Synthesis of sulfhydryl-functionalized polymers for the efficient adsorption of Pd²⁺ and Ag⁺ from aqueous solution

Herein, two sulfhydryl-functionalized polymers, namely, EDT-HCPS and TMPMP-HCPS, were synthesized according to the Friedel-Craft s alkylation and nucleophilic substitution, and they were used to adsorb Pd2+ and Ag+ from aqueous solution. The Friedel-Crafts alkylation offered the polymers with hyper-cross-linking frameworks composed of plentiful rigid methylene. The nucleophilic substitution brought abundant functional SH groups (the sulfur contents were 12.6 and 9.4 wt%, respectively) to the polymers. The adsorption results showed that the capacities of Pd2+ and Ag+ on EDT-HCPS were larger than TMPMP-HCPS, and the higher quantities of functional SH groups and the porosity played a beneficial role. The equilibrium data can be characterized by the Langmuir model, and the maximum capacities of Pd2+ and Ag+ on EDT-HCPS at 308 K were predicted to be 383.92 and 212.93 mg g(-1), respectively. The produced polymers represented superior adsorption selectivity, reproducibility, and reusability, demonstrating their excellent performance for the adsorption of Pd2+ and Ag+, and analysis of the adsorption mechanism demonstrated that the SH groups played a major role due to the strong chemical complexation of the functional SH with Pd2+/Ag+.