Chitosan functionalization with vinyl monomers via ultraviolet illumination under cryogenic conditions for efficient palladium recovery from waste electronic materials

Abstract

Retrieving valuable metals like palladium, gold, and platinum from electronic waste poses significant challenges. In this study, we developed highly macroporous and flexible antibacterial chitosan-based cryogel through rapid cryopolymerization induced by ultraviolet exposure. This designed cryogel exhibited exceptional palladium adsorption capabilities within an acidic environment, demonstrating swift and efficient adsorption. Remarkably, the chitosan-based cryogel showed an impressive palladium adsorption capacity, reaching 184.93 mg g−1 as Langmuir isotherm model, thus highlighting its promising potential for palladium recovery. The adsorption efficiency and concentration examination was conducted using an Inductively Coupled Plasma Optical Emission Spectrometer in the presence of multiple coexisting ions. Various factors and parameters, including pH, contact time, temperature, concentration, and selectivity, were investigated to assess the effectiveness of the biopolymeric cryogel in palladium adsorption. Additionally, the thermal stability of the developed cryogel was explored within the temperature range of 25-100˚C, revealing a commendable palladium adsorption capacity even at 100˚C. This finding underscores the material's potential for application under challenging conditions. The cryogel that was synthesized exhibits an extended shelf-life of up to six months and can be reused without any discernible alteration in its adsorption efficiency. Furthermore, the palladium adsorption capacity was evaluated in a real-world sample, demonstrating commendable adsorption capabilities. Remarkably, the biosorbent displayed a higher selectivity of 91% for palladium, even in the competing ions presence. In summary, biosorbent offers superior adsorption performance and remarkable stability, making it a valuable contribution to polymer chemistry and environmental science. Its potential for recovering precious metals from wastewater is indeed noteworthy.