Palladium Recovery from Dilute Effluents using Biopolymer‐Immobilized Extractant

Recovery and reduction of Au(III) from mixed metal solution by thiourea-resorcinol-formaldehyde microspheres

To develop a novel adsorbent that can efficiently and rapidly recover gold from the leaching solution of electronic appliances, thiourea-resorcinol-formaldehyde resin microspheres (TRF) were prepared by a one-pot solvothermal method. Fourier transform infrared (FT-IR), thermogravimetric (TGA), X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron micrograph and energy dispersive X-ray spectroscopy (SEM and SEM-EDS) were used to analyze the morphology and physical properties of TRF microspheres. The first time, TRF was successfully used to capture gold ions. The results showed that it had very high absorption capacity (1432 mg·g^-1), good selectivity (Au(III) ≫ Fe³⁺ > Ni²⁺ > Co²⁺ ≈ Cu²⁺ > Al³⁺ > Na⁺ ≈ K⁺) and excellent reuse performance for gold ions. Based on the study of adsorption isotherms and kinetics, Au(III) adsorption on TRF is mainly chemisorption and the adsorption sites are uniform. In acidic systems, Au(III) was reduced by TRF and deposited on TRF as elemental gold. This work provides the possibility to further develop the application of sulfur- and nitrogen-containing polymer materials in gold recovery from mixed metal solution.

Role of EDTA on the Pd(II) adsorption characteristics of chitosan cross-linked 3-amino-1,2,4-triazole-5-thiol derivative from synthetic electroless plating solutions

This article targets the efficacy of chitosan cross-linked 3-Amino-1,2,4-triazole-5-thiol derivative for the recovery of Pd from synthetic electroless plating solutions (ELP) whose solution chemistry complexity is brought forward with ethylenediaminetetraacetic acid (EDTA), ammonium hydroxide (NH₄OH), and surfactant (cetyl trimethyl ammonium bromide (CTAB)). Batch adsorption characteristics of the resin were investigated in the parametric range of 2-10 pH, 0.2-2 g L^-1 adsorbent dosage, 5-1080 min contact time, 50-300 mg L^-1 Pd concentration and 25-60 °C operating temperature. Equilibrium, kinetic and thermodynamic model fitness studies were also considered. Pd(II) adsorption characteristics were determined using NaOH, KOH and HCl solutions with variant eluent concentrations (0.1-2 N). The solution chemistry complexity has been evaluated to have profound impact in detrimentally influencing Pd sorption characteristics of the CH-AZ resin. The resin has been characterized to be highly effective for Pd removal from synthetic ELP solutions but with moderate efficacy towards the noble metal recovery and reuse.

Wastes generated by automotive industry – Spent automotive catalysts

Rhodium, ruthenium, palladium, and platinum are classified as platinum group metals (PGM). A demand for PGM has increased in recent years. Their natural sources are limited, therefore it is important, and both from economical and environmental point of view, to develop effective process to recover PGM from waste/secondary sources, such as spent automotive catalysts. Pyrometallurgical methods have always been used for separation of PGM from various materials. However, recently, an increasing interest in hydrometallurgical techniques for the removal of precious metals from secondary sources has been noted. Among them, liquid-liquid extraction by contacting two liquid phases: aqueous solution of metal ions and organic solution of extractant is considered an efficient technique to separate valuable metal ions from solutions after leaching from spent catalysts.

Selective sorption of palladium by thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resin: application to leach liquors of automotive catalysts

Thiocarbamoyl-substituted thiacalix[n]arene derivatives immobilized on amberlite resins have the potential for application as new adsorbents for selective separation of Pd(ii) ions from leach liquors of automotive catalysts.