Advances in bioleaching of copper and nickel from electronic waste using Acidithiobacillus ferrooxidans: evaluating daily pH adjustmentMahdokht Arshadi and Soheila Yaghmaei Chemical and Petroleum Engineering Department, Sharif University of Technology, Tehran, Iran
E-mail: yaghmaei@sharif.edu Received: 2 October 2019 Accepted: 8 January 2020 Abstract: The waste stream of electrical and electronic equipment is three times faster than other municipal waste streams. Recycling of electronic waste is necessary for both reducing environmental pollution and saving natural ores. Bioleaching is known as an efficient technology for metal leaching. In most of the previous studies on the bioleaching of electronic waste, the pH of the process was adjusted daily under the optimal pH of the bacterium growth. Using acid causes increasing process costs and unsustainability of the process. In this work, the effect of daily pH adjustment on the bioleaching efficiency of electronic waste using adapted Acidithiobacillus ferrooxidans was studied. Simultaneously, Cu and Ni leaching efficiency, bacterial growth characteristics, and chemical characteristics (including field emission scanning electron microscopy, Fourier transform infrared spectrometer, and X-ray diffraction) were discussed. The results showed that at a pulp density of 1.5% (w/v) with pH adjustment, the maximum leaching efficiency of Cu and Ni was, respectively, about 90% and 88%, while for the sample without pH adjustment, the maximum leaching efficiency of Cu and Ni was, respectively, 100% and 92%. All the results confirmed pH adjustment of the bioleaching solution is not necessary and even reduces the process efficiency. Graphic Abstract:  Keywords: Bioleaching; Mesophilic acidophiles; Metal leaching efficiency; Solid waste; Sulfuric acid addition Full paper is available at www.springerlink.com. DOI: 10.1007/s11696-020-01055-y
Chemical Papers 74 (7) 2211–2227 (2020) |
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