Although a thiourea-immobilized polystyrene sorbent has been reported to exhibit high Ag⁺ sorption capacity (135 mg/g), it is not stable under the acidic conditions commonly employed for desorption. In this research, we synthesized novel thiourea-immobilized polystyrene (TA-PS) nanoparticles to be highly acid resistant via a two-step procedure from polystyrene nanoparticles: acetylation and the subsequent immobilization of thiourea. We investigated the influences of pH, contact time, and initial concentration of AgNO₃ solution on the Ag⁺ sorption of the polymer nanoparticles and estimated the maximum Ag⁺ sorption capacity to be 190 ± 5 mg/g at a pH of 6. The sorption performance did not significantly decrease in tap water containing competing ions. The sorption kinetic data were well fitted to the pseudo-second-order kinetic model. Overall, the TA-PS nanoparticles exhibited a high Ag⁺ sorption capacity and high selectivity against alkaline and alkaline earth-metal ions. In particular, their high acid resistance allows them to be used for long time periods in sorption − desorption processes.

中文翻译：

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硫脲固定化聚苯乙烯纳米粒子的合成及其在水相中对银离子的吸附行为

尽管已经报道了固定有硫脲的聚苯乙烯吸附剂表现出高的Ag ⁺吸附能力（135 mg / g），但是在通常用于解吸的酸性条件下不稳定。在这项研究中，我们从聚苯乙烯纳米颗粒通过两步过程合成了高度耐酸的新型硫脲固定化聚苯乙烯（TA-PS）纳米颗粒：乙酰化和随后的硫脲固定化。我们研究了pH，接触时间和AgNO ₃溶液的初始浓度对聚合物纳米颗粒对Ag ⁺吸附的影响，并估算了最大Ag ⁺pH值为6时，吸附能力为190±5 mg / g。在含有竞争离子的自来水中，吸附性能并未显着降低。吸附动力学数据很好地拟合了伪二级动力学模型。总体而言，TA-PS纳米颗粒表现出高的Ag ⁺吸附能力和对碱金属和碱土金属离子的高选择性。特别是，它们的高耐酸性使得它们可以在吸附-解吸过程中长时间使用。