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Abstract：
Chitosan is a promising adsorbent for removing a wide range of pollutants from wastewater. However, its practical application is hindered by instability in acidic environments, which significantly impairs its adsorption capacity and limits its utilization in water purification. While cross-linking can enhance the acid stability of chitosan, current solvent-based methods are often costly and environmentally unfriendly. In this study, a solvent-free mechanochemical process was developed using high-energy ball milling to cross-link chitosan with various polyanionic linkers, including dextran sulfate (DS), poly[4-styrenesulfonic acid-co-maleic acid] (PSSM), and tripolyphosphate (TPP). The mechanochemically cross-linked (MCCL) chitosan products exhibited superior adsorption capacity and stability in acidic solutions compared to pristine chitosan. Chitosan cross-linked with DS (Cht-DS) showed the highest Reactive Red 2 (RR2) adsorption capacity, reaching 1559 mg·g-1 at pH 3, followed by Cht-PSSM (1352 mg·g-1) and Cht-TPP (1074 mg·g-1). The stability of MCCL chitosan was visually confirmed by the negligible mass loss of Cht-DS and Cht-PSSM tablets in pH 3 solution, unlike the complete dissolution of the pristine chitosan tablet. The MCCL significantly increased the microhardness of chitosan, with the order Cht-DS > Cht-PSSM > Cht-TPP, consistent with the RR2 adsorption capacity. When tested on simulated rinsing wastewater from chromium electroplating, Cht-DS effectively removed Cr(VI) (98.75% removal) and three per- and polyfluoroalkyl substances (87.40-95.87% removal), following pseudo-second-order adsorption kinetics. This study demonstrates the potential of the cost-effective and scalable MCCL approach to produce chitosan-based adsorbents with enhanced stability, mechanical strength, and adsorption performance for treating highly acidic industrial wastewater containing a mixture of toxic pollutants.
摘要：
壳聚糖是一种很有前途的用于去除废水中各种污染物的吸附剂。然而,它的实际应用受到酸性环境中不稳定的阻碍，这大大削弱了其吸附能力，并限制了其在水净化中的利用。交联可以增强壳聚糖的酸稳定性,目前的基于溶剂的方法通常是昂贵的和环境不友好的。在这项研究中,开发了一种无溶剂的机械化学工艺，使用高能球磨将壳聚糖与各种聚阴离子连接剂交联，包括硫酸葡聚糖（DS），聚[4-苯乙烯磺酸-共马来酸](PSSM)，和三聚磷酸盐（TPP）。与原始壳聚糖相比，机械化学交联（MCCL）壳聚糖产品在酸性溶液中具有出色的吸附能力和稳定性。壳聚糖交联DS(Cht-DS)表现出最高的反应性红2(RR2)吸附容量,在pH3时达到1559mg·g-1，其次是Cht-PSSM（1352mg·g-1）和Cht-TPP（1074mg·g-1）。MCCL壳聚糖的稳定性通过Cht-DS和Cht-PSSM片剂在pH3溶液中的可忽略的质量损失来直观地证实，与原始壳聚糖片剂的完全溶解不同。MCCL显著提高了壳聚糖的显微硬度,订单Cht-DS>Cht-PSSM>Cht-TPP，与RR2吸附能力一致。在模拟镀铬冲洗废水中进行测试时，Cht-DS有效去除Cr（VI）（98.75％去除）和三种全氟和多氟烷基物质（87.40-95.87％去除），遵循伪二级吸附动力学。这项研究证明了具有成本效益和可扩展的MCCL方法生产具有增强稳定性的壳聚糖基吸附剂的潜力，机械强度,和吸附性能，用于处理含有有毒污染物混合物的高酸性工业废水。
