title: Chemical and biological processes for multi-metal extraction from waste printed circuit boards of computers and mobile phones.
abstract: E-waste printed circuit boards (PCB) of computers, mobile-phones, televisions, LX (LongXiang) PCB in LED lights and bulbs, and tube-lights were crushed to ≥250 µm particle size and 16 different metals were analysed. A comparative study has been carried out to evaluate the extraction of Cu-Zn-Ni from computer printed circuit boards (c-PCB) and mobile-phone printed circuit boards (m-PCB) by chemical and biological methods. Chemical process showed the extraction of Cu-Zn-Ni by ferric sulphate was best among the studied chemical lixiviants. Bioleaching experiments were carried out with the iron oxidising consortium, which showed that when E-waste and inoculum were added simultaneously in the medium (one-step process); 60.33% and 87.50% Cu, 75.67% and 85.67% Zn and 71.09% and 81.87% Ni were extracted from 10 g L(-1) of c-PCB and m-PCB, respectively, within 10-15 days of reaction time. Whereas, E-waste added after the complete oxidation of Fe(2+) to Fe(3+) iron containing medium (two-step process) showed 85.26% and 99.99% Cu, 96.75% and 99.49% Zn and 93.23% and 84.21% Ni extraction from c-PCB and m-PCB, respectively, only in 6-8 days. Influence of varying biogenerated Fe(3+) and c-PCB concentrations showed that 16.5 g L(-1) of Fe(3+) iron was optimum up to 100 g L(-1) of c-PCB. Changes in pH, acid consumed and redox potential during the process were also studied. The present study shows the ability of an eco-friendly process for the recovery of multi-metals from E-waste even at 100 g L(-1) printed circuit boards concentration.
authors.affiliation: Department of Microbiology and Biotechnology, Gujarat University, Ahmedabad, India.
authors.forename: Monal B
authors.initials: MB
authors.lastname: Shah
authors.affiliation: Department of Microbiology and Biotechnology, Gujarat University, Ahmedabad, India.
authors.forename: Devayani R
authors.initials: DR
authors.lastname: Tipre
authors.affiliation: Department of Microbiology and Biotechnology, Gujarat University, Ahmedabad, India shaileshrdave@yahoo.co.in.
authors.forename: Shailesh R
authors.initials: SR
authors.lastname: Dave
mesh_terms: D001419:Bacteria / Q000378:metabolism; D040421:Cell Phone; D003201:Computers; D059029:Electronic Waste / Q000032:analysis*; D008670:Metals / Q000737:chemistry*; D059027:Recycling / Q000379:methods*
chemical_list: D008670:Metals
keywords: Bioleaching; E-waste; computer printed circuit boards; ferric iron; high pulp density; mobile-phone printed circuit boards