Yuan Xiaoqing, Li Jingxia, Luo Lin, Zhong Zhenyu, Xie Xiande
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China.
Hunan Research Academy of Environmental Sciences, Changsha 410014, China.
Polymers (Basel). 2023 Jan 11;15(2):388. doi: 10.3390/polym15020388.
Sorptive removal of hexavalent chromium (Cr(VI)) bears the advantages of simple operation and easy construction. Customized polymeric materials are the attracting adsorbents due to their selectivity, chemical and mechanical stabilities. The mostly investigated polymeric materials for removing Cr(VI) were reviewed in this work. Assembling of robust functional groups, reduction of self-aggregation, and enhancement of stability and mechanical strength, were the general strategies to improve the performance of polymeric adsorbents. The maximum adsorption capacities of these polymers toward Cr(VI) fitted by Langmuir isotherm model ranged from 3.2 to 1185 mg/g. Mechanisms of complexation, chelation, reduction, electrostatic attraction, anion exchange, and hydrogen bonding were involved in the Cr(VI) removal. Influence factors on Cr(VI) removal were itemized. Polymeric adsorbents performed much better in the strong acidic pH range (e.g., pH 2.0) and at higher initial Cr(VI) concentrations. The adsorption of Cr(VI) was an endothermic reaction, and higher reaction temperature favored more robust adsorption. Anions inhibited the removal of Cr(VI) through competitive adsorption, while that was barely affected by cations. Factors that affected the regeneration of these adsorbents were summarized. To realize the goal of industrial application and environmental protection, removal of the Cr(VI) accompanied by its detoxication through reduction is highly encouraged. Moreover, development of adsorbents with strong regeneration ability and low cost, which are robust for removing Cr(VI) at trace levels and a wider pH range, should also be an eternally immutable subject in the future. Work done will be helpful for developing more robust polymeric adsorbents and for promoting the treatment of Cr(VI)-containing wastewater.
吸附去除六价铬（Cr(VI)）具有操作简单、易于构建的优点。定制的聚合材料因其选择性、化学和机械稳定性而成为有吸引力的吸附剂。本文综述了用于去除Cr(VI)的最常研究的聚合材料。组装强大的官能团、减少自聚集以及提高稳定性和机械强度是提高聚合吸附剂性能的一般策略。这些聚合物对Cr(VI)的最大吸附容量通过朗缪尔等温线模型拟合，范围为3.2至1185 mg/g。去除Cr(VI)涉及络合、螯合、还原、静电吸引、阴离子交换和氢键等机制。详细列出了影响Cr(VI)去除的因素。聚合吸附剂在强酸性pH范围（例如pH 2.0）和较高的初始Cr(VI)浓度下表现更好。Cr(VI)的吸附是一个吸热反应，较高的反应温度有利于更稳定的吸附。阴离子通过竞争吸附抑制Cr(VI)的去除，而阳离子对其影响不大。总结了影响这些吸附剂再生的因素。为实现工业应用和环境保护的目标，强烈鼓励通过还原去除Cr(VI)并使其解毒。此外，开发具有强再生能力和低成本、能在痕量水平和更宽pH范围内有效去除Cr(VI)的吸附剂，也应是未来永恒不变的主题。所做的工作将有助于开发更强大的聚合吸附剂，并促进含Cr(VI)废水的处理。
