海泡石改性纳米零价铁协同去除 As(III)和 Cd(II)及相关机理研究。
Synergistic removal of As(III) and Cd(II) by sepiolite-modified nanoscale zero-valent iron and a related mechanistic study.
机构信息
College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, China; Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agriculture Sciences, Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing, 100081, China.
Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agriculture Sciences, Key Laboratory of Agro-Environment, Ministry of Agriculture and Rural Affairs, Beijing, 100081, China; College of Environmental Science & Engineering, China West Normal University, Nanchong, Sichuan, 637009, China.
出版信息
J Environ Manage. 2022 Oct 1;319:115658. doi: 10.1016/j.jenvman.2022.115658. Epub 2022 Jul 14.
Arsenic (As) and cadmium (Cd) are two highly toxic elements. In recent years, many newly synthesized chemical materials have been used widely for treatments of As- and Cd-contaminated effluents. However, most materials do not exhibit high efficiencies for simultaneous removal of As and Cd from water systems. Our study established a simple scheme for synthesizing a sepiolite (SEP)-modified nanoscale zero-valent iron (S-nZVI) for simultaneous removal of coexisting As and Cd from water and illuminated a possible underlying mechanism. Batch experiments showed that the maximum capacities for adsorption of As(III) and Cd(II) by S-nZVI were 230.29 mg/g and 11.37 mg/g, respectively, which represented better effects than those of other materials, as reported previously. Removal of Cd(II) depended on pH, but As(III) removal showed little dependence on pH. Coexisting ions such as phosphate (PO) and the conjugate base of humic acid (HA) significantly inhibited simultaneous removal of As(III) and Cd(II). In the mixed As(III)-Cd(II) system, the presence of As(III)-pretreated S-nZVI significantly enhanced Cd(II) adsorption by a factor of four over that seen for aqueous solution without As(III). XRD and XPS results showed that CdFeO (Fe-O-Cd), FeAsO or FeAsO (Fe-O-As) were formed after As(III) and Cd(II) were captured by S-nZVI. However, a further zeta (ζ) potential analysis showed that the mechanism for As(III) and Cd(II) adsorption by S-nZVI is not just simple formation of the above chemicals, since the adsorbed As(III) increased the negative charge of S-nZVI; this suggested an electrostatic attraction between S-nZVI and Cd(II) and indicated that adsorbed As(III) created new sorption sites for Cd(II), which enhanced Cd(II) sorption via formation of ternary complexes (Fe-As-Cd). These results suggested that S-nZVI is a promising material for in situ remediation of heavy metal-contaminated groundwaters or paddy soils.
砷（As）和镉（Cd）是两种毒性很高的元素。近年来，许多新合成的化学物质已被广泛用于处理含砷和镉的废水。然而，大多数材料对同时从水系统中去除砷和镉的效率并不高。我们的研究建立了一种简单的方案，用于合成沸石（SEP）修饰的纳米零价铁（S-nZVI），以同时从水中去除共存的砷和镉，并阐明了一种可能的潜在机制。批量实验表明，S-nZVI 对砷（III）和镉（II）的最大吸附容量分别为 230.29 mg/g 和 11.37 mg/g，优于以前报道的其他材料。Cd(II)的去除取决于 pH，但 As(III)的去除对 pH 的依赖性较小。共存离子如磷酸盐（PO）和腐殖酸的共轭碱（HA）会显著抑制砷（III）和镉（II）的同时去除。在混合 As(III)-Cd(II)体系中，存在经 As(III)预处理的 S-nZVI 会显著增强 Cd(II)的吸附，其增强倍数是不含 As(III)的水溶液的四倍。XRD 和 XPS 结果表明，在 S-nZVI 捕获 As(III)和 Cd(II)后，形成了 CdFeO（Fe-O-Cd）、FeAsO 或 FeAsO（Fe-O-As）。然而，进一步的 ζ 电位分析表明，S-nZVI 吸附 As(III)和 Cd(II)的机制不仅仅是简单地形成上述化学物质，因为吸附的 As(III)增加了 S-nZVI 的负电荷；这表明 S-nZVI 和 Cd(II)之间存在静电吸引，表明吸附的 As(III)为 Cd(II)创造了新的吸附位，通过形成三元配合物（Fe-As-Cd）增强了 Cd(II)的吸附。这些结果表明，S-nZVI 是一种很有前途的原位修复重金属污染地下水或稻田土壤的材料。
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