Abstract
This work reports a kinetic study of the bioleaching process for Cu extraction from waste printed circuit boards (WPCBs), using iron as an oxidant agent. The kinetic study considered both the Fe2+ oxidation by bacteria metabolism and the chemical reaction between Fe3+ and Cu within WPCBs. The model was composed of a system of three differential equations characterized by three dependent variables and seven parameters. The first equation describes the bacteria abundance trend, the second one represents the variation of Fe2+ concentration, and the third one focuses on the Cu extraction by the biogenerated Fe3+. The developed model was consistent with experimental data with an R2 higher than 0.97. The results showed that the bacteria metabolism was 1.8–2.5 times faster than the chemical reaction. The determined mathematical model, suitable for the implementation at an industrial scale, could be an important tool to predict the bioleaching mechanism in a metal recovery process.
Highlights
The modern society is becoming more and more dependent on electronic devices, which are characterized by a short replacement cycle.[1]
The Cu extraction from waste printed circuit boards (WPCBs) by biotechnologies is studied by several works, mainly using Acidithiobacillus ferrooxidans (At. ferrooxidans).[26−35] The mechanism for the Cu leaching from WPCBs follows eq 1: Cu0 + 2 Fe3+ → Cu2+ + 2 Fe2+
The kinetics and the mechanism of the Cu bioleaching from WPCBs by At. ferrooxidans was studied in detail
Summary
The modern society is becoming more and more dependent on electronic devices, which are characterized by a short replacement cycle.[1]. The chemical processes include pyrolysis, gasification, combustion, or the use of a chemical agent (i.e., HCl, H2SO4, HNO3, ammonium, or ethylenediaminetetraacetic acid).[9,14,24] the acid and the gases produced during the chemical processes generate a secondary pollution For this reason, the biotechnologies have become more and more attractive in the last decades as an eco-friendly and sustainable alternative.[9,25] The Cu extraction from WPCBs by biotechnologies is studied by several works, mainly using Acidithiobacillus ferrooxidans (At. ferrooxidans).[26−35] The mechanism for the Cu leaching from WPCBs follows eq 1: Cu0 + 2 Fe3+ → Cu2+ + 2 Fe2+
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