Hexavalent chromium (Cr(VI)) is one class of highly toxicant heavy metal ion that severely threatens the environmental quality and human health. Herein, a class of magnetic hydrogel beads (MHB) has been facilely developed with poly(ethylenimine)/chitosan (PEI/CS) hydrogel as the substrate material and Fe₃O₄ as the incorporated magnetic nanoparticles, followed by covalently chemical modification with gallic acid (GA). The well-designed MHB was then evaluated for their performance for synergistic reduction and adsorptive removal of Cr(VI) from aqueous environment. Results showed that electrostatic attraction played a crucial role in adsorption of Cr(VI) onto MHB; meanwhile, the GA grafting could not only significantly accelerate the Cr(VI) reduction, but also facilitate the chelating adsorption of resultant trivalent chromium (Cr(III)) onto PEI/CS substrate due to the proton consumption accompanied by Cr(VI) reduction, resulting in the synergistic enhancement of total chromium (Cr(T)) sorption and Cr(VI) detoxification. The batch adsorption experiments revealed that the Cr(T) adsorption capacity increased with temperature rising and the pseudo-second-order kinetic and Langmuir models could well describe the Cr(T) sorption behaviors, suggesting a single-layer, exothermal, and chemical sorption process. Maximal Cr(VI) removal capacity of GA-functionalized MHB was estimated to be 476.2 mg∙g^-1, exceeding most of other related adsorbents. Moreover, the GA-functionalized MHB exhibited satisfactory reusability with no remarkable loss in Cr(VI) removal efficiency after five cycles. As compared with other reported adsorbents, the newly synthesized GA-functionalized MHB was promising for chromium wastewater treatment due to its synergistic reduction and adsorption process, ultra-high Cr(VI) removal capacity, facile magnetic separation and superior recycling performance.

六价铬（Cr（VI））是一类剧毒的重金属离子，严重威胁着环境质量和人体健康。在此，已经以聚（乙烯亚胺）/壳聚糖（PEI / CS）水凝胶为基质材料和Fe ₃ O ₄轻松开发了一类磁性水凝胶珠（MHB）。作为掺入的磁性纳米粒子，然后用没食子酸（GA）进行共价化学修饰。然后对设计良好的MHB进行评估，以评估其在水性环境中协同还原和吸附去除Cr（VI）的性能。结果表明，静电吸引力在Cr（VI）吸附到MHB上起着至关重要的作用。同时，GA接枝不仅可以显着加速Cr（VI）的还原，而且还可以促进质子消耗并伴随Cr（VI）的还原，从而将生成的三价铬（Cr（III））螯合吸附到PEI / CS基底上。 ，导致总铬（Cr（T））吸附和Cr（VI）排毒的协同增强。批量吸附实验表明，Cr（T）的吸附容量随温度的升高而增加，拟二级动力学模型和Langmuir模型可以很好地描述Cr（T）的吸附行为，表明单层，放热和化学吸附处理。经GA功能化的MHB的最大Cr（VI）去除能力估计为476.2 mg∙g^-1，超过大多数其他相关吸附剂。此外，GA官能化的MHB在五个循环后表现出令人满意的可重复使用性，并且对Cr（VI）的去除效率没有明显损失。与其他已报道的吸附剂相比，新合成的GA官能化MHB具有协同还原和吸附过程，超高的Cr（VI）去除能力，易磁分离和优异的回收性能等优点，有望用于铬废水处理。