Palladium Recovery from Dilute Effluents using Biopolymer‐Immobilized Extractant
Cyanex 301‐immobilized material (prepared by immobilization into an alginate matrix) was tested for Pd sorption in 1 M HCl solutions with a special attention to sorption isotherms and uptake kinetics. This immobilized extractant had great affinity for Pd, as shown by the initial slope of the sorption isotherms. Sorption capacities as high as 150 mg Pd g −1 were obtained in 1 M HCl solutions. However, kinetics was slow, compared to conventional resins. The main limiting step in the process is the diffusion of metal ions into the matrix. The influence of parameters such as HCl concentration, NaCl addition, presence of Pt (as a competitor metal) has been checked. It appeared that sorption performance of Cyanex 301‐immobilized material was hardly influenced by the addition of NaCl and by HCl concentration (below 2.5 M). The resin was remarkably selective for Pd, versus Pt, especially at 1 M HCl concentration. Loaded resins can be desorbed using thiourea solutions.