Academic literature on the topic 'Alkaline chloride electrolyte'
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Journal articles on the topic "Alkaline chloride electrolyte"
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Shekhanov, Ruslan F. "PROTECTIVE ABILITY OF TIN-NICKEL COATINGS." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 10 (November 16, 2017): 75. http://dx.doi.org/10.6060/tcct.20176010.5605.
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The calculation of the corrosion current of the steel – plating allowed us to estimate the protective properties and the porosity of the Tin-Nickel coatings. Measured in 3% NaCl solution the potential of steel electrode covered by tin alloy-Nickel thickness of 5, 10, 15 µm, respectively, has values of -277 mV, -314 mV, -355 mV, and the potential of steel 0.8 KP was 440 mV relative to the standard hydrogen electrode. At a thickness of 15 µm and at the mentioned potential the current density of corrosion for system steel – coating from tin-Nickel oxalate electrolyte was 2.3 µa/cm2, and for the coating from fluoride-chloride electrolyte was 7.5 µA/cm2. Therefore, the protective ability of tin-Nickel coatings obtained from oxalate-sulfate electrolytes is 3 times higher than similar coatings from fluoride-chloride electrolyte. Corrosion tests in salt spray chamber for Sn-Ni coatings obtained from oxalate-ammonium electrolyte confirmed the high corrosion resistance of tin-Nickel coatings when the ratio of the metals in the electrolyte was Ni/Sn = 5/1. The coatings obtained from oxalate electrolytes, distinguished by small size grains, in contrast to the coatings deposited from fluoride-chloride electrolyte. The increase in the microhardness of the coatings contributes a more microcrystalline surface topography of the alloy tin-Nickel deposited from oxalate-sulfate electrolytes, as it was evidenced by the results of crystallographic calculations. The test of specimens for microhardness showed that the samples obtained from oxalate-sulfate electrolytes are a bit harder (255 MPa) than samples obtained from fluoride-chloride electrolyte (245 MPa). The study of the structure of the coatings was performed using scanning electron microscope. SEM data showed that coatings obtained from the fluoride-chloride electrolyte have the pores, whereas poros are practically absent for caotings obtained from oxalate-ammonium. Probably, for these reasons the tin-Nickel coating obtained from oxalate-ammonium electrolyte better resists to corrosion in comparison with similar coating prepared from fluoride-chloride electrolyte. The technological process of depositing tin-nickel alloy from said weakly acid electrolyte is twice as effective and high-speed as compared to alkaline tinning, since the electrochemical equivalent of tin (II) is twice as high as for tin (IV) deposited from the alkaline electrolyte. It has been established that coatings obtained from oxalate-ammonium electrolytes, due to increased polarization during electrodeposition, are finer-grained, corrosion-resistant in comparison with coatings obtained from fluoride-chloride electrolytes. High dissipation ability of oxalate-ammonium electrolytes makes it possible to deposit tin-nickel coatings on composite products. The new technological processes studied in the result of the work made it possible to improve the physical and chemical properties of the coatings, to reduce material costs and to reduce environmental pollutionForcitation:Shekhanov R.F. Protective ability of tin-nickel coatings. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 75-81
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Harchegani, R. K., and A. R. Riahi. "Effect of Cerium Chloride on the Self-Corrosion and Discharge Activity of Aluminum Anode in Alkaline Aluminum-air Batteries." Journal of The Electrochemical Society 169, no. 3 (March 1, 2022): 030542. http://dx.doi.org/10.1149/1945-7111/ac5c06.
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One of the key impediments to aluminum (Al) as an anode in alkaline Al-air batteries is self-corrosion, which limits the battery’s efficiency due to the capacity loss and lifespan reduction. Thus, it is vital to find an efficient electrolyte additive that reduces self-corrosion in Al anodes. In this study, the effect of adding 0.5 to 1.5 wt% of cerium chloride to 4 mol l−1 KOH electrolyte on the self-corrosion of pure Al anode was investigated using electrochemical experiments. The results show that the addition of cerium chloride to the electrolyte reduces self-corrosion of the Al anode with a negligible effect on the anode activity. Cerium chloride forms cerium hydroxide (Ce (OH)3) in the alkaline electrolyte, which is adsorbed on the Al surface. Therefore, the corrosion potential increased, and self-corrosion current density decreased. As the cerium chloride concentration increased, the Al anode efficiency increased from 43.8% to 76.1%, and the capacity density increased from 1294 to 2244 mAh g−1. Furthermore, increasing the immersion time of the Al anode in the electrolyte containing cerium chloride increased the self-corrosion resistance and provided the self-healing properties for the anode.
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Проценко, В. С., Т. Е. Бутырина, Д. А. Богданов, С. А. Корний, and Ф. И. Данилов. "Электрохимический синтез композиционных покрытий Ni/TiO2 из низкотемпературного эвтектического растворителя и электрокаталитические свойства осадков." Elektronnaya Obrabotka Materialov 57, no. 6 (December 2021): 1–13. http://dx.doi.org/10.52577/eom.2021.57.6.01.
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Kinetics of electrodeposition of composite Ni/TiO2 coatings was studied using the electrolyte based on a deep eutectic solvent (DES) containing choline chloride, ethylene glycol, water additive, and nickel chloride. Degussa P 25 nanopowder was used as a dispersed phase in the electrolyte (1–10 g dm3). The developed electrolyte allows depositing composite coatings with the content of titanium dioxide reaching ~ 10 wt.%. The electrolytic deposition of the composite was shown to obey Guglielmi's kinetic model. The main parameters of co-deposition of TiO2 particles into a nickel matrix were determined in the framework of this kinetic model. The co-deposition of titanium dioxide was found to inhibit the reaction of the nickel ions discharge. Electrocatalytic properties of the prepared composite Ni/TiO2 coatings were evaluated with respect to the hydrogen evolution reaction in an aqueous alkaline solution. A noticeable improvement in the electrocatalytic activity was observed when titanium dioxide particles were introduced into an electrodeposited nickel matrix.
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Samsudin, Asep Muhamad, Sigrid Wolf, Michaela Roschger, and Viktor Hacker. "Poly(vinyl alcohol)-based Anion Exchange Membranes for Alkaline Polymer Electrolyte Fuel Cells." International Journal of Renewable Energy Development 10, no. 3 (February 12, 2021): 435–43. http://dx.doi.org/10.14710/ijred.2021.33168.
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Crosslinked anion exchange membranes (AEMs) made from poly(vinyl alcohol) (PVA) as a backbone polymer and different approaches to functional group introduction were prepared by means of solution casting with thermal and chemical crosslinking. Membrane characterization was performed by SEM, FTIR, and thermogravimetric analyses. The performance of AEMs was evaluated by water uptake, swelling degree, ion exchange capacity, OH- conductivity, and single cell tests. A combination of quaternized ammonium poly(vinyl alcohol) (QPVA) and poly(diallyldimethylammonium chloride) (PDDMAC) showed the highest conductivity, water uptake, and swelling among other functional group sources. The AEM with a combined mass ratio of QPVA and PDDMAC of 1:0.5 (QPV/PDD0.5) has the highest hydroxide conductivity of 54.46 mS cm-1. The single fuel cell tests with QPV/PDD0.5 membrane yield the maximum power density and current density of 8.6 mW cm-2 and 47.6 mA cm-2 at 57 °C. This study demonstrates that PVA-based AEMs have the potential for alkaline direct ethanol fuel cells (ADEFCs) application.
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Othman, Raihan, Farouq Ahmat, Muhd Amlie Ibrahim, Assayidatul Laila Nor Hairin, and Hanafi Ani Mohd. "Effect of Bath Formulation and Plating Current Density on Electrodeposited Zinc Anode’s Capacity in Zinc-Air Cell." Advanced Materials Research 576 (October 2012): 484–87. http://dx.doi.org/10.4028/www.scientific.net/amr.576.484.
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Zinc anode is electrodeposited from a 2-M zinc chloride electrolytic bath with varying ammonium chloride supporting electrolyte concentrations (0-5 M) and plating current density (0.1 – 0.6 A cm-2). The total charge quantity supplied during electrodeposition is fixed at 150 mAh. Alkaline zinc-air cell is fabricated using the electrodeposited zinc anode and characterized according to its discharge capacity at constant load current of 20 mA. The effect of various qualities of zinc electrodeposits on the cell discharge performance is discussed. It is found that zinc electrodeposits prepared from electrolytic bath of 5-M ammonium chloride and 0.5 A cm-2 plating current density produced zinc-air cell with the highest output energy i.e. 24 mWh. We observe that the influence of plating current density is more prominent than the plating bath formulation on the zinc anode performance in the cell.
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Ismail, W. M. I. W., N. S. W. Zulkefeli, and M. N. Masri. "A Sight of Zinc Corrosion in Various Alkaline Media." Journal of Tropical Resources and Sustainable Science (JTRSS) 4, no. 2 (August 13, 2021): 95–97. http://dx.doi.org/10.47253/jtrss.v4i2.614.
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This review concentrates on corrosion properties that expose to zinc by various alkaline media. The assumption has been advanced that zinc corrodes electrochemically in the first stage of exposition, but the chemical corrosion prevails after a longer time. Different types of electrolyte had been tested on zinc such as sodium chloride, sodium hydroxide and potassium hydroxide. Each of alkaline media can produced corrosion product such as zinc hydroxide chloride, zinc hydroxide carbonate, zinc oxide, and zinc hydroxide. The production of corrosion products is depending on the carbon dioxide content that introduced to the air. Potassium hydroxide is the highest and active alkaline where it contains the highest ionic conductivity potassium ions, K+ after hydronium, H3O+ among the cations and hydroxide, OH ? has the highest ionic conductivity among the anions.
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Ganiev, I. N., O. Kh Niyezov, N. M. Mulloeva, and B. B. Eshov. "INFLUENCE OF ALKALINE – EARTH METALS ON ANODIC BEHAVIOR OF ALLOY ССУЗ IN NEUTRAL ENVIRONMENT OF THE ELECTROLYTE NaCl." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 1 (April 6, 2018): 84–89. http://dx.doi.org/10.21122/1683-6065-2018-1-84-89.
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The anodic behavior of a lead-antimony alloy (3 wt% Sb) doped with alkaline-earth metals was investigated in potentiostatic method in the potentiodynamic mode at a potential sweep rate of 2 mV/s and it was shown that with an increase in the content of alkaline earth metals in the alloy (SSUZ), the potentials of free Corrosion and pitting are slightly shifted to the positive region. As the concentration of the chloride ion in the electrolyte increases, these potentials decrease. The current density of corrosion and, accordingly, the corrosion rate of alloys with an increase in the content of alkaline earth metals are reduced by 75–85%, and the concentration of chloride ion increases.In transition from alloys with calcium to alloys with strontium, the corrosion rate of alloys increases by 20–30%, and to alloys with barium it decreases by 25–30%.
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Tikhonov, Robert Dmitrievich. "Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe." European Journal of Engineering and Technology Research 6, no. 2 (February 4, 2021): 19–28. http://dx.doi.org/10.24018/ejers.2021.6.2.2081.
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The nature of phenomena that occurs in the electrolyte during the electrochemical deposition of CoNiFe films and the mechanism leading to the difference in the relative content of elements in the electrolyte and film was clarified. This clarification was obtained with the help of a spectrophotometric study of chloride electrolytes and the electrochemical deposition of CoNiFe films at 70 °C. An experimental study of the absorption spectra and the pH values of the FeCl2, NiCl2 and CoCl2 salt solutions at concentrations of 0.005 to 1 mol/l showed the complex nature of the ion-formation balance in single-component and mixed solutions and the dependence of ion formation on acidic and alkaline additives. The deposited CoNiFe film was made from a chloride electrolyte with a component content ratio of 1:1:1 at both high (0.5 mol/l) and low (0.006 mol\l) concentrations of each component. The content of each component in the film after the electrochemical deposition of the three component solution (FeCl2, CoCl2, and NiCl2 at equal concentrations) did not correspond to the composition of the electrolyte. The mechanism for the abnormal deposition of Co, Fe, Ni occurred due to the incomplete ionization of atoms and the differences in the mobility of ions. The magnetic susceptibility of the films formed in the triple CoNiFe system was higher than that of a permalloy. Therefore, the triple system shows promise for use in magnetic field converters.
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Tikhonov, Robert Dmitrievich. "Features of the Electrochemical Deposition of Films from a Triple System of CoNiFe." European Journal of Engineering and Technology Research 6, no. 2 (February 4, 2021): 19–28. http://dx.doi.org/10.24018/ejeng.2021.6.2.2081.
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The nature of phenomena that occurs in the electrolyte during the electrochemical deposition of CoNiFe films and the mechanism leading to the difference in the relative content of elements in the electrolyte and film was clarified. This clarification was obtained with the help of a spectrophotometric study of chloride electrolytes and the electrochemical deposition of CoNiFe films at 70 °C. An experimental study of the absorption spectra and the pH values of the FeCl2, NiCl2 and CoCl2 salt solutions at concentrations of 0.005 to 1 mol/l showed the complex nature of the ion-formation balance in single-component and mixed solutions and the dependence of ion formation on acidic and alkaline additives. The deposited CoNiFe film was made from a chloride electrolyte with a component content ratio of 1:1:1 at both high (0.5 mol/l) and low (0.006 mol\l) concentrations of each component. The content of each component in the film after the electrochemical deposition of the three component solution (FeCl2, CoCl2, and NiCl2 at equal concentrations) did not correspond to the composition of the electrolyte. The mechanism for the abnormal deposition of Co, Fe, Ni occurred due to the incomplete ionization of atoms and the differences in the mobility of ions. The magnetic susceptibility of the films formed in the triple CoNiFe system was higher than that of a permalloy. Therefore, the triple system shows promise for use in magnetic field converters.
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Naidu Gopu, Ganesh, and Sofi Androse Joseph. "Corrosion Behavior of Fiber-Reinforced Concrete—A Review." Fibers 10, no. 5 (April 21, 2022): 38. http://dx.doi.org/10.3390/fib10050038.
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Corrosion study of conventional reinforcement in concrete has been accorded wider importance in the last few decades based on the losses occurring in monitoring concrete structures. It is well known that the presence of chloride ions is one of the most significant factors contributing to the corrosion of reinforcing steel. Practically, it is observed that in the marine environment, the activating substances such as chlorides that penetrate the steel can counteract the passivity locally when the electrolyte is highly alkaline. The concrete cover is changed chemically when chloride ionspenetrate into the material, whereupon the pore solution is neutralized. Based on numerous studies, it is evident that steel fibers and glass fibers have less impact on cracked sections in a chloride environment and can oppose chloride infiltration. Glass fibers, when exposed to repeated freeze and thaw conditions, protect the passive layer. This review article highlights the corrosion behavior of reinforced concrete involving various factors such as cracking behavior, transportation, electric conductivity, resistivity, and diffusion of chloride ions in the presence of steel and glass fibers.
Dissertations / Theses on the topic "Alkaline chloride electrolyte"
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Вороніна, Олена Володимирівна. "Електродні процеси на сплавах та сполуках ванадію в водневій енергетиці." Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/38323.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.03 – технічна електрохімія. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018 р.
Дисертація присвячена розробці технологічного процесу виробництва водню з використанням нових електродних матеріалів на основі ванадієвих сплавів і алюмінієвих сплавів. Матеріал електрода на основі ванадію виключає утворення феритів при лужному електролізі. Алюмінієві сплави виключають виділення кисню на анодах через корозійний процес з деполяризацією водню. Тому на обох електродах можна виділяти водень на електролізерах без мембрани при електролізі лужної води. Досліджені основні показники анодних процесів на сплаві алюмінію АМЦ в лужних розчинах з домішками хлоридів. В інтервалах густин струму 1-5 А/дм² та температурах 18-20 ⁰С розчинення сплаву забезпечується негативними потенціалами. При збільшенні швидкості розчинення в умовах анодної поляризації потенціал аноду зміщується в позитивну область на 150-200 мВ. Керування гальваностатичним режимом електролізу в досліджуваних розчинах дозволяє збільшити швидкість виділення водню при розчиненні сплаву за рахунок прискорення дифузійних процесів в анодному просторі та забезпечення відведення продуктів електролізу в прианодному шарі. Визначено кінетичні залежності і механізми виділення водню на алюмінієвих сплавах, що призводить до зменшення перенапруги реакції виділення водню на катодах і утворення водню на анодах шляхом розчинення алюмінію. Наведено дослідно-промислові випробування безкисневого електросинтезу на вдосконалених електролізерах при напругах електролізу 0,3-1 В. Це дозволяє знизити матеріальні та енергетичні витрати на електроліз.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.17.03 – Technical Electrochemistry. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2018. The thesis deals with the development of the technological process of hydrogen production using new electrode materials based on vanadium alloys and aluminum alloys. The vanadium based electrode material exclude the formation of ferrites in alkaline electrolysis. Aluminum alloys exclude the oxygen evolution on the anodes due to the corrosion process with hydrogen depolarization. Therefore it is possible to produce hydrogen on both electrodes in electrolyzers without membrane in alkaline water electrolysis. The kinetic dependences and mechanisms of hydrogen evolution on aluminum alloys have been determined, which leads to the reduce of overvoltage of hydrogen evolution reaction on cathodes and produce hydrogen on anodes by aluminum dissolving. Experimental-industrial tests of oxygen-free hydrogen production in developed electrolyzers at cell voltages of 0.3-1 V are presented. This allows to reduce the material and energy costs of electrolysis.
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Вороніна, Олена Володимирівна. "Електродні процеси на сплавах та сполуках ванадію в водневій енергетиці." Thesis, НТУ "ХПІ", 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/38316.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.17.03 – технічна електрохімія. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2018 р.
Дисертація присвячена розробці технологічного процесу виробництва водню з використанням нових електродних матеріалів на основі ванадієвих сплавів і алюмінієвих сплавів. Матеріал електрода на основі ванадію виключає утворення феритів при лужному електролізі. Алюмінієві сплави виключають виділення кисню на анодах через корозійний процес з деполяризацією водню. Тому на обох електродах можна виділяти водень на електролізерах без мембрани при електролізі лужної води. Досліджені основні показники анодних процесів на сплаві алюмінію АМЦ в лужних розчинах з домішками хлоридів. В інтервалах густин струму 1-5 А/дм² та температурах 18-20 ⁰С розчинення сплаву забезпечується негативними потенціалами. При збільшенні швидкості розчинення в умовах анодної поляризації потенціал аноду зміщується в позитивну область на 150-200 мВ. Керування гальваностатичним режимом електролізу в досліджуваних розчинах дозволяє збільшити швидкість виділення водню при розчиненні сплаву за рахунок прискорення дифузійних процесів в анодному просторі та забезпечення відведення продуктів електролізу в прианодному шарі. Визначено кінетичні залежності і механізми виділення водню на алюмінієвих сплавах, що призводить до зменшення перенапруги реакції виділення водню на катодах і утворення водню на анодах шляхом розчинення алюмінію. Наведено дослідно-промислові випробування безкисневого електросинтезу на вдосконалених електролізерах при напругах електролізу 0,3-1 В. Це дозволяє знизити матеріальні та
енергетичні витрати на електроліз.Thesis for granting the Degree of Candidate of Technical sciences in speciality 05.17.03 – Technical Electrochemistry. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2018. The thesis deals with the development of the technological process of hydrogen production using new electrode materials based on vanadium alloys and aluminum alloys. The vanadium based electrode material exclude the formation of ferrites in alkaline electrolysis. Aluminum alloys exclude the oxygen evolution on the anodes due to the corrosion process with hydrogen depolarization. Therefore it is possible to produce hydrogen on both electrodes in electrolyzers without membrane in alkaline water electrolysis. The kinetic dependences and mechanisms of hydrogen evolution on aluminum alloys have been determined, which leads to the reduce of overvoltage of hydrogen evolution reaction on cathodes and produce hydrogen on anodes by aluminum dissolving. Experimental-industrial tests of oxygen-free hydrogen production in developed electrolyzers at cell voltages of 0.3-1 V are presented. This allows to reduce the material and energy costs of electrolysis.
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ALEXOPOULOS, HIRAKLITS. "Etude de la pile aluminium-chlore en milieu de chlorures alcalins fondus." Paris 6, 1988. http://www.theses.fr/1988PA066013.
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Cerisier, Jacky. "Caracterisation et etude physico-chimique de conducteurs ioniques afecl::(4) (a : alcalin) et de li::(4)fei::(6) : ionicite des liaisons mecanismes de conduction." Nantes, 1987. http://www.theses.fr/1987NANT2003.
Full textBooks on the topic "Alkaline chloride electrolyte"
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Macmullin, Robert Burns. Chlor-Alkali and Chlorate Technology: R.B. Macmullin Memorial Symposium: Proceedings of the Symposium (Proceedings). Electrochemical Society, 1999.
Find full textConference papers on the topic "Alkaline chloride electrolyte"
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Amamoto, Ippei, Naoki Mitamura, Tatsuya Tsuzuki, Yasushi Takasaki, Atsushi Shibayama, Tetsuji Yano, Masami Nakada, and Yoshihiro Okamoto. "Removal of Fission Products in the Spent Electrolyte Using Iron Phosphate Glass as a Sorbent." In ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2010. http://dx.doi.org/10.1115/icem2010-40272.
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This study is carried out to make the pyroprocessing hold a competitive advantage from the viewpoint of environmental load reduction and economical improvement. As one of the measures to reduce the volume of the high-level radioactive waste (HLW), the phosphate conversion method is applied for removal of fission products (FP) from the melt, referring to the spent electrolyte in this paper. Among the removing target chlorides in the spent electrolyte i.e., alkali metals, alkaline earth metals and rare earth elements, only the rare earth elements and lithium form the precipitates as insoluble phosphates by reaction with Li3PO4. The sand filtration method was applied to separate FP precipitates from the spent electrolyte. The iron phosphate glass (IPG) powder, which is a compatible material for the immobilization of FP, was used as a filter medium. After filtration experiment, it was proven that insoluble FP could almost be completely removed from the spent electrolyte. Subsequently, we attempted to separate the dissolved FP from the spent electrolyte. The IPG was being used once again but this time as a sorbent instead. This is possible because the IPG has some unique characteristics, e.g., changing the valence of iron, which is one of its network modifiers due to its manufacturing temperature. Therefore, it would be likely to sorb some FP when the chemical condition of IPG is unstable. We produced three kinds of IPG under different manufacturing temperature and confirmed that those glasses could sorb FP as anticipated. According to the experimental result, its sorption efficiency of metal cations was attained at around 20–40%.
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Vesely, Andreas. "Processes for the Treatment of NORM and TENORM." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4623.
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By contract with the Austrian government, the ARC is treating radioactive waste from research institutions and industries. In the last years, one focus was the development of processes for the treatment of NORM and TENORM. Our goal in developing such processes is to recycle valuable compounds for further industrial usage and to concentrate the radioactive elements as far as possible, to save space in the waste storage facilities. Austria is an important producer of tungsten-thoria- and tungsten-molybdenum-thoria-cermets. Scrap is generated during the production process in the form of turnings and grinding sludge and dust. Although big efforts have been undertaken to replace Thorium compounds, waste streams from past production processes are still waiting for treatment. The total amount of this waste stored in Austria may be estimated to be approx. 100 tons. In close co-operation with the tungsten industries, recycling processes were tested and further developed at ARC in laboratory, bench scale and pilot plants. Three different approaches to solve the problem were studied: Dissolution of tungsten in molten iron in an arc or induction furnace, thus producing an Fe-W or Fe-W-Mo alloy. Slag is produced upon the addition of lime and clay. This slag extracts nearly all of the Thorium contained in the metal melt. Selective dissolution of Tungsten in aqueous alkaline medium after oxidation of the metal to the hexavalent state by heating the scrap in air at temperatures of 500°C to 600°C. The resulting oxides are treated with sodium hydroxide solution. Tungsten and Molybdenum oxides are readily dissolved, while Thorium oxide together with silicon and aluminum compounds remain insoluble and are separated by filtration. Sodium tungstate solution is further processed by the usual hydrometallurgical tungsten mill process. Oxidation and dissolution of Tungsten can be achieved in one step by an electrochemical process. Thus, thoriated Tungsten scrap is used as an anode in an electrolysis cell, while sodium hydroxide or ammonia serve as electrolyte. After dissolution of Tungsten, the solids are separated from the liquid by filtration. With the electrochemical process, treatment of Tungsten-Thoria scrap can be achieved with high throughput in rather small reactors at moderate temperatures and ordinary pressure. The Tungsten solution exhibits high purity. Another process which we examined in detail is the separation of radium from rare earth compounds. Radium was separated by co-precipitation with barium sulfate from rare earth chloride solutions. The efficiency of the separation is strongly pH-dependent. Again, the valuable rare earth compound can be reused, and the radioactive elements are concentrated.