Selective Recovery of Palladium from Plating Wastewater Using Chitosan Nanofiber Hydrogels

In recent years, the scientific and technological advances have led to environmental issues, including water pollution and depletion of natural resources. Palladium, a precious metal, is a limited resource, so there is a need to establish a technology for its selective and highly efficient recovery. In this study, a selective recovery method for palladium from plating wastewater (containing palladium 2 ppm and tin 200 ppm) was investigated using chitosan nanofiber hydrogel (CNF hydrogel), which is expected to exhibit high adsorption properties due to its high specific surface area. The adsorption experiments using standard palladium solutions on the gel revealed that the adsorption rate depended on the solution’s pH and initial concentration. It was confirmed that the adsorption of palladium on the hydrogel was fitted better to the Langmuir isotherm than the Freundlich, indicating monolayer adsorption. Palladium recovery from plating wastewater was attempted, and palladium was selectively recovered from a tin-rich solution. These findings imply that CNF hydrogel holds potential as a precious metal recovery material.