Effective Recovery of Au from Low-Concentration Solutions by a Self-Synthesized Mesoporous Resin Modified by Dimethylamine

Abstract

In this study, the recovery of Au(III) from low-concentration HAuCl4 solutions was systematically investigated by a self-synthesized dimethylamine-modified mesoporous resin (DMR). The apparent morphology and pore structure of the DMR were characterized, and the adsorption property of the DMR was studied by static adsorption experiments to evaluate the effects of pH value, adsorbent dosage, and initial concentration of AuCl4– on the Au(III) adsorption from low-concentration HAuCl4 solutions. At 298 K and pH 2.0, the adsorption capacity of Au(III) was 221.16 mg/g and the recovery of Au(III) was 95%. In addition, the adsorption isotherms, thermodynamics, and kinetics were determined and modeled. The results showed that the Langmuir isotherm model and the pseudo-first-order model were more fitted to depict the adsorption of Au(III) onto the DMR, indicating that Au(III) was monolayer-adsorbed onto the surface of the DMR via chemical sorption. ΔG0 < 0 and ΔH0 > 0 indicated that the process was spontaneous and endothermic. The adsorption capacity of Au(III) was much higher than that reported in the literature due to the coordination interaction and electrostatic force between the amino groups and AuCl4−, which indicated that the DMR was an adsorbent with great application potential for the recovery of Au from low-concentration solutions.