Khezerloo Samaneh, Nasirpour Niloofar, Pourhossein Fatemeh, Mousavi Seyyed Mohammad
Biotechnology Group, Chemical Engineering Department, Tarbiat Modares University, Tehran, Iran.
Chemical Engineering Department, University of Mohaghegh Ardabili, Ardabil, Iran.
J Environ Manage. 2023 Jun 1;335:117520. doi: 10.1016/j.jenvman.2023.117520. Epub 2023 Feb 22.
The spent light emitting diode (LED) monitors are one of the fastest-growing waste streams that could provide indium, an essential element for the industry. This study presents a comprehensive strategy for indium extraction from spent LED monitors, including bioleaching followed by solvent extraction, stripping, and precipitation. Effects of A. thiooxidans and A. ferrooxidans inoculum percentage in mixed culture, pulp density, and time on indium, aluminum, and strontium bioleaching were investigated. In this regard, at optimized inoculum percentages (1.5 and 0.5% (v/v) of A. ferrooxidans and A. thiooxidans, respectively) and pulp density (60 g/L) at initial pH of 2, approximately 100% indium recovery was obtained in 18 days. The solubilized indium in the bioleaching solution has been extracted by the organic solvent of 20% (v/v) D2EHPA in kerosene. Following extraction, the stripping step was carried out to recover indium rather than iron selectively. The effect of two-phase contact time and aqueous to organic phase volume ratio in the extraction step and the acid type and concentration in the stripping step on indium and iron recovery percentages have been evaluated. For indium extraction, the optimum ratio of aqueous to organic phase volume and time were determined as 1 and 30 min, respectively, recovering 91.5% of indium. Using 5 M sulfuric acid has also resulted in an efficient stripping process. Finally, sodium hydroxide performed indium precipitation and a final precipitate of 94% (w/w) indium was obtained.
废旧发光二极管（LED）显示器是增长最快的废物流之一，它能够提供铟，而铟是该行业的一种关键元素。本研究提出了一种从废旧LED显示器中提取铟的综合策略，包括生物浸出，随后进行溶剂萃取、反萃取和沉淀。研究了氧化硫硫杆菌和氧化亚铁硫杆菌混合培养时接种物百分比、矿浆密度和时间对铟、铝和锶生物浸出的影响。在这方面，在初始pH为2时，优化接种物百分比（氧化亚铁硫杆菌和氧化硫硫杆菌分别为1.5%和0.5%（v/v））和矿浆密度（60 g/L）的条件下，18天内铟的回收率约为100%。生物浸出溶液中溶解的铟已用20%（v/v）二（2-乙基己基）磷酸（D2EHPA）的煤油有机溶剂进行萃取。萃取后，进行反萃取步骤以选择性回收铟而非铁。评估了萃取步骤中两相接触时间和水相与有机相体积比以及反萃取步骤中酸的类型和浓度对铟和铁回收率的影响。对于铟的萃取，水相与有机相的最佳体积比和时间分别确定为1和30分钟，铟的回收率为91.5%。使用5 M硫酸也导致了高效的反萃取过程。最后，氢氧化钠进行铟的沉淀，得到了铟含量为94%（w/w）的最终沉淀物。
