbed Scots pine (Pinus sylvestris L.) from first thinnings for integrated production of kraft pulp and energy

    Energy Technology Data Exchange (ETDEWEB)

    Jylhae, P.

    2011-12-15

    The present study evaluates the feasibility of undelimbed Scots pine (Pinus sylvestris L.) for integrated production of pulp and energy in a kraft pulp mill from the technical, economic and environmental points of view, focusing on the potential of bundle harvesting. The feasibility of tree sections for pulp production was tested by conducting an industrial wood-handling experiment, laboratory cooking and bleaching trials, using conventional small-diameter Scots pine pulpwood as a reference. These trials showed that undelimbed Scots pine sections can be processed in favourable conditions as a blend with conventional small-diameter pulpwood without reducing the pulp quality. However, fibre losses at various phases of the process may increase when using undelimbed material. In the economic evaluation, both pulp production and wood procurement costs were considered, using the relative wood paying capability of a kraft pulp mill as a determinant. The calculations were made for three Scots pine first-thinning stands with the breast-height diameter of the removal (6-12 cm) as the main distinctive factor. The supply chains included in the comparison were based on cut-to-length harvesting, whole-tree harvesting and bundle harvesting (whole-tree bundling). With the current ratio of pulp and energy prices, the wood paying capability declines with an increase in the proportion of the energy fraction of the raw material. The supply system based on the cut-to-length method was the most efficient option, resulting in the highest residual value at stump in most cases. A decline in the pulp price and an increase in the energy price improved the competitiveness of the whole-tree systems. With short truck transportation distances and low pulp prices, however, the harvesting of loose whole trees can result in higher residual value at stump in small-diameter stands. While savings in transportation costs did not compensate for the high cutting and compaction costs by the second

  19. 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

  20. 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...

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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.

  8. 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.

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    Elias Retulainen

    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.

  11. 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

  12. 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...

  13. 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...

  14. INCLUSION OF A PRESSURIZED ACIDOLYSIS STAGE IN CHEMICAL PULP BLEACHING

    Directory of Open Access Journals (Sweden)

    Samar K. Bose

    2011-02-01

    Full Text Available Hardwood soda-AQ pulps are believed to be rich in benzyl sugar ethers (BSE that can be partially cleaved by aqueous acidic treatments. The aim of this investigation was to evaluate the effect of acidolysis on final bleached brightness for kraft and soda-AQ (SAQ hardwood pulps. The increase in final brightness due to acidolysis at 110 °C was twice as high for a eucalyptus SAQ pulp as compared to the kraft pulp. An oxygen delignified maple C-SAQ pulp (carbonate pre-treated SAQ was acidolyzed at 120 °C and pH 2.6 for 30 min. When 1.60% ClO2 + 0.25% H2O2 on pulp was used in DEPD final bleaching of the control sample a brightness of 91.5% was achieved. When only 1.00% ClO2 + 0.25% H2O2 on pulp was used for the acidolyzed sample a brightness of 92.0% was attained. Analyses of the maple pulp after the acidolysis showed no major change in lignin content, brightness, or pulp yield. The minor changes suggest that a facile reaction such as benzyl ether cleavage was responsible for the improved bleachability. Preliminary research involving a lignin model compound and commercial birch xylan showed that lignin-carbohydrate condensation products were generated under SAQ cooking conditions. Furthermore, a fraction of these lignin-carbohydrate moieties were subsequently cleaved by acidolysis at pH 2.5 and 105 °C.

  15. Branes and the Kraft-Procesi Transition

    CERN Document Server

    Cabrera, Santiago

    2016-01-01

    The Coulomb and Higgs branches of certain 3d N=4 gauge theories can be understood as closures of nilpotent orbits. Furthermore, a new theorem by Namikawa suggests that this is the simplest possible case, thus giving this class a special role. In this note we use branes to reproduce the mathematical work by Kraft and Procesi. It studies the classification of all nilpotent orbits for classical groups and it characterizes an inclusion relation via minimal singularities. We show how these minimal singularities arise naturally in the Type IIB superstring embedding of the 3d theories. The Higgs mechanism can be used to remove the minimal singularity, corresponding to a transition in the brane configuration that induces a new effective 3d theory. This reproduces the Kraft-Procesi results, endowing the family of gauge theories with a new underlying structure. We provide an efficient procedure for computing such brane transitions.

  16. PEROXYACID ENHANCED OXYGEN DELIGNIFICATION OF KRAFT PULP

    Institute of Scientific and Technical Information of China (English)

    JianZhao; XuezhiLi; ShulanShi; HuirenHu

    2004-01-01

    Effect of peroxyacid (a mixture ofperoxymonosulfuric acid and peroxyacetic acid)pretreatment on oxygen delignification of kraft pulpfrom eucalyptus was studied, and the conditions ofpretreatment (e.g. DTPA charge, peroxyacid charge,pretreatment time, pretreatment temperature and pHvalue) were optimized. The results show thatperoxyacid pretreatment prior to oxygendelignification could enhance oxygen delignificationof kraft pulp, and result in selective delignificationand increased delignified-pulp brightness. Theoptimum conditions of peroxyacid pretreatment wereas follows: peroxyacid charge 3% (onperoxymonosulfuric acid), 60~C, 30min, 12% pulpconsistency, pH5.0. Pretreatment with 0.5%DTPAwas essential before peroxyacid pretreatment. Underthe optimum conditions, the degree of delignificationand brightness of final pulp were increased by 12.4%(from 44.9% to 57.3%) and 4.9%(ISO, from 54.0%to 58.9%) respectively while maintaining a similarviscosity of final pulps compared to single oxygendelignification.

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. Bleaching of Black Human Hair

    Institute of Scientific and Technical Information of China (English)

    林琳

    2001-01-01

    Bleaching of black human hair has been studied systematically. On the basis of experimental data the technology of human hair bleaching through five processes was established. The optimum technology of improving the whiteness and reducing damage on fibers has been found. The technology can provide good luster,smooth handle and relatively high strength retention to human hair used for wigs or drama articles, meeting the needs of people better. Moreover, it also has important reference value to bleaching of other colored fibers.

  2. 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...

  3. 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.

  4. 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...

  5. 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.

  6. 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

  7. EFFECT OF XYLANASE TREATMENT ON DEWATERING PROPERTIES OF BIRCH KRAFT PULP

    Directory of Open Access Journals (Sweden)

    Minna Marianne Blomstedt

    2010-04-01

    Full Text Available In this study it was shown that the enzymatic removal of xylan from ECF-bleached birch kraft pulp enhances the water removal from the pulp, especially in the late stages of pulp drying. The effect of xylanase treatments on dewatering was clarified by using a moving belt former (MBF, a press simulator (MTS, and an IR-drying equipment, to simulate and to measure dewatering properties on wire, press and drying sections of a paper machine. The xylanase treatment slightly increased the pulp freeness indicating improved pulp drainage properties. At the moving belt former, however, no significant changes that would indicate enhanced dewatering in forming were observed. The xylanase treatments slightly enhanced the dewatering in wet pressing and furthermore, at the thermal drying the xylanase treatment had a positive effect on the dry solid content (DSC development, and time to reach the 95% dry solids content was reduced by up to 15%. This was also confirmed by the decrease in the fiber saturation point (FSP values and the amount of bulk water. Our results indicate that the xylanase treatment affected the water-binding xylan in the fiber cell wall, yielding enhanced dewatering properties, without deteriorating the pulp and paper properties.

  8. 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...

  9. 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

  10. 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 ...

  11. 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)

  12. 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

  13. 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

  14. 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.

  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. 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

  17. 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)

  18. Caracterização tecnológica da madeira de Eucalyptus benthamii para produção de celulose kraft

    Directory of Open Access Journals (Sweden)

    Isabel Cristina Nogueira Alves

    2011-01-01

    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.

  19. 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....

  20. 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...

  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. Utilization of by-product sulfur in Kraft pulping process

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L.; Liu, S. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Chung, K.H. [Syncrude Canada Ltd., Edmonton, AB (Canada). Edmonton Research Centre

    2004-07-01

    This presentation describes how sulfur derived from heavy oil processing can be used by the pulp and paper industry to increase yield, accelerate delignification and shorten the cooking time in the kraft pulping process. The liquor used in the kraft pulping process is a solution of sodium sulfide and sodium hydroxide. The reaction kinetics of delignification in the cooking process was examined and a new method was proposed. The 3 key kinetic steps in the new method include: (1) adsorption of hydroxide and hydrosulfide ions on the fiber wall, (2) chemical reaction on the solid surface to produce degraded lignin products, and (3) desorption of degradation products from the solid surface. The surface reaction is the most important step in the delignification process. A newly developed kinetic model based on the proposed mechanism can be used to accurately predict the pulping behaviour under a variety of conditions.

  3. 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...

  4. 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...

  5. 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. ...

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. [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

  11. THE STUDY ON TCF BLEACHING OF NS REED PULP

    Institute of Scientific and Technical Information of China (English)

    Meihong Niu; Shulan Shi; Jinghui Zhou; Yunzhan Zhang

    2004-01-01

    In this paper, we have researched TCF bleaching on reed pulp including oxygen delignification, oxygen delignification with H2O2 intensification and H2O2 bleaching. The results show that Op-P bleaching process on NS reed pulp is suitable and the brightness of bleached pulp is up to 82% ISO.

  12. THE STUDY ON TCF BLEACHING OF NS REED PULP

    Institute of Scientific and Technical Information of China (English)

    MeihongNiu; ShulanShi; JinghuiZhou; YunzhanZhang

    2004-01-01

    In this paper, we have researched TCF bleaching on reed pulp including oxygen delignification, oxygen delignification with H202 intensification and H2O2 bleaching. The results show that Op-P bleaching process on NS reed pulp is suitable and the brightness of bleached pulp is up to 82%ISO.

  13. PEROXIDE BLEACHING OF LOW-FREENESS TMP

    Institute of Scientific and Technical Information of China (English)

    Zhong Liu; Y. Ni; Z. Li; G. Court

    2004-01-01

    Peroxide bleaching is an essential unit operation to produce value-added mechanical pulp-based paper grade. In this paper, we presented the results from peroxide bleaching of low-freeness TMP for the production of SC paper. Two aspects were addressed; the effect of pulp strength and the formation of anionic trashes. The strength properties,such as tensile, burst and zero-span tensile, are improved after the peroxide bleaching process. The amount of anionic trashes formed is almost proportional to the hydrogen peroxide charge.

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

    DEFF Research Database (Denmark)

    Langkjær, Michael Alexander

    2000-01-01

    journals - as sources of our knowledge of the genesis and development of his Brief Account of the Savage Peoples, I address the following questions: A. On what did Kraft base his ideas about a universal developmental cultural history of man? B. What was Kraft's true purpose in demonstrating empirically...... forward the following theses: 1. Brief Account of the Savage Peoples is informed by a mathematical/physical epistemology; Kraft's method of reducing forms to types of cultural expression by way of "statistical" comparison followed by generalising inductively to (natural) laws of development, as well....... Brief Account of the Savage Peoples shows that Kraft attempted a synthesis of empiricism and rationalism, and that he regarded physical and metaphysical explanations as necessary to the understanding of human nature. 4. Kraft was a heterodox Christian, whose Brief Account of the Savage Peoples should...

  15. 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.

  16. 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, ...

  17. 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.

  18. 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

  19. Laser and LED external teeth-bleaching

    Science.gov (United States)

    Zanin, Fatima A.; Brugnera, Aldo, Jr.; Marchesan, Melissa A.; Pecora, Jesus D.

    2004-09-01

    Teeth-bleaching is an initial phase in the reproduction of an aesthetic smile; thus, it is very important that the dentist knows how to diagnose the causes of color changes and indicate whitening before proposing dental treatment. Technological advances in teeth-whitening lead to the development of new techniques, improving comfort, security and decreasing time of execution: argon laser, diode Laser, LED whitening, xenon light whitening. The clearing agent used in all techniques, including home whitening, is hydrogen peroxide (H2O2) in different concentrations. In this study, the authors describe mechanisms of gel activation, the use of Laser and LED"s for teeth-bleaching, the importance of diagnosis and the comfort of the patient in in-office teeth-bleaching techniques.

  20. 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...

  1. 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...

  2. Characterization of cassava starch based foam blended with plant proteins, kraft fiber, and palm oil.

    Science.gov (United States)

    Kaisangsri, Nattapon; Kerdchoechuen, Orapin; Laohakunjit, Natta

    2014-09-22

    Cassava starch foam (CSF) trays blended with zein, gluten, soy protein, kraft fiber, and palm oil at various concentrations: 0, 5, 10 and 15% by weight of starch, were characterized. The addition of zein and gluten into CSF resulted in consolidated and homogeneous structural foams compared to its controls. Moreover, the flexural and compressive strength increased with increasing kraft, zein and gluten. CSF containing 15% kraft gave the highest flexural and compressive strength. However, the addition of palm oil into CSF gave the lowest flexural strength and compressive strength. The observed water absorption and water solubility index of CSFs blended with 15% zein and 15% gluten protein was lowest. Although kraft, zein and gluten could improve mechanical properties, water absorption and water solubility were greater than the expanded polystyrene foam (EPS). The CSF trays in this study might be an alternative for packing low water content foods.

  3. Effects of biological pre-treatment of pine chips on the beating performance of Kraft pulp

    Institute of Scientific and Technical Information of China (English)

    Sami IMAMOGLU; Celil ATIK

    2007-01-01

    The Calabrien pine (Pinus brutia ) wood chips prior to kraft pulping were biologically pre-treated with selected whiterot fungi ( Ceriporiopsis subvermispora ), which was recorded to be preferentially attacking the lignin component of the wood. The effects of this treatment on beating performance and physical strength of resultant papers were studied in detail. Bio-treated samples showed comparable and, in most cases, higher physico-mechanical properties than those obtained from untreated controls. Under the same beating conditions the bio-treated kraft pulp was noted to have the lower SR° indicating a lower degree of external fibrillation. The paper made from bio-treated kraft pulp has a higher density, tensile property, air permeability and swellability. Furthermore, remarkable energy savings up to 33 % were observed when beating bio-treated kraft pulp. This study contributes to a better understanding of the mechanisms taking place during bio-treatment and the modification processes of cell wall components.

  4. 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 ... 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...

  5. Detrimental effects of host anemone bleaching on anemonefish populations

    Science.gov (United States)

    Saenz-Agudelo, P.; Jones, G. P.; Thorrold, S. R.; Planes, S.

    2011-06-01

    Coral bleaching and related reef degradation have caused significant declines in the abundance of reef-associated fishes. Most attention on the effects of bleaching has focused on corals, but bleaching is also prevalent in other cnidarians, including sea anemones. The consequences of anemone bleaching are unknown, and the demographic effects of bleaching on associated fish recruitment, survival, and reproduction are poorly understood. We examined the effect of habitat degradation including host anemone bleaching on fish abundance, egg production, and recruitment of the panda anemonefish ( Amphiprion polymnus) near Port Moresby, Papua New Guinea. Following a high-temperature anomaly in shallow waters of the region, most shallow anemones to a depth of 6 m (approximately 35% of all the anemones in this area) were severely bleached. Anemone mortality was low but bleached anemones underwent a ~34% reduction in body size. Total numbers of A. polymnus were not affected by bleaching and reduction in shelter area. While egg production of females living in bleached anemones was reduced by ~38% in 2009 compared to 2008, egg production of females on unbleached anemones did not differ significantly between years. Total recruitment in 2009 was much lower than in 2008. However, we found no evidence of recruiting larvae avoiding bleached anemones at settlement suggesting that other factors or different chemical cues were more important in determining recruitment than habitat quality. These results provide the first field evidence of detrimental effects of climate-induced bleaching and habitat degradation on reproduction and recruitment of anemonefish.

  6. INFLUENCES OF BLAECHING ADDITIVES ON REED PULP FAST BLEACHING

    Institute of Scientific and Technical Information of China (English)

    Yanjun Tang; Bingyue Liu; Runan Yang; Zheng Lu

    2004-01-01

    The influences of bleaching additives on hypochlorite single-stage high temperature fast bleaching of neutral-sulfite reed pulp were studied. The influencing factors of bleaching velocity and result were as follows: the order and time of adding imide type additives, additives dosage, the dosage of NaOH and MgO used as buffer to turn up pH.

  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. 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 ...

  9. 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...

  10. 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...

  11. 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.

  12. 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.

  13. REMINERALIZATION POTENTIAL OF A CARBAMIDE BLEACHING AGENT

    Directory of Open Access Journals (Sweden)

    Borislavova Marinova-Takorova Mirela

    2016-03-01

    Full Text Available Background: Bleaching has gradually became a popular procedure for people searching for aesthetic improvement. The aim of this in vitro study was to investigate the effect of bleaching with 45% carbamide peroxide on the level of mineralization of enamel, using laser fluorescence. Materials and methods: Sixty extracted human teeth were treated with 45% carbamid peroxide (Opalescence, Ultradent, 4 consecutive days for one hour each day. The effect of the bleaching agent on the level of mineralization of enamel was measured with DIAGNO dent pen. The statistical method we use was descriptive analysis. Results: The average values, measured before the applications of the carbamid peroxide were 6.33. On the first day they were 5.41, on the second 5.38, on the third 5.11 and 5.35 on the forth. Conclusion: There was observed a slight remineralization effect due to the incorporated Ca2+ and F- ions in the bleaching agent that we have used.

  14. HYDROGEN PEROXIDE BLEACHING OF CMP PULP USING MAGNESIUM HYDROXIDE

    Directory of Open Access Journals (Sweden)

    Farhad Zeinaly

    2009-11-01

    Full Text Available Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH2 show significant benefits over bleaching with sodium hydroxide (NaOH under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF were more for the Mg(OH2-based process. The residual peroxide of filtrate from the Mg(OH2-based process was very high as compared to conventional bleaching.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. 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.

  6. 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...

  7. New Parameter for In-Office Dental Bleaching

    OpenAIRE

    Presoto, Cristina Dupim; Janaina Freitas BORTOLATTO; Carvalho, Priscila Petrucelli Freire de; 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 Araraq...

  8. 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...

  9. 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...

  10. 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:...

  11. 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.

  12. 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...

  13. 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.

  14. 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

  15. 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.

  16. 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 

  17. 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 ...

  18. 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.

  19. 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...

  20. 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...

  1. 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...

  2. On the influence of chlorides and sulphureous compounds on the corrosion of superheater tubes in boilers with special consideration on kraft recovery boilers

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Fredrik [AaF-IPK AB, Stockholm (Sweden)

    1999-03-01

    This report reviews the thermochemistry of the most relevant corrosion reactions and mechanisms with chloride especially considering the kraft pulp mill recovery boiler. The flue gas side corrosion of superheater tubes is governed by the fuel constituents, and by the carryover particles and the gaseous impurities accompanying the flue gases and the local chemical conditions they cause on the superheater tube surface. A study made on coal-fired boilers in Germany has been interpreted so that the protective ability of the oxide layer on the tube surface of a superheater tube is limited, which causes a close to linear time dependence of the material loss due to corrosion. The thermochemistry of the reactions of the protective oxide layer itself with the components of the deposited carryover and the flue gas sulphur components seems thus to govern the mechanism of the corrosion. The corrosion in the recovery boiler is concluded to be more dependant on this combined action of carry-over and sulphureous oxides, so the presence of chlorides in the flue gases only influences the melting range properties of the sulphate deposits, but seems to exert less influence on the chemical reactions which attack the oxides of the passive layer. The thermochemistry also explains the formation of a sulphide layer often found between the deposits and the surface of the tube metal on superheater tubes as a result of reaction with sulpureous oxides from the flue gas and carbon in the carryover. The factors which in practice limit the superheater corrosion in the recovery boiler are interpreted as both material and process dependent. The main limiting factor for the steam temperature is still the melting range of the sulphate deposit. There seems thus to be little hope for the aim to raise the steam temperature of the kraft recovery boiler above the range which is already achievable with the presently available composite tubes 22 refs, 10 figs

  3. 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.

  4. 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

  5. Evaluation of Extraradicular Diffusion of Hydrogen Peroxide during Intracoronal Bleaching Using Different Bleaching Agents

    Directory of Open Access Journals (Sweden)

    Mohammad E. Rokaya

    2015-01-01

    Full Text Available Objectives. Extra radicular diffusion of hydrogen peroxide associated with intracoronal teeth bleaching was evaluated. Methods. 108 intact single rooted extracted mandibular first premolars teeth were selected. The teeth were instrumented with WaveOne system and obturated with gutta percha and divided into four groups (n=27 according to the bleaching materials used. Each main group was divided into three subgroups (n=9 according to the time of extra radicular hydrogen peroxide diffusion measurements at 1, 7, and 14 days: group 1 (35% hydrogen peroxide, group 2 (35% carbamide peroxide, group 3 (sodium perborate-30% hydrogen peroxide mixture, and group 4 (sodium perborate-water mixture. Four cemental dentinal defects were prepared just below the CEJ on each root surface. The amount of hydrogen peroxide that leached out was evaluated after 1, 7, and 14 days by spectrophotometer analysis. The results were analyzed using the ANOVA and Tukey’s test. Results. Group 1 showed highest extra radicular diffusion, followed by group 3 and group 2, while group 4 showed the lowest mean extra radicular diffusion. Conclusion. Carbamide peroxide and sodium perborate-water mixture are the most suitable bleaching materials used for internal bleaching due to their low extra radicular diffusion of hydrogen peroxide.

  6. Bleach Plant Capital Reduction with Rapid DO Bleaching and Simplified (D/E/D) Stages

    Energy Technology Data Exchange (ETDEWEB)

    T. J. McDonough; C. E. Courchene; J-C. Baromes

    2000-08-01

    The objective of this work was to demonstrate the capabilities of a bleaching sequence that combined a short retention time initial chlorine dioxide stage, referred to as rapid D0, (D0R), with simplified bleaching stages, (D1/E/D2), that required only one final bleach washer. The test sequence DR(EPO)(D/E/D/) was compared to a control sequence, D(EPO)D, for both hardwood and softwood pulps. The capabilities of the DR(EPO)(D/E/D) sequence were successfully demonstrated. An existing three- or four-stage bleach plan can be converted to the more powerful DR(EPO)(D/E/D) sequence without the major capital cost of additional washers. The results from this study showed that the DR(EPO)(D/E/D) sequence can reach 85 brightness on SW with 2.8% total C1O2, while the control sequence, D(EPO)D, required 3.9% C1O2. There was a corresponding decrease in AOX for the test sequence. The strength of pulp bleached in the test sequence was similar to or slightly higher than the control. For the HW pu lp, the test sequence reached 88 brightness with 2.2% C1O2 compared to 3.3% C1O2 for the control. There was a corresponding decrease in AOX generation with the lower chemical requirements. The final viscosity and pulp strength for the test sequence on HW was significantly higher than the corresponding values for the control sequence.

  7. A NEW PULP YIELD PREDICTION METHOD APPLIED TO KRAFT,KRAFT-AQ,POLYSULFIDE AND PSAQ PULPING OF ROCK MAPLE

    Institute of Scientific and Technical Information of China (English)

    Adriaan van Heiningen; Yang Gao; Mehmet Sefik Tunc

    2004-01-01

    Pulp yield has a major impact on the competitiveness of a mill. In order to optimize pulp yield, for example by changing operating conditions, a mill must be able to monitor the yield accurately. In our previous work,a new method was presented for prediction of pulp yield. The method is based on a fundamental relationship derived from the kinetics of the alkaline hydrolysis, peeling and stopping reactions of cellulose and the cellulose mass balance during pulping. In this paper the application of the pulp yield prediction equation for pulping of Rock Maple is investigated. The effect of different operating conditions, such as H-factor, temperature, alkali charge, sulfidity, and the presence of anthraquinone and polysulfide are described.

  8. A NEW PULP YIELD PREDICTION METHOD APPLIED TO KRAFT, KRAFT-AQ, POLYSULFIDE AND PSAQ PULPING OF ROCK MAPLE

    Institute of Scientific and Technical Information of China (English)

    AdriaanvanHeiningen; YangGao; MehmetSefikTunc

    2004-01-01

    Pulp yield has a major impact on the competitiveness of a mill. In order to optimize pulp yield, for example by changing operating conditions, a mill must be able to monitor the yield accurately. In our previous work, a new method was presented for prediction of pulp yield. The method is based on a fundamental relationship derived from the kinetics of the alkaline hydrolysis, peeling and stopping reactions of cellulose and the cellulose mass balance during pulping. In this paper the application of the pulp yield prediction equation for pulping of Rock Maple is investigated. The effect of different operating conditions, such as H-factor, temperature, alkali charge, sulfidity, and the presence of anthraquinone and polysulfide are described.

  9. 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 ...

  10. 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.…

  11. 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 872.6475 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching...

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. The effect of bleaching on toothbrush abrasion of resin composites

    Directory of Open Access Journals (Sweden)

    Hila Hajizadeh

    2013-01-01

    Full Text Available Aim: This experimental study was designed to focus on the effects of bleaching on toothbrush abrasion in three types of composites with different filler size. Materials and Methods: Forty eight disks were prepared from three types of composite and divided into 6 groups. In the first three groups the abrasion test was done. The remaining groups were bleached and the abrasion test was performed. The weight of the samples before and after abrasion was measured. Statistical analysis was done with one-way ANOVA and Duncan test. Results: There was a significant difference in abrasion of composites with different filler size (P < 0.05. The most amount of abrasion was observed in Z100 after being bleached. An increase in abrasion was noticed in all three types of tested composite after bleaching. Conclusion: According to the findings, it is suggested to use a nano filled resin composite for restoration if the bleaching treatment is required.

  17. 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

  18. The use of lactoperoxidase for the bleaching of fluid whey.

    Science.gov (United States)

    Campbell, R E; Kang, E J; Bastian, E; Drake, M A

    2012-06-01

    Lactoperoxidase (LP) is the second most abundant enzyme in bovine milk and has been used in conjunction with hydrogen peroxide (H₂O₂) and thiocyanate (SCN⁻) to work as an antimicrobial in raw milk where pasteurization is not feasible. Thiocyanate is naturally present and the lactoperoxidase system purportedly can be used to bleach dairy products, such as whey, with the addition of very little H₂O₂ to the system. This study had 3 objectives: 1) to quantify the amount of H₂O₂ necessary for bleaching of fluid whey using the LP system, 2) to monitor LP activity from raw milk through manufacture of liquid whey, and 3) to compare the flavor of whey protein concentrate 80% (WPC80) bleached by the LP system to that bleached by traditional H₂O₂ bleaching. Cheddar cheese whey with annatto (15 mL of annatto/454 kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a standard Cheddar cheesemaking procedure. Various levels of H₂O₂ (5-100 mg/kg) were added to fluid whey to determine the optimum concentration of H₂O₂ for LP activity, which was measured using an established colorimetric method. In subsequent experiments, fat-separated whey was bleached for 1h with 250 mg of H₂O₂/kg (traditional) or 20 mg of H₂O₂/kg (LP system). The WPC80 was manufactured from whey bleached with 250 mg of H₂O₂/kg or 20mg of H₂O₂/kg. All samples were subjected to color analysis (Hunter color values and norbixin extraction) and proximate analysis (fat, protein, and moisture). Sensory and instrumental volatile analyses were conducted on WPC80. Optimal LP bleaching in fluid whey occurred with the addition of 20mg of H₂O₂/kg. Bleaching of fluid whey at either 35 or 50°C for 1 h with LP resulted in > 99% norbixin destruction compared with 32 or 47% destruction from bleaching with 250 mg of H₂O₂/kg, at 35 or 50°C for 1 h, respectively. Higher aroma intensity and increased lipid oxidation compounds were documented in WPC80 from

  19. Compound taper milling machine

    Science.gov (United States)

    Campbell, N. R.

    1969-01-01

    Simple, inexpensive milling machine tapers panels from a common apex to a uniform height at panel edge regardless of the panel perimeter configuration. The machine consists of an adjustable angled beam upon which the milling tool moves back and forth above a rotatable table upon which the workpiece is held.

  20. The effect of wood supply and bleaching process on pulp brightness stability O efeito do tipo de madeira e do processo de branqueamento na estabilidade da alvura da polpa

    Directory of Open Access Journals (Sweden)

    Romildo Lopes Oliveira

    2006-06-01

    Full Text Available One hundred different 5.5-year-old Eucalyptus grandis x Eucalyptus urophylla wood clones were cooked to kappa number 15-17.5 and the resulting kraft pulps oxygen-delignified to kappa 9.5-11.5 under fixed conditions, except for chemical charges. Thirteen samples showing large variations in effective alkali requirement, pulp yield and O-stage efficiency and selectivity were selected for brightness reversion studies. These samples were bleached to 90-91% ISO by DEDD and DEDP sequences and their brightness stability and chemical characteristics determined. Heat reversion of the eucalyptus kraft pulps was strongly influenced by the wood supply, with brightness loss varying in the range of 2.1-3.6 and 0.8-1.7 %ISO for ODEDD and ODEDP bleached pulps, respectively. Pulps bleached by the ODEDP sequence showed reversion values 1.3-1.9 % ISO lower than those bleached by the ODEDD sequence. Pulp carbonyl content decreased by 35-40% during the final peroxide bleaching stage. Carbonyl and carboxyl groups correlated positively with brightness reversion, as did permanganate number and acid soluble lignin. Pulp final viscosity and metal and DCM extractives contents showed no significant correlation with brightness reversion. Pulping, oxygen delignification and ECF bleaching performances also showed no correlation with brightness reversion.Madeiras de 100 diferentes clones de Eucalyptus grandis e Eucalyptus urophylla, com aproximadamente 5,5 anos de idade, foram cozidas ao número kappa 15-17,5. As polpas kraft produzidas foram pré-deslignificadas com oxigênio ao número kappa 9,5-11,5, sob condições fixas. Treze polpas, que mostraram grandes variações na exigência da carga de álcali efetivo e rendimento no processo de polpação, seletividade e eficiência no estágio de Pré-O, foram selecionadas e branqueadas à alvura DE 90-91% ISO pelas seqüências DEDD e DEDP, para estudos de estabilidade de alvura e características químicas. A reversão de

  1. 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.

  2. 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.

  3. 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

  4. STUDY ON FORMAMIDINE SULPHINIC ACID BLEACHING OF POPLAR APMP

    Institute of Scientific and Technical Information of China (English)

    Meiyun Zhang; Zhaoqing Lu

    2004-01-01

    Bleaching of poplar APMP with Formamidine sulphinic acid (FAS) was investigated in this paper.The effects of FAS charges, ratio of treatment on the brightness gain, color reduction and pulp strength were studied. A single-stage FAS bleaching was optimized. Under the conditions of 10 % pulp consistency, 60 minutes time and 70℃ reaction temperature and 0.6 %, FAS (on 0.d.pulp), ratio of FAS to NaOH was 2, we produced a bleached pulp with a brightness of 62.3 %(SBD), a brightness gain of 9.2 units.

  5. STUDY ON FORMAMIDINE SULPHINIC ACID BLEACHING OF POPLAR APMP

    Institute of Scientific and Technical Information of China (English)

    MeiyunZhang; ZhaooinLu

    2004-01-01

    Bleaching of poplar APMP with Formamidinesulphinic acid (FAS) was investigated in this paper.The effects of FAS charges, ratio of treatment on thebrightness gain, color reduction and pulp strengthwere studied. A single-stage FAS bleaching wasoptimized. Under the conditions of 10 % pulpconsistency, 60 minutes time and 70~C reactiontemperature and 0.6 %, FAS (on 0.d.pulp), ratio ofFAS to NaOH was 2, we produced a bleached pulpwith a brightness of 62.3 %(SBD), a brightness gainof 9.2 units.

  6. 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.

  7. 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

  8. 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...

  9. 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 ...

  10. 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...

  11. 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.

  12. Comparison of two continuous fungal bioreactors for posttreatment of anaerobically pretreated weak black liquor from kraft pulp mills.

    Science.gov (United States)

    Ortega-Clemente, Alfredo; Marín-Mezo, G; Ponce-Noyola, M T; Montes-Horcasitas, M C; Caffarel-Méndez, S; Barrera-Cortés, Josefina; Poggi-Varaldo, Héctor M

    2007-03-01

    The purpose of this work was to evaluate and compare two continuous systems of posttreatment of anaerobically pretreated weak black liquor (WBL). The first system consisted of a packed bed reactor (PBR) with Trametes versicolor (Tv) immobilized on wood cubes of holm oak (biocubes). The second system was a fluidized bed reactor (FBR) with Lentinus edodes (Le) immobilized on wood cubes of holm oak. The reactors operated for 65 days at a hydraulic retention time (HRT) of 5 days, at 28 degrees C, with continuous aeration. Response variables monitored were conventional and specific, unit, net removal efficiency (eta and eta(sun), respectively) of chemical oxygen demand (COD), color, and ligninoids, and enzymatic activities of manganese peroxidase (MnP), lignin peroxidase (LiP), laccase (Lac) and proteases. The PBR showed an average color eta superior to that of the FBR (52.42 +/- 21.78% and 25.34 +/- 14.38% for PBR and FBR, respectively); removals of COD and ligninoids presented a similar pattern to that of color. Lac activity was significantly larger in PBR than in FBR. Activity of MnP in PBR was higher than that of the FBR (0.004 and 0.002 U MnP/mL, respectively). This difference could be ascribed to the different fungi present in each bioreactor. LiP activity was very low in both reactors. Average value of proteases was almost double in the FBR as compared with PBR (0.472 and 0.209 U Proteases/mL, respectively). During the last 2 weeks of operation, biocubes in the FBR experienced a significant loss of the attached Le biomass, probably by attrition. This and higher protease activity in the FBR could explain the lower pollutant removals achieved in the FBR. Overall, PBR with immobilized Tv showed a better performance than the FBR with Le for the posttreatment of the recalcitrant anaerobic effluent. Extended and sustained pollutant removal (65 days) was achieved in the PBR, although more research is needed to evaluate bioreactor performance at shorter hydraulic retention times. PMID:16937406

  13. 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

  14. 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).

  15. New Parameter for In-Office Dental Bleaching.

    Science.gov (United States)

    Presoto, Cristina Dupim; 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). PMID:27375906

  16. 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

  17. 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.

  18. 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.

  19. Insight in the Chemistry of Laser-Activated Dental Bleaching

    Directory of Open Access Journals (Sweden)

    Roeland Jozef Gentil De Moor

    2015-01-01

    Full Text Available The use of optical radiation for the activation of bleaching products has not yet been completely elucidated. Laser light is suggested to enhance the oxidizing effect of hydrogen peroxide. Different methods of enhancing hydrogen peroxide based bleaching are possible. They can be classified into six groups: alkaline pH environment, thermal enhancement and photothermal effect, photooxidation effect and direct photobleaching, photolysis effect and photodissociation, Fenton reaction and photocatalysis, and photodynamic effect.

  20. 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

  1. Insight in the Chemistry of Laser-Activated Dental Bleaching

    OpenAIRE

    Roeland Jozef Gentil De Moor; Jeroen Verheyen; Andrii Diachuk; Peter Verheyen; Maarten August Meire; Peter Jozef De Coster; Filip Keulemans; Mieke De Bruyne; Laurence James Walsh

    2015-01-01

    The use of optical radiation for the activation of bleaching products has not yet been completely elucidated. Laser light is suggested to enhance the oxidizing effect of hydrogen peroxide. Different methods of enhancing hydrogen peroxide based bleaching are possible. They can be classified into six groups: alkaline pH environment, thermal enhancement and photothermal effect, photooxidation effect and direct photobleaching, photolysis effect and photodissociation, Fenton reaction and photocata...

  2. 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...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. 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 ...

  10. 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...

  11. The effect of combined bleaching techniques on oral microbiota

    Directory of Open Access Journals (Sweden)

    Franz-Montan Michelle

    2009-01-01

    Full Text Available Aims : To evaluate the antimicrobial activity of 10% and 37% carbamide peroxide during dental bleaching in three different modes. Materials and Methods : This five-week double-blind randomized controlled trial included 32 volunteers assigned to four groups (n = 8. Each group received bleaching agents or placebo as an in-office and at-home treatment. The dental bleaching techniques were: In-office bleaching (37% carbamide peroxide: CP37; at-home bleaching (10% carbamide peroxide: CP10 and the association of both (CP37 and CP10. Saliva samples were collected right before (baseline, right after, 12 hours after, and seven days after the treatment. Counts of total microorganisms, Streptococci, and Mutans streptococci were carried out. Friedman test (α = 0.05 was used to compare the microorganism counts. Results : The number of the all oral microorganisms remained stable during all experiment. Conclusions : No bleaching agent (CP37, CP10 or the combination of both was able to reduce the oral microorganisms tested.

  12. 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.A.

    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 ...

  13. 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

  14. 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)

  15. Study on Kraft Pulping and Bleaching of the Pulp from E. Globulus%蓝桉硫酸盐法制浆和漂白性能研究

    Institute of Scientific and Technical Information of China (English)

    赵建; 李雪芝; 石淑兰; 胡惠仁

    2003-01-01

    对蓝桉硫酸盐法制浆和漂白性能进行了研究.结果表明,蓝桉具有优良的制浆造纸性能,其较佳的蒸煮工艺条件为:用碱量14%(Na2O),硫化度30%,液比1:5,H-因子1000.采用有元素氯漂白、ECF漂白和TCF漂白程序,均可制得高白度、高强度的蓝桉漂白硫酸盐浆.其中采用CEpH、DEpP漂白程序,漂白浆白度均在86%ISO以上,抗张指数分别达到85.26N@m/g和78.12N@m/g,撕裂指数分别达到7.48mN@m2/g和9.06mN@m2/g.

  16. Eucalyptus Kraft Pulp Bleaching with Chlorine Dioxide at High Temperature%桉木硫酸盐浆在高温用二氧化氯漂白

    Institute of Scientific and Technical Information of China (English)

    劳嘉葆

    2005-01-01

    评价了热二氧化氯(DHT段)操作条件对桉木硫酸盐浆的无元素氯漂白的影响.DHT段比普通D段对减少卡伯值更有效,但延长DHT段在95℃的反应时间超过60~90 min,会引起纸浆变黑.

  17. 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.

  18. 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

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

    Science.gov (United States)

    Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

    2009-09-01

    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. 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.

  1. 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

  2. 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.

  3. 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...

  4. Bacteria associated with the bleached and cave coral Oculina patagonica.

    Science.gov (United States)

    Koren, Omry; Rosenberg, Eugene

    2008-04-01

    The relative abundance of bacteria in the mucus and tissues of Oculina patagonica taken from bleached and cave (azooxanthellae) corals was determined by analyses of the 16S rRNA genes from cloned libraries of extracted DNA and from isolated colonies. The results were compared to previously published data on healthy O. patagonica. The bacterial community of bleached, cave, and healthy corals were completely different from each other. A tight cluster (>99.5% identity) of bacteria, showing 100% identity to Acinetobacter species, dominated bleached corals, comprising 25% of the 316 clones sequenced. The dominant bacterial cluster found in cave corals, representing 29% of the 97 clones sequenced, showed 98% identity to an uncultured bacterium from the Great Barrier Reef. Vibrio splendidus was the most dominant species in healthy O. patagonica. The culturable bacteria represented 0.1-1.0% of the total bacteria (SYBR Gold staining) of the corals. The most abundant culturable bacteria in bleached, cave, and healthy corals were clusters that most closely matched Microbulbifer sp., an alpha-proteobacterium previously isolated from healthy corals and an alpha-protobacterium (AB026194), respectively. Three generalizations emerge from this study on O. patagonica: (1) More bacteria are associated with coral tissue than mucus; (2) tissue and mucus populations are different; (3) bacterial populations associated with corals change dramatically when corals lack their symbiotic zooxanthellae, either as a result of the bleaching disease or when growing in the absence of light.

  5. 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.

  6. AFM analysis of bleaching effects on dental enamel microtopography

    Science.gov (United States)

    Pedreira de Freitas, Ana Carolina; Espejo, Luciana Cardoso; Botta, Sergio Brossi; Teixeira, Fernanda de Sa; Luz, Maria Aparecida A. Cerqueira; Garone-Netto, Narciso; Matos, Adriana Bona; Salvadori, Maria Cecilia Barbosa da Silveira

    2010-02-01

    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 × 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.

  7. 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.

  8. 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.

  9. 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)

  10. 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.

  11. Tooth bleaching--a critical review of the biological aspects

    DEFF Research Database (Denmark)

    Dahl, J E; Pallesen, Ulla

    2003-01-01

    model, indicated that hydrogen peroxide might act as a promoter. Multiple exposures of hydrogen peroxide have resulted in localized effects on the gastric mucosa, decreased food consumption, reduced weight gain, and blood chemistry changes in mice and rats. Our risk assessment revealed that a sufficient......-bleaching technique is used, the first subjective change in tooth color may be observed after 2-4 nights of tooth bleaching, and more than 90% satisfactory results have been reported. Tooth sensitivity is a common side-effect of external tooth bleaching observed in 15%-78% of the patients, but clinical studies...... 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...

  12. 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.

  13. 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

  14. 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...

  15. 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...

  16. 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...

  17. 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

  18. Sunflower oil bleaching by adsorption onto acid-activated bentonite

    Directory of Open Access Journals (Sweden)

    E. L. Foletto

    2011-03-01

    Full Text Available Two bentonite clays with different mineralogical compositions from Mendoza, Argentine, were activated with H2SO4 solutions of 4 and 8 N at 90ºC for 3.5 hours. This treatment affected clay structural properties, as was shown by thermogravimetry, infrared spectrometry and chemical analysis. Bleaching efficiency for sunflower oil was strongly dependent on the acid concentration used for clay activation. The samples have bleaching capacity comparable to that observed with a commercial adsorbent standard. The mineralogical composition of natural clays influenced the properties of the activated clays.

  19. 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

  20. KINETICS OF DELIGNIFICATION AND CARBOHYDRATE DEGRADATION DURING OXYGEN BLEACHING

    Institute of Scientific and Technical Information of China (English)

    K. L Nguyen

    2004-01-01

    Carbohydrate degradation during oxygen bleaching is associated with cleavage reactions. It is apparent that the loss of the cellulose DP (degree ofpolymisation)is strongly affected by the extent of the delignification. A strong linear correlation can be established between the DP of cellulose chains and the residual lignin in the pulp. The Nuclear Growth concept and Percolation Theory for heterogenous system can be combined to formulate kinetic models for both the delignification and the degradation of carbohydrate. The models prediction is statistically robust and can be applied to different pulps at different bleaching conditions.

  1. 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...

  2. 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; Tay, Lidia Yileng

    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 composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3).

  3. Characterization of fatty acid composition in healthy and bleached corals from Okinawa, Japan

    Science.gov (United States)

    Bachok, Zainudin; Mfilinge, Prosper; Tsuchiya, Makoto

    2006-11-01

    Under bleaching conditions, corals lose their symbiotic zooxanthellae, and thus, the ability to synthesize fatty acids (FAs) from photosynthetically derived carbon. This study investigated the lipid content and FA composition in healthy and bleached corals from the Odo reef flat in Okinawa, southern Japan, following a bleaching event. It was hypothesized that the FA composition and abundance would change as algae are lost or die, and possibly microbial abundance would increase in corals as a consequence of bleaching. The lipid content and FA composition of three healthy coral species ( Pavona frondifera, Acropora pulchra, and Goniastrea aspera) and of partially bleached and completely bleached colonies of P. frondifera were examined. The FA composition did not differ among healthy corals, but differed significantly among healthy, partially bleached, and completely bleached specimens of P. frondifera. Completely bleached corals contained significantly lower lipid and total FA content, as well as lower relative amounts of polyunsaturated FAs and higher relative amounts of saturated FAs, than healthy and partially bleached corals. Furthermore, there was a significantly higher relative concentration of monounsaturated FAs and odd-numbered branched FAs in completely bleached corals, indicating an increase in bacterial colonization in the bleached corals.

  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; Tay, Lidia Yileng

    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 bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

  5. 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 bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

  6. 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

  7. 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.

  8. Correlation of Process Data and Electrocheical Noise to Assess Kraft Digester Corrosion: Second Year at Spring Grove

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, SJ

    2004-04-27

    Electrochemical noise (EN) probes were deployed in the carbon steel continuous kraft digester at Spring Grove at four locations and at one location in the bottom cone of the associated flash tank for a second consecutive year of a corrosion study. The probes contained dual electrodes of 309LSi stainless steel overlay--representing a field repair material applied to a portion of the vessel--and dual electrodes of 312 stainless steel overlay. Current and potential noise, the temperature at each probe location, and the value of 23 process parameters (flow rates, liquor chemistry, etc.) were again monitored continuously for a period of almost one year. Historical vessel inspection data and post-test evaluation of the probe components were used to assess/compare EN corrosion activity with physical changes in wall thickness and corrosion patterns on the digester shell. In addition, attempts were made to correlate EN activity from each electrode type with process parameters. The results indicate the corrosion conditions aggressive to mild steel persist within the digester, as post-test inspection of the vessel revealed localized corrosion of mild steel in locations previously free of attack. Further, there was evidence that the depth of localized attack of exposed steel had increased in some locations. Nevertheless, the stainless steel overlay in the digester was essentially immune to corrosion, as evidenced by retained surface relief and heat tint associated with the original deposition process. The 309LSi electrodes also appeared visually pristine, and post-exposure metallographic examination of the 309LSi electrode materials revealed no attack. The 312 electrode materials were similar in appearance, but exhibited very minor interdendritic attack over the exposed surface. The silver electrodes in the probes were consumed (to Ag{sub 2}S) to variable degree over the course of the exposure indicating a useful life of not more than a year in digester service in this vessel

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. Enzymatic Transesterification of Kraft Lignin with Long Acyl Chains in Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Lise Hulin

    2015-09-01

    Full Text Available Valorization of lignin is essential for the economic viability of the biorefinery concept. For example, the enhancement of lignin hydrophobicity by chemical esterification is known to improve its miscibility in apolar polyolefin matrices, thereby helping the production of bio-based composites. To this end and due to its many reactive hydroxyl groups, lignin is a challenging macromolecular substrate for biocatalyzed esterification in non-conventional media. The present work describes for the first time the lipase-catalyzed transesterification of Kraft lignin in ionic liquids (ILs. Three lipases, three 1-butyl-3-methylimidazolium based ILs and ethyl oleate as long chain acyl donor were selected. Best results were obtained with a hydrophilic/hydrophobic binary IL system (1-butyl-3-methylimidazolium trifluoromethanesulfonate/1-butyl-3-methylimidazolium hexafluoro- phosphate, 1/1 v/v and the immobilized lipase B from Candida antarctica (CALB that afforded a promising transesterification yield (ca. 30%. Similar performances were achieved by using 1-butyl-3-methylimidazolium hexafluorophosphate as a coating agent for CALB rather than as a co-solvent in 1-butyl-3-methylimidazolium trifluoromethane-sulfonate thus limiting the use of hydrophobic IL. Structural characterization of lignin oleate was performed by spectroscopic studies (FTIR and 1H-NMR. The synthesized lignin oleate exhibited interesting thermal and textural properties, different from those of the original Kraft lignin.

  15. Bio-based polyurethane prepared from Kraft lignin and modified castor oil

    Directory of Open Access Journals (Sweden)

    L. B. Tavares

    2016-11-01

    Full Text Available Current challenges highlight the need for polymer research using renewable natural sources as a substitute for petroleum-based polymers. The use of polyols obtained from renewable sources combined with the reuse of industrial residues such as lignin is an important agent in this process. Different compositions of polyurethane-type materials were prepared by combining technical Kraft lignin (TKL with castor oil (CO or modified castor oil (MCO1 and MCO2 to increase their reactivity towards diphenylmethane diisocyanate (MDI. The results indicate that lignin increases the glass transition temperature, the crosslinking density and improves the ultimate stress especially for those prepared from MCO2 and 30% lignin content from 8.2 MPa (lignin free to 23.5 MPa. Scanning electron microscopy (SEM micrographs of rupture surface after uniaxial tensile tests show ductile-to-brittle transition. The results show the possibility to develop polyurethane-type materials, varying technical grade Kraft lignin content, which cover a wide range of mechanical properties (from large elastic/low Young modulus to brittle/high Young modulus polyurethanes.

  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. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

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

    Science.gov (United States)

    Cartagena, Andrés Felipe; Parreiras, Sibelli Olivieri; Loguercio, Alessandro Dourado; Reis, Alessandra; Campanha, Nara Hellen

    2015-01-01

    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.

  3. 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.

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

    Directory of Open Access Journals (Sweden)

    Eric Dario Acuña

    2016-01-01

    Full Text Available 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 (p3.3.

  5. 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.

  6. 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...

  7. 7 CFR 868.310 - Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice...

    Science.gov (United States)

    2010-01-01

    ... Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled Rice. (See also Â... Milled Rice Principles Governing Application of Standards § 868.310 Grades and grade requirements for the classes Long Grain Milled Rice, Medium Grain Milled Rice, Short Grain Milled Rice, and Mixed Milled...

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Effect of desensitizer application on shear bond strength of composite resin to bleached enamel

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2013-01-01

    Full Text Available Objective: Tooth sensitivity is common after vital tooth bleaching. The aim of this study is to evaluate the effect of a desensitizing agent on shear bond strength of composite resin to bleached enamel; and determine whether a delay of one or two weeks in bonding procedure is sufficient subsequent to bleaching/desensitizer regimen. Materials and Methods: Buccal enamel surfaces of ninety-six human sound molars were prepared and divided into eight groups. The surfaces of specimens in Group 1 as negative control group were bonded by composite resin using the single bond adhesive. Specimens in Groups 2-4 were bleached with an at-home bleaching agent (Daywhite ACP. Relief ACP desensitizing gel alone was applied in Group 5. In Groups 6-8, specimens were bleached same as in Group 2 and relief ACP desensitizing gel was applied same as inGroup 5 subsequent to each bleaching session. Composite cylinders were bonded after 24 h, 7 days and 14 days in Groups 2-4, respectively, and also in Groups 6-8, respectively. The shear bond strengths of the cylinders were tested and data was analyzed using two-way ANOVA and Tukey test (α = 0.05. Results: The results showed that bleaching and bleaching/desensitizer regimens significantly reduced the bond strength of composite resin to enamel. However, desensitizer alone did not reduce bond strength. No statistically significant differences were found between bleaching and bleaching/desensitizer regarding bond strength. Conclusion: Bleaching or bleaching/desensitizer treatment significantly decreases bond strength of composite resin to enamel. In both regimens, adhesive bonding is recommended after two weeks.

  18. The potential optical coherence tomography in tooth bleaching quantitative assessment

    Science.gov (United States)

    Ni, Y. R.; Guo, Z. Y.; Shu, S. Y.; Zeng, C. C.; Zhong, H. Q.; Chen, B. L.; Liu, Z. M.; Bao, Y.

    2011-12-01

    In this paper, we report the outcomes from a pilot study on using OCT functional imaging method to evaluate and quantify color alteration in the human teeth in vitro. The image formations of the dental tissues without and with treatment 35% hydrogen peroxide were obtained by an OCT system at a 1310 nm central wavelength. One parameter for the quantification of optical properties from OCT measurements is introduced in our study: attenuate coefficient (μ). And the attenuate coefficient have significant decrease ( p bleaching process. From the experimental results, it is found that attenuate coefficient could be useful to assess color alteration of the human tooth samples. OCT has a potential to become an effective tool for the assessment tooth bleaching. And our experiment offer a now method to evaluate color change in visible region by quantitative analysis of the infrared region information from OCT.

  19. THE SHEAR-THINNING PHENOMENON OF BAGASSE KRAFT BLACK LIQUOR FLUID

    Institute of Scientific and Technical Information of China (English)

    Rendang Yang; Kefu Chen; Jun Xu; Heng Zhang; Qifeng Chen; Jin Wang

    2004-01-01

    The flow curves of bagasse Kraft black liquor over a shear-rate range of 10-1s-l~103s-1 were investigated by using the Rheometric RFSⅡ rheometer.Experimental results show that Bagasse black liquors are non-Newtonian fluids instead of Newtonian fluids at higher solids contents, and the viscosities of black liquor would decrease .about 2~3 orders of magnitude with an increase in the shear rates. The apparent viscosity and flow behavior of bagasse black liquor are also affected by its solids content, and the higher solids content the more shear-thinning bagasse black liquor fluid is. In addition, the power-law equation was utilized to fit these flow curves at different conditions. Finally, the significances of shear-thinning properties of bagasse black liquor in the chemical recovery system, such as friction calculation of pipe and design optimization of the whole recovery system, were presented.

  20. 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)

  1. 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.

  2. Molecular Characteristics of Kraft-AQ Pulping Lignin Fractionated by Sequential Organic Solvent Extraction

    Directory of Open Access Journals (Sweden)

    Kun Wang

    2010-08-01

    Full Text Available Kraft-AQ pulping lignin was sequentially fractionated by organic solvent extractions and the molecular properties of each fraction were characterized by chemical degradation, GPC, UV, FT-IR, 13C-NMR and thermal analysis. The average molecular weight and polydispersity of each lignin fraction increased with its hydrogen-bonding capacity (Hildebrand solubility parameter. In addition, the ratio of the non-condensed guaiacyl/syringyl units and the content of β-O-4 linkages increased with the increment of the lignin fractions extracted successively with hexane, diethylether, methylene chloride, methanol, and dioxane. Furthermore, the presence of the condensation reaction products was contributed to the higher thermal stability of the larger molecules.

  3. 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

  4. 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.

  5. Multicolor bleach-rate imaging enlightens in vivo sterol transport

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Sage, Daniel

    2011-01-01

    , dehydroergosterol (DHE) in the genetically tractable model organism Caenorhabditis elegans (C. elegans). DHE is structurally very similar to cholesterol and ergosterol, two sterols used by the sterol-auxotroph nematode. We developed a new computational method measuring fluorophore bleaching kinetics at every pixel...... with a lysosomal marker, GFP-LMP1. Our new methods hold great promise for further studies on endosomal sterol transport in C. elegans....

  6. 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 ...

  7. 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...

  8. 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 ...

  9. KINETICS OF DELIGNIFICATION AND CARBOHYDRATE DEGRADATION DURING OXYGEN BLEACHING

    Institute of Scientific and Technical Information of China (English)

    K.LNguyen

    2004-01-01

    Carbohydrate degradation during oxygen bleaching isassociated with cleavage reactions. It is apparent thatthe loss of the cellulose DPis strongly affected by(degree ofpolymisation) the extent of thedelignification. A strong linear correlation can beestablished between the DP of cellulose chains andthe residual lignin in the pulp. The Nuclear Growthconcept and Percolation Theory for heterogenoussystem can be combined to formulate kinetic modelsfor both the delignification and the degradation ofcarbohydrate. The models prediction is statisticallyrobust and can be applied to different pulps atdifferent bleachin~ conditions.

  10. 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

  11. 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)

  12. 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.

  13. 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.

  14. 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

  15. Examination of native and carbamide peroxide-bleached human tooth enamel by atomic force microscopy.

    Science.gov (United States)

    Mahringer, Christoph; Fureder, Monika; Kastner, Markus; Ebner, Andreas; Hinterdorfer, Peter; Vitkov, Ljubomir; Hannig, Matthias; Kienberger, Ferry; Schilcher, Kurt

    2009-10-01

    Atomic force microscopy (AFM) was used to study the effects of bleaching on the morphology of the enamel surface with nanoscale resolution. Samples of human tooth enamel with native (pumiced) or fine-polished surfaces were examined before and after bleaching with 30% carbamide peroxide. The obtained profilometric AFM data revealed significant morphological surface alterations. After 1 h of bleaching, the surface roughness increased significantly from 19 +/- 4nm to 33 +/- 5 nm. Six-hour bleaching did not produce any significant further increase in enamel surface roughness. The interrod junction depth raised more than twice after 1 h of bleaching. After 6 h of bleaching, a further and significant increase in interrod junction depth was recorded. This alteration might be a consequence of oxidation and a subsequent partial lysis of the tooth enamel matrix proteins.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    Science.gov (United States)

    Added, N.; Rizzutto, M. A.; Curado, J. F.; Francci, C.; Markarian, R.; Mori, M.

    2006-08-01

    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.

  1. 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.

  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. 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...

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

    OpenAIRE

    Eric Dario Acuña; Leyla Delgado-Cotrina; Francisco Aurelio Rumiche; Lidia Yileng Tay

    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), gr...

  5. 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...

  6. 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

  7. EFFECT OF LAST STAGE BLEACHING WITH PERACETIC ACID ON BRIGHTNESS DEVELOPMENT AND PROPERTIES OF EUCALYPTUS PULP

    Directory of Open Access Journals (Sweden)

    Denise P. Barros

    2010-05-01

    Full Text Available Investigation of last stage bleaching with peracetic acid is the main subject of this paper. Proper conditions were established to apply peracetic acid as the last bleaching stage of the D(EpD/Paa, DHT(EpD/Paa, A/D(EpD/Paa, DHT/Q(POPaa and Z/ED/Paa sequences. In addition, the impact of last stage bleaching with Paa on pulp refinability and strength properties was determined. Peracetic acid was consumed relatively fast when applied as the last stage of ECF bleaching sequences. A reaction time of 120 min at 75 oC and pH 5.0 is seemingly adequate regardless of the Paa dose, in the range of 1-5 kg/odt pulp and bleaching sequence. The optimum dose of Paa depends upon the sequence under investigation. In general the Paa application as last bleaching stage caused slight decrease in pulp viscosity, kappa number and HexA content but had no significant effect on pulp reversion and L*a*b* coordinates. The refinability and bonding strength properties of the pulps bleached with the sequences DHT(EpDD and DHT(EpD/Paa were quite similar when the pH of the last bleaching stage of both sequences were near 5. These properties improved slightly when Paa bleaching pH was raised to 8.5.

  8. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Groppo, Daniela Piai; Caldas, Linda V.E., E-mail: dpgroppo@usp.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    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 ({sup 90}Sr+{sup 90}Y); 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. (author)

  9. 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.

  10. Bleached Porites compressa and Montipora capitata corals catabolize δ13C-enriched lipids

    Science.gov (United States)

    Grottoli, Andréa G.; Rodrigues, Lisa J.

    2011-09-01

    Corals rely on stored energy reserves (i.e., lipids, carbohydrates, and protein) to survive bleaching events. To better understand the physiological implications of coral bleaching on lipid catabolism and/or synthesis, we measured the δ13C of coral total lipids (δ13CTL) in experimentally bleached (treatment) and non-bleached (control) Porites compressa and Montipora capitata corals immediately after bleaching and after 1.5 and 4 months of recovery on the reef. Overall δ13CTL values in treatment corals were significantly lower than in control corals because of a 1.9 and 3.4‰ decrease in δ13CTL immediately after bleaching in P. compressa and M. capitata, respectively. The decrease in δ13CTL coincided with decreases in total lipid concentration, indicating that corals catabolized δ13C-enriched lipids. Since storage lipids are primarily depleted during bleaching, we hypothesize that they are isotopically enriched relative to other lipid classes. This work further helps clarify our understanding of changes to coral metabolism and biogeochemistry when bleached and helps elucidate how lipid classes may influence recovery from bleaching and ultimately coral survival.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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...

  18. 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.

  19. 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.

  20. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large...... part. For this investigation 200 microns end mills are considered. Visual inspection of the micro tools requires high magnification and depth of focus. 3D reconstruction based on scanning electron microscope (SEM) images and stereo-pair technique is foreseen as a possible method for quantification...

  1. 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.

  2. 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.

  3. 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)...

  4. Changes in coral-associated microbial communities during a bleaching event.

    Science.gov (United States)

    Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

    2008-04-01

    Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were

  5. 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.

  6. 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

  7. 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.

  8. Abstract Milling with Turn Costs

    CERN Document Server

    Fellows, M; Knauer, C; Paul, C; Rosamond, F; Whitesides, S; Yu, N

    2009-01-01

    The Abstract Milling problem is a natural and quite general graph-theoretic model for geometric milling problems. Given a graph, one asks for a walk that covers all its vertices with a minimum number of turns, as specified in the graph model by a 0/1 turncost function fx at each vertex x giving, for each ordered pair of edges (e,f) incident at x, the turn cost at x of a walk that enters the vertex on edge e and departs on edge f. We describe an initial study of the parameterized complexity of the problem. Our main positive result shows that Abstract Milling, parameterized by: number of turns, treewidth and maximum degree, is fixed-parameter tractable, We also show that Abstract Milling parameterized by (only) the number of turns and the pathwidth, is hard for W[1] -- one of the few parameterized intractability results for bounded pathwidth.

  9. 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...

  10. 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

    Electron Microscopy (SEM). Materials and Methods: Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5) treated as follows: G1- storage in artificial saliva (control group); G2- four 30-minute applications of 35% carbamide peroxide (total exposure...... 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 were...

  11. 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.

  12. 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...

  13. In vitro colorimetric evaluation of the efficacy of various bleaching methods and products

    OpenAIRE

    Dietschi, Didier; Rossier, Sandrine; Krejci, Ivo

    2006-01-01

    Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficacy is unknown. The aim of this in vitro study was to evaluate the ability of different bleaching products and protocols to lighten enamel and dentin.

  14. 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.

  15. 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.

  16. The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

    Science.gov (United States)

    Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

    2012-04-01

    The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

  17. Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

    Science.gov (United States)

    Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching o...

  18. INDICATORS OF UV EXPOSURE IN CORAL 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. Bleaching can destroy large areas of a reef with limited recovery or recruitment, and it may be induced by a variety of stressors ranging from exposure to temperature and salinity extrem...

  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. 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)

  1. Tooth bleaching using three laser systems, halogen-light unit, and chemical action agents

    Science.gov (United States)

    Dostalova, Tatjana; Jelinkova, Helena; Housova, Devana; Sulc, Jan; Nemec, Michal; Koranda, Petr; Miyagi, Mitsunobu; Shi, Yi-Wei; Matsuura, Yuji

    2004-09-01

    μThe study describes the preclinical experience with laser-activated bleaching agent for discolored teeth. Extracted human upper central incisors were selected, and in the bleaching experiment 35% hydrogen peroxide was used. Three various laser systems and halogen-light unit for activation of the bleaching agent were applied. They were Alexandrite laser (wavelength 750 nm and 375 nm - SHG), Nd:YAG laser (wavelength 1.064 m), and Er:YAG laser (wavelength 2.94 μm). The halogen-light unit was used in a standard regime. The enamel surface was analyzed in the scanning electron microscope. The method of chemical oxidation results in a 2-3 shade change in one treatment. The halogen-light units produced the same effect with shorter time of bleaching process (from 630 s to 300 s). The Alexandrite laser (750 nm) and bleaching agent helped to reach the desired color shade after a shorter time (400 s). Alexandrite laser (375 nm) and Nd:YAG laser had no effect on the longevity of the process of bleaching. Overheating of the chemical bleaching agent was visible after Er:YAG laser activation (195 s). Slight surface modification after bleaching process was detected in SEM.

  2. 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 ...

  3. 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...

  4. 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...

  5. 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...

  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. 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

  10. 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.

  11. CHLORINE DIOXIDE BLEACHING OF SODA-ANTHRAQUINONE JUTE PULP TO A VERY HIGH BRIGHTNESS

    Directory of Open Access Journals (Sweden)

    M. Sarwar Jahan

    2010-05-01

    Full Text Available Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2 was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use of Mg(OH2 in the D1 and D2 stages improved the final brightness due to the formation of less chlorate and chlorite during the Mg(OH2- based ClO2 brightening stages. The strength properties of pulp bleached by peroxide in the final stage was slightly better than that from ClO2 as the final ClO2 bleaching stage.

  12. 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.

  13. 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.

  14. 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.

  15. Determination of optical properties of oxidative bleaching human dental tissue samples using optical coherence tomography

    Science.gov (United States)

    Ni, Y. R.; Guo, Z. Y.; Shu, S. Y.; Zeng, C. C.; Zhong, H. Q.; Chen, B. L.; Liu, Z. M.; Bao, Y.

    2011-10-01

    Oxidative bleaching changes of human teeth induced changes in the optical properties of dental tissue. We introduced 1310 nm wavelengths of optical coherence tomography (OCT) attenuation coefficient method which is a relatively novel and rarely reported methodology to measure the correlation coefficient during the teeth oxidative bleaching procedure. And the quantitative parameters of enamel optical thickness and disruption of the entrance signal (DES) were extracted from the OCT images. The attenuation coefficient of the bleached tissue is 6.2 mm-1 which is significant (p bleaching oxidation in 35% hydrogen peroxide-induced optical thickness of enamel is similar with unbleached tissue which may indicate the refractive index of enamel is unchanged. Moreover, disruption of the entrance signal (DES) analysis showed that remarkable difference was appeared at enamel surface. The results indicate that optical properties of oxidative bleaching human dental tissue can be determined by attenuation coefficient using OCT system.

  16. 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.

  17. 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

  18. Wet strength improvement of unbleached kraft pulp through laccase catalyzed oxidation.

    Science.gov (United States)

    Lund, M; Felby, C

    2001-06-01

    Previous investigations have shown that laccase catalyzed oxidation of lignin containing wood fibers can enhance the strength of medium density fiberboards. In the present work it was investigated if laccase treatment had any impact on the tensile strength of a high yield unbleached kraft pulp. Treatment with laccase alone had only a very little effect on the wet strength of the pulp, whereas addition of lignin rich extractives increased the wet strength after the enzyme treatment significantly. A mediated oxidation gave a similar improvement of the wet tensile strength although no lignin was added to the fiber suspension. Furthermore, it was found that a heat treatment combined with a mediated oxidation gave a higher improvement in wet tensile strength than could be accounted for by the individual treatments. No change in dry tensile strength from the laccase treatment was observed. It is suggested that the observed improvement in wet tensile strength is related to polymerization of lignin on fibers in the hand sheet and/or coupling of phenoxy radicals on lignin associated to adjacent fibers. For the different mediators studied, a correlation was found between oxygen consumption upon mediated oxidation and generation of wet strength in the pulp. PMID:11397456

  19. Preparation of porous carbons from polymeric precursors modified with acrylated kraft lignin

    Science.gov (United States)

    Sobiesiak, M.

    2016-04-01

    The presented studies concern the preparation of porous carbons from a BPA.DA-St polymer containing acrylated kraft lignin as a monomer. The porous polymeric precursor in the form of microspheres was synthesized in suspension polymerization process. Next samples of the polymer were impregnated with acetic acid or aqueous solution of acetates (potassium or ammonia), dried and carbonised in nitrogen atmosphere at 450°C. After carbonization microspherical shape of the materials was remained, that is desired feature for potential application in chromatography or SPE technique. Chemical and textural properties of the porous carbon adsorbents were characterized using infrared spectroscopy (ATR-FTIR), thermogravimetry analyses with mass spectrometry of released gases (TG-MS) and nitrogen sorption experiments. The presented studies revealed the impregnation is useful method for development of porous structure of carbonaceous materials. The highest values of porous structure parameters were obtained when acetic acid and ammonium acetate were used as impregnating substances. On the surface of the materials oxygen functional groups are present that is important for specific interactions during sorption processes. The highest contents of functionalities were observed for carbon BPA.DA-St-LA-C-AcNH4.

  20. Use of Electrochemical Noise to Assess Corrosion in Kraft Continuous Digesters

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, S.J.

    2004-11-29

    Electrochemical noise (EN) probes were deployed in two continuous kraft digesters at a variety of locations representative of corrosion throughout the vessels. Current and potential noise, the temperature at each probe location, and the value of up to 60 process parameters (flow rates, liquor chemistry, etc.) were monitored continuously during each experiment. The results indicate that changes in furnish composition and process upsets were invariably associated with concurrent substantial changes in EN activity throughout the vessels. Post-test evaluation of the mild steel electrode materials in both vessels confirmed general corrosion of a magnitude consistent with historical trends in the respective vessels as well as values qualitatively (and semi-quantitatively) related to EN current sums for each electrode pair. Stainless steel electrodes representing 309LSi and 312 overlay repairs exhibited zero wastage corrosion--as did the actual overlays--but the EN data indicated periodic redox activity on the stainless steel that varied with time and position within the vessel. Little or no correlation between EN probe activity and other operational variables was observed in either vessel. Additional details for each digester experiment are summarized.

  1. IMPROVEMENT OF PAPER PROPERTIES OF RECYCLED UNBLEACHED SOFTWOOD KRAFT PULPS BY POLY(ALLYLAMINE HYDROCHLORIDE

    Directory of Open Access Journals (Sweden)

    Paulina Mocchiutti

    2011-02-01

    Full Text Available Polyelectrolytes containing amine functional groups such as PAH (poly(allylamine hydrochloride can be useful, under certain conditions, for improving paper strength. In this work, the charge density of PAH was determined at different pH and ionic strengths; PAH adsorption onto the cellulosic fibers was characterized, and the effects of low PAH dosage on the papermaking properties were evaluated. It was found that the ionization of PAH is complete in acid media, but it is partial and depends on the ionic strength in neutral media. The adsorption isotherms of PAH on a recycled pulp from kraft liner allowed us to determine the amount needed to saturate the adsorption capacity of the fibers. For the three ionic strengths analyzed, the swelling of the fibers decreased when PAH was added in an amount corresponding to saturation (0.23% PAH on dried pulp. Nevertheless, the swelling was recovered when the amount of PAH was the double the saturation level (0.46% PAH on dried pulp. At these levels of addition, the papermaking properties were clearly improved, especially compressive strengths SCT (short compressive test and CMT (concora medium test. The Page equation of tensile strength showed that PAH improved the shear bond strength, while the relative bonding area slightly decreased.

  2. THE REACTIVITY OF PREHYDROLYZED SOFTWOOD KRAFT PULPS AFTER PROLONGED COOKING FOLLOWED BY CHLORITE DELIGNIFICATION

    Directory of Open Access Journals (Sweden)

    Ulf Germgard

    2011-05-01

    Full Text Available In a laboratory study high-quality spruce chips were prehydrolyzed to remove hemicelluloses and then kraft cooked to different kappa numbers by varying the cooking time. Each pulp sample was then chlorite delignified to selectively remove the remaining lignin. The reactivities of the pulp samples before and after chlorite delignification were determined by Fock’s test, which is supposed to measure the pulp’s reactivity in the conventional viscose process. A number of analyses were carried out to determine which parameters affected pulp reactivity, as, for example: intrinsic viscosity, kappa number, pulp yield, carbohydrate composition, levelling-off degree of polymerization (LODP, and alkali solubility. The results of the study showed that the pulp reactivity increased with decreasing kappa number, and the highest reactivity was obtained after total lignin removal using chlorite delignification. It was also found that the carbohydrate composition had no influence on the pulp reactivity, but lower intrinsic viscosity either obtained by prolonged cooking or chlorite delignification correlated with higher pulp reactivity. Finally, lower alkali solubility, i.e. higher R18, reduced the reactivity.

  3. Sulphidation behaviour of advanced materials for elevated kraft recovery boiler conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yli-Olli, S.; Pohjanne, P.; Heikinheimo, L.; Kinnunen, T.; Pankakoski, P.H. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2007-06-15

    The behaviour of new kraft recovery boiler materials in reducing conditions has been evaluated in this study. Sanicro 38, Sanicro 36Mo, Sanicro 65, 4C54 and HR11N were tested in gas mixtures containing hydrogen sulphide (H{sub 2}S) and carbon monoxide (CO) with and without water vapour. Steel 304L and a basic carbon steel were used as reference materials. A thin (max. 1 'm) oxide layer, probably a spinel (FeCr{sub 2}O{sub 4}), was observed on some of the exposed materials in the tests with 15% water vapour. This layer protected the materials from sulphidation. The protective effect of water vapour was not eliminated by the increase in temperature from 400 deg C to 440 deg C or in H{sub 2}S concentration from 500 to 5000 ppm. However, water vapour did not protect carbon steel. Without water vapour, sulphidation started at low levels of H{sub 2}S and was accelerated by increasing H{sub 2}S concentration. The reference material 304L and Sanicro 36 Mo showed the best sulphidation resistance. The formed layers of corrosion products were analysed with EDS and compared to thermodynamic modelling by FactSage. In most cases the thermodynamic predictions agreed very well with the EDS analyses. The results suggest that alloying with molybdenum will restrain sulphidation. (orig.)

  4. Acid-catalysed xylose dehydration into furfural in the presence of kraft lignin.

    Science.gov (United States)

    Lamminpää, Kaisa; Ahola, Juha; Tanskanen, Juha

    2015-02-01

    In this study, the effects of kraft lignin (Indulin AT) on acid-catalysed xylose dehydration into furfural were studied in formic and sulphuric acids. The study was done using D-optimal design. Three variables in both acids were included in the design: time (20-80 min), temperature (160-180°C) and initial lignin concentration (0-20 g/l). The dependent variables were xylose conversion, furfural yield, furfural selectivity and pH change. The results showed that the xylose conversion and furfural yield decreased in sulphuric acid, while in formic acid the changes were minor. Additionally, it was showed that lignin has an acid-neutralising capacity, and the added lignin increased the pH of reactant solutions in both acids. The pH rise was considerably lower in formic acid than in sulphuric acid. However, the higher pH did not explain all the changes in conversion and yield, and thus lignin evidently inhibits the formation of furfural.

  5. Kraft lignin/silica-AgNPs as a functional material with antibacterial activity.

    Science.gov (United States)

    Klapiszewski, Łukasz; Rzemieniecki, Tomasz; Krawczyk, Magdalena; Malina, Dagmara; Norman, Małgorzata; Zdarta, Jakub; Majchrzak, Izabela; Dobrowolska, Anna; Czaczyk, Katarzyna; Jesionowski, Teofil

    2015-10-01

    Advanced functional silica/lignin hybrid materials, modified with nanosilver, were obtained. The commercial silica Syloid 244 was used, modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane to increase its chemical affinity to lignin. Similarly, kraft lignin was oxidized using a solution of sodium periodate to activate appropriate functional groups on its surface. Silver nanoparticles were grafted onto the resulting silica/lignin hybrids. The systems obtained were comprehensively tested using available techniques and methods, including transmission electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, elemental analysis and atomic absorption spectroscopy. An evaluation was also made of the electrokinetic stability of the systems with and without silver nanoparticles. Conclusions were drawn concerning the chemical nature of the bonds between the precursors and the effectiveness of the method of binding nanosilver to the hybrid materials. The antimicrobial activity of the studied materials was tested against five species of Gram-positive and Gram-negative bacteria. The addition of silver nanoparticles to the silica/lignin hybrids led to inhibition of the growth of the analyzed bacteria. The best results were obtained against Pseudomonas aeruginosa, a dangerous human pathogen.

  6. Influence of dental bleaching on marginal leakage of Class V restorations

    Directory of Open Access Journals (Sweden)

    Andréia Cristina Ramos Dorini

    2010-04-01

    Full Text Available Objective: Evaluate the in vitro effect of bleaching performed in the dental office and waiting time on the degree of microleakage in class V cavities with margins in enamel, restored with resin composite. Methods: Forty-five human third molars were used, in which the vestibular faces were bleached with 35% hydrogen peroxide activated with LED and the palatine faces were not bleached (control. The teeth were randomly divided into 3 groups with 15 teeth in each: Group 1, restored immediately after bleaching; Group 2, seven days after bleaching; and Group 3, fourteen days after bleaching. After cavity preparation, 35% phosphoric acid, Adper Single Bond 2 adhesive (3M ESPE, St. Paul, Mn, USA, and resin composite Filtek Z250 (3M ESPE, St. Paul, MN, USA were applied. The teeth were thermal cycled and sealed with red nail polish on the bleached faces and blue on the non bleached faces, except for 1mm around the restored region. The samples were classified according to the following scores: 0 = no leakage, 1 = minimum leakage (less than 1 / 3 the length of the wall, 2 = moderate leakage (1/3 to 2/3 of the wall and 3 = extensive leakage (over 2/3 of the wall. The data were submitted to the Kruskal-Wallis test at a level of significance of 5%. Results: The restorative procedure immediately after bleaching resulted in statistically higher microleakage values (p 0.05. Conclusion: Based on the results, it is advisable to wait at least 7 days after bleaching to make the definitive restoration.

  7. Bleaching of leaf litter and associated microfungi in subboreal and subalpine forests.

    Science.gov (United States)

    Hagiwara, Yusuke; Matsuoka, Shunsuke; Hobara, Satoru; Mori, Akira S; Hirose, Dai; Osono, Takashi

    2015-10-01

    Fungal decomposition of lignin leads to the whitening, or bleaching, of leaf litter, especially in temperate and tropical forests, but less is known about such bleaching in forests of cooler regions, such as boreal and subalpine forests. The purposes of the present study were to examine the extent of bleached area on the surface of leaf litter and its variation with environmental conditions in subboreal and subalpine forests in Japan and to examine the microfungi associated with the bleaching of leaf litter by isolating fungi from the bleached portions of the litter. Bleached area accounted for 21.7%-32.7% and 2.0%-10.0% of total leaf area of Quercus crispula and Betula ermanii, respectively, in subboreal forests, and for 6.3% and 18.6% of total leaf area of B. ermanii and Picea jezoensis var. hondoensis, respectively, in a subalpine forest. In subboreal forests, elevation, C/N ratio and pH of the FH layer, and slope aspect were selected as predictor variables for the bleached leaf area. Leaf mass per area and lignin content were consistently lower in the bleached area than in the nonbleached area of the same leaves, indicating that the selective decomposition of acid unhydrolyzable residue (recalcitrant compounds such as lignin, tannins, and cutins) enhanced the mass loss of leaf tissues in the bleached portions. Isolates of a total of 11 fungal species (6 species of Ascomycota and 5 of Basidiomycota) exhibited leaf-litter-bleaching activity under pure culture conditions. Two fungal species (Coccomyces sp. and Mycena sp.) occurred in both subboreal and subalpine forests, which were separated from each other by approximately 1100 km.

  8. USING Mg(OH2 IN PEROXIDE BLEACHING OF WHEAT STRAW SODA-AQ PULP

    Directory of Open Access Journals (Sweden)

    Yanlan Liu

    2011-04-01

    Full Text Available The peroxide bleaching of high yield pulps from wood with Mg(OH2 has been developing recently in the pulp and paper industry. However, there is still a lack of data on the application of Mg(OH2 in peroxide bleaching of non-wood fibres. In this work, our purpose was to study the effect of Mg(OH2 on peroxide bleaching of wheat straw soda-AQ pulp. The results showed that Mg(OH2 significantly improved peroxide bleaching efficiency (expressed as the ratio between the brightness gain and the H2O2 consumption and selectivity (expressed as the ratio between the brightness gain and the viscosity losses of wheat straw soda-AQ pulp. The brightness, viscosity, and yield of bleached pulp can be significantly enhanced by increasing the replacement ratio of Mg(OH2. However, at 100% replacement of NaOH with Mg(OH2, the brightness of bleached pulp was much lower than that of the bleached pulp with NaOH as the sole alkaline source. When 24 to 73% of the NaOH was replaced with Mg(OH2, the COD of the bleaching filtrate was 11 to 38% lower than that of the NaOH as the sole alkaline source. The lower solubility and alkalinity of Mg(OH2, as well as the reduction of Cu ion content in bleached pulp were proposed as accounting for the favorable effect of Mg(OH2 on peroxide bleaching of wheat straw soda-AQ pulp.

  9. YANG-MILLS FIELD CAPACITOR

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2015-10-01

    Full Text Available The article presents a project of the capacitor in the Yang-Mills theory. Model capacitor represents the equipotential surfaces separated by a space. To describe the mechanism of condensation chromodynamics field used numerical models developed based on an average of the Yang-Mills theory. In the present study, we used eight-scalar component model that in the linear case is divided into two groups containing three or five fields respectively. In contrast to classical electrodynamics, a static model of the Yang-Mills is not divided into independent equations because of the nonlinearity of the model itself. However, in the case of a linear theory separation is possible. It is shown that in this particular case, the Yang-Mills theory is reduced to Poisson theory, which describes the electrostatic and magnetostatic phenomena. In the present work it is shown that in a certain region of the parameters of the capacitor of the Yang-Mills theory on the functional properties of the charge accumulation and retention of the field is similar to the capacitor of the electrostatic field or a magnet in magnetostatics. This means that in nature there are two types of charges, which are sources of macroscopic Yang-Mills field, which are similar to the properties of electric and magnetic charges in the Poisson theory. It is shown that in Yang-Mills only one type of charge may be associated with the distribution density of the substance, while another type of charge depends on the charge distribution of the first type. This allows us to provide an explanation for the lack of symmetry between electric and magnetic charges

  10. Noise exposure in oil mills

    Directory of Open Access Journals (Sweden)

    Prasanna Kumar G

    2008-01-01

    Full Text Available Context: Noise of machines in various agro-based industries was found to be the major occupational hazard for the workers of industries. The predominant noise sources need to be identified and the causes of high noise need to be studied to undertake the appropriate measures to reduce the noise level in one of the major agro-based industries, oil mills. Aims: To identify the predominant noise sources in the workrooms of oil mills. To study the causes of noise in oil mills. To measure the extent of noise exposure of oil mill workers. To examine the response of workers towards noise, so that appropriate measures can be undertaken to minimize the noise exposure. Settings and Design: A noise survey was conducted in the three renowned oil mills of north-eastern region of India. Materials and Methods: Information like output capacity, size of power source, maintenance condition of the machines and workroom configurations of the oil mills was collected by personal observations and enquiry with the owner of the mill. Using a Sound Level Meter (SLM (Model-824, Larson and Davis, USA, equivalent SPL was measured at operator′s ear level in the working zone of the workers near each machine of the mills. In order to study the variation of SPL in the workrooms of the oil mill throughout its operation, equivalent SPL was measured at two appropriate locations of working zone of the workers in each mill. For conducting the noise survey, the guidelines of Canadian Centre for Occupational Health and Safety (CCOHS were followed. Grid points were marked on the floor of the workroom of the oil mill at a spacing of 1 m x 1 m. SPL at grid points were measured at about 1.5 m above the floor. The direction of the SLM was towards the nearby noisy source. To increase accuracy, two replications were taken at each grid point. All the data were recorded for 30 sec. At the end of the experiment, data were downloaded to a personal computer. With the help of utility software of

  11. Einstein-Yang-Mills from pure Yang-Mills amplitudes

    CERN Document Server

    Nandan, Dhritiman; Schlotterer, Oliver; Wen, Congkao

    2016-01-01

    We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.

  12. Integration of the Mini-Sulfide Sulfite Anthraquinone (MSS-AQ) Pulping Process and Black Liquor Gasification in a Pulp Mill

    Energy Technology Data Exchange (ETDEWEB)

    Hasan Jameel, North Carolina State University; Adrianna Kirkman, North Carolina State University; Ravi Chandran,Thermochem Recovery International Brian Turk Research Triangle Institute; Brian Green, Research Triangle Institute

    2010-01-27

    As many of the recovery boilers and other pieces of large capital equipment of U.S. pulp mills are nearing the end of their useful life, the pulp and paper industry will soon need to make long-term investments in new technologies. The ability to install integrated, complete systems that are highly efficient will impact the industry’s energy use for decades to come. Developing a process for these new systems is key to the adoption of state-of-the-art technologies in the Forest Products industry. This project defined an integrated process model that combines mini-sulfide sulfite anthraquinone (MSS-AQ) pulping and black liquor gasification with a proprietary desulfurization process developed by the Research Triangle Institute. Black liquor gasification is an emerging technology that enables the use of MSS-AQ pulping, which results in higher yield, lower bleaching cost, lower sulfur emissions, and the elimination of causticization requirements. The recently developed gas cleanup/absorber technology can clean the product gas to a state suitable for use in a gas turbine and also regenerate the pulping chemicals needed to for the MSS-AQ pulping process. The combination of three advanced technologies into an integrated design will enable the pulping industry to achieve a new level of efficiency, environmental performance, and cost savings. Because the three technologies are complimentary, their adoption as a streamlined package will ensure their ability to deliver maximum energy and cost savings benefits. The process models developed by this project will enable the successful integration of new technologies into the next generation of chemical pulping mills. When compared to the Kraft reference pulp, the MSS-AQ procedures produced pulps with a 10-15 % yield benefit and the ISO brightness was 1.5-2 times greater. The pulp refined little easier and had a slightly lower apparent sheet density (In both the cases). At similar levels of tear index the MSS-AQ pulps also

  13. 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.

  14. 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...

  15. Antioxidant activity of phenolic fractions in olive mill wastewater.

    Science.gov (United States)

    Azaizeh, Hassan; Halahlih, Fares; Najami, Naim; Brunner, Doris; Faulstich, Martin; Tafesh, Ahmed

    2012-10-15

    Olive mill wastewater (OMW) contains a substantial amount of valuable antioxidant phenols that can be recovered for industrial application as food additives and pharmaceuticals. The present study was aimed at extracting different phenolic OMW fractions, and determining their antioxidant potential. Five different OMW fractions were obtained using fractionation techniques, their antioxidant potential determined by DPPH, ORAC and a β-carotene bleaching test. The total phenol level ranged between 115 and 170 mg/l. The phenolic compounds present in individual fractions were identified using the HPLC-PAD method, where the main compounds were hydroxytyrosol, tyrosol, caffeic acid, vanillic acid, verbascoside, oleuropein, ferulic acid, and p-coumaric acid. The five OMW fractions showed different antioxidant levels depending on the test used. DPPH test showed that the fraction of alkyl aromatic alcohols (AAAs) was the best with EC(50) of 20 mg/l and the pure hydroxytyrosol with 2 mg/l. ORAC test showed that AAA and semi hydrolysed total phenol (s-TP) fractions were significantly better than Trolox when compared to 20 mg/l of Trolox. PMID:23442678

  16. 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.

  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. MODIFIED OPAL: A NOVEL STABILIZER FOR HYDROGEN PEROXIDE BLEACHING OF PULPS

    Institute of Scientific and Technical Information of China (English)

    XuerenQian; XianhuiAn; WenboLiu; GangYu; ZhanqianSong

    2004-01-01

    The possibility of modified opal as the stabilizer ofhydrogen peroxide bleaching was investigated. Theresults showed that the modified opal in place ofsodium silicate as the stabilizer of hydrogen peroxidebleaching is feasible. At the same dosage, above 3%ISO can be increased for both wheat straw pulp anddeinked pulp. The stabilizing ability of the modifiedopal to hydrogen peroxide bleaching of pulp isimproved markedly. It is favorable for bleaching toincrease temperature and time within a permissiveextent. The suitable process conditions are I0% ofpulp consistency, 3% of hydrogen peroxide, 1.5% ofsodium hydroxide, 3% of the modified opal, 70~"and 60 min when the modified opal is used as thestabilizer of hydrogen peroxide bleaching. At theseconditions, the brightness gain can reach about 16%ISO for wheat straw pulp. In addition, it is favorablefor bleaching to add a little magnesium sulfate whenthe modified opal is used as the stabilizer ofhydrogen peroxide bleaching, the brightness of pulpcan increase 1%ISO if0.05% of magnesium sulfate isadded. The cost analysis indicated that the modifiedopal is superior to sodium silicate as the stabilizer ofhydrogen peroxide bleaching in economical aspectand has further the potential of market development.

  19. 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.

  20. Ion release from a composite resin after exposure to different 10% carbamide peroxide bleaching agents

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    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.

  1. Effect of three nanobiomaterials on the surface roughness of bleached enamel

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    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.

  2. Effect of different restorative procedures on the fracture resistance of teeth submitted to internal bleaching

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    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.

  3. Skeletal isotope records of growth perturbations in Porites corals during the 1997-1998 mass bleaching event

    Science.gov (United States)

    Suzuki, A.; Gagan, M.; Fabricius, K.; Isdale, P.; Yukino, I.; Kawahata, H.

    2003-04-01

    Severe coral bleaching occurred throughout the tropics in 1997/98. We report skeletal UV fluorescence, oxygen isotope, and carbon isotope evidence for perturbations in coral skeletal growth due to bleaching at Ishigaki Island, Japan, and Pandora Reef, Great Barrier Reef. Bleached corals showed abrupt reductions in skeletal extension rate immediately after summer temperature maxima, indicating that bleaching inhibits coral calcification. A colony growing at the low tide line in Ishigaki exhibited clear blue UV fluorescent bands associated with recurrent growth interruptions. Based on the length of time-gaps observed in the annual isotopic cycle, the typical time required for a coral to recover from bleaching is estimated to be about 5--6 months. The effect of bleaching on the oxygen isotope ratio -- temperature relationship was negligible. However, the Ishigaki corals showed lower carbon isotope ratios during bleaching indicating depressed coral metabolism associated with a reduction in calcification. In contrast, skeletal carbon isotope ratios in the Pandora Reef corals exhibited little change in response to bleaching. This is because the records for Pandora Reef were derived from the shaded sides of coral colonies, where algal photosynthesis was particularly slow prior to bleaching, thus subduing the carbon isotope response to bleaching. Taken together, the isotopic and UV fluorescence signals can be used to reconstruct past bleaching events.

  4. PREPARATION OF XYLOSE AND KRAFT PULP FROM POPLAR BASED ON FORMIC/ACETIC ACID /WATER SYSTEM HYDROLYSIS

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    Junping Zhuang

    2009-08-01

    Full Text Available A formic/acetic acid/water system was used in the ratios of 30:60:10, 20:60:20, and 30:50:20 separately for efficient hydrolysis and bioconversion of poplar chips, under the solid/liquid ratio of 1:12(g/ml, at 105 oC for 30, 45, 60, 75, and 90 min, respectively. The highest yield of 69.89% was at a formic/acetic acid /water ratio of 30:50:20(v/v/v, with solid/liquid in the ratio of 1:12(g/ml at 105 oC for 90min. Lower kappa number and similar yield were achieved when hydrolytic residual woodchips were used for kraft pulping with over 2% Na2O and temperature 5 °C lower compared to untreated chips. Pulps from prehydrolysis-treated chips were easy to beat. But the tensile index, tear index, and burst index of the handsheets obtained from pulp with lowest kappa number from prehydrolysis-treated poplar chips were lower than those of the pulp from the untreated chips. Considerable xylose could be obtained from the prehydrolysis stage following kraft pulping under the same conditions for prehydrolysis-treated chips and untreated chips. However, by building on the mature kraft pulping and xylitol processes, large amounts of xylose from the hemicellulose were obtained in prehydrolysis, allowing production of high-valued products via biorefinery pathways. An economical balance of chemical dosage, energy consumption, pulp properties, and xylose value for prehydrolysis with organic acid should be reached with further investigation.

  5. Effect of replacing polyol by organosolv and kraft lignin on the property and structure of rigid polyurethane foam

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    Pan Xuejun

    2013-01-01

    Full Text Available Abstract Background Lignin is one of the three major components in plant cell walls, and it can be isolated (dissolved from the cell wall in pretreatment or chemical pulping. However, there is a lack of high-value applications for lignin, and the commonest proposal for lignin is power and steam generation through combustion. Organosolv ethanol process is one of the effective pretreatment methods for woody biomass for cellulosic ethanol production, and kraft process is a dominant chemical pulping method in paper industry. In the present research, the lignins from organosolv pretreatment and kraft pulping were evaluated to replace polyol for producing rigid polyurethane foams (RPFs. Results Petroleum-based polyol was replaced with hardwood ethanol organosolv lignin (HEL or hardwood kraft lignin (HKL from 25% to 70% (molar percentage in preparing rigid polyurethane foam. The prepared foams contained 12-36% (w/w HEL or 9-28% (w/w HKL. The density, compressive strength, and cellular structure of the prepared foams were investigated and compared. Chain extenders were used to improve the properties of the RPFs. Conclusions It was found that lignin was chemically crosslinked not just physically trapped in the rigid polyurethane foams. The lignin-containing foams had comparable structure and strength up to 25-30% (w/w HEL or 19-23% (w/w HKL addition. The results indicated that HEL performed much better in RPFs and could replace more polyol at the same strength than HKL because the former had a better miscibility with the polyol than the latter. Chain extender such as butanediol could improve the strength of lignin-containing RPFs.

  6. Biopulping of sugarcane bagasse and decolorization of kraft liquor by the laccase produced by Klebsiella aerogenes NCIM 2098

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    Jha H.

    2013-12-01

    Full Text Available Aims: Laccase, a copper-containing enzyme, oxidizes variety of aromatic compounds. Since laccase is essential for lignin degradation, it can be used for lignin removal in the pulp and paper industry (biopulping. Laccase is also employed as a dechlorinating agent (biobleaching, along with the removal of phenolic and other aromatic pollutants. In the present investigation it was aimed to employ the laccase produced by the bacterium Klebsiella aerogenes along with the bacterium itself in biopulping of sugarcane bagasse and biobleaching of kraft liquor effluent. Methodology and results: A laccase was isolated from the bacterium K. aerogenes, purified to homogeneity and characterized. The enzyme was purified by conventional techniques following salt precipitation, ion exchange chromatography, and affinity chromatography on Con A sepharose. The purified laccase was found to be monomeric glycoprotein with a Mr of 64 kDa when measured by Sephadex G-200 gel chromatography and SDS-PAGE. The Vmax and Km of laccase towards the substrate guaiacol was determined. The optimum pH of the laccase was found to be 5.0. biopulping and biobleaching activities were determined by TAPPI standard methods. Treatment of sugarcane baggase by K. aerogenes also significantly reduced lignin content of the bagasse. Conclusion, significance and impact of study: The bacterium K. aerogenes and a laccase produced by it were used separately for biopulping of sugarcane bagasse and biobleaching of kraft liquor effluent. Treatment with both brought significant reduction in lignin content and kappa number of the pulp. The handsheets prepared from the treated pulp showed improved brightness without affecting the strength properties of paper. The bacterium and the laccase efficiently decolorized the kraft liquor proving to have biobleaching potential.

  7. Uranium mill tailings and radon

    International Nuclear Information System (INIS)

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the United States may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100

  8. YANG-MILLS FIELD AMPLIFIER

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    Trunev A. P.

    2015-09-01

    Full Text Available The article presents a project of the Yang-Mills amplifier. Amplifier model is a multilayer spherical shell with increasing density towards the center. In the center of the amplifier is the core of high-density material. It is shown that in such a system, the amplitude of the Yang-Mills waves rises from the periphery to the center of several orders of magnitude. The role of the Yang-Mills field in the processes occurring in the nuclei of galaxies, stars and planets is discussed. The data modeling to strengthen the Yang-Mills field in the bowels of the planet, with an atomic explosion, and in some special devices such as the voltaic pile. To describe the mechanism of amplification chromodynamics field used as accurate results in Yang-Mills theory and numerical models developed based on an average and the exact equations as well. Among the exact solutions of the special role played by the centralsymmetric metric describing the contribution of the Yang-Mills field in the speed of recession of galaxies. Among the approximate numerical models can be noted the eight-scalar model we have developed for the simulation of non-linear color oscillations and chaos in the Yang-Mills theory. Earlier models were investigated spatio-temporal oscillations of the YangMills theory in the case of three and eight colors. The results of numerical simulation show that the nonlinear interaction does not lead to a spatial mixing of colors as it might be in the case of turbulent diffusion. Depending on the system parameters there is a suppression of the amplitude of the oscillations the first three by five colors or vice versa. The kinetic energy fluctuations or shared equally between the color components, or dominated by the kinetic energy of repressed groups of colors. In the present study, we found that amplification chromodynamic field leads to a sharp increase in the amplitude of the suppressed color, which can lead to an increase in entropy, excitation of nuclear

  9. Uranium mill tailings and radon

    International Nuclear Information System (INIS)

    The major health hazard from uranium mill tailings is presumed to be respiratory cancer resulting from the inhalation of radon daughter products. A review of studies on inhalation of radon and its daughters indicates that the hazard from the tailings is extremely small. If the assumptions used in the studies are correct, one or two people per year in the US may develop cancer as a result of radon exhaled from all the Uranium Mill Tailings Remedial Action Program sites. The remedial action should reduce the hazard from the tailings by a factor of about 100

  10. A comparative analysis of bleached and sound enamel structure through scanning electron microscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    To analyze the effects of bleaching agent on enamel structure and to characterize the morphological and chemical changes in enamel due to bleaching. Study Design: Experimental study. Place and Duration of Study: School of Chemical and Material Engineering (SCME), NUST Islamabad from Feb to May 2013. Materials and Methods: Ten recently extracted pre molars between the 12-22 years age group were randomly assigned into two groups. Group one was a non-bleached control group with sound enamel. Group two was bleached with Everbrite In office tooth whitening system after specimen preparation, surface morphology was observed under SEM (scanned electron microscope) and AFM (Atomic force microscope). Results: The detrimental effects of hydrogen per-oxide on enamel were evident in bleached specimens under SEM, and AFM analysis. Conclusion: There were significant surface alterations found in the bleached specimens as compared to control group. However salivary buffering potentials could overcome the demineralizing effect of bleaching gel. (author)

  11. Dietary shift in corallivorous Drupella snails following a major bleaching event at Koh Tao, Gulf of Thailand

    Science.gov (United States)

    Hoeksema, B. W.; Scott, C.; True, J. D.

    2013-06-01

    The island Koh Tao in the western Gulf of Thailand suffered severe coral bleaching in 2010. Its mushroom coral fauna of 20 species was surveyed during the bleaching in 2010 and after the bleaching in 2011. Multi-species assemblages of free-living mushroom corals occurred around the island, two of which were invaded by corallivorous Drupella snails after the bleaching. Previously these gastropods were known to mainly consume branching corals and hardly any mushroom corals. The snails were found preying on four fungiid species, three of which were susceptible to bleaching. The dietary shift became apparent after populations of preferred prey species (Acroporidae and Pocilloporidae) had died during the bleaching event. It seems that bleaching mortality reduced the availability of preferred prey, causing the corallivores to switch to less preferred species that occur in dense aggregations.

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

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    Xingxiang Ji

    2012-08-01

    Full Text Available 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 brightness stability, not easy to reverse. By experiment of OD, ODED, ODQP bleach Triploid of Populus Tomentos with stable chlorine dioxide activated by sulfuric acid (H2SO4. Moreover, the result of the experiment can prove that principle of activation of HCl to ClO2 is similar to H2SO4 to ClO2, that is, to provide an acid environment for ClO2.

  13. Effects of different concentrations of carbamide peroxide and bleaching periods on the roughness of dental ceramics

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    Sérgio Augusto Morey Ourique

    2011-10-01

    Full Text Available The wide use of dental bleaching treatment has brought concern about the possible effects of hydrogen peroxide on dental tissue and restorative materials. The objective of this study was to evaluate in vitro the effect of nightguard bleaching on the surface roughness of dental ceramics after different periods of bleaching treatment. Fifteen specimens of 5 × 3 × 1 mm were created with three dental ceramics following the manufacturers' instructions: IPS Classic (Ivoclar-Vivadent; IPS d.Sign (Ivoclar-Vivadent; and VMK-95 (Vita. A profilometer was used to evaluate baseline surface roughness (Ra values of all ceramics by five parallel measurements with five 0.25 mm cut off (Λc at 0.1 mm/s. Afterwards, all specimens were submitted to 6-h daily bleaching treatments with 10% or 16% carbamide peroxide (Whiteness- FGM for 21 days, while control groups from each ceramic system were stored in artificial saliva. The surface roughness of all groups was evaluated after 18 h, 42 h, 84 h, and 126 h of bleaching treatment. The surface roughness of each specimen (n = 5 was based on the mean value of five parallel measurements in each time and all data were submitted to two-way repeated measures ANOVA and Tukey's post-hoc test (α = 0.05. No significant differences in ceramic surface roughness were observed between untreated and bleached ceramic surfaces, regardless of bleaching intervals or bleaching treatments. This study provided evidence that at-home bleaching systems do not cause detrimental effects on surface roughness of dental ceramics.

  14. Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis

    Science.gov (United States)

    Públio, Juliana do Carmo; D’Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

    2016-01-01

    This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey’s test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy. PMID:27708725

  15. Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

    Science.gov (United States)

    Eakin, C. Mark; Morgan, Jessica A.; Heron, Scott F.; Smith, Tyler B.; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W.; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D.; Chiappone, Mark; Christensen, Tyler R. L.; Crabbe, M. James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L.; Gilliam, David S.; Ginsburg, Robert N.; Gore, Shannon; Guzmán, Héctor M.; Hendee, James C.; Hernández-Delgado, Edwin A.; Husain, Ellen; Jeffrey, Christopher F. G.; Jones, Ross J.; Jordán-Dahlgren, Eric; Kaufman, Les S.; Kline, David I.; Kramer, Philip A.; Lang, Judith C.; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W. Jeff; Mueller, Erich M.; Muller, Erinn M.; Orozco Toro, Carlos A.; Oxenford, Hazel A.; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B.; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F.; Sánchez, Juan A.; Schmahl, George P.; Shank, Burton V.; Skirving, William J.; Steiner, Sascha C. C.; Villamizar, Estrella; Walsh, Sheila M.; Walter, Cory; Weil, Ernesto; Williams, Ernest H.; Roberson, Kimberly Woody; Yusuf, Yusri

    2010-01-01

    Background The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate. PMID:21125021

  16. Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea.

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    Orit Nir

    Full Text Available Coral bleaching occurs when environmental stress induces breakdown of the coral-algae symbiosis and the host initiates algae expulsion. Two types of coral bleaching had been thoroughly discussed in the scientific literature; the first is primarily associated with mass coral bleaching events; the second is a seasonal loss of algae and/or pigments. Here, we describe a phenomenon that has been witnessed for repeated summers in the mesophotic zone (40-63 m in the northern Red Sea: seasonal bleaching and recovery of several hermatypic coral species. In this study, we followed the recurring bleaching process of the common coral Stylophora pistillata. Bleaching occurred from April to September with a 66% decline in chlorophyll a concentration, while recovery began in October. Using aquarium and transplantation experiments, we explored environmental factors such as temperature, photon flux density and heterotrophic food availability. Our experiments and observations did not yield one single factor, alone, responsible for the seasonal bleaching. The dinoflagellate symbionts (of the genus Symbiodinium in shallow (5 m Stylophora pistillata were found to have a net photosynthetic rate of 56.98-92.19 µmol O2 cm(-2 day(-1. However, those from mesophotic depth (60 m during months when they are not bleached are net consumers of oxygen having a net photosynthetic rate between -12.86 - (-10.24 µmol O2 cm(-2 day(-1. But during months when these mesophotic corals are partially-bleached, they yielded higher net production, between -2.83-0.76 µmol O2 cm(-2 day(-1. This study opens research questions as to why mesophotic zooxanthellae are more successfully meeting the corals metabolic requirements when Chl a concentration decreases by over 60% during summer and early fall.

  17. Caribbean corals in crisis: record thermal stress, bleaching, and mortality in 2005.

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    C Mark Eakin

    Full Text Available BACKGROUND: The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. METHODOLOGY/PRINCIPAL FINDINGS: Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. CONCLUSIONS/SIGNIFICANCE: Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate.

  18. Coscinaraea marshae corals that have survived prolonged bleaching exhibit signs of increased heterotrophic feeding

    Science.gov (United States)

    Bessell-Browne, Pia; Stat, Michael; Thomson, Damian; Clode, Peta L.

    2014-09-01

    Colonies of Coscinaraea marshae corals from Rottnest Island, Western Australia have survived for more than 11 months in various bleached states following a severe heating event in the austral summer of 2011. These colonies are situated in a high-latitude, mesophotic environment, which has made their long-term survival of particular interest as such environments typically suffer from minimal thermal pressures. We have investigated corals that remain unbleached, moderately bleached, or severely bleached to better understand potential survival mechanisms utilised in response to thermal stress. Specifically, Symbiodinium (algal symbiont) density and genotype, chlorophyll- a concentrations, and δ13C and δ15N levels were compared between colonies in the three bleaching categories. Severely bleached colonies housed significantly fewer Symbiodinium cells ( p coral in both severely and moderately bleached colonies, with clade C and a mixed clade population detected. In unbleached colonies, only clade B was observed. Levels of δ15N indicate that severely bleached colonies are utilising heterotrophic feeding mechanisms to aid survival whilst bleached. Collectively, these results suggest that these C. marshae colonies can survive with low symbiont and chlorophyll densities, in response to prolonged thermal stress and extended bleaching, and increase heterotrophic feeding levels sufficiently to meet energy demands, thus enabling some colonies to survive and recover over long time frames. This is significant as it suggests that corals in mesophotic and high-latitude environments may possess considerable plasticity and an ability to tolerate and adapt to large environmental fluctuations, thereby improving their chances of survival as climate change impacts coral ecosystems worldwide.

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

    Science.gov (United States)

    Khoroushi, Maryam; Saneie, Tahereh

    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 investigated: Optibond FL (OFL) (three-step etch-and-rinse), Optibond Solo Plus (two-step etch-and-rinse), and Optibond all-in-one (OA) (one-step self-etch) (Kerr, Orange, USA). Unbleached dentin groups (groups 1-3) were prepared as negative controls (NC). The remainder surfaces (groups 4-12) were bleached with 20% Opalescent PF (Ultradent, USA). Specimens were bonded immediately after bleaching (groups 4-6), after 1 week (groups 7-9), or after using 10% sodium ascorbate (SA) gel (groups 10-12). Subsequent to bonding of composite resin, the samples were tested for SBS and analyzed using Kruskal-Wallis and Mann-Whitney tests (α=0.05). Results: Regarding control groups, OA showed the highest SBS among the studied adhesives (P0.05) except the of delay bonding with OA. 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. PMID:22363363

  20. A dynamical systems proof of Kraft-McMillan inequality and its converse for prefix-free codes

    Science.gov (United States)

    Nagaraj, Nithin

    2009-03-01

    Uniquely decodable codes are central to lossless data compression in both classical and quantum communication systems. The Kraft-McMillan inequality is a basic result in information theory which gives a necessary and sufficient condition for a code to be uniquely decodable and also has a quantum analogue. In this letter, we provide a novel dynamical systems proof of this inequality and its converse for prefix-free codes (no codeword is a prefix of another—the popular Huffman codes are an example). For constrained sources, the problem is still open.

  1. Effect of carry-over on the kinetics of chlorine dioxide delignification of an unbleached hardwood kraft pulp

    OpenAIRE

    Simões, Rogério Manuel dos Santos; Barroca, Maria J. M. C.; Castro, José Almiro A. M.

    2010-01-01

    This work is concerned with the kinetics of the prebleaching stage of a kraft pulp of Eucalyptus globulus with chlorine dioxide. Its main purpose is to discuss the influence of the degree of washing, expressed as the COD of the pulp, on the kinetics and stoichiometry of chlorine dioxide delignification. The effect of the carry-over on the rate of delignification of a Do stage was studied over time for pulps with different initial organic charges (COD). A set of experiments was specially desig...

  2. KRAFT PULPING CHARACTERISTICS OF THREE MOROCCAN EUCALYPTI. PART 1. PHYSICAL AND CHEMICAL PROPERTIES OF WOODS AND PULPS

    OpenAIRE

    Mohammed El Moussaouiti,; Badr. Barcha,; Ericka F. Alves,; Raymond C. Francis

    2012-01-01

    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 ra...

  3. Efeito do tratamento hiperbárico na hidrólise de pasta Kraft com xilanase

    OpenAIRE

    Oliveira, Sandra Cristina Tavares de

    2010-01-01

    O principal objectivo deste trabalho consistiu no estudo da influência do tratamento hiperbárico na hidrólise enzimática de xilanas presentes na pasta kraft de Eucalyptus globulus branqueada. A hidrólise foi efectuada utilizando uma endo enzima (EC 3.2.1.8) proveniente do fungo Thermomyces lanuginosus designada comercialmente por Pentopan Mono BG. Previamente à reacção de hidrólise, a pasta celulósica foi submetida a pressões entre 200- 400 MPa durante intervalos de 15 e 45 ...

  4. Tentative Research of Short Process of Jute Degumming and Bleaching

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-ming; WANG Feng; CAI Zai-sheng; YU Jian-yong

    2008-01-01

    The feasibility of combination process of jute degumming and bleaching with alkali-hydrogen peroxide in one-step-one-bath was discussed.The combination process basically has the similar function as the traditional two-step-two-bath method.The factors such as hydrogen peroxide concentration.CBI concentration, sodium hydroxide concentration, treatment time and temperature were studied respectively, and then an orthogonal experiment was designed to study the interactions among the hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration.After the designed experiments, the optimum treatment conditions were obtained as follows: hydrogen peroxide of 12 g/L, sodium hydroxide of 4 g/L, CBI of 4 g/L, JFC of 1 g/L, treatment time of 60 min and temperature of 75℃

  5. Integration of micro milling highspeed spindle on a microEDM-milling machine set-up

    DEFF Research Database (Denmark)

    De Grave, Arnaud; Hansen, Hans Nørgaard; Andolfatto, Loic

    2009-01-01

    In order to cope with repositioning errors and to combine the fast removal rate of micro milling with the precision and small feature size achievable with micro EDM milling, a hybrid micro-milling and micro-EDM milling centre was built and tested. The aim was to build an affordable set-up, easy t...

  6. SYSTEM FOR DETECTION AND CONTROL OF DEPOSITION IN KRAFT CHEMICAL RECOVERY BOILERS AND MONITORING GLASS FURNACES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Peter Ariessohn

    2003-04-15

    Combustion Specialists, Inc. has just completed a project designed to develop the capability to monitor and control the formation of deposits on the outside of boiler tubes inside an operating kraft recovery furnace. This project, which was carried out in the period from April 1, 2001 to January 31, 2003, was funded by the Department of Energy's Inventions and Innovations program. The primary objectives of the project included the development and demonstration of the ability to produce clear images of deposits throughout the convective sections of operating recovery boilers using newly developed infrared imaging technology, to demonstrate the automated detection and quantification of these deposits using custom designed image processing software developed as part of the project, and to demonstrate the feasibility of all technical elements required for a commercial ''smart'' sootblowing control system based on direct feedback from automated imaging of deposits in real-time. All of the individual tasks have been completed and all objectives have been substantially achieved. Imaging of deposits throughout the convective sections of several recovery boilers has been demonstrated, a design for a combined sootblower/deposit inspection probe has been developed and a detailed heat transfer analysis carried out to demonstrate the feasibility of this design, an improved infrared imager which can be sufficiently miniaturized for this application has been identified, automated deposit detection software has been developed and demonstrated, a detailed design for all the necessary communications and control interfaces has been developed, and a test has been carried out in a glass furnace to demonstrate the applicability of the infrared imaging sensor in that environment. The project was completed on time and within the initial budget. A commercial partner has been identified and further federal funding will be sought to support a project to develop a

  7. Economic consequences of petroleum activities; KonKraft rapport 7; Ringvirkninger av petroleumsvirksomheten

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    The oil and gas business is highly significant for the Norwegian economy, and creates big spin-offs nationwide. Just under 150 000 people are directly employed in the petroleum sector. KonKraft report 7 deals with the Norwegian gas industry, activities related to gas exports, operations at the land-based plants and the use of gas in Norway. This report also identifies development opportunities as gas operations move north up the Norwegian continental shelf (NCS). In addition, it discusses terms and frame conditions for expanding the use of gas for industrial purposes in Norway. And a more detailed description is provided of operations and spin-offs which could be generated by greater activity in the far north. The economic effects of petroleum activities concern far more than the human resources mobilised in direct relation to each field development. Another form of direct spin-off is the operation of offshore installations with associated bases, transport services and logistics. StatoilHydro, for example, maintained a portfolio of 17 transport helicopters, four rescue machines and two charter helicopters at six different Norwegian bases in 2007. Base operations not only play a key role in offshore operations but also lay the foundation for further industrial development - not least with supply services. A case in point is the Bergen Base at Aagotnes, which also embraces an industrial site currently occupied by more than 100 companies with some 1 600 work years. The base receives almost 2 000 ship calls every year. Another example is Kristiansund Base (Vestbase), which serves a number of fields in the Norwegian Sea and provides some 750 jobs on its site. Roughly 50 people work at the Sandnessjoeen base, which is responsible for supplying the Norne field and had almost 390 ship calls in 2007. (Author)

  8. Economic consequences of petroleum activities. Summary; KonKraft rapport 7

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    The oil and gas business is highly significant for the Norwegian economy, and creates big spin-offs nationwide. Just under 150 000 people are directly employed in the petroleum sector. KonKraft report 7 deals with the Norwegian gas industry, activities related to gas exports, operations at the land-based plants and the use of gas in Norway. This report also identifies development opportunities as gas operations move north up the Norwegian continental shelf (NCS). In addition, it discusses terms and frame conditions for expanding the use of gas for industrial purposes in Norway. And a more detailed description is provided of operations and spin-offs which could be generated by greater activity in the far north. The economic effects of petroleum activities concern far more than the human resources mobilised in direct relation to each field development. Another form of direct spin-off is the operation of offshore installations with associated bases, transport services and logistics. StatoilHydro, for example, maintained a portfolio of 17 transport helicopters, four rescue machines and two charter helicopters at six different Norwegian bases in 2007. Base operations not only play a key role in offshore operations but also lay the foundation for further industrial development - not least with supply services. A case in point is the Bergen Base at Aagotnes, which also embraces an industrial site currently occupied by more than 100 companies with some 1 600 work years. The base receives almost 2 000 ship calls every year. Another example is Kristiansund Base (Vestbase), which serves a number of fields in the Norwegian Sea and provides some 750 jobs on its site. Roughly 50 people work at the Sandnessjoeen base, which is responsible for supplying the Norne field and had almost 390 ship calls in 2007. (Author)

  9. Would John Stuart Mill have regulated pornography?

    OpenAIRE

    McGlynn, C.; Ward, I

    2014-01-01

    John Stuart Mill dominates contemporary pornography debates where he is routinely invoked as an authoritative defence against regulation. This article, by contrast, argues that a broader understanding of Mill's ethical liberalism, his utilitarianism, and his feminism casts doubt over such an assumption. New insights into Mill's approach to sex, sexual activity, and the regulation of prostitution reveal an altogether more nuanced and activist approach. We conclude that John Stuart Mill would a...

  10. Structural modifications of flax and sisal lignin during the pulping and bleaching processes

    OpenAIRE

    Marques, Gisela; Gutiérrez Suárez, Ana; Nieto Garrido, Lidia; Jiménez-Barbero, Jesús; Martínez, Ángel T.; Río Andrade, José Carlos del

    2011-01-01

    We have studied the structural modifications of the lignin of flax and sisal during the pulping (soda/AQ) and bleaching (TCF and ECF) processes. The residual lignins were isolated by acidolysis and subsequently characterized by Py-GC/MS and 2D-NMR. Flax residual lignins have a predominance of G-lignin and low amounts of S-lignin units in the unbleached pulp, which are also present in similar abundances in the residual lignin after TCF bleaching. After ECF bleaching, lignin was still present, ...

  11. CHLORINE DIOXIDE BLEACHING OF SODA-ANTHRAQUINONE JUTE PULP TO A VERY HIGH BRIGHTNESS

    OpenAIRE

    M. Sarwar Jahan; Yonghao Ni,; Zhibin He

    2010-01-01

    Bleaching of soda-anthraquinone jute pulp by chlorine dioxide (ClO2) was studied to reach a target brightness of above 88% for the purpose of using less bleaching chemicals. The performance of either chlorine dioxide or peroxide in the final bleaching to boost brightness was also studied. The experimental results revealed that the final brightness depended on ClO2 charge in the Do and D1 stages. The brightness reversion was lower when the final stage brightening was done by peroxide. The use ...

  12. Bleaching of browned water yam (Dioscorea alata) with African oil bean seed lipoxygenase (Part 2).

    Science.gov (United States)

    Anokwulu, M N

    2004-01-01

    Purified African oil bean seed lipoxygenase was used to bleach water yam tubers that were browned by exposing their cut surfaces to air. The enzyme solution destroyed the polyphenols extracted from the browned water yams and the polyphenols at the browned yam tubers which resulted in the bleaching of the browned yam tubers to their original white colour. The destruction of the polyphenol extract and the bleaching of the browned yam tubers were found to be dependent on the enzyme concentration of the enzyme.

  13. Machine Shop. Module 6: Milling. Instructor's Guide.

    Science.gov (United States)

    Walden, Charles H.

    This document consists of materials for a 12-unit course on the following topics: (1) introduction to milling; (2) structure and accessories; (3) safety and maintenance; (4) cutting-tool variables; (5) basic set-up activities; (6) squaring a workpiece; (7) hole-making operations; (8) form milling; (9) machining keyways; (10) milling angular…

  14. 77 FR 14837 - Bioassay at Uranium Mills

    Science.gov (United States)

    2012-03-13

    ... COMMISSION Bioassay at Uranium Mills AGENCY: Nuclear Regulatory Commission. ACTION: Draft regulatory guide... for public comment draft regulatory guide (DG), DG-8051, ``Bioassay at Uranium Mills.'' This guide describes a bioassay program acceptable to the NRC staff for uranium mills and applicable portions...

  15. Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf.

    Science.gov (United States)

    Shuail, Dawood; Wiedenmann, Jörg; D'Angelo, Cecilia; Baird, Andrew H; Pratchett, Morgan S; Riegl, Bernhard; Burt, John A; Petrov, Peter; Amos, Carl

    2016-04-30

    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), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site. PMID:26971815

  16. J. S. Mill on Education

    Science.gov (United States)

    Ryan, Alan

    2011-01-01

    Mill may be said either to have written rather little on education or to have written a very great deal. He himself distinguished between a "narrow" and a "wider" sense of education, the former limited to what happens in formal educational settings, the latter embracing all the influences that make us who and what we are. He wrote rather little on…

  17. Fibrillation of Aspen by Alkaline Cold Pre-treatment and Vibration Milling

    Directory of Open Access Journals (Sweden)

    Kärt KÄRNER

    2016-09-01

    Full Text Available In this article an attempt to fibrillate aspen bleached chemi-thermo mechanical pulp (BCTMP fibre in an environmentally friendly way is reported. The effects of various NaOH, KOH, urea and ethanol aqueous solutions at lowered temperature were tested for pre-treatment. The pre-treatment was followed by vibration milling aiming to peel off outer cell wall layers and to fibrillate S2 layer of the aspen wood fibre. The effects of the treatments were evaluated by scanning electron microscopy (SEM. The results show that it is possible to fibrillate BCTMP aspen fibres by using alkaline aqueous solutions at low temperatures followed by a mechanical treatment. A strong dependence on fibrillation of cellulose on temperature, time and alkali concentration was established.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7412

  18. The effect of two bleaching agents on the phosphate concentration of the enamel evaluated by Raman spectroscopy: An ex vivo study

    Directory of Open Access Journals (Sweden)

    Sokkalingam Mothilal Venkatesan

    2012-01-01

    Full Text Available Aim : The aim of this ex vivo study was to evaluate the effect of in-office bleaching agents,-35% and 38% hydrogen peroxide containing bleaching agents, on the phosphate concentration of the enamel evaluated by Raman spectroscopy. Materials and Methods : Forty noncarious, craze-free human maxillary incisors, extracted for periodontal reasons, were used in this study. Baseline Raman spectra from each specimen were obtained before the application of the bleaching agent to assess the phosphate content present in the teeth. The teeth were divided into two groups: Group A - bleached with pola office bleach (35% hydrogen peroxide, potassium nitrate (light activated. Group B - bleached with opalescence Xtra bleach (38% hydrogen peroxide potassium nitrate and fluoride (chemical activated. After the bleaching procedure, the treated specimens were taken to obtain Raman spectra to assess the phosphate loss after bleaching treatment. Results : The results showed that the chemically activated bleaching agent showed less phosphate loss when compared with the light activated bleaching agent. Conclusion : Within the limitations of this study, it can be concluded that the chemically activated bleaching agent showed minimal phosphate loss when compared to light activated bleaching agent. The chemically activated bleaching agent was better than the light activated bleaching agent when values were evaluated statistically.

  19. NOAA's Coral Reef Conservation Program: 2016 Projects Monitoring the Effects of Thermal Stress on Coral Bleaching

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Climate change impacts have been identified as one of the greatest global threats to coral reef ecosystems. As temperature rise, mass bleaching, and infectious...

  20. Formalising a mechanistic linkage between heterotrophic feeding and thermal bleaching resistance

    Science.gov (United States)

    Wooldridge, Scott A.

    2014-12-01

    In this paper, I utilise the CO2 (sink) limitation model of coral bleaching to propose a new biochemical framework that explains how certain (well-adapted) coral species can utilise heterotrophic carbon acquisition to combat the damaging algal photoinhibition response sequence that underpins thermal bleaching, thereby increasing thermal bleaching resistance. This mechanistic linkage helps to clarify a number of previously challenging experimental responses arising from feeding (versus starved) temperature stress experiments, and isotope labelling (tracer) experiments with heterotrophic carbon sources (e.g., zooplankton). In an era of rapidly warming surface ocean temperatures, the conferred fitness benefits arising from such a mechanistic linkage are considerable. Yet, various ecological constraints are outlined which caution against the ultimate benefit of the mechanism for raising bleaching thresholds at the coral community (reef) scale. Future experiments are suggested that can strengthen these proposed arguments.