Photoelectrochemical cell for simultaneous electricity generation and heavy metals recovery from wastewater.
The feasibility of simultaneous recovery of heavy metals from wastewater (e.g., acid mining and electroplating) and production of electricity is demonstrated in a novel photoelectrochemical cell (PEC). The photoanode of the cell bears a nanoparticulate titania (TiO2) film capped with the block copolymer [poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol)] hole scavenger, which consumed photogenerated holes, while the photogenerated electrons transferred to a copper cathode reducing dissolved metal ions and produced electricity. Dissolved silver Ag+, copper Cu2+, hexavalent chromium as dichromate Cr2O72-and lead Pb2+ions in a mixture (0.2mM each) were removed at different rates, according to their reduction potentials. Reduced Ag+, Cu2+and Pb2+ions produced metal deposits on the cathode electrode which were mechanically recovered, while Cr2O72-reduced to the less toxic Cr3+in solution. The cell produced a current density Jscof 0.23mA/cm2, an open circuit voltage Vocof 0.63V and a maximum power density of 0.084mW/cm2. A satisfactory performance of this PEC for the treatment of lead-acid battery wastewater was observed. The cathodic reduction of heavy metals was limited by the rate of electron-hole generation at the photoanode. The PEC performance decreased by 30% after 9 consecutive runs, caused by the photoanode progressive degradation.
Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xi Kang Road #1, Nanjing 210098, PR China.
Dawei
D
Wang
Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xi Kang Road #1, Nanjing 210098, PR China. Electronic address: envly@hhu.edu.cn.
Yi
Y
Li
Environmental Nanocatalysis & Photoreaction Engineering, Department of Chemical Engineering, Loughborough University, Loughborough LE11 3TU, United Kingdom. Electronic address: g.lipuma@lboro.ac.uk.
Gianluca
G
Li Puma
Department of Chemical Engineering, University of Patras, 26500 Patras, Greece.
Panagiotis
P
Lianos
Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xi Kang Road #1, Nanjing 210098, PR China.
Chao
C
Wang
Key Laboratory of Integrated Regulation and Resource Development of Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xi Kang Road #1, Nanjing 210098, PR China.
Peifang
P
Wang
Electricity generation; Heavy metals reduction; Photoelectrochemical cell; Wastewater treatment