Recovery of indium by biosorption and its application to recycling of waste liquid crystal display panel

Abstract

Microbial adsorption of soluble indium ( III ) was successfully achieved at room temperature over the pH range 2.3 to 3.5 using the gram-negative bacterium Shewanella algae. The microbial uptake of indium by the resting cells of S. algae was a fast process: 10-100 ppm indium (III) ions were completely collected into the bacterial cells within 30 min. The pH value and the cell concentration in aqueous indium(III) solutions had a significant effect on the adsorption fraction of soluble indium(III). The adsorption capacity of S. algae cells was determined as 41 ± 2 mg-In/g-dry cells, indicating that the 100 ppm aqueous InC1 3 solution was concentrated up to 680-fold by the microbial adsorption. The optimal pH for microbial adsorption was found to be 0.9-1.4 for Sn(IV), pH 2.3-3.5 for In(III), pH 2.9-4.3 for Al(III), respectively. For microbial recovery of indium from waste liquid crystal display (LCD) panel, moreover, S. algae cells were able to collect selectively indium (III ) to the bacterial cells, after indium leaching from spent LCD panel with dilute HCl solution under hydrothermal conditions (120°C, 0.198 MPa, 5 min). © 2011 The Japan Institute of Metals.