High selectivity of new thiourea-modified resins for gold: Adsorption performance, mechanism, and recovery

A thiourea-modified weak base anion exchange resin, ZGA451 (thiourea@ZGA451), was prepared. Thiourea@ZGA451 exhibited excellent potential for Au(III) adsorption. The maximum adsorption capacity of Au(III) by thiourea@ZGA451 was 995.6 mg/g at 298 K. The adsorption process followed the Freundlich and pseudo-second-order models, which are monolayer and chemisorption adsorption, respectively. The adsorption mechanism of Au(III) on thiourea@ZGA451 involves electrostatic attraction, chelation, and redox. Thermodynamic experiments showed that the reaction exhibited spontaneous endothermic behavior. Thus, thiourea@ZGA451 possesses outstanding Au(III) adsorption properties.