Efficient and selective adsorption of Au(III) and Pd(II) by trimesoyl chloride-crosslinked polyethyleneimine

Abstract

It is a clear and present problem to separate precious metals from metallurgical wastewater selectively. In this study, an adsorbent is prepared via polyethyleneimine crosslinked by trimesoyl chloride (TMC@PEI), and then used to adsorb Au(III) and Pd(II). TMC@PEI has excellent and stable adsorption properties for Au(III) at pH = 1–9. TMC@PEI exhibits faster adsorption rate for Pd(II) than Au(III). Adsorption equilibrium time of Au(III) and Pd(II) at 10 mg/L are 20 min and 15 min, respectively. The maximum adsorption capacity of TMC@PEI for Au(III) and Pd(II) are 953.98 mg/g and 369.05 mg/g, respectively. In addition, TMC@PEI shows outstanding ions selectivity and reusability for Au(III) and Pd(II) adsorption. The adsorption of Au(III) by TMC@PEI is an endothermic process, while the adsorption of Pd(II) is an exothermic process. Adsorption kinetics of Au(III) and Pd(II) by TMC@PEI is suitable for pseudo second-order kinetic model. There exist electrostatic adsorption, redox reaction and chelation during adsorption of Au(III) by TMC@PEI. Adsorption of Pd(II) by TMC@PEI is accompanied by chelation.