Design of Novel Thioether-Amide-Functionalized Polymers for Au(III) Adsorption in Complex Wastewater Systems: Selectivity and Reusability

Recovery of gold (Au(III)) from wastewater can not only alleviate environmental pollution but also solve the depletion of natural gold resources. In this work, a novel polymer MPPTD containing amide and thioether functional groups was synthesized and investigated for its efficiency in gold recovery. MPPTD exhibited an excellent adsorption capacity of 970.07 mg/g at 318 K and pH 3, and its adsorption process was an endothermic reaction. The adsorption process can be well described by the Redlich–Peterson (R-P) and Elovich models, indicating that it is a hybrid chemical adsorption process with internal diffusion as the main limiting step. Extensive characterization by ζ-potential, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that MPPTD adsorbs Au(III) mainly through electrostatic interaction, chelation, and reduction processes. Importantly, MPPTD exhibited superior selectivity for Au(III) over competing ions and maintained a stable adsorption efficiency of more than 81.39% after five cycles. These findings make MPPTD an efficient, sustainable, and reusable adsorbent for gold recovery, demonstrating its potential for application in industrial wastewater treatment.