Recycling of REMS and removal of toxic metals from fluorescent and CRT waste: a review

Abstract

Fluorescent lamp and cathode ray tube (CRT) waste considered as hazardous waste by commission of European communities and resource conservation and recovery act (RCRA). Due to the presence of mercury and lead in fluorescent waste and cathode ray tube waste, it is highly toxic for environment. Simultaneously, these wastes are also a vital source of different rare earth elements (REEs) such as Y, Eu, Ce, Tb and La. REEs are the most critical resources in the development of both traditional and high-tech industries all over the world. In order to prevent the misuse of natural resources, recycling of REEs from fluorescent and CRT waste is an effective step for accelerating the sustainable use of resources and protect environmental pollution from mining. So, recovery of REEs as well as removal of contaminated hazardous metals such as Hg and Pb from waste is a challenging task. Many researchers in the last few years focused on the development of different process such as solvent extraction, selective leaching, and precipitation for recovery of rare earth elements as well as the removal of toxic metal from waste. Particularly recoveries of yttrium and europium metals are the main interest of many researchers due to huge application in CFL bulbs and CRT tubes. Selective leaching of Y and Eu can be obtained in dilute acid solution with moderate temperature. Dissolution of Pb in leaching process can be avoided by leaching with H2SO4 as it forms insoluble sulfate. While coming to solvent extraction, three major classes of conventional extractantshavebeen used for extraction of REEs such as cation exchanger, solvating extractants and anion exchangers. The use of ionic liquids instead of conventional extractantsismore interesting in modern research because of their high thermal stability, nontoxic and high extraction ability. They are used for effective recovery of REEs from e-waste.