Abstract:The main goal of this study was to recover indium from the waste liquid crystal display (LCD) panel. In this context, an ionic liquid Cyphos IL 101 was explored. The extraction parameters such as equilibration period, acid concentration, chloride ion concentration, hydrogen ion concentration were examined on the extraction efficiency of Cyphos IL 101 towards In(III). Quantitative extraction of indium was found at 2.0 mol/L HCl using 0.005 mol/L Cyphos IL 101 and quantitative stripping with 1.0 mol/L H₂SO₄. Job’s method was used to determine the extracted species and R₃R''''PInCl₄ (R=C₆H₁₃; R′=C₁₄H₂₉) was proposed. Based on the observations on multi-metal studies, Cyphos IL 101 was further employed for the removal of indium, tin and copper from the leach liquors of waste LCDs. Optimized conditions were generated for the recovery of indium from waste LCDs. McCabe-Thiele diagram analysis, counter-current extraction and selective stripping were carried out to separate the metal ions, i.e., indium, tin and copper. Two stages at O/A ratio of 1:3 were required for complete removal of tin from the feed and selective stripping of In and Sn was achieved using 0.1 mol/L H₂SO₄. A scheme for separating indium from the waste LCDs was proposed.

Key words: indium; extraction; separation; Cyphos IL 101; liquid crystal display panel