Mphahlele, Malehlogonolo R.R.Mosai, Alseno KagisoTutu, HlangananiKotze, Izak A.2025-07-032025-07-032025Mphahlele, M.R.R., Mosai, A.K., Tutu, H. & Kotze, I.A. Enhanced platinum and palladium recovery from aqueous solutions: a comparative study of acylthiourea and amine-modified silica gel adsorbents', RSC Advances, vol. 15, no. 6, pp. 4607-4618, doi : 10.1039/d4ra07935c.2046-2069 (online)10.1039/d4ra07935chttp://hdl.handle.net/2263/103162DATA AVAILABILITY : The data supporting the findings of this study are available within the article and the ESI.The recovery of precious metals from secondary sources is becoming increasingly important due to their natural scarcity and rising industrial demand. This study introduces a novel adsorbent, N-triethoxysilylpropyl-N′-benzoylthiourea-modified silica gel (TESP-BT-SG), developed for the selective recovery of platinum (Pt) and palladium (Pd) from aqueous solutions that simulate refinery wastewater. The extraction capabilities of TESP-BT-SG were compared with those of an amine-bearing adsorbent, (3-aminopropyl)triethoxy-silane-modified silica gel (APTES-SG), previously recognized for Pt and Pd recovery. Under optimal conditions, TESP-BT-SG achieved extraction efficiencies of 97% for Pt and 99% for Pd. Both adsorbents demonstrated rapid adsorption kinetics for Pd relative to Pt, reaching equilibrium within 3 hours for Pd and within 6 hours (TESP-BT-SG) and 24 hours (APTES-SG) for Pt. In solutions with elevated competing ion concentrations (5–100 mg L−1), both adsorbents retained high selectivity (>97%) for Pt and Pd. Adsorption isotherms and kinetic models were applied to elucidate the adsorption mechanisms, with the Langmuir isotherm and pseudo-second-order models providing the best fits, indicating monolayer coverage and chemisorption, respectively. Notably, the APTES-SG sorbent demonstrated enhanced performance with an increased loading capacity of 2.45 mmol g−1 compared to the previously reported 1.15 mmol g−1, achieved through our improved synthesis method. This modified APTES-SG showed significantly higher affinity for Pd (98%), Pt (97%), and iridium (Ir) (89%) compared to previous values of 8%, 33%, and 42%, respectively. The exceptional efficiency and selectivity of these silica-anchored adsorbents underscore their potential as cost-effective solutions for industries seeking to recover precious metals.en© 2025 The Author(s). Published by the Royal Society of Chemistry. This article is licensed under aCreative Commons Attribution-NonCommercial 3.0 Unported Licence.N-triethoxysilylpropyl-N′-benzoylthiourea-modified silica gel (TESP-BT-SG)PlatinumPalladiumAqueous solutionsWastewater3-aminopropyl)triethoxy-silane-modified silica gel (APTES-SG)Article