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Extraction of rare earth oxides from discarded compact fluorescent lamps
摘要： Discarded CFL samples are evaluated as a potential source of REEs (Y, Eu, Ce, Tb). The phosphors powder obtained from mechanical separation contains 31% rare earth values. The quantitative XRD analysis of phosphor sample yielded 39.9% red (YOX: Y1.90Eu0.10O3), 14.6% green (CAT: Al11Ce0.67MgO19Tb0.33), and 21.4% blue (BAM: Al10.09Ba0.96Mg0.91O17: Eu2+) phosphor along with 14.1% silica. Planetary ball milling was found promising in the liberation of REEs from given phosphor sample. A short milling of 20–30 min and 3–4 M acid concentration was found adequate for optimal recovery (> 90%) of REEs. Calcination of the precipitates resulted in the formation of REO with Y-Eu purity of > 98% and > 90% recovery rate. Eu, Y phase dissolution behavior was found completely different than Ce, Tb phase due to inert nature of Al11Ce0.67MgO19Tb0.33 till 120 min milling and 6 M acid concentration in leaching. Excessive milling promotes overall dissolution along with impurities dissolution and which further restrict the precipitation process. Based on the complete material balance 13 g of a mixed oxide of Y and Eu can be obtained from 100 units of CFLs.
关键词： Discarded CFL,Phosphor,Rare earth elements,Leaching,Mechanical milling
更新于2025-11-21 11:18:25
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Purification and comprehensive utilization of sapphire kerf waste
摘要： Sapphire kerf waste (a fine powder) is a great potential source of high-purity α-Al2O3 and is currently discarded without reutilization, which is a waste of this resource and causes environmental problems, such as occupying space and generating dust. Herein, we report a feasible combined method to recycle valuable high-purity α-Al2O3 from sapphire kerf waste through the ultrasound-assisted leaching of nickel, diamond removal by bulk heating and a grinding process. The impurities in the waste were collected, and their existence states were characterized as independent metal nickel and diamond. The nickel impurity was removed from the waste by ultrasound-assisted leaching using a mixture of sulfuric acid and nitric acid, and the optimal leaching efficiency reached 99.67% under the conditions of sulfuric acid: nitric acid = 2:1 (v/v), 4 mol/L H+ concentration, 4 mL/g liquid-solid ratio, 45 °C, 30 min, 200 rpm, 240 W ultrasonic power and 45 kHz ultrasonic frequency. Subsequently, nickel ions in the lixivium were recycled in the form of nickel sulfate through extraction and stripping treatments. The diamond impurity was removed by bulk heating in flowing oxygen, and the optimal removal ratio was 99.65% under the conditions of 800 °C, 30 min and oxygen flow of 400 mL/min. High-purity α-Al2O3 was successfully recovered from the sapphire kerf waste after the grinding process, which had a purity higher than 99.99 wt% and an average diameter of 0.6 mm. In addition, the kinetics of leaching nickel and diamond removal were systematically analysed based on the shrinking model, and the chemical reaction was found to be the control step. The reaction mechanisms of the two processes were also studied. The economic evaluation revealed that the profit from dealing with 1 kg sapphire kerf waste with this method was $13.68. Therefore, the proposed method is promising for providing technical and economical guidance for industrial production.
关键词： Purification,Sapphire kerf waste,Carbon removal,Nickel leaching,Recycle
更新于2025-09-23 15:23:52
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Colorimetric detection of copper ions using gold nanorods in aquatic environment
摘要： On the basis of that Cu2+ can accelerate the leaching rate of Au by thiosulfate, a colorimetric, unlabeled and non-aggregating gold nanorod (GNR) probe has been developed for the determination of trace-level Cu2+ in aqueous solutions. Our study demonstrates a high sensitivity and rapid response towards Cu2+ with a detectable range (20–200 nM). E?ect factors such as the ratio of NH3/NH4Cl, the concentration of S2O3 2?, the bath temperature and the heating time were researched to investigate the in?uences on the copper detection process by GNRs sensor. The method studied in this project is highlighted by its high selectivity and high tolerance to interferences, which can be used to detect trace amounts of Cu2+ ions in water samples quickly and sensitively, indicating the potential suitability of copper detection in various applications.
关键词： Gold nanorods,Copper ions,Catalytic leaching,Colorimetric detection
更新于2025-09-23 15:22:29
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Spectrophotometric determination of manganese in acidified matrices from (pore)waters and from sequential leaching of sediments
摘要： Manganese (Mn) is a major redox reactive element in marine sediments and it plays an important role in the biogeochemical cycles of carbon, nitrogen, phosphorus, or trace metals. Mn cycle in marine sediments is characterized by an alternation of oxidation and reduction processes depending on physicochemical and biological conditions: assessing the quantification and the speciation of Mn is thus an essential issue to understand redox reaction-transport processes in sedimentary deposits. Solid Mn phases can be determined through chemical extractions techniques that permits selective leaching of operationally defined Mn fractions. Mn oxides and oxyhydroxides are extracted with an ascorbate leaching solution, while the whole Mn (oxyhydr-)oxides and Mn associated to carbonates is extracted with HCl. An existing spectrophotometric method allows to quantify Mn dissolved in (sea) water. We present here a modified version, which permits to measure Mn in acidified matrices, including ascorbate and HCl solutions. A metallic substitution occurs between a Cd-TCPP complex and Mn at pH 7.5–8.0, with imidazole as catalyst. We propose here to use a NaHCO3 solution to dilute the samples in order to be in the necessary pH range to perform the metal substitution. Using this method, Mn(II,III) concentrations were determined in standard solutions with a precision of 3% within a concentration range of 0.5–80 μM. The procedure was successfully applied to determine Mn in acidified pore waters and in ascorbate and HCl sequential extractions from muddy sediments of the Bay of Biscay. Spectrophotometric results agreed closely with results from atomic absorption spectrometry, validating the proposed method.
关键词： Sediment,Acidified matrices,Sequential leaching,Spectrophotometric method,Manganese
更新于2025-09-23 15:22:29
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Leaching Kinetics of Yttrium and Europium Oxides from Waste Phosphor Powder
摘要： Phosphor powder sample was characterized, and the leaching kinetics of yttrium, and europium in hydrochloric acid were investigated. Under optimized leaching conditions, 98% Y and 97% Eu were extracted, and a reaction curve was generated using the percentage of extraction as a function of time and temperature. Based on R2 values, shrinking spherical particle and shrinking core model were not applicable. SEM analysis also con?rmed shrinking core behavior was not applicable due to the lack of core–shells in the leach residue. The kinetic data were best ?tted by a logarithmic rate expression of the empirical model. Activation energy was calculated to be 77.49 kJ/mol for Y and 72.75 kJ/mol for Eu in the temperature range of 298–343 K.
关键词： Leaching,Phosphor powder,Rare earth elements,Waste ?uorescent lamp,Kinetics
更新于2025-09-23 15:21:01
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Effective Separation and Recovery of Valuable Components from CIGS Chamber Waste via Controlled Phase Transformation and Selective Leaching
摘要： Copper indium gallium diselenide (CIGS) chamber waste formed during CIGS solar-cell production was subjected to two-stage sulfation roasting for controlled phase transformation and selective leaching to separate valuable components. Selenium was initially separated in the first stage of sulfation roasting. Under the optimal conditions, 99.96% of selenium was volatilized into gas in the form of selenium dioxide, and the remaining components were converted to sulfates. The second stage of roasting followed by water leaching was investigated for the separation and recovery of the remaining components in slag. Controlled phase transformation of sulfates was completed in the second stage roasting. Indium and gallium sulfates are converted to oxides, whereas CuSO4 remained nearly unchanged. Afterward, 95.90% of copper was selectively leached into liquor, and the leaching rates of indium and gallium were only 5.67% and 2.89%, respectively. Consequently, the content of mixed indium and gallium oxides in the leach residue was 91.09%. Exploratory experiments show that indium and gallium can be effectively separated via alkali leaching and precipitation. Therefore, effective separation of valuable metals from CIGS chamber waste was achieved based on the different physical and chemical properties of the components.
关键词： Phase transformation,Valuable components,Separation,Leaching,CIGS chamber waste
更新于2025-09-23 15:19:57
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Pb-Based Perovskite Solar Cells and the Underlying Pollution behind Clean Energy: Dynamic Leaching of Toxic Substances from Discarded Perovskite Solar Cells
摘要： Toxicants like Pb in lead-based perovskite solar cells (PSCs) may become available to humans through leaching and transport through water, air, and soil. Here, we summarize the potential toxicity of di?erent substances in PSCs and determine the leaching concentration of typical heavy metals used in PSCs through dynamic leaching tests (DLTs). Extraction ?uids for the standard toxicity characteristic leaching procedure, synthetic precipitation leaching procedure, and deionized water were used as the DLT leaching solutions. Results indicated that the leaching concentration of Pb exceeded the hazardous waste limit of 5 mg/L. In addition, Pb was found to continuously leach out in the leaching cycles of water extraction. The ?ndings con?rmed that discarded PSCs may release Pb when subjected to water, rain, and land?ll leachate. Total organic carbon and chemical oxygen demand analyses indicated that discarded PSCs could increase the oxygen consumption and may release CO2 into the environment.
关键词： leaching,Pb-based perovskite solar cells,toxic substances,environmental impact,hazardous waste
更新于2025-09-23 15:19:57
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Potential environmental risk of solar cells: Current knowledge and future challenges
摘要： Photovoltaic (PV) technology such as solar cells and devices convert solar energy directly into electricity. Compared to fossil fuels, solar energy is considered a key form of renewable energy in terms of reducing energy-related greenhouse gas emissions and mitigating climate change. To date, the development and improvement of PV technologies has received substantial attention; however, their potential environmental risks remain unknown. Therefore, this review focuses on the potential risks of leachates derived from solar cell devices. We collect scientific literature on toxicity and leaching potential, tabulate the existing data, and discuss related challenges. Insufficient toxicity and environmental risk information currently exists. However, it is known that lead (PbI2), tin (SnI2), cadmium, silicon, and copper, which are major ingredients in solar cells, are harmful to the ecosystem and human health if discharged from broken products in landfills or after environmental disasters. Several research directions and policy initiatives for minimizing the environmental risks of PV technology are suggested. This review contributes to both solar energy and environmental science research.
关键词： Solar cell,Photovoltaic,Recycling,Toxicity,Leaching
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Light Shaping for Reconfigurable Microscale Temperature Control
摘要： Recycling rare-earth elements (REEs) from Nd-Fe-B magnet waste is an important step towards building a sustainable REE supply chain. In this study, two different processes were systematically investigated and compared. In the leaching stage, the effect of increasing H2SO4 or HCl concentrations were studied and it was determined that, although both can successfully promote REEs, B, Fe and Co leaching, HCl solutions extracted a wider range of metals. After leaching, the oxalate and double-sulfate precipitation methods were utilized to separate REEs from either HCl or H2SO4 leachates. Results suggest that, although > 99% REEs precipitation rates could be achieved with oxalate, the purity of REE-containing products is significantly affected by impurities like Fe and Co. In contrast, REE double-sulfate precipitation resulted in a product purity of > 99%; however, high levels of Na2SO4 (8 times the stoichiometric amount) were needed to achieve > 98% of REE precipitation.
关键词： rare-earth elements,precipitation,leaching,Nd-Fe-B magnets,recycling
更新于2025-09-12 10:27:22
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Leaching of indium from waste LCD screens by oxalic acid in temperature-controlled aciduric stirred reactor
摘要： Recovery of rare metal indium from waste LCD screens is important since its content is about 500 times of the original ore. Oxalic acid has excellent ability to leach indium from waste LCD screens, and how to achieve reactor scale operation is critical to promote indium recovery. In this study, a temperature-controlled aciduric stirred reactor (TCASR) was constructed to investigate the effects of operational conditions on the leaching efficiency of indium at reactor scale. Results showed that complete leaching was realized in 10 min under the conditions of 0.2 mol/L oxalic acid, 300 g/L of ITO glass powder dosage, 90℃ and 500 rpm of stirring speed, the consumption of oxalic acid decreased 3/5, dosage increased by 6 times and reaction time decreased 7/9 compared with the previous study. Meanwhile, maintaining duration of indium ion concentration achieved 20 min instead of decreasing immediately after reaching the peak, which was advantageous for actual application. The process kinetics model illustrated that the most important factor affecting the reaction rate was temperature. The potential reason of longer indium ion concentration maintaining duration was preliminarily speculated as a faster leaching of indium than calcium result in less coprecipitation caused by calcium oxalate. Therefore, the TCASR is applicable for leaching of indium from waste LCD screens by oxalic acid due to the higher leaching efficiency, less reagents consumption and stronger processing ability.
关键词： Waste LCD screens,Operational conditions,Indium,Reactor,Leaching
更新于2025-09-11 14:15:04