Contact Behavior between Cells and Particles in Bioleaching of Precious Metals from Waste Printed Circuit Boards

• Published in: ACS sustainable chemistry & engineering Vol. 6; no. 9; pp. 11570 - 11577
• Main Authors: Yuan, Zhihui, Huang, Zhe, Ruan, Jujun, Li, Yaying, Hu, Jian, Qiu, Rongliang
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04-09-2018
• Subjects: E-waste; Precious metal; Bioleaching; Polyvinylpyrrolidone; Diffusion control
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.8b01742

Bioleaching of precious metals from waste printed circuit boards such as using cyanogenic cultures for extraction of gold and silver has gained considerable attention. It has the advantages of low cost and environmental friendliness. However, low efficiency hindered its industrialization. In this study, a novel strategy has been proposed to improve bioleaching efficiency. We applied optical microscopy to investigate the surface interactions between bacteria and silver particles in two-step bioleaching. Results showed that bacterial adsorption and extracellular polymeric substances (EPS) binding were the primary negative behavior that hindered the leaching reaction. Functional group analysis by Fourier-transform infrared spectroscopy indicated that carboxyl, hydroxyl, and amine groups were the main chemical structures responsible for the negative influences. Bacteria–metal interactions were reduced in the presence of polyvinylpyrrolidone (PVP), and the silver recovery increased 1.8 times. Imaging analysis showed bacteria and EPS were dispersed from silver surface in the case of PVP addition. Zeta potential analysis indicated that PVP exhibited high affinity binding to silver particles and suppressed the attachment of the microbial materials onto silver surface. Our results demonstrated the utility of PVP addition for the bioleaching of precious metals.