Efficient recovery of palladium (Pd) from waste sources is of paramount importance due to its limited natural reserves and potential environmental hazards. Herein, a carbon sorbent, namely sulfur-functionalized porous carbon microspheres (SPCMs), was used to selectively capture Pd(II) from acidic solution. SPCMs exhibited high efficiency for the adsorption separation of Pd(II) from 0.5 M to 6 M HNO₃ solution. The adsorption kinetics of Pd(II) matched well with the pseudo-second-order model. The adsorption reached equilibrium after 130 minutes and the adsorption capacity of Pd(II) was 79.3 mg g⁻¹ in 1 M HNO₃ solution. The Freundlich isotherm model exhibited a better description of the Pd(II) adsorption, suggesting that the Pd(II) adsorption is a multilayer adsorption process. SPCMs showed a high selectivity for the capture of Pd(II) in simulated acidic wastewater with 26 metal ions, and the selectivity increased with the increase of HNO₃ concentration. The adsorption capacity per US dollar of Pd(II) by SPCMs from HNO₃ solution is much higher than those of previously reported sorbents, exhibiting a high economic viability of SPCMs for Pd(II) capture from acidic solution. The adsorbed Pd(II) could be desorbed using 1.0 M thiourea and 0.1 M HNO₃, and the SPCM sorbent maintained a high adsorption capacity after five adsorption–desorption cycles. Characterization and theoretical calculations revealed that the adsorption of Pd(II) on the SPCM sorbent is dominated by the coordination of [Pd(NO₃)₂] with O/S containing groups and some of the Pd(II) is reduced to Pd(0). The excellent adsorption performance of SPCMs provides a feasible and low-cost strategy for the selective recovery of Pd(II) from acidic wastewater.

中文翻译：

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硫功能化多孔碳微球从酸性溶液中高选择性捕获钯：性能与机理


由于钯 （Pd） 的自然储量有限且存在潜在的环境危害，因此从废物源中有效回收钯 （Pd） 至关重要。在此，使用碳吸附剂，即硫官能化多孔碳微球 （SPCM） 从酸性溶液中选择性捕获 Pd（II）。SPCM 对 0.5 M 至 6 M HNO₃ 溶液中 Pd（II） 的吸附分离表现出高效率。Pd（II） 的吸附动力学与准二级模型匹配良好。吸附在 130 分钟后达到平衡，Pd（II） 在 1 M HNO₃ 溶液中的吸附容量为 79.3 mg ^g-1。Freundlich 等温线模型对 Pd（II） 吸附表现出更好的描述，表明 Pd（II） 吸附是一个多层吸附过程。SPCMs 对 26 个金属离子模拟酸性废水中 Pd（II） 的捕获表现出高选择性，并且选择性随着 HNO₃ 浓度的增加而增加。SPCM 从 HNO₃ 溶液中吸附每美元 Pd（II） 的容量远高于以前报道的吸附剂，表现出 SPCM 从酸性溶液中捕获 Pd（II） 的高经济可行性。吸附的 Pd（II） 可以使用 1.0 M 硫脲和 0.1 M HNO₃ 进行解吸，并且 SPCM 吸附剂在 5 次吸附-解吸循环后仍保持较高的吸附容量。 表征和理论计算表明，Pd（II） 在 SPCM 吸附剂上的吸附主要由 [Pd（NO₃）₂] 与含有 O/S 的基团的配位决定，并且一些 Pd（II） 被还原为 Pd（0）。SPCMs 优异的吸附性能为从酸性废水中选择性回收 Pd（II） 提供了一种可行且低成本的策略。