Carboxymethyl cellulose–poly-m-phenylenediamine composite membrane for gold recovery from e-waste†

Abstract

E-waste contains a variety of non-renewable precious metal resources, and the amount is significantly higher than the abundance of precious metals in the corresponding ores. Therefore, it is of great significance to recover and reuse precious metals in e-waste. In this study, we successively used a simple one-step oxidation method and physical cross-linking to prepare a poly-m-phenylenediamine composite membrane material (CMC–PmPD composite membrane) containing a large number of recycling groups. The prepared CMC–PmPD composite membrane has high adsorption capacity and adsorption efficiency for Au(III), and the maximum adsorption capacity for Au(III) reaches 421.1 mg g⁻¹. The adsorption follows a second-order kinetic process and a Langmuir isotherm model, indicating that the adsorption mechanism is a monolayer chemisorption. The regeneration of the composite membrane material can be realized after a simple thiourea solution immersion, and 89.5% adsorption efficiency is maintained after five regeneration cycles. In addition, when the CMC–PmPD composite membrane was applied to the treatment of mixed heavy metal ion solutions with different concentrations and compositions, the CMC–PmPD composite membrane was always able to selectively adsorb more than 95% of Au(III) from the simulated solution or e-waste leachate, which was highly selective and applicable. The CMC–PmPD composite membrane has a broad application prospect in metallurgy and fine chemical industry.