Mphahlele Malehlogonolo R R, Mosai Alseno K, Tutu Hlanganani, Kotzé Izak A
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand Private Bag X3, WITS Johannesburg 2050 South Africa
Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria Lynnwood Road Pretoria 0002 South Africa.
RSC Adv. 2025 Feb 11;15(6):4607-4618. doi: 10.1039/d4ra07935c. eCollection 2025 Feb 6.
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, -triethoxysilylpropyl-'-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), 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 compared to the previously reported 1.15 mmol g, 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.
由于贵金属天然稀缺且工业需求不断增加，从二次资源中回收贵金属变得越来越重要。本研究介绍了一种新型吸附剂，即 - 三乙氧基甲硅烷基丙基 - '- 苯甲酰基硫脲改性硅胶（TESP - BT - SG），它是为从模拟炼油厂废水的水溶液中选择性回收铂（Pt）和钯（Pd）而开发的。将TESP - BT - SG的萃取能力与一种含胺吸附剂，即（3 - 氨丙基）三乙氧基硅烷改性硅胶（APTES - SG）的萃取能力进行了比较，APTES - SG此前已被认可用于回收Pt和Pd。在最佳条件下，TESP - BT - SG对Pt的萃取效率达到97%，对Pd的萃取效率达到99%。两种吸附剂对Pd的吸附动力学均相对于Pt更快，Pd在3小时内达到平衡，Pt在6小时内（TESP - BT - SG）和24小时内（APTES - SG）达到平衡。在竞争离子浓度升高的溶液（5 - 100 mg/L）中，两种吸附剂对Pt和Pd均保持高选择性（>97%）。应用吸附等温线和动力学模型来阐明吸附机制，Langmuir等温线和伪二级模型拟合效果最佳，分别表明为单层覆盖和化学吸附。值得注意的是，通过我们改进的合成方法，APTES - SG吸附剂的负载量从之前报道的1.15 mmol/g提高到了2.45 mmol/g，性能得到了增强。这种改性的APTES - SG对Pd（98%）、Pt（97%）和铱（Ir）（89%）的亲和力明显高于之前分别为8%、33%和42%的值。这些硅胶锚定吸附剂的卓越效率和选择性突出了它们作为寻求回收贵金属的行业的经济有效解决方案的潜力。
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