Chitosan-poly(m-phenylenediamine) membranes for efficient gold recovery from acidic aqueous solutions

Abstract

Poly(m-phenylenediamine) has a wide range of applications in adsorption due to its high amino content; however, its nanoparticles tend to aggregate in water and are not easily separated from aqueous solutions. In this research, a soft and easily separable adsorbent material was successfully prepared by cross-linking poly(m-phenylenediamine) and chitosan through hydrogen bonding. Experimental results showed that the prepared chitosan and poly(m-phenylenediamine) hybrid membrane (CS/PmPD) could selectively reduce Au(III) from a mixture of multiple metal ions (Cu²⁺, Zn²⁺, Ni²⁺, Cd²⁺, and Au(III)). The maximum treatment capacity of Au(III) reached 410 mg g⁻¹ under optimal adsorption conditions (pH = 3.0 and adsorption time of 120 min). The CS/PmPD membrane can be regnerated after rinsing with sodium bisulfite solution, and its performance remains stable after multiple cycles. In addition, the membrane has achieved satisfactory results in treating the actual CPU gold-containing leachate. Therefore, the CS/PmPD membrane has a promising application in gold recovery from electronic wastes.