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Letteratura scientifica selezionata sul tema "Chromium Environmental aspects"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 25 gennaio 2023

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Articoli di riviste sul tema "Chromium Environmental aspects"

Puccini, Monica, e Domenico Castiello. "Use of Glucose to Improve the Environmental Aspects of Chrome Tanning Process". Advanced Materials Research 933 (maggio 2014): 144–50. http://dx.doi.org/10.4028/www.scientific.net/amr.933.144.

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A tanning process based on a preliminary stabilization with glucose, followed by a chromium tannage, has been optimized on semi-industrial scale. A higher chromium content in the tanned leather and a better exhaustion of the floats indicate that the presence of glucose in the hide improves the penetration and fixation of chromium. The stabilization with glucose allows the production of chromium-free waste shavings that may be reutilized through more sustainable routes. The crust leather obtained is characterized by mechanical and technical properties comparable to those of the traditionally chromium tanned crust leather. As far as roundness, fullness and hand, the glucose stabilized leather display better performances. The results obtained assess the glucose stabilized leather as a good candidate for producing high quality bovine upper leather through a more environmental sound chromium tannage, in terms of lower chromium consumption and discharge in the wastewaters and of better reutilization of chromium-free wastes.

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Gochfeld, M., e C. Witmer. "A research agenda for environmental health aspects of chromium." Environmental Health Perspectives 92 (maggio 1991): 141–44. http://dx.doi.org/10.1289/ehp.9192141.

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Lindström, David, Yolanda Hedberg e Inger Odnevall Wallinder. "Chromium(III) and Chromium(VI) Surface Treated Galvanized Steel for Outdoor Constructions: Environmental Aspects". Environmental Science & Technology 44, n. 11 (giugno 2010): 4322–27. http://dx.doi.org/10.1021/es1003022.

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Franchini, I., e A. Mutti. "Selected toxicological aspects of chromium(VI) compounds". Science of The Total Environment 71, n. 3 (giugno 1988): 379–87. http://dx.doi.org/10.1016/0048-9697(88)90210-0.

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MORIKAWA, Tsutomu, e Takuo NAKADE. "Environmental Aspects and Controlling Cr⁶⁺ Emissions of Chromium Electroplating". Journal of the Surface Finishing Society of Japan 68, n. 1 (2017): 14–20. http://dx.doi.org/10.4139/sfj.68.14.

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Biswal, Sudhansu Sekhar, Chittaranjan Panda, Priyanka Dash, Trilochan Jena, Smruti Ranjan Parida e Duryodhan Sahu. "Feasibility and Environmental Compatibility of Concrete using Chromium Bearing Wastewater". Asian Journal of Chemistry 34, n. 6 (2022): 1483–87. http://dx.doi.org/10.14233/ajchem.2022.23695.

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The effluents of chrome plating industry seepage contain toxic hexavalent chromium generally in the range of 100 to 300 mg/L. The said values of chromium are not advisable to dispose to surface water bodies or land and the treatment process of this wastewater is quite expensive. Herein, we found a course of action to reuse the wastewater in cement matrix in manufacturing concrete work. The M-30 grade concrete samples were casted with portland slag cement (PSC) at wastewater to binder ratio of 0.45. The technical compatibility of concrete specimen i.e. the chromium immobilization and other properties are well satisfied nevertheless a small decrease in hardened concrete values also observed. XRD study revealed that the hydration product Ca(OH)2 is replaced by more insoluble CaCrO4. Scanning electron microscopy study (SEM) with energy dispersive spectrum (EDS) study exhibited the immobilization of chromium and quantification of chromium content. The mortar samples from concrete after 56 days of air curing were subjected to toxicity characteristic leaching procedure (TCLP) test at pH 2.88. In addition, two days’ short tank leaching test was conducted with the concrete samples as a whole. The leachability of toxic Cr6+ found in the range 0.03-0.09 mg/L and the total chromium (TCr) values in the range 0.12 -0.17 mg/L, which are less than discharge standard as per EP Act (1986), India. All these leaching test results comply with the discharge norms to land and inland surface water, respectively. Thus, the concrete specimens using aforesaid wastewater satisfy the technical aspects and fulfil the environmental requirement.

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Kress, Nurit. "Chemical Aspects of Coal Fly Ash Disposal at Sea: Predicting and Monitoring Environmental Impact". Water Science and Technology 27, n. 7-8 (1 aprile 1993): 449–55. http://dx.doi.org/10.2166/wst.1993.0581.

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Monitoring studies at a deep sea fly ash dumping site found that the ash accumulates at the sea bed, causing a physical change in the sediments. Partial leaching of cadmium and chromium to seawater was detected in laboratory experiments, but no evidence of it was found in the sediments or benthic fauna sampled at the dumping site.

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Farooqi, Zahoor H., Muhammad Waseem Akram, Robina Begum, Weitai Wu e Ahmad Irfan. "Inorganic nanoparticles for reduction of hexavalent chromium: Physicochemical aspects". Journal of Hazardous Materials 402 (gennaio 2021): 123535. http://dx.doi.org/10.1016/j.jhazmat.2020.123535.

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Malovanyy, Myroslav, Oleg Blazhko, Halyna Sakalova e Tamara Vasylinych. "Ecological Aspects of Clay Sorption Materials Usage in Leather and Fur Production Technologies". Materials Science Forum 1038 (13 luglio 2021): 276–81. http://dx.doi.org/10.4028/www.scientific.net/msf.1038.276.

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The work is devoted to solving the current problem of increasing the level of environmental safety of treatment industrial wastewater of leather production from chromium ions (III) through the use of natural and modified bentonite. The studies of natural and modified bentonite use in the adsorption of Cr3 + ions were conducted. The influence of the process duration on the sorption efficiency of chromium ions was studied. Studies were conducted to use spent bentonite in tanning and filling processes. The efficiency of modification of montmorillonite has been proved and the expediency of using mineral dispersion for qualitative formation of the structure and properties of the leather during tanning has been established.

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Mytych, Piotr, Andrzej Karocki e Zofia Stasicka. "Mechanism of photochemical reduction of chromium(VI) by alcohols and its environmental aspects". Journal of Photochemistry and Photobiology A: Chemistry 160, n. 3 (agosto 2003): 163–70. http://dx.doi.org/10.1016/s1010-6030(03)00235-1.

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Tesi sul tema "Chromium Environmental aspects"

Abdol, Rahim Kartini. "Chromium dynamics in soil". Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/37605/.

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Due to increasing awareness of potential Cr toxicity, there is a pressing need to establish sensitive and robust Cr fractionation and speciation methodologies that will be enable separation of the two redox Cr species (CrIII and CrVI) from different environmental phases and their quantification. The intention of this work was to assess the behaviour of Cr species, especially CrVI, in soils and the factors controlling Cr solubility, fractionation, redox transformation rates and uptake by plants. The analysis methods relied on alkaline extraction in TMAH, liquid chromatography (LC) to separate the chromium species and inductively couple plasma mass spectrometry (ICP-MS) for quantification of chromium. The interference of 40Ar12C+ background peak at mass 52 was reduced by using the CCT-KED facility of the ICP-MS. A solution of 50 mM TRIS buffer, 40 mM NH4NO3, 10-5 M ammonium-EDTA at pH 7.0 was used as the chromatographic eluent. The method developed is suitable for determining CrVI in soil, following alkaline extraction in TMAH, but not for CrIII due to poor recovery, redox transformation and strong binding of CrIII with humic acid despite attempts to preserve the trivalent species using EDTA and heating. The extraction method was applied to assessing Cr speciation and fractionation in a wide range of soil ecosystems collected from urban sites in Wolverhampton, Nottingham, London and a historical sewage sludge disposal farm in Nottinghamshire. To predict soil CrVI content the use of TMAH-extractable Cr (CrTMAH) was better (R=0.911) compared to total soil Cr content (Crtotal; R=0.554). The same analytical approaches were also applied to the development of a method to determine isotopically exchangeable CrVI in soils. This employed isotopically enriched 50CrVI as a ‘spike’ isotope added to soils suspended in varying concentrations of TMAH in an attempt to resolve a consistent fraction of isotopically exchangeable, or ‘labile’, CrVIO42- in soil. It was apparent that, because of the slow exchange kinetics of CrVI in soils, it was difficult to determine a consistent isotopically exchangeable fraction. Nevertheless, the investigation did suggest a refinement of the simple TMAH extraction protocol could enable direct determination of labile soil CrVI. The kinetics of CrVI interaction with a geocolloid (humic acid) was assessed and humic acid was found capable of both reducing CrVI and binding with the resulting CrIII species. Finally, Cr uptake by maize grown on a historical sewage sludge disposal farm was assessed with several approaches to finding a correlation between Cr in soil and Cr uptake by plants. The concentration of CrVI in soil, and its solubility, could be reasonably well predicted from Crtotal or CrTMAH and soil properties. However, restricted uptake of CrVI by the maize plants, and probably reduction of CrVI to CrIII in the root system, made it impossible to predict Cr transfer to shoots or the speciation of the Cr in maize shoots. Overall, due mainly to the apparent ability of the maize plants to control uptake and speciation of CrVI, the produce was considered safe to be consumed by ruminants as regards CrVI content.

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Anestis, Ioannis D. "Preference avoidance reactions of rainbow trout (Salmo gairdneri) following long term sublethal exposure to chromium and copper". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75767.

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A standard methodology was developed for performing avoidance-preference tests, using Rainbow Trout (Salmo gairdneri) as the test organism. Experiments were conducted in a hydraulic channel, 9.15 m long by 0.30 m wide, partly divided along its length, and at a flow depth of 0.30 m. The design combined steep and shallow gradient characteristics. The toxicants investigated included Cu(II), Cr(III) and Cr(VI). The lowest avoidance threshold values were established at 2.1 $ mu$g/l for Cu(II) and 0.0026 mg/l and 0.026 mg/l for Cr(III) and Cr(VI) respectively while avoidance reactions increased with levels of toxicant in the channel. Similar experiments were performed with rainbow trout which were pre-exposed at sublethal levels to the toxicant, in order to assess the influence of toxic pre-exposure to the subsequent fish avoidance response. The length of pre-exposure varied between 7-20 weeks. Avoidance threshold values were correlated with safe levels of toxicant exposure.
Pre-exposed fish exhibited decreasing avoidance reactions compared to non-exposed populations. Increased tolerance to the toxicant, was suggested by the increase in avoidance threshold values with pre-exposure levels. Fish exposed to test concentrations matching their pre-exposure levels, clearly preferred this same concentration over the adjacent lower or higher test concentration.
A two mechanism avoidance model was proposed independent of toxicant used or level of pre-exposure. The toxicant concentration where the second mechanism begins to dominate was referred to as avoidance breakpoint, and was correlated to a MATC level for the toxicant in question. Olfactory responses were proposed to be associated with fish avoidance responses below the avoidance breakpoint, while hypoxic stress along with osmo- and iono regulatory stress appeared to be responsible for driving fish avoidance reactions beyond the avoidance breakpoint.
A clearance period of 7 days was sufficient to allow fish to recover normal avoidance behaviour following pre-exposure to Cr(VI) below the avoidance breakpoint.

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Kamaludeen, Sara Parwin Banu. "Biotic-abiotic transformations of chromium in long-term tannery waste contaminated soils : implications to remediation". Title page, table of contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phk15.pdf.

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Bibliography: leaves 166-180. Determines the effect of chromium on the soil microbial community and its activity, the biotic-abiotic mechanisms involved in chromium oxidation, and phytostabilization of chromium using plants and organic amendment in tannery-waste contaminated soil.

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Cheung, Ka-hong, e 張嘉康. "Chromate toxicity assessment and detoxification by bacteria from the marine environment". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B45015351.

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Gendusa, Tony C. "Toxicity of Chromium and Fluoranthene From Aqueous and Sediment Sources to Selected Freshwater Fish". Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc330672/.

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Research efforts in aquatic toxicology have historically centered on the chemical analyses and toxic effects of waters to aquatic organisms. More recently, sediment-source toxicity has been explored, with efforts concentrated on establishing sensitive and accurate methodologies. This study focused on the toxicity of trivalent chromium, hexavalent chromium, and fluoranthene to Pimephales promelas, Ictalurus punctatus, and Lepomis macrochirus. Test fish were exposed to both water-borne and sediment-source toxicants for 96 hours (h) and 30 days (d). A 96-h and 30-d LC50 (mg/L Cr, ug/L Fluoranthene) was determined for each fish species exposed to aqueous toxicants. In addition, 96-h and 30-d LC50s were determined for each fish species from sediment chromium concentrations (mg/kg) and sediment fluoranthene concentrations (ug/kg). Although lethality endpoints were used throughout this research, acute effects other than mortality were determined for Lepomis macrochirus exposed to hexavalent chromium. Lethal toxicity values (96-h and 30-d LC50 and their 95% confidence limits) for trivalent chromium could not be determined since trivalent chromium concentations above 6.0 mg/L could not be obtained at water pHs compatible with these fish species. Trivalent chromium addition to test waters at pHs compatible with fish survival resulted in a chromium precipitate that was not lethal to test fish. In contrast, fathead minnows, channel catfish, and bluegill sunfish exposed to hexavalent chromium in water and sediments experienced mortality. Fathead minnows exposed to fluoranthene in water for 96h demonstrated a maximum mortality of 69%, while 100% mortality was achieved with channel catfish in similar tests. Sediment tests with fluoranthene resulted in 100% mortality with both fathead minnows and channel catfish.

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Meza, Maria I. "The use of PRBs (permeable reactive barriers) for attenuation of cadmium and hexavalent chromium from industrial contaminated soil". Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/432.

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Sedumedi, Hilda N. "Chromium contamination in the vicinity of [the] Xstrata Wonderkop plant". Thesis, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000304.

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M. Tech. Chemistry.
The aim of this study was to develop and evaluate an analytical method for the determination of Cr(VI) in ferrochrome dusts and to apply the method in the analysis of environmental samples (grass, soil and tree bark) for Cr(VI) content (that might be caused by dust emissions originating from the smelter). Both the public and Xstrata Wonderkop ferrochrome plant will benefit from data of Cr(VI) determination generated from the study. The information can potentially be incorporated into health risk assessments of the affected geographical areas. The results of the investigation showed that ferrochrome smelter dust emissions were the source of contamination of the environment with Cr(VI). With time, Cr(VI) could accumulate in soil to unacceptable levels, thereby endangering both plants and animals.

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Subramanian, Avudainayagam. "Long-term tannery waste contamination: effect on chromium chemistry / by Avudainayagam Subramanian". 2002. http://hdl.handle.net/2440/21824.

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Corrigenda inside front cover.
Includes bibliographical references (leaves 205-232)
xii, 232, [27] leaves : ill., plates ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002

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Kamaludeen, Sara Parwin Banu. "Biotic-abiotic transformations of chromium in long-term tannery waste contaminated soils : implications to remediation / by Sara Parwin Banu Kamaludeen". Thesis, 2002. http://hdl.handle.net/2440/21767.

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Bibliography: leaves 166-180.
180, [4] leaves : ill. (chiefly col.) ; 30 cm.
Determines the effect of chromium on the soil microbial community and its activity, the biotic-abiotic mechanisms involved in chromium oxidation, and phytostabilization of chromium using plants and organic amendment in tannery-waste contaminated soil.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002

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Like, David E. "Management of chromium wastes in industry". Thesis, 1991. http://hdl.handle.net/1957/37990.

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Chromium hydroxide sludge is the end product of the aluminum phosphate coating process used by a truck manufacturer in the Pacific Northwest. This sludge is listed as an (F019) hazardous waste by the Environmental Protection Agency, and must be landfilled in a hazardous waste landfill site. The purpose of this thesis is to evaluate the characteristics of this sludge, and to then recommend suitable methods for handling and disposal. The chemical analysis of the sludge found total chromium to be 5.4% by weight. Industrial hygiene monitoring found the highest concentrations of 0.002 mg/m3 total chromium and 0.00006 mg/m3 hexavalent chromium at the waste treatment plant. The eight hour permissible exposure limit for total chromium is 0.5 mg/m3 and 0.05 mg/m3 for hexavalent chromium. Given the chemical analysis and industrial hygiene monitoring, a management plan is proposed for this truck manufacturer that discusses possible options for handling the (F019) waste, and provides a cost analysis for each of the options. The options that were investigated were onsite treatment, recycling, no change, and delisting. Onsite treatment was not required since the sludge passed the TCLP extraction test. Recycling costs were determined by contacting four recycling firms. Costs were found to be $600/ton and above, which exceeded the current disposal costs of $466/ton. Delisting the sludge from the hazardous waste listing was determined to be the most feasible from a management, cost, and environmental standpoint. Delisting would reduce the costs of handling the waste, would allow a reduction in landfilling costs, and reduce recycling costs. A literature survey provides background information on industrial uses of chromium, health problems associated with chromium, and discusses the regulations that govern disposal of these chromium sludges.
Graduation date: 1991

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Più fonti

Libri sul tema "Chromium Environmental aspects"

Jaworski, J. F. Chromium update: Environmental and nutritional effects of chromium. Ottawa: National Research Council of Canada, NRCC Associate Committee on Scientific Criteria for Environmental Quality, 1985.

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Medvedev, A. N. Vozdeĭstvie na okruzhai͡u︡shchui͡u︡ sredu predprii͡a︡tii͡a︡ po dobyche khromovykh rud. Ekaterinburg: Rossiĭskai͡a︡ akademii͡a︡ nauk, Uralʹskoe otd-nie, In-t promyshlennoĭ ėkologii, 1996.

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Katz, Sidney A. The biological and environmental chemistry of chromium. New York: VCH, 1994.

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O, Nriagu Jerome, e Nieboer Evert, a cura di. Chromium in the natural and human environments. New York: Wiley, 1988.

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Brandhuber, Philip. Low-level hexavalent chromium treatment options: Bench-scale evaluation. Denver, CO: AWWA Research Founcation, 2004.

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Thiravetyan, Philip. Treatment of chromium contamination in the environment. Hauppauge, N.Y: Nova Science Publishers, 2011.

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Hering, Janet G. Geochemical controls on chromium occurrence, speciation, and treatability. Denver, CO: Awwa Research Foundation, 2004.

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Thiravetyan, Philip. Treatment of chromium contamination in the environment. Hauppauge, N.Y: Nova Science Publishers, 2011.

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California. Legislature. Senate. Committee on Health and Human Services. Joint informational hearing of the Senate Committee on Health and Human Services and Senate Committee on Natural Resources and Wildlife and the Assembly Committee on Environmental Safety and Toxic Materials: Health effects of chromium VI contamination of drinking water. Sacramento, CA: Senate Publications, 2000.

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Murria, María José Balart. Management of hazardous residues containing Cr(VI). Hauppauge, N.Y: Nova Science Publishers, 2009.

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Capitoli di libri sul tema "Chromium Environmental aspects"

Hoet, Perinne. "Speciation of Chromium in Occupational Exposure and Clinical Aspects". In Handbook of Elemental Speciation II - Species in the Environment, Food, Medicine and Occupational Health, 136–57. Chichester, UK: John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470856009.ch2f(ii).

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Agrawal, Bipin Jagdishprasad. "Prospective Sustainability of Utilization of Effective Techniques for Remediation of Heavy Metals From Textile Effluents". In Research Anthology on Emerging Techniques in Environmental Remediation, 517–42. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3714-8.ch028.

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Textile industries are one of the prevalent water consumers and contaminators ensuing high generation of waste water. Wastewater from dyeing and printing units is often rich in organic compounds, colours, and heavy metals containing residues of various dyes and chemicals. Among these waste water pollutants, heavy metals are of serious environmental concern in recent years. Metals are extensively used for manufacture of synthetic dyestuffs and for colouration of natural dyes on textiles to achieve different shades and hues. Heavy metals such as lead (Pb), chromium (Cr), cadmium (Cd), iron (Fe), zinc (Zn), copper (Cu), etc. are widely used for production of colour pigments of textile dyes. These heavy metals, highly toxic, get conveyed to the environment, and can bio-accumulate in the human body, aquatic life, natural water-bodies, and also possibly become trapped in the soil. The chapter deals with the utilization of heavy metals in textile wet processing, their important characteristics, various toxic aspects, and different methods for their elimination from the textile effluent liquors.

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Agrawal, Bipin Jagdishprasad. "Prospective Sustainability of Utilization of Effective Techniques for Remediation of Heavy Metals From Textile Effluents". In Biostimulation Remediation Technologies for Groundwater Contaminants, 19–49. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-4162-2.ch002.

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Atti di convegni sul tema "Chromium Environmental aspects"

Foss, Dyan L., e Briant L. Charboneau. "Groundwater Remediation of Hexavalent Chromium Along the Columbia River at the Hanford Site in Washington State, USA". In ASME 2011 14th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2011. http://dx.doi.org/10.1115/icem2011-59030.

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

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Kirsten, A., M. Oechsle e R. F. Moll. "Carbide Containing Materials for Hard Chromium Replacement by HVOF-Spraying". In ITSC2005, a cura di E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2005. http://dx.doi.org/10.31399/asm.cp.itsc2005p0957.

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Abstract Hard chromium, electrochemical deposited, is a widely used and established coating solution for surface protection against wear and corrosion as well as for decorative applications. Due to the possibility to coat bulk goods also, this technique is well suitable to protect small pieces and mass-produced goods. However, the most disadvantage of that technique is the appearance of highly carcinogenic hexa-valence chromium. Because of human health and environmental aspects the replacement of this coating technique is more and more required. At least for bigger parts with larger surfaces H(igh) V(elocity) O(xy) F(uel) -spraying can already produce competitive coatings to galvanic hard chromium with equal or even better properties. Especially thermal sprayed carbide coatings with in terms of corrosion resistance tailored metallic matrices offering the best potential to replace hard chromium in various applications. Beside of the material properties also the spraying conditions have essential influence on the corrosion resistance of those coatings. The present paper will give an overview of different carbide containing materials for HVOF-spraying and their properties with special respect to the replacement of galvanic hard chromium. The closest attention will be on the corrosion resistance of HVOF-coatings of those materials in different aqueous solutions compared with hard chromium. For a liquid fuel high velocity spraying system also the trends will be shown in which way the spraying parameters are influencing the general corrosion behaviour of such coatings. Those tendencies by conviction of the authors are also transferable to other HVOF systems.

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Stalder, Jean-Pierre, e Peter A. Huber. "Use of Chromium Containing Fuel Additive to Reduce High Temperature Corrosion of Hot Section Parts". In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0138.

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The use of “clean” fuel is a prerequisite at today’s elevated gas turbine firing temperature, modern engines are more sensitive to high temperature corrosion if there are impurities present in the fuel and/or in the combustion air. It is a common belief that distillate grade fuels are contaminant-free, which is often not true. Frequently operators burning distillates ignore the fuel quality as a possible source of difficulties. This matter being also of concern in plants mainly operated on natural gas and where distillate fuel oil is the back-up fuel. Distillates may contain water, dirt and often trace metals such as sodium, vanadium and lead which can cause severe damages to the gas turbines. Sodium being very often introduced through contamination with seawater during the fuel storage and delivery chain to the plant, and in combination, or with air borne salt ingested by the combustion air. Excursions of sodium in treated crude or heavy fuel oil can occur during unnoticed malfunctions of the fuel treatment plant, when changing the heavy fuel provenience without centrifuge adjustment, or by inadequate fuel handling. For burning heavy fuel, treatment with oil-soluble magnesium fuel additive is state of the art to inhibit hot corrosion caused by vanadium. Air borne salts, sodium, potassium and lead contaminated distillates, gaseous fuels, washed and unwashed crude and residual oil can not be handled by simple magnesium based additives. The addition of elements like silicon and/or chromium is highly effective in reducing turbine blade hot corrosion and hot section fouling. This paper describes field experience with the use of chromium containing fuel additive to reduce high temperature corrosion of hot section parts, as well as the interaction of oil-soluble chromium and magnesium-chromium additives on material behaviour of blades and vanes, and their economical and environmental aspects.

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Pelz, A. "Analysis of Fe-base Materials and Evaluation of their Suitability for Wear Protection Coatings". In ITSC2010, a cura di B. R. Marple, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima e G. Montavon. DVS Media GmbH, 2010. http://dx.doi.org/10.31399/asm.cp.itsc2010p0751.

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Abstract Recently much research work has been undertaken worldwide to develop iron base materials which can be used for thermal spraying of anti-wear coatings. Besides economical ideas reasons exist like health- and environmental aspects for the usability of iron base materials instead of Ni- or Co containing carbide coatings. Until now, however, iron base materials showed a worse life time under abrasive wear compared with conventional carbide coatings like WC/ CO or NiCr-CrC. This article presents the research work on new iron base materials for wear protection purposes. Thereby, the focus is set on high carbon containing iron-chromium base alloys which solidify under the formation of primary carbides. The material development included the study of different additional alloying elements. The relation of different chemical compositions and their typical microstructure to the wear behaviour is presented in this paper, too. To follow an integral way for the evaluation of the wear behaviour both powders and cored-wires could be produced. Therefore the wear tests considered coatings produced via HVOF, PTA and arc-spraying.

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Kloss-Grote, Benjamin, Michael Wechsung, Rainer Quinkertz e Henning Almstedt. "Advanced Steam Turbine Technology for Unique Double Reheat Steam Power Plant Layout". In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90934.

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Abstract Environmental aspects have increased the pressure on the fossil power generation industry to reduce carbon dioxide (CO2) emissions. One way to achieve this is by increasing the overall plant efficiency, which also fosters an economical plant operation. How can the efficiency of a next generation coal fired ultra super critical (USC) steam power plant (SPP) be increased significantly in the nearest future while maintaining its familiar reliability and availability at the same time? In China’s national USC SPP demonstration project, Pingshan Phase II, this challenge is met by a double reheat cross compound turboset with one elevated and one conventional turbine layout, together with increased steam parameters of up to 325 bar and steam temperatures of up to 630°C. The nominal electrical capacity of the plant will be 1350 megawatts (MW). With this set up, a ‘half-net’ efficiency of more than 52.2 percent is expected [‘half-net’ = gross efficiency with generator power reduced by boiler feed water pump power consumption]. The first, elevated turbine train consists of two high-pressure modules having different pressure stages and one generator and it is located close to the main headers of the boiler at a height of appr. 83 meters. This unique turbine arrangement allows the expensive high-temperature pipes to be shortened, leading to substantially reduced pipe pressure losses and costs. The second turbine train will be installed on a conventional turbine deck at a height of appr. 17 meters and consists of two intermediate pressure and three low pressure turbine modules as well as a second generator. In this paper, the advanced steam turbine technology for this power plant concept is presented and discussed in detail. To achieve the next level of efficiency with an SPP today, the application of the 700°C material class is not possible to due to the slow progress of the associated technology development. It is more expedient to exploit the limits of the 600°C material class to the highest possible extent in USC conditions i.e. to the pressures and temperatures mentioned above. Design concept studies have shown that 52.2% ‘half-net’ efficiency cannot be achieved with a single reheat layout, so a double reheat (DRH) layout has been chosen. In addition, 1350 MW cannot be achieved with one turbine train (tandem compound), but only with two turbine trains (cross compound). In order to achieve the highest reliability possible, proven turbine design topologies and features have been used. The major change to the Siemens barrel type VHP turbine was a material change from 10% Chromium steels to FB2 and CB2. The HP turbine received increased wall thicknesses as well as a similar material change compared to a standard USC design. In order to control the oxidation at these elevated temperatures, oxidation protection measures have been applied where required. The startup procedure has been tailored specifically to the needs of a double reheat cross compound configuration.

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Polishetty, Ashwin, Mohanad Fakhri Abdulqader Alabdullah, Nihal Pillay e Guy Littlefair. "A Preliminary Study on Machinability of Super Austenitic Stainless Steel". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50224.

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Stainless steel is the most widely used alloys of steel. The reputed variety of stainless steel having customised material properties as per the design requirements is Duplex Stainless Steel and Austenitic Stainless Steel. The Austenite Stainless Steel alloy has been developed further to be Super Austenitic Stainless Steel (SASS) by increasing the percentage of the alloying elements to form the half or more than the half of the material composition. SASS (Grade-AL-6XN) is an alloy steel containing high percentages of nickel (24%), molybdenum (6%) and chromium (21%). The chemical elements offer high degrees of corrosion resistance, toughness and stability in a large range of hostile environments like petroleum, marine and food processing industries. SASS is often used as a commercially viable substitute to high cost non-ferrous or non-metallic metals. The ability to machine steel effectively and efficiently is of utmost importance in the current competitive market. This paper is an attempt to evaluate the machinability of SASS which has been a classified material so far with very limited research conducted on it. Understanding the machinability of this alloy would assist in the effective forming of this material by metal cutting. The novelty of research associated with this is paper is reasonable taking into consideration the unknowns involved in machining SASS. The experimental design consists of conducting eight milling trials at combination of two different feed rates, 0.1 and 0.15 mm/tooth; cutting speeds, 100 and 150 m/min; Depth of Cut (DoC), 2 and 3 mm and coolant on for all the trials. The cutting tool has two inserts and therefore has two cutting edges. The trial sample is mounted on a dynamometer (type 9257B) to measure the cutting forces during the trials. The cutting force data obtained is later analyzed using DynaWare supplied by Kistler. The machined sample is subjected to surface roughness (Ra) measurement using a 3D optical surface profilometer (Alicona Infinite Focus). A comprehensive metallography process consisting of mounting, polishing and etching was conducted on a before and after machined sample in order to make a comparative analysis of the microstructural changes due to machining. The microstructural images were capture using a digital microscope. The microhardness test were conducted on a Vickers scale (Hv) using a Vickers microhardness tester. Initial bulk hardness testing conducted on the material show that the alloy is having a hardness of 83.4 HRb. This study expects an increase in hardness mostly due to work hardening may be due to phase transformation. The results obtained from the cutting trials are analyzed in order to judge the machinability of the material. Some of the criteria used for machinability evaluation are cutting force analysis, surface texture analysis, metallographic analysis and microhardness analysis. The methodology followed in each aspect of the investigation is similar to and inspired by similar research conducted on other materials. However, the novelty of this research is the investigation of various aspects of machinability and drawing comparisons between each other while attempting to justify each result obtained to the microstructural changes observed which influence the behaviour of the alloy. Due to the limited scope of the paper, machinability criteria such as chip morphology, Metal Removal Rate (MRR) and tool wear are not included in this paper. All aspects are then compared and the optimum machining parameters are justified with a scope for future investigations.

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Lervik, Jens Kristian, Harald Kulbotten, Gunnar Klevjer e Øyvind Iversen. "Hydrate and Wax Prevention in Flowlines by Electrical Heating". In 2000 3rd International Pipeline Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/ipc2000-229.

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Traditional chemical treatment methods have considerable operation costs and represent a risk to the environment. Since 1987 Norwegian oil companies have been investigating alternative electrical heating methods for prevention of hydrate and wax plugs. A joint industry project ‘Concept Verification – Direct Heating of Oil & Gas Pipelines’ was initiated in 1996 and terminated in October 1999. During this work an electrical heating system was proved to be feasible on several fields in the North Sea. It will be installed on 7 flowlines of 13% Chromium (Crl3) with lengths between 6 km and 16 km. Electrical heating is used to maintain or raise the thermally insulated steel pipe temperature above the critical value for hydrate formation (typically 15–25 °C) or wax formation (typically 20–40°C). A single-phase power supply for the heating system is based on commercial components and connected to the platform power supply. The qualification work for the direct heating system has included full scale testing for single and parallel pipes, end termination at the template, bypass of a template and aspects concerning corrosion control. The rating of the system is dependent on the magnetic and electrical characteristics of the steel material. Such data is not commonly available. Measurements performed during the qualification program confirm that the magnetic characteristic may vary within a wide range for a specific steel quality and that mechanical stress and heat treatment can effect the magnetic characteristic. The difference in magnetic characteristic of individual Crl3 pipes results in variation of the pipe temperature and problems concerning differential pressure during melting. The problem can be handled by dividing the pipeline into a number of sections, each with a limited variation of the magnetic characteristic, thus keeping the temperature for the whole pipeline within acceptable limits. As a part of the pipe specification both electrical and magnetic characteristic should be available. These data can be determined by measuring arrangements in the production line of the mill. Measures to limit the variation of magnetic characteristic should be discussed.

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