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Materials recovery from waste liquid crystal displays: A focus on indium

TitleMaterials recovery from waste liquid crystal displays: A focus on indium
Publication TypeArticolo su Rivista peer-reviewed
Year of Publication2015
AuthorsFontana, Danilo, Forte Federica, De Carolis R., and Grosso M.
JournalWaste Management
Keywords1, 10-phenanthroline, ABSs, acetic acid ethyl ester, Acetone, Aqueous biphasic system, aqueous phase, article, Chemical treatments, controlled study, crystal, electronic waste, Extraction, Hydrometallurgy, Indium, Indium concentration, Initial concentration, leaching, limonene, Liquid, liquid crystal display waste, Liquid crystal displays, Liquid nitrogen, macrogol, Materials recovery, Metal recovery, Metallurgy, partitioning, physical phase, pollutant removal, precipitation, priority journal, Recovery, Room temperature, Salt concentration, solubilization, Solvent extraction, Waste treatment

In the present work the recovery of indium and of the polarizing film from waste liquid crystal displays was experimentally investigated in the laboratory. First of all, the polarizing film was removed by employing a number of different techniques, including thermal and chemical treatments. Leaching of indium was then performed with HCl 6. N, which allowed solubilisation of approximately 90% In (i.e. 260. mg In per kg of glass) at room temperature, without shredding. Indium recovery from the aqueous phase was then investigated through solvent extraction with polyethylene glycol (PEG)-based aqueous biphasic systems. Indium extraction tests through the PEG-ammonium sulphate-water system were conducted as a function of PEG concentration, salt concentration and molecular weight of PEG, using 1,10 phenanthroline as a ligand. The experimental results demonstrated that indium partitioning between the bottom (salt-rich) and the top (PEG-rich) phase is quite independent on the composition of the system, since 80-95% indium is extracted in the bottom phase and 5-20% in the top phase; it was also found that when PEG concentration is increased, the ratio between the bottom and the upper phase volumes decreases, resulting in an increase of indium concentration in the bottom phase (at [PEG]. =. 25% w/w, indium concentration in the bottom phase is 30% higher than the initial concentration before the extraction). © 2015 Elsevier Ltd.


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Citation KeyFontana2015