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Journal articles on the topic 'Leaching agent'

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Published: 4 June 2021

Last updated: 7 February 2022

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Zhang, Gui Fang, Peng Yan, and Qing Rong Yang. "Experimental Study on Concentrating Scandium by Leaching from Associated Scandium Ore." Advanced Materials Research 734-737 (August 2013): 1033–36. http://dx.doi.org/10.4028/www.scientific.net/amr.734-737.1033.

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Based on the benefication of the complex silicate ore containing scandium, the research about aid-leaching agent used in the leaching of the scandium concentrate was been conducted. And the suitable leaching agent and aid-leaching agent which the useful ions entered into leaching liquid and the harmful ions were kept in leaching residue were been found according to the experiment results. For the scandium of sample existed various complex silicate ore as isomorphism form, the research has adopted hydrochloric acid with aid-leaching agent to dissociate the silicate ore and make scandium entering into solution. The research results has shown that the scandium leaching rate could reach 92.06% under the optimal conditions which the hydrochloric acid concentration is 22.8%, the dosage of aid leaching agent is 6%, liquid solid ratio is 4:1, particle size of leaching material totally is less than 0.15mm and leaching time is 8h.

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Chen, Yuqian, Junwen Zhou, Libo Zhang, et al. "Microwave-assisted and regular leaching of germanium from the germanium-rich lignite ash." Green Processing and Synthesis 7, no. 6 (2018): 538–45. http://dx.doi.org/10.1515/gps-2017-0137.

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Abstract Demand for germanium (Ge) is rapidly growing in recent years in various fields including semiconductors, aerospace, and solar cells. However, the Ge resources are very limited in the world. Hence, in this work, microwave-assisted leaching and conventional leaching methods are employed for the leaching of Ge from the Ge-rich lignite ash (GA). The effects of leaching temperature, leaching time, initial acid concentration, oxidizing agent amount, and stirring speed on leaching of Ge were investigated and microwave-assisted and conventional methods of leaching were compared. Here, HCl solution is used as a leaching agent, and MnO2 is used as an oxidizing agent. From the results, the leaching rate of Ge was found to be 89.49% in the microwave-assisted method, and 83.62% in the conventional leaching method. The optimal conditions for microwave-assisted method include a leaching temperature of 65°C, a leaching time of 90 min, an oxidizing agent amount of 10 g/l, an initial acid concentration of 10 mol/l, and a stirring speed of 250 rpm. The leaching rate of Ge significantly improved in the microwave-assisted method as compared to the conventional method. Therefore, the microwave-assisted method is a suitable method for the leaching of Ge from the GA and is a novel way for the efficient utilization of Ge concentrate.

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da Silva, Wagner Claudio, and F. R. Valenzuela-Díaz. "Nanomaterial as Microbial Agent to Paints." Materials Science Forum 727-728 (August 2012): 1751–56. http://dx.doi.org/10.4028/www.scientific.net/msf.727-728.1751.

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Quaternary ammonium compounds are widely used as antiseptic agents, disinfectants, detergents and preservatives. In addition, quaternary ammonium compounds are often used as algaecides, and chloride dodecyl dimethyl benzyl ammonium chloride (benzalkonium chloride) is the most effective against these microorganisms. However benzalkonium chloride is not used as surface algaecide compound due its high hydrophobicity, bring on high leaching of this compound when the surface is exposed to high humidity. Currently, compounds such as diuron and s-triazine are used as algaecides, but had been detected in coastal regions in high levels concentration showing the leaching of these biocides. Then raise the necessity to develop a new algaecide to overcome the failings of leaching of the compounds used nowadays. Nanomaterial as organoclay is an excellent alternative because they have highly hydrophobic. Therefore in this work was synthesized a new nanomaterial using benzalkonium chloride, which was applied in a house paint formulation. The nanomaterial was characterized by the techniques of X-ray diffraction and thermo gravimetric analysis. The biocide capability as well as resistance to weathering of the nanomaterial was checked thought microbiological and leaching test. The new nanomaterial synthesized in this study had a high potential to be used as a microbial agent in paints.

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Wu, Dan Dan, Shu Ming Wen, Jing Yang, Yi Jie Wang, and Chao Lv. "A Study on Leaching of Zinc Oxide Ore in Ammonium Sulfate Solution." Applied Mechanics and Materials 522-524 (February 2014): 1463–66. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.1463.

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In this paper, the leaching effect of zinc oxide ore was investigated using ammonium sulfate solution as leaching agent. The effects of temperature, concentration of ammonium sulfate, average particle size and stirring speed on the leaching of zinc oxide ore were studied. The leaching rate increased with increasing solution temperature, concentration, and stirring speed as well as with decreasing average particle size. Ammonium sulfate solution can therefore be used as an effective leaching agent for zinc extraction from zinc oxide ore.

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Dong, Hua Sheng, and Jing Yang. "The Leaching of Copper Oxide Ore in Ammonium Chloride Solution." Applied Mechanics and Materials 675-677 (October 2014): 1459–62. http://dx.doi.org/10.4028/www.scientific.net/amm.675-677.1459.

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In this study, the leaching effect of copper oxide ore was investigated using ammonium chloride solution as leaching agent. The effects of temperature, concentration of ammonium chloride, average particle size and stirring speed on the leaching of copper oxide ore were investigated. The leaching rate increased with increasing solution temperature, concentration, and stirring speed as well as with decreasing average particle size. Ammonium chloride solution can therefore be used as an effective leaching agent for copper extraction from copper oxide ore.

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Yang, Jin Lin, Shao Jian Ma, Wei Mo, Jin Peng Feng, Xiu Juan Su, and Gui Fang Wang. "Study on Recovering Zinc from Gossan." Advanced Materials Research 454 (January 2012): 329–32. http://dx.doi.org/10.4028/www.scientific.net/amr.454.329.

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In this paper, the conventional physical separation method such as flotation, gravity separation, magnetic separation, alkaline leaching and sulfuric acid leaching were studied. The effects of grinding fineness, amount of agent, magnetic intensity, roasting temperature, roasting time, the leaching agent and leaching time on the leaching of zinc were investigated, respectively. The results show that the leaching rate of zinc is below 50% in the conventional alkaline leaching, and the leaching rate of zinc is below 85% and the leaching rate of iron is above 35% in sulfuric acid leaching. Compared with XRD pattern of the raw ore, the different diffraction peaks of smithsonite is off in alkaline leaching products. In sulfuric acid leaching, the different diffraction peaks of smithsonite are off in the leaching products when sulfuric acid concentration is less than 60 g/L. After 60 g/L, the different diffraction peaks of smithsonite and siderite are off in the leaching products.

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He, Wei, Guo Hua Ye, and Xiong Tong. "Study on Direct Acid Leaching Vanadium without Grinding and Roasting from Clay Vanadium Ore in Hunan." Applied Mechanics and Materials 316-317 (April 2013): 882–86. http://dx.doi.org/10.4028/www.scientific.net/amm.316-317.882.

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Abstract：A new technology of direct acid leaching vanadium without grinding and roasting was put forward, and the effects of leaching factors including dosage of sulfuric acid, type and dosage of assistant leaching agent, leaching time and temperature, liquid-solid ratio on the vanadium leaching rate were systematically investigated. The results show that vanadium leaching rate could be up to 92.58% under the optimal conditions of sulfuric acid dosage of 30%, MnO2 as assistant leaching agent and its dosage of 1.5%, leaching time of 6h, leaching temperature of 90°C, liquid-solid ratio of 1:1, and the leaching performance is perfect. Due to leaving out the high costing grinding system and the complex roasting system, the new technology has advantages in shortening the process, decreasing the cost, avoiding pollution generated by roasting comparing with the traditional technologies, and it can meet the requirement of modern metallurgy very well.

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Jiang, Chen Guang, and Qing Jie Tang. "Study on Extracting Technology of Vc from Momordica charantia." Advanced Materials Research 781-784 (September 2013): 606–9. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.606.

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Balsam pear was used as the research object in experiment, the technological parameters were studied such as the way of crushing, leaching agent type and its concentration, solid-liquid ratio, ultrasonic extraction temperature, time, power's influence on the extraction yield of Vc, and the ultrasonic extraction time, temperature, ultrasonic power on the L9 (34) orthogonal test analysis. Results showed that bitter melon slices, and solid-liquid ratio is 1:7, citric acid as leaching agent and the concentration of 1%, ultrasonic power is 80 w, leaching temperature 30 °C, 40 min leaching time, leaching of balsam pear Vc the highest rate.

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Lie, Jenni, Stefani Tanda, and Jhy-Chern Liu. "Subcritical Water Extraction of Valuable Metals from Spent Lithium-Ion Batteries." Molecules 25, no. 9 (2020): 2166. http://dx.doi.org/10.3390/molecules25092166.

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The leaching of valuable metals (Co, Li, and Mn) from spent lithium-ion batteries (LIBs) was studied using subcritical water extraction (SWE). Two types of leaching agents, hydrochloric acid (HCl) and ascorbic acid, were used, and the effects of acid concentration and temperature were investigated. Leaching efficiency of metals increased with increasing acid concentration and temperature. Ascorbic acid performed better than HCl, which was attributed to ascorbic acid’s dual functions as an acidic leaching agent and a reducing agent that facilitates leaching reactions, while HCl mainly provides acidity. The chemical analysis of leaching residue by X-ray photoelectron spectroscopy (XPS) revealed that Co(III) oxide could be totally leached out in ascorbic acid but not in HCl. More than 95% of Co, Li, and Mn were leached out from spent LIBs’ cathode powder by SWE using 0.2 M of ascorbic acid within 30 min at 100 °C, initial pressure of 10 bar, and solid-to-liquid ratio of 10 g/L. The application of SWE with a mild concentration of ascorbic acid at 100 °C could be an alternative process for the recovery of valuable metal in spent LIBs. The process has the advantages of rapid reaction rate and energy efficiency that may benefit development of a circular economy.

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Zhu, Wei-Jun, Guo-Qiang Tian, Yang Lu, Kai Miao, and Di-Chen Li. "Leaching improvement of ceramic cores for hollow turbine blades based on additive manufacturing." Advances in Manufacturing 7, no. 4 (2019): 353–63. http://dx.doi.org/10.1007/s40436-019-00273-2.

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Abstract The precision casting method based on alumina-based ceramic cores is one of the main techniques used to manufacture hollow turbine blades. Additive manufacturing (AM) technology provides an alternate solution to fabricating ceramic cores quickly and precisely. As the complexity of the structure increases and the strength of the material improves, the leaching process of the cores becomes more complicated. This study proposes a compound pore-forming method to increase the porosity of ceramic cores by adding a preformed-pore agent and materials that convert to easy-to-corrode phases. The preformed-pore agents (e.g., carbon fibers) can be burned off during sintering to form pores before the leaching, and the easy-to-corrode phases (e.g., CaCO3, SiO2, β-Al2O3) can be leached firstly to form pores during the leaching process. The pores formed in the aforementioned two stages increase the contact area of the cores and leaching solution, thus improving the leaching rate. In the current study, the additive amount of the preformed-pore agent was optimized, and the effect of the easy-to-corrode phases on the comprehensive properties of the cores was then compared. Based on this, the corresponding model was established.

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Long, Yun Fei, Jing Su, Xian Jia Ye, Hai Feng Su, and Yan Xuan Wen. "Reduction-Roast Leaching of Low-Grade Pyrolusite Using Bagasse as a Reducing Agent." Advanced Materials Research 699 (May 2013): 28–33. http://dx.doi.org/10.4028/www.scientific.net/amr.699.28.

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Bagasse, a fibrous residue from sugarcane juice extraction, was used as a reducing agent to roast low-grade pyrolusite in N2. The roasted ore was further leached using sulfuric acid, to convert manganese oxide in the ore to manganese sulfate. The effects of weight ratio of bagasse to manganese ore, roasting temperature, roasting time, leaching temperature, leaching time, stirring speed and sulfuric acid concentration on the leaching recovery of manganese were investigated. Optimal conditions were determined to be a bagasse to manganese ore weight ratio of 0.8:10, roasting temperature of 500°C for 40 min, leaching stirring speed of 100 rpm, sulfuric acid concentration of 3 mol•L-1 and leaching temperature of 50°C for 40 min. The leaching recovery rate of manganese was up to 97.8% at the optimal conditions.

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Chai, Xiuwei, Guoqing Li, Zhenyue Zhang, Ruan Chi, and Zhuo Chen. "Leaching Kinetics of Weathered Crust Elution-Deposited Rare Earth Ore with Compound Ammonium Carboxylate." Minerals 10, no. 6 (2020): 516. http://dx.doi.org/10.3390/min10060516.

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Due to the special properties of the ammonium salts, ammonium acetate and ammonium citrate were used to explore the best leaching conditions of rare earth with compound ammonium carboxylate. This paper explored the influence of the molar ratio, ammonium concentration, experimental temperature, and pH of the compound leaching agents on the leaching efficiency of rare earth and aluminum, and it analyzed the leaching process based on the leaching kinetics, which provides a new method for leaching rare earth from the weathered crust elution-deposited rare earth ore. The results showed that under the conditions where the molar ratio of ammonium acetate and ammonium citrate was 7:3 and the ammonium concentration was 0.15 mol/L, the leaching efficiency of rare earth was the highest when the pH of leaching agent was 4.0 and the experimental temperature was 313 K. Meanwhile, when CH3COONH4 and (NH4)3Cit were used to leach rare earth ore, the leaching reaction kinetics equation of rare earth and aluminum were obtained. In the temperature range of 283–323 K, the apparent activation energy of rare earth was 14.89 kJ/mol and that of aluminum was 19.17 kJ/mol. The reaction order of rare earth was 0.98 and that of aluminum was 0.79. The results were in accordance with the shrinking core model and indicate that the concentration of the leaching agent had a greater influence on rare earth than aluminum. This process can reduce the use of ammonium salt, and it is of great significance to extract rare earth elements from weathered crust elution-deposited rare earth ore and improve the utilization rate of resources.

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Chen, Bo Wei, Jian Zhi Sun, He Shang, Biao Wu, and Jian Kang Wen. "Biooxidation of a Refractory Gold Ore: Implications of Whole-Ore Heap Biooxidation." Solid State Phenomena 262 (August 2017): 65–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.65.

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The Sawayardun Gold Mine, the first Muruntau type gold mine in China, was located in the south Tianshan Mountain, Xinjiang Province. The gold reserve was 127 t with an average gold grade of 2.36 g/t. Due to the high content of arsenic and antimony, the traditional flotation-roasting-cyanidation process was not suitable. The direct cyanidation gold extraction for the raw ore was 44.70 %. Thus, biooxidation experiments in shaker flasks were conducted for this ore. The optimum conditions were obtained as inoculation volume 10 %, initial pH 1.7, pulp density 15 %, temperature 33 °C, leaching time 10 days, with the arsenic oxidation rate of 75.12 %. Then the biooxidation residues were test for gold leaching using NaCN, green gold leaching agent and thiourea. After 24 h leaching rate at pulp density of 33%, gold leaching agent dosage of 2 kg/t ore, the gold extraction for NaCN, green gold leaching agent and thiourea were 91.50 %, 86.23 % and 91.09 %, respectively. The high gold extraction showed a bright future for the whole-ore heap biooxidation of this refractory gold ore.

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Song, Si Jeong, Viet Nhan Hoa Nguyen, and Man Seung Lee. "Leaching of a Mixture of Palladium and Zinc Metal Using Hydrochloric and Sulfuric Acid Solutions." Korean Journal of Metals and Materials 59, no. 7 (2021): 469–75. http://dx.doi.org/10.3365/kjmm.2021.59.7.469.

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Spent electroplating solutions contain small amounts of Pd(II). Cementation of Pd(II) with zinc metal powder is practiced to concentrate the Pd. Dissolution of the cemented Pd metal is necessary to recover pure Pd metal or compounds. In this work, the leaching behavior of Pd metal in inorganic acid solutions (hydrochloric and sulfuric acid) in the presence of an oxidizing agent such as H2O2, NaClO3, or NaClO was investigated. To determine the optimum conditions for Pd leaching, experiments were conducted by adjusting the concentration of the acids and oxidizing agents, reaction temperature and time, and pulp density. Complete leaching of Pd was possible using a hydrochloric acid solution with 3 kinds of oxidizing agents, whereas only NaClO was effective in the leaching with sulfuric acid solution. The chloride ions of HCl and NaClO3/NaClO play an important role in enhancing the leaching of Pd, due to the formation of Pd chlorocomplexes and by decreasing the reduction potential of Pd(II). Compared to H2O2, NaClO3 and NaClO showed some merits as oxidizing agents in terms of reaction time, temperature and low acid concentration. Based on the optimum leaching conditions of single Pd metal, the conditions for the complete leaching of Pd and Zn from the metallic mixtures were obtained.

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He, Qiang, Jiang Qiu, Minglu Rao, and Yanfei Xiao. "Leaching Behaviors of Calcium and Aluminum from an Ionic Type Rare Earth Ore Using MgSO4 as Leaching Agent." Minerals 11, no. 7 (2021): 716. http://dx.doi.org/10.3390/min11070716.

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During the leaching process of ionic rare earth ore (ICREO), ion-exchangeable phase calcium (IEP-Ca) and ion-exchangeable phase aluminum (IEP-Al) are leached along with rare earth, which causes many problems in the enrichment process, such as increasing the precipitant agent consumption and rare earth loss, etc. The agitation leaching kinetics and the column leaching mass transfer process of IEP-Ca and IEP-Al were studied to understand the leaching behavior of impurity in ICREO, which provides guides for the adjustment of the leaching process and to limit the co-leaching of impurities. IEP-Ca and IEP-Al were leached by ion exchange, with the leaching agent cations and the leaching kinetics described by an internal diffusion-controlled shrinking core model with an apparent activation energy of 8.97 kJ/mol and 10.48 kJ/mol, respectively. In addition, a significant reduction in the leaching efficiency of aluminum was caused by the hydrolysis reaction reinforced by the increase in MgSO4 concentration and temperature. The leaching kinetic data of IEP-Ca and IEP-Al was verified by the column leaching mass transfer process. There was a synchronous increase in the peak concentration of the outflow curve and leaching efficiency of calcium with the concentration of MgSO4 since IEP-Ca was easily leached. Therefore, as the leaching efficiency of calcium was already very high in the 0.20 mol/L MgSO4 leaching process, the leaching rate of calcium was limited by the leaching temperature and injection rate of MgSO4. For aluminum, the hydrolysis of Al3+ was promoted by increasing the MgSO4 concentration and the leaching temperature, thereby effectively reducing the content of aluminum in the leachate.

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Ji, Cui Cui, Dan Dan Wu, Shu Ming Wen, and Jiu Shuai Deng. "The Effect of Temperature on the Leaching of Malachite in Phosphoric Acid Solution." Advanced Materials Research 962-965 (June 2014): 818–21. http://dx.doi.org/10.4028/www.scientific.net/amr.962-965.818.

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In this study, the effect of leaching of malachite was investigated using phosphoric acid solution as leaching agent. The effect of temperature on the leaching of malachite was investigated. The leaching rate increased with increasing solution temperature, and a kinetic model was developed to represent this relationship. The leaching was controlled by the shrinking core model for surface chemical reaction. The activation energy of the leaching process was determined to be 30.65kJ/mol.

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Prica, Miljana, Milena Dalmacija, Bozo Dalmacija, et al. "Immobilization of Cadmium from Contaminated Sediment Using Cardboard Mill Sludge." Archives of Environmental Protection 38, no. 4 (2012): 109–18. http://dx.doi.org/10.2478/v10265-012-0039-z.

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Abstract Sludge from cardboard mill is most commonly landfilled, but it could also be recycled on-site into production or reused in some other way. In this study the use of sludge from cardboard mill as stabilizing agent in the stabilization treatment of cadmium polluted sediment was examined. The effectiveness of treatment and long-term leaching behavior of cadmium was evaluated by determining the cumulative percentage of cadmium leached, diffusion coefficients (De) and by applying different leaching tests (semi-dynamic test, toxicity characteristic leaching procedure, waste extraction test). In order to simulate the “worst case” leaching conditions, the semi-dynamic leaching test was modified using 0.014 M acetic acid (pH = 3.25) and humic acids solution (20 mg l-1 TOC) as leachants instead of deionized water. A diffusion-based model was used to elucidate the controlling leaching mechanisms. Applied treatment was effective in immobilizing cadmium irrespective of high availability in the untreated sample. The controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of cadmium could be expected when the cardboard mill sludge as stabilization agent is applied.

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Rong, Chen, Hou Yanan, Zhao Yaming, and Liang Hongwei. "Study on the properties and gold leaching kinetics of a new organic leaching agent." IOP Conference Series: Earth and Environmental Science 186 (October 11, 2018): 012035. http://dx.doi.org/10.1088/1755-1315/186/4/012035.

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Wang, Kui, Qiwu Zhang, Huimin Hu, and Yanchu Liu. "Leaching of Cu from malachite using Fe2(SO4)3 solution as the leaching agent." ScienceAsia 47, no. 1 (2021): 72. http://dx.doi.org/10.2306/scienceasia1513-1874.2021.012.

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Prica, Miljana, Milena Dalmacija, Bozo Dalmacija, Jelena Trickovic, and Snezana Maletic. "The use of cardboard factory sludge in the remediation of zinc contaminated sediment." Journal of the Serbian Chemical Society 77, no. 8 (2012): 1097–107. http://dx.doi.org/10.2298/jsc111111022p.

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Paper and cardboard factory sludges are generated by various processes during pulp, cardboard and paper production, and the increasing quantities produced make the disposal of this sludge a problem. This study investigates the use of cardboard factory sludge as a stabilizing agent in the solidification/stabilization (S/S) treatment of zinc polluted sediment. Semidynamic and toxicity leaching tests were conducted to assess the effectiveness of the solidification/stabilization treatment and long-term zinc leaching behaviour. A diffusion-based model was used to elucidate the controlling leaching mechanisms. The applied S/S treatment was effective in immobilizing zinc, and the controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of zinc could be expected when cardboard mill sludge is applied as a S/S agent.

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Cerchier, Pietrogiovanni, Manuele Dabalà, and Katya Brunelli. "Gold Recovery from PCBs with Thiosulfate as Complexing Agent." Materials Science Forum 879 (November 2016): 289–94. http://dx.doi.org/10.4028/www.scientific.net/msf.879.289.

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Waste of electrical and electronic equipment (WEEE) is the fastest growing advanced type of solid waste streams in the urban environment worldwide and contains interesting amounts of precious metals. Hydrometallurgical technique is fast emerging as preferred process for the recovery of a variety of metals due to its lower energy consume and lower smelter emissions than conventional pyrometallurgical processes. In this work, a hydrometallurgical process for the recovery of gold and silver from electronic scraps was studied. In place of cyanide, thiosulfate was chosen as complexing agent for gold. Thiosulfate leaching can be considered a non-toxic process and the gold dissolution rates can be faster than conventional cyanidation. The electronic scraps, obtained from “end of life” mobile phones, were crushed and pre-treated with nitric acid before the leaching. Different parameters were studied: concentration of thiosulfate, temperature and reaction time. Moreover, the use of ultrasound to assist the hydrometallurgical gold extraction was investigated, as its application in ores leaching shows a greater metals release in shorter time and the advantage of working at lower concentration of reagents and at lower temperature. In this work, the use of ultrasound allowed a higher recovery of the precious metals than conventional leaching in all the conditions studied (different concentrations of reagents, temperature and reaction time). Moreover, the studied process allowed also the recovery of the other metals present in the waste (Cu, Sn and Ag).

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Shuang, Cui, Han Qing, and Zhang Tianyi. "Overview of leaching remediation of heavy metal contamination in soil." E3S Web of Conferences 245 (2021): 02005. http://dx.doi.org/10.1051/e3sconf/202124502005.

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The remediation methods of heavy metal contaminated soil can be divided into bioremediation, physical remediation and chemical remediation. Chemical remediation mainly includes soil leaching and chemical curing. There are two kinds of soil leaching remediation methods: in situ soil leaching remediation and ectopic leaching remediation. The eluent of heavy metals in soil includes inorganic eluent, chelating agent, surfactant and so on. Soil leaching can be applied to the remediation of contaminated soil alone or combined with other remediation methods.

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Urbańska, Weronika. "Recovery of Co, Li, and Ni from Spent Li-Ion Batteries by the Inorganic and/or Organic Reducer Assisted Leaching Method." Minerals 10, no. 6 (2020): 555. http://dx.doi.org/10.3390/min10060555.

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The battery powder (anodic and cathodic mass) manually separated from spent Li-ion batteries used in laptops was subjected to acidic reductive leaching to recover the Co, Li, and Ni contained in it. In the laboratory experiments, 1.5 M sulfuric acid was used as the leaching agent and the reducing agents were 30% H2O2 solution or/and glutaric acid. Glutaric acid is a potential new reducing agent in the leaching process of spent lithium-ion batteries (LIBs). The influence of the type of the used reducer on obtained recovery degrees of Co, Li, and Ni as well as the synergism of the two tested reducing compounds were analyzed. As a result, it was determined that it is possible to efficiently hydrometallurgically separate Co, Li, and Ni from battery powder into solutions. The highest recovery degrees of the investigated metals (Co: 87.85%; Li: 99.91%; Ni: 91.46%) were obtained for samples where two reducers, perhydrol and glutaric acid, were added, thus confirming the assumed synergic action of H2O2 and C5H8O4 in a given reaction environment.

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Yun, Sung-Wook, and Chan Yu. "Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test." Journal of Chemistry 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/641415.

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Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

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Xu, Shuan, Yan Hai Shao, and Ming Ming Li. "Extract Vanadium and Molybdenum from Spent Catalyst." Advanced Materials Research 926-930 (May 2014): 128–31. http://dx.doi.org/10.4028/www.scientific.net/amr.926-930.128.

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Based on the analysis of the properties of spent catalyst, extract vanadium and molybdenum from spent catalyst by roasting alkaline leaching. Sodium carbonate was leaching agent. The effects of roasting temperature, roasting time, the concentration of sodium carbonate and the number of leaching times on the leaching rate of vanadium and molybdenum were studied. Roasting temperature of 650°C, roasting time of 3h, the concentration of sodium carbonate of 50g/L and once counter-current leaching, under this condition, the leaching of vanadium is 83% and the leaching of molybdenum is 93%.Roasting alkaline leaching has good effect on extracting vanadium and molybdenum from spent catalyst.

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Pantazopoulou, Erasmia, and Anastasios Zouboulis. "Chromium recovery from tannery sludge and its ash, based on hydrometallurgical methods." Waste Management & Research 38, no. 1 (2019): 19–26. http://dx.doi.org/10.1177/0734242x19866903.

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The recovery of chromium from tannery sludge and from its respective ash constitutes an alternative process of tannery sludge treatment in order to ensure safe disposal. Chromium recovery was investigated based on simple hydrometallurgical processes, that is, leaching using aqueous solutions of acids. Leaching was applied either directly to air-dried sludge or to its respective ash, which results from thermal treatment of the air-dried sludge under anoxic conditions. The major parameters that influence the effectiveness of the leaching process were investigated to optimize chromium leaching. Specifically, contact time, pH value, temperature, liquid per solid ratio, and leaching agent (H2SO4 or HCl) were tested. Leached chromium, obtained directly from the initial tannery waste after 100 min leaching with H2SO4 at pH 1 and at 60°C, was used for the trivalent chromium precipitation by adding magnesia, calcium hydroxide, and sodium hydroxide as precipitation agents. The results revealed satisfactory leaching of trivalent chromium directly from the air-dried sludge. The chromium content in the solid precipitated using sodium hydroxide was about 59 wt %. In contrast, chromium was difficult to leach from the respective ash.

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Yao, Lu, Yong Feng, and Guoxi Xi. "A new method for the synthesis of LiNi1/3Co1/3Mn1/3O2 from waste lithium ion batteries." RSC Advances 5, no. 55 (2015): 44107–14. http://dx.doi.org/10.1039/c4ra16390g.

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Wu, Fangfang, Zhu Xiao, Bin Zeng, et al. "Experimental and reduction leaching kinetics simulation of iron-rich manganese oxide ore using tobacco stem concrete as reducing agent." Metallurgical Research & Technology 116, no. 4 (2019): 422. http://dx.doi.org/10.1051/metal/2019017.

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Reduction leaching behaviors of Fe and Mn from an iron-rich manganese oxide ore using waste tobacco stem concrete as reducing agent were investigated in this paper with a view to determining the feasibility of tobacco stem concrete used in reduction leaching of Mn from iron-rich manganese oxide ore. Results indicated that the leaching processes of Fe and Mn were both dominated by internal diffusion, but the effects of leaching parameters on leaching ratios of Fe and Mn were different based on established leaching kinetic equations. The leaching ratio of Mn reached up to 96.18% while that of Fe kept a lower concentration (17.66%) under optimal leaching conditions, which achieved high selectivity recovery of Mn from iron-rich manganese oxide ore. In addition, the leached solution can be used as electrolytic stock solution in the production of electrolytic manganese. Characterization of the obtained electrolytic manganese product indicated that the quality of electrolytic manganese fully met the standards of YB/T 051-2003, which disclosing a novel recycling approach of utilizing the resource coming from the tobacco industry.

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Widodo, Sri, Sufriadin Sufriadin, and Erwin Suhendar. "DESULFURISASI DAN DEASHING PADA BATUBARA MENGGUNAKAN NaOH DAN HCl SEBAGAI LEACHING AGENT." Jurnal Geomine 7, no. 1 (2019): 67. http://dx.doi.org/10.33536/jg.v7i1.342.

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Penelitian mengenai desulfurisasi dan deashing pada batubara, selain untuk meningkatkan kualitas batubara juga merupakan usaha untuk mengurangi unsur-unsur yang menjadi penyebab terjadinya pencemaran lingkungan. Sampel batubara pada penelitian ini berasal dari batubara Desa Tondongkura, Kecamatan Tondong Tallasa, Kabupaten Pangkep, Provinsi Sulawesi Selatan. Desulfurisasi dan deashing batubara Tondongkura pada penelitian ini dilakukan dengan menggunakan NaOH dan HCl sebagai leaching agent. Untuk mengetahui pengaruh dari beberapa faktor dalam proses leaching, maka percobaan dilakukan dalam beberapa variabel, yaitu waktu, suhu, ukuran partikel, konsentrasi larutan NaOH, dan konsentrasi HCl. Hasil percobaan menunjukkan kadar total sulfur awal dari 3,67% turun hingga 2,93%, atau persentase penurunan maksimum total sulfur sebesar 20,03%, sedangkan persentase maksimum penurunan kadar abu sebesar 12,29%, atau dari kadar abu awal 27,44% turun hingga 24,06%. HCl digunakan sebagai leaching agent pada leaching tahap kedua pada batubara yang sebelumnya dileaching menggunakan larutan NaOH pada kondisi optimum. Dari hasil percobaan didapatkan maksimum persentase penurunan total sulfur sebesar 42,51%, yaitu dari total sulfur awal sebesar 3,67% diturunkan hingga 2,11% dan kadar abu sampel pada awalnya sebesar 27,44% diturunkan hingga 22,04%, atau persentase maksimum penurunan kadar abu sebesar 19,67%.

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Yuliusman, Radifan Fajaryanto, Annisaa Nurqomariah, and Silvia. "Acid leaching and kinetics study of cobalt recovery from spent lithium-ion batteries with nitric acid." E3S Web of Conferences 67 (2018): 03025. http://dx.doi.org/10.1051/e3sconf/20186703025.

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Relentless development of technology triggers the smartphone production. The increasing number of smartphone use is followed by escalation of its waste, where its battery is usually left unrecycled. The analysis of the battery content shows that it is consist of a considerable amount of cobalt that can be reutilized based on its relatively high economic value, which valued USD 61/kg. Leaching as a form of hydrometallurgy was used in this research to recover cobalt using HNO3 as leaching agent and H2O2 as reducing agent. Process optimization was done by varying concentration of nitric acid and reaction temperature. The result showed that the optimum leaching condition was earned in 30 minutes of leaching reaction using 3.0 M HNO3 at the reaction temperature of 90°C, resulting 98.01% of cobalt leaching efficiency. Reaction kinetics study was also done in this research and the result demonstrates that recovery of cobalt from spent lithium-ion battery by nitric acid leaching was controlled by diffusion through product layer with activation energy value of 44.67 kJ/mol.

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Zhou, Cheng Ying, and Wei Qu. "Rapid Determination of Copper and Iron in Ore Leaching Solution by Iodometry." Advanced Materials Research 781-784 (September 2013): 2328–31. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2328.

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This paper provides a pretreatment method for ore leaching solution by adding an agent level of hydrogen peroxide. Pretreatment temperature, agent level of hydrogen peroxide and pretreatment time were investigated. The results show that relative standard deviation of copper or iron in ore leaching solution determined by iodometry is less than 1.00% with good accuracy and precision under the following conditions: pretreatment temperature of 60°C, agent level of hydrogen peroxide 1.0mL, pretreatment time of 30 minutes. This pretreatment process is simpler, faster, easier to control, and less environmental pollution comparing with the traditional pretreatment.

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Liu, Shuai Xia, Liang Chen, and Yu Mei Gao. "Hexavalent Chromium Leaching Influenced Factors in the Weathering Chrome Slag." Advanced Materials Research 952 (May 2014): 16–19. http://dx.doi.org/10.4028/www.scientific.net/amr.952.16.

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The distribution of hexavalent chromium in the weathering slag was studied, as well as the influenced factors of aqueous agent leaching chromium. Results showed an optimal leaching condition: the chromium particle size is 100~200 mesh, the liquid-solid ratio is 25:1, the leaching time is 4~8h. Enhanced temperature and reduced pH value are benefit to hexavalent chromium leaching. Considering the equipment corrosion of low pH, the optimal pH value is 3~4.

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Zhu, Jun, Ji Ke Guo, Jing Jing Xue, and Xin Li. "Experimental Study on Intensified Leaching of Vanadium Ore." Materials Science Forum 724 (June 2012): 355–58. http://dx.doi.org/10.4028/www.scientific.net/msf.724.355.

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The wet technology for vanadium extraction from the complex refractory vanadium ores was studied as a preferred approach with phosphoric acid as helper leaching agent. The results showed that the addition of phosphoric acid could improve the vanadium leaching rate significantly. Combination with sulfuric acid, high amount of phosphoric acid and high leaching temperature can promote the leaching of vanadium. With the sulfuric acid concentration of 425.6 g/L, leaching temperature of 90 °C, leaching time of 4 h and liquid-solid mass ratio 2:1, the vanadium leaching rate of 90 wt.% can be achieved. Meanwhile, about 15% of the consumption of sulfuric acid could be reduced with 39 wt.% phosphoric acid.

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Wu, Ping Ping, Cheng Zhang, Hai Fang Xu, De Xin Huang, Bing Xu, and Dan Yu Jiang. "Corrosion Behaviors of Borosilicate Glasses in Various Leaching Agents." Advanced Materials Research 177 (December 2010): 466–69. http://dx.doi.org/10.4028/www.scientific.net/amr.177.466.

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Static short-term corrosion tests were performed to two kinds of borosilicate glasses in deionized water, at 70°C and 150°C, respectively. Same corrosion experiments were also carried out in other leaching agents, such as simulated under ground water of Beishan, sulfuric acid solution (pH=0.5) and potassium hydroxide solution (pH = 13). Experimental results show that both leaching agent and corrosion temperature co-dominate the corrosion process, and the temperature plays more important role. At low temperature of 70°C, the corrosion reaction is controlled by the ion diffusing in DIW at earlier stage. While in PHS, network hydrolysis reaction is the main corrosion mechanism.

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Wu, Dan Dan, Shu Ming Wen, Jing Yang, Qi Cheng Feng, and Ying Bo Mao. "The Dissolution of Zinc Oxide Ore in Sulfamic Acid Solution." Advanced Materials Research 881-883 (January 2014): 1554–57. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1554.

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In this study, the dissolution effect of zinc oxide ore was investigated using sulfamic acid solution as leaching agent. The effects of temperature, concentration of sulfamic acid, average particle size and stirring speed on the dissolution of zinc oxide ore were investigated. The dissolution rate increased with increasing solution temperature, concentration, and stirring speed as well as with decreasing average particle size. Sulfamic acid solution can therefore be used as an effective leaching agent for zinc extraction from zinc oxide ore.

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Li, Shui E., Fu Zhong Wu, and Qian Wang. "pH Control of Flue Gas Desulfurization in Sintering Process with Pyrolusite." Advanced Materials Research 864-867 (December 2013): 1592–97. http://dx.doi.org/10.4028/www.scientific.net/amr.864-867.1592.

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The effect of rhodochrosite as the annexing agent of pH of pyrolusite slurry on desulfurization and manganese leaching was studied. The influence of the byproduct of sulfuric acid in the sintering flue gas desulfurization process on desulfurization and resource utilization of absorbent was also investigated. The results show that rhodochrosite produced the same effect as a pH buffering agent. High desulfurization and manganese leaching rates were maintained for a long period. This study showed the possibility of resource utilization of low-grade rhodochrosite.

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Ismail, S., Norazharuddin Shah Abdullah, H. Hussin, and S. F. Saiyid Hashim. "Bamboo Sawdust as a Reduction Agent in Leaching Applications: Characterization Studies." Advanced Materials Research 620 (December 2012): 405–11. http://dx.doi.org/10.4028/www.scientific.net/amr.620.405.

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One of the promising and environmentally friendly hydrometallurgical processes for the recovery of manganese is acid leaching in the presence of carbohydrate as a reducing agent. The aim of this study is to characterize bamboo sawdust (BSD), in particular, the carbohydrate within, for possible usage as a reduction agent in acid leaching applications. Characterization were done using Malvern analyzer (particle size distribution), SEM (morphology), XRD (crystalline index) and FTIR (molecular framework). Detailed BSD constituents were also analyzed, to determine the cellulose, hemicellulose and lignin content. Results exhibited a wide size range distribution with a span value of 1.86, and geometric mean diameter of ~100 µm. The dominant composition, meanwhile, were cellulose (38.96%) hemicellulose (26.95%) and lignin (25.86%). The morphology characteristic by SEM revealed a smooth fibrous surface with multiple aligned bundles. The assessable crystalline index of cellulose was 56.12%. The molecular framework of cellulose, hemicellulose and lignin were clearly illustrated in BSD. The obtained characteristics are valuable information in utilizing BSD as a source of carbohydrate for leaching application.

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Hammadi, Mohammed Qasim, Rabiha Saleh Yassen, and Kadhim Noori Abid. "Recovery of Platinum and Palladium from Scrap Automotive Catalytic Converters." Al-Khwarizmi Engineering Journal 13, no. 3 (2017): 131–41. http://dx.doi.org/10.22153/kej.2017.04.002.

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Abstract  The hydrometallurgical method was used to platinum and palladium leaching with aqua regia solution (3HCl: HNO3). The leaching experiments were designed to obtain the optimum conditions by using Taguchi method with 16 experiments at three different factors (time, temperature and solid to liquid ratio), and each factor has four different levels. In this study, leaching the powder sample of catalytic converter that contains platinum and palladium was conducted on the basis of the formation of chloro complexes platinum and palladium (PtCl62-, PdCl42-) with different concentrations in the acidic solution. The optimum conditions for leaching process are (time = 120 minutes, temperature = 100°C, and solid to liquid ratio = 1/20).The best efficiency for platinum and palladium leaching at these conditions were 97.58%, 93.23%, respectively. After leaching process at optimum conditions, platinum was firstly precipitated in the form of (NH4)2PtCl6 (ammonium chloroplatinate) by adding (5ml/l) of ammonium chloride (NH4Cl) as a precipitant agent .Then, palladium was precipitated in the form of (NH4)2PdClO3 (palladium ammonium chlorate) by adding (5g/l) of sodium chlorate (NaClO3) as a precipitant agent to the remaining solution after the removal of platinum. The best efficiency for platinum and palladium recovery at optimum leaching conditions were 91.94%, and 98.82%, respectively.  Keywords: Aqua regia, catalytic converter, PGMs, Platinum, Palladium, recovery, catalytic converter, 3HCl:HNO3.

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Künkül, Asım, Abdulvahap Gülezgin, and Nizamettin Demirkiran. "Investigation of the use of ammonium acetate as an alternative lixiviant in the leaching of malachite ore." Chemical Industry and Chemical Engineering Quarterly 19, no. 1 (2013): 25–34. http://dx.doi.org/10.2298/ciceq120113039k.

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The solutions containing ammonia allow for selective leaching of the copper from a copper ore. In this study, the leaching and kinetics of malachite ore were examined using ammonium acetate solutions as an alternative lixiviant. The effects of some experimental parameters on the leaching of malachite ore were investigated. A kinetic model to represent the effects of these parameters on the leaching rate was developed. It was determined that the leaching rate increased with increasing solution concentration, temperature and stirring speed, and decreasing particle size and solid-to-liquid ratio. It was found that the leaching reaction followed the mixed kinetic control model. The activation energy of this leaching process was determined to be 59.6 kJmol-1. Consequently, it was determined that ammonium acetate solutions could be used as an effective leaching agent for the copper extraction form malachite ore.

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Kindelan, J. D. "In vitro Measurement of Enamel Demineralization in the Assessment of Fluoride-leaching Orthodontic Bonding Agents." British Journal of Orthodontics 23, no. 4 (1996): 343–49. http://dx.doi.org/10.1179/bjo.23.4.343.

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The aim of this study was to measure in vitro demineralization around orthodontic brackets, bonded with five different bonding agents. Two conventional bonding agents, two fluoride-leaching agents, and a glass ionomer were tested. A sixth group utilized a fluoride varnish after bonding. The amount of dissolved enamel mineral was determined from increases in the phosphorus concentration in the demineralizing solution and measurements were made over a 4 week period. The results confirmed that when fluoride is present in the form of a fluoride-leaching bonding agent or a fluoride varnish, resistance to demineralization is enhanced. Analysis of variance showed that Ketac-cem®, Concise® with Duraphat, and Pulpdent O.B.A.® performed statistically significantly better than Concise®, Bond-fast®, and Rely-a-bond®, in resisting enamel demineralization.

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Chen, Kaihua, Jiannan Pei, Shaohua Yin, Shiwei Li, Jinhui Peng, and Libo Zhang. "Leaching behaviour of rare earth elements from low-grade weathered crust elution-deposited rare earth ore using magnesium sulfate." Clay Minerals 53, no. 3 (2018): 505–14. http://dx.doi.org/10.1180/clm.2018.37.

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ABSTRACTThe present study investigates the use of magnesium sulfate (MgSO4) instead of (NH4)2SO4 as a lixiviant in the recovery of rare earth elements (REEs) from clays. Experiments were carried out to investigate the influence of leaching conditions such as leaching time, lixiviant concentration and liquid:solid ratio on the leaching efficiency. The optimum leaching conditions, leading to 75.48% of total REE leaching efficiency, required a stirring speed of 500 rpm, a leaching time of 30 min, a lixiviant concentration of 3 wt.% and a liquid:solid ratio of 3:1. After extension of the leaching process by a second stage, the leaching efficiency may reach up to 96.19%, which is slightly higher than that obtained by (NH4)2SO4. Leaching varies from element to element, with Ce presenting the lowest leaching efficiency, and the partition in leaching solution is in agreement with that in raw ore other than for Ce. Based on these findings, MgSO4 lixiviant is an excellent alternative leaching agent for a sustainable REE industry because it reduces or eliminates NH4+–N pollution.

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Li, Xiaojun, Ruizhi Yang, Hao Li, Hao Yi, and Hongjun Jing. "Experimental Study on Solidification and Stabilization of Heavy-Metal-Contaminated Soil Using Cementitious Materials." Materials 14, no. 17 (2021): 4999. http://dx.doi.org/10.3390/ma14174999.

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In order to solve the shortcomings of the traditional curing agent in the treatment of composite heavy-metal-contaminated soil with the solidification and stabilization method, a new type of cementing material A was used as a curing agent, and the Pb, Cd, Cu composite heavy-metal-contaminated soil was artificially prepared to carry out an experimental study on solidification and stabilization (SS) restoration by the mechanical properties test, leaching performance test, and microscopic test. The results show that in the range of test dosage, with the increase in the curing agent content, the unconfined compressive strength of the solidified body increased, and the resistance to deformation was enhanced. From the perspective of leaching characteristics, the new curing agent A had an excellent curing effect on the composite heavy-metal-contaminated soil. To achieve safe disposal, a curing agent content of 10% applies only for the soil heavily contaminated by heavy metals. The curing agent A could significantly reduce the content of acid-extractable heavy metals after solidifying the heavy metal Pb, Cd, and Cu composite contaminated soil and effectively converted it into a residue state. The solidified phase contained hydrated products such as calcium silicate hydrate (CSH) and ettringite (AFt). These hydrated products can inhibit the leaching performance of heavy metal ions through adsorption, encapsulation, and ion exchange. The study provides a feasible method and reference for the solidification, restoration, and resource utilization of heavy-metal-contaminated soil in the subgrade.

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Haryono, Didied, Harisma Nugraha, Warsito Purwo Taruno, Marlin Ramadhan Baidillah, Rommy Iman Sulaiman, and Mahfudz Al Huda. "Online Monitoring of Copper Leaching Process Heterogeneity Using Electrical Capacitance Volume Tomography." Advanced Materials Research 896 (February 2014): 714–17. http://dx.doi.org/10.4028/www.scientific.net/amr.896.714.

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In this study, we have performed the monitoring of copper leaching process using electrical capacitance volume tomography (ECVT). The ECVT has been used to measure electrical signals generated from the copper leaching process and reconstruct volumetric image of the signals in real time. This method is based on the fact that permittivity changes with the changes of ions concentration caused by leaching reaction. From the 3D image, we were able to analyze the heterogeneity of leaching reaction. There are two important features of leaching measurement, the online capability of the method and the ability to describe the leaching process heterogeneity. The current methods of leaching process usually have only one of the two important features. ECVT with high speed capability can provide both features. The experiment was carried out for 3 hours at room temperature without stirring, in which, copper foil and 2M H2SO4 were used as leaching object and leaching agent. The ECVT reconstructed image shows the heterogeneity permittivity distributions which shows the heterogeneous nature of leaching process.

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Mustin, C., Ph Donato, J. Berthelin, and Ph Marion. "Surface sulphur as promoting agent of pyrite leaching byThiobacillus ferrooxidans." FEMS Microbiology Reviews 11, no. 1-3 (1993): 71–77. http://dx.doi.org/10.1111/j.1574-6976.1993.tb00269.x.

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Han, Yong, Yong Jun Hao, Lei Zhang, Zhi Kun Zhang, and Ai Min Li. "Anaerobic Leaching-Bed Reactor Treating Food Waste for Organic Acid Production: Effect of Bulking Agent." Applied Mechanics and Materials 768 (June 2015): 289–98. http://dx.doi.org/10.4028/www.scientific.net/amm.768.289.

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Food waste was a troublesome organic waste stream, but a highly desirable substrate for anaerobic digestion to recover energy. Among the diverse reactor configurations, the leaching-bed reactor was reported to be best choice to treating the particular organic waste for platform compounds (volatile fatty acid). In this study, we carried out a series of experiments to investigate the bulking agent and pH control on process performance, and special focus was put on the biodegradability of bulking agent. The supplement of bulking agent greatly improved the leaching rate by 3.6 folds. Although the hydrolytic and acidogenic bacteria were resistant to low pH, the pH control (neutralization) caused a significantly increased volatile fatty acid (VFA) productions from 39.1 g COD/kg VSaddedto 183.4 g VFA/kg VSadded. Comparing with the undegradable bulking agent, the case with supplementing corncob as a bulking agent showed superior VFA yields (225 g COD/kg VSadded) which could be ascribed to the good adhesive properties for microorganisms and biodegradability. The ultimate analysis of the substrate (excluding the bulking agent) also showed that most of food waste was degraded with relative short reaction time. In addition, the TG/DTA and FTIR of residual corncob results indicated some components (cellulose, hemi-cellulose) were degraded, which could contribute to the additional VFA production (14 g COD/kg VSadded). This study suggested that the corncob could be considered as a good bio-compatible bulking agent for leaching-bed reactor, which not only increased the VFA productivity, but provided additional VFA production.

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Wacharanad, Sirorat, and Stephan Thierry Dubas. "Tunable Silver Leaching from Polyelectrolyte Multilayers Thin Films." Advanced Materials Research 701 (May 2013): 145–49. http://dx.doi.org/10.4028/www.scientific.net/amr.701.145.

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Silver nanoparticles were deposited on glass slides and surgical suture as antibacterial agent. The silver nanoparticles were prepared by chemical reduction with sodium borohydride and using a synthetic polyelectrolyte as capping agent. Poly (4-styrenesulfonic acid-co-maleic acid) sodium salt PSSMA was used to stabilize the silver nanoparticles and provide an anionic surface charge which then allowed the layer-by-layer deposition method with poly (dially dimethyl ammonium chloride) PDADMAC. Various concentration of capping agent were used to prepare the silver nanoparticles which were then deposited on glass slide and surgical suture. The layer-by-layer deposition of the nanoparticles was studied using UV-Vis spectroscopy by monitoring the intensity of the characteristic Plasmon band of the nanoparticles at 400nm. The leaching of the silver nanoparticles in buffered solutions of pH 3,7 and 9 was monitored by recording the decrease in absorbance of silver nanoparticles film as a function of time for each pH solutions and each capping concentrations. Finally, suture material coated with silver nanoparticles were tested for their antibacterial activity against Staphylococcus aureus and results showed that all coated sutures had more than 99% bacterial reduction. So these suture material could be applied to use in medical products for promoted wound healing and decreased bacterial colony leading to relieve inflammation of patient.

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Ukiwe, Lugard N., Allinor J.I, Ejele A.E, Anyadiegwu C.I.C, and Ibeneme S.I. "Chemical and Biological Leaching Methods to Remove Heavy Metals from Sewage Sludge: A Review." JOURNAL OF ADVANCES IN CHEMISTRY 4, no. 3 (2008): 509–17. http://dx.doi.org/10.24297/jac.v4i3.948.

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The removal of heavy metals (HMs) in sewage sludge (SS) is important since sludge is often disposed or applied on farmland to enhance soil fertility. The present study reviewed two conceptual approaches (chemical and biological leaching) of removing HMs present in SS. In the chemical leaching method, traditional acid treatment together with novel methods such as aeration, complexation and sequential extraction procedure have been reviewed extensively. Certain factors influence the removal of HMs in SS. These factors include; pH, leaching agent, redox potential, and contact time. Nitric acid (HNO3), hydrochloric acid (HCl), sulphuric acid (H2SO4), phosphoric acid (H3PO4), ethylenediamine tetraacetic acid (EDTA), as well as Thiobacillus thiooxidans and Thiobacillus ferrooxidans are the most widely studied leaching agents and substrates involved in the chemical and bioleaching processes. However, the bioleaching process has been proposed as a safe, efficient, economical, environmental friendly method to remove HMs in SS due to its simplicity, high yield of metal extraction, low acid consumption, and low sludge solids concentration. Nevertheless, the present review has noted that most researchers are of the opinion that more studies are needed in the bioleaching method in order to enhance its commercial attraction.

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Jekic, Jelena, Vladimir Beskoski, Gordana Gojgic-Cvijovic, Mirjana Grbavcic, and Miroslav Vrvic. "Bacterially generated Fe2(SO4)3 from pyrite, as a leaching agent for heavy metals from lignite ash." Journal of the Serbian Chemical Society 72, no. 6 (2007): 615–19. http://dx.doi.org/10.2298/jsc0706615j.

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Investigations of heavy metals from lignite ash, which is a coal combustion by-product, have for years been very interesting from different aspects of environmental protection. In this study, the possibility of microbiological ash leaching, with a strong oxidation agent, bacterially generated Fe2(SO4)3 was investigated in order to minimize the concentration of toxic ash elements. Leaching experiment by the shake flask testing technique was performed during a period of 20 d at a temperature of 28?C. The results obtained show 5- to 22-fold (for Cd and Ni approx. 5, Zn approx. 6, Mn approx. 8, Cr approx. 13 and Cu approx. 22) higher metal leaching efficiency in the suspension with bacterially generated Fe2(SO4)3 than in the control suspension. .

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Raza, Nadeem, Zafar Iqbal Zafar, and Najam-ul-Haq. "An Analytical Model Approach for the Dissolution Kinetics of Magnesite Ore Using Ascorbic Acid as Leaching Agent." International Journal of Metals 2013 (June 26, 2013): 1–6. http://dx.doi.org/10.1155/2013/352496.

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Ascorbic acid was used as leaching agent to investigate the dissolution kinetics of natural magnesite ore. The effects of various reaction parameters such as acid concentration, liquid-solid ratio, particle size, stirring speed, and temperature were determined on dissolution kinetics of the magnesite ore. It was found that the dissolution rate increased with increase in acid concentration, liquid-solid ratio, stirring speed, and temperature and decrease in the particle size of the ore. The graphical and statistical methods were applied to analyze the kinetic data, and it was evaluated that the leaching process was controlled by the chemical reaction, that is, . The activation energy of the leaching process was found to be 57.244 kJ mol−1 over the reaction temperature range from 313 to 343 K.

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Fan, Xiao Dan, and Xiang Kai Zhang. "Heavy Metals Leaching of Active Carbon from Sewage Sludge Modified by Chitosan for Dye Wastewater Treatment." Advanced Materials Research 627 (December 2012): 399–403. http://dx.doi.org/10.4028/www.scientific.net/amr.627.399.

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Heavy metal leaching limits activated carbon from sewage sludge (referred as ACS) to be used for wastewater treatment. Cr and Cd leaching from ACS exceed the permitted values. The leaching content of Cr and Cd decrease much with depositing ACS with chitosan (CS),below the permitted values. This is mainly due to the bind of Cr and Cd with the much group –NH2 of CS. The effects of initial dye concentration, pH and contact time had been studied. The dye adsorbed can act as a supple complexion agent with increasing initial dye concentration, increase the affinity for Cr and Cd. For Cd, the amount leaching of CS/ACS or ACS remains content with pH.The amount leaching of Cr decreases when the pH from 1 to 5 and then increases above the pH of 6.0. The contact time has no important influence on the leaching contents of Cr or Cd.

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