Batch and flow-through column adsorption study: recovery of Pt 4+ from aqueous solutions by 3-aminopropyl(diethoxy)methylsilane functionalised zeolite (APDEMSFZ)

The recovery of platinum from waste is of high importance since significant concentrations are lost during processing, but the current methods are not economically effective. The removal of Pt4+ from aqueous solutions at different conditions using zeolite functionalised with 3-aminopropyl(diethoxy)methylsilane (APDEMS) was investigated. The adsorbent was used to assess the effect of adsorbent mass, pH, concentration, time and competing ions on the removal of Pt4+ so that optimum working conditions could be determined. The two- and three-parameter isotherm models as well as kinetic models were fitted using the experimental data. Effect of adsorbent bed height (2 and 5 cm), pH (2–7) and initial concentration (2 and 5 mg L−1) was determined with column experiments. Significant adsorption capacity was achieved with 100 mg adsorbent at pH 2, within 180 min. Adsorption capacity of Pt4+ significantly decreased at pH > 2. Higher bed depth increased the exhaustion and breakthrough times. The adsorption capacity of Pt4+ increased as bed height and concentration increased. The highest breakthrough and exhaustion times were achieved at pH 2. Strong Pt4+-adsorbent interaction concluded from the experiments, adsorption kinetics and isotherms models indicates that APDEMSFZ is suitable for Pt4+ recovery from mining wastewater.