Herein, L-cysteine (Cys) was modified on zero-valent iron (C-ZVI^bm) by using a mechanical ball-milling method to improve the surface functionality and the Cr(VI) removal efficiency. Characterization results indicated that Cys was modified on the surface of ZVI by the specific adsorption of Cys on the oxide shell to form a -COO-Fe complex. The Cr(VI) removal efficiency of C-ZVI^bm (99.6%) was much higher than that of ZVI^bm (7.3%) in 30 min. The attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis inferred that Cr(VI) was more likely to be adsorbed on the surface of C-ZVI^bm to form bidentate binuclear inner-sphere complexes. The adsorption process was well-matched to the Freundlich isotherm and the pseudo-second-order kinetic model. Electrochemical analysis and electron paramagnetic resonance (ESR) spectroscopy revealed that Cys on the C-ZVI^bm lowered the redox potential of Fe(III)/Fe(II), and favored the surface Fe(III)/Fe(II) cycling mediated by the electrons from Fe⁰ core. These electron transfer processes were beneficial to the surface reduction of Cr(VI) to Cr(III). Our findings provide new understandings into the surface modification of ZVI with a low-molecular weight amino acid to promote in-situ Fe(III)/Fe(II) cycling, and have great potential for the construction of efficient systems for Cr(VI) removal.

在此，通过使用机械球磨方法在零价铁 (C-ZVI ^{bm ) 上修饰}L-半胱氨酸 (Cys)，以提高表面功能性和 Cr(VI) 去除效率。表征结果表明，通过Cys在氧化物壳层上的特异性吸附，Cys在ZVI表面被修饰，形成-COO-Fe络合物。^{在 30 分钟内，C-ZVI bm}的 Cr(VI) 去除效率(99.6%) 远高于 ZVI ^bm (7.3%)。衰减全反射傅里叶变换红外光谱 (ATR-FTIR) 分析推断 Cr(VI) 更有可能吸附在 C-ZVI ^bm的表面形成双齿双核内球复合物。吸附过程与 Freundlich 等温线和伪二级动力学模型非常匹配。^{电化学分析和电子顺磁共振 (ESR) 光谱表明，C-ZVI bm}上的 Cys降低了 Fe(III)/Fe(II) 的氧化还原电位，并有利于表面 Fe(III)/Fe(II) 循环介导的来自 Fe ⁰核心的电子。这些电子转移过程有利于 Cr(VI) 表面还原为 Cr(III)。我们的研究结果为用低分子量氨基酸对 ZVI 进行表面改性以促进原位 Fe(III)/Fe(II) 循环提供了新的认识，并具有构建高效 Cr(VI) 体系的巨大潜力移动。