Synthesis of carbon disulfide modified chitosan resin and its adsorption properties for palladium(Ⅱ) in wastewater

A novel chitosan resin microsphere (CDCR) adsorbent, which was synthesized by secondary crosslinking and carbon disulfide modification, and was evaluated for its efficacy in recovering palladium from wastewater. The physicochemical properties and adsorption mechanism of CDCR were determined using scanning electron microscope energy dispersive system (SEM-EDS), fourier-transform infrared spectroscopy (FTIR), simultaneous thermal analyzer (TG-DSC), X-ray photoelectron spectroscopy (XPS), etc. The experimental results showed that its saturated adsorption capacity was about 204.34 mg/g. And the adsorption process of Pd(Ⅱ) was found to be in accordance with the pseudo-second-order kinetic model and the Freundlich model. Thermodynamic analysis indicated that the reaction between CDCR and Pd(Ⅱ) was a spontaneous endothermic process. CDCR showed good reusability, maintaining a Pd(Ⅱ) removal efficiency of 99.99% after eight adsorption–desorption cycles. In the multi-ion coexistence solution, CDCR also exhibited excellent selectivity towards Pd(Ⅱ) adsorption. Furthermore, the adsorption of Pd(Ⅱ) by CDCR was primarily attributed to electrostatic interaction with protonated amine groups and complexation with sulfur groups.