Recovery of palladium from a low grade palladium solution by anionic-ion exchange: kinetics, equilibrium, and metal competition

Kinetic and Thermodynamic Studies of Precious Metals Sorption on Impregnated Lewatit VP OC 1026 from Chloride Solutions

Precious metals are used in many branches of industries. Due to their rarity and diminishing natural resources, more and more new methods are being sought to recover them from secondary sources, which can be electronic waste or spent car exhaust converters. This paper presents the research on the recovery of precious metals from chloride solutions using the Aliquat 336-impregnated Lewatit VP OC 1026 sorbent. The study used a warm impregnation method without toxic solvents, which is beneficial for the environment. The maximal sorption capacities obtained for model solutions in 0.1 M HCl were: 95.6 mg/g for gold, 38.2 mg/g for palladium, and 36.2 mg/g for platinum. There were studied: kinetics and thermodynamics of sorption, as well as amounts of the sorbent, effects of phase contact time and HCl concentration on the sorption of precious metals. Positive values of enthalpy change ΔH° validate that the process is endothermic. The research was also carried out on a real leaching solution obtained by digesting a spent catalytic converter, containing small amounts of platinum group metals. Desorption of precious metal ions was conducted using 1 M thiourea in 1 M hydrochloric acid. The obtained impregnated sorbent proved to be effective for sorption of Au(III), Pd(II), Pt(IV) ions.

Efficient treatment of palladium from wastewater by acrolein cross-linked chitosan hydrogels: Adsorption, kinetics, and mechanisms

Herein we present a study on the preparation and properties of a hydrogel adsorbent for treatment of wasted palladium souring from actial petrochemical industrial wastewater. Chitosan was used as the raw material and acrolein as the cross-linking agent for the hydrogel (A/CS). The adsorption behaviors of the hydrogel for Pd(II) ions were characterized and analyzed. The effect of pH, temperature, adsorption kinetics, and thermodynamics were investigated. Langmuir models were employed to describe the adsorption isotherms, while the pseudo-second-order equation was applied to describe the adsorption kinetics. The experimental results demonstrated that the adsorption was a monolayer chemical adsorption, and the adsorption capacity was found to reach 505.05 mg/g under optimal conditions. In addition, FT-IR and XPS analyses, combined with MS calculations confirmed that chelation and electrostatic attraction were dominated in the adsorption process. Overall, the development of this hydrogel adsorbent will provide a practical approach to the treatment of industrial wastewater containing palladium and have great potential for practical applications.