title: Chelant-induced reclamation of indium from the spent liquid crystal display panels with the aid of microwave irradiation.
abstract: Indium is a rare metal that is mostly consumed as indium tin oxide (ITO) in the fabrication process of liquid crystal display (LCD) panels. The spent LCD panels, termed as LCD-waste hereafter, is an increasing contributor of electronic waste burden worldwide and can be an impending secondary source of indium. The present work reports a new technique for the reclamation of indium from the unground LCD-waste using aminopolycarboxylate chelants (APCs) as the solvent in a hyperbaric environment and at a high-temperature. Microwave irradiation was used to create the desired system conditions, and a substantial abstraction of indium (≥80%) from the LCD-waste with the APCs (EDTA or NTA) was attained in the acidic pH region (up to pH 5) at the temperature of ≥120 °C and the pressure of ~50 bar. The unique point of the reported process is the almost quantitative recovery of indium from the LCD-waste that ensured via the combination of the reaction facilitatory effect of microwave exposure and the metal extraction capability of APCs. A method for the selective isolation of indium from the extractant solution and recycle of the chelant in solution is also described.
authors.affiliation: Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan. Electronic address: hhiroshi@t.kanazawa-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan; Department of Applied and Environmental Chemistry, University of Chittagong, Chittagong 4331, Bangladesh. Electronic address: I.M.M.Rahman@gmail.com.
authors.forename: Ismail M M
authors.initials: IMM
authors.lastname: Rahman
authors.affiliation: Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Egawa
authors.affiliation: Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Sawai
authors.affiliation: Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Zinnat A
authors.initials: ZA
authors.lastname: Begum
authors.affiliation: Institute of Science and Engineering, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan.
authors.forename: Teruya
authors.initials: T
authors.lastname: Maki
authors.affiliation: Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-Ku, Osaka 558-8585, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mizutani
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D059029:Electronic Waste; D006863:Hydrogen-Ion Concentration; D007204:Indium / Q000737:chemistry*; D050866:Liquid Crystals; D008872:Microwaves; D009571:Nitrilotriacetic Acid / Q000737:chemistry*; D059027:Recycling / Q000379:methods; D052616:Solid Phase Extraction; D013696:Temperature
chemical_list: D002614:Chelating Agents; D007204:Indium; D004492:Edetic Acid; D009571:Nitrilotriacetic Acid