School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China.
College of Environmental Science and Engineering, Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, Nankai University, Tianjin 300350, China.
Sci Total Environ. 2017 Oct 1;595:743-751. doi: 10.1016/j.scitotenv.2017.03.282. Epub 2017 Apr 11.
FeS-coated iron (Fe/FeS) magnetic nanoparticles were easily prepared, characterized, and applied for Cr(VI) removal in simulated groundwater. TEM, XRD, and BET characterization tests showed that FeS coating on the surface of Fe inhibited the aggregation of Fe and that Fe/FeS at a S/Fe molar ratio of 0.207 possessed a large surface area of 62.1m/g. Increasing the S/Fe molar ratio from 0 to 0.138 decreased Cr(VI) removal by 42.8%, and a further increase to 0.207 enhanced Cr(VI) removal by 63% within 72h. Moreover, Fe/FeS inhibited the leaching of Fe, reducing the toxicity of the particles. Mechanistic analysis indicated that Fe, Fe, and S were synergistically involved in the reduction of Cr(VI) to nontoxic Cr(III), which further precipitated as (CrFe)(OH) and Cr(III)-Fe-S. The process of Cr(VI) sorption by Fe/FeS (S/Fe=0.207) was fitted well with a pseudo-second-order kinetic model, and the isotherm data were simulated by Langmuir isotherm model with a maximum sorption capacity of 69.7mg/g compared to 48.9mg/g for Fe. Low pH and initial Cr(VI) concentration favored Cr(VI) removal. Continuous fixed bed column studies showed that simulated permeable reactive barriers (PRB) with Fe/FeS was considerably effective for in situ removal of Cr(VI) from groundwater. This study demonstrated the high potential of Fe/FeS for Cr(VI) immobilization in water, groundwater, and soil.
FeS 包覆铁（Fe/FeS）磁性纳米颗粒易于制备、表征，并应用于模拟地下水中 Cr(VI)的去除。TEM、XRD 和 BET 特征测试表明，FeS 包覆在 Fe 表面上抑制了 Fe 的聚集，并且 S/Fe 摩尔比为 0.207 的 Fe/FeS 具有 62.1m2/g 的大表面积。在 72 小时内，将 S/Fe 摩尔比从 0 增加到 0.138 会降低 42.8%的 Cr(VI)去除率，进一步增加到 0.207 会提高 63%的 Cr(VI)去除率。此外，Fe/FeS 抑制了 Fe 的浸出，降低了颗粒的毒性。机理分析表明，Fe、Fe 和 S 协同参与了将 Cr(VI)还原为无毒的 Cr(III)的过程，进一步沉淀为(CrFe)(OH)和 Cr(III)-Fe-S。Fe/FeS（S/Fe=0.207）对 Cr(VI)的吸附过程符合准二级动力学模型，等温线数据通过 Langmuir 等温模型进行模拟，最大吸附容量为 69.7mg/g，而 Fe 的最大吸附容量为 48.9mg/g。低 pH 值和初始 Cr(VI)浓度有利于 Cr(VI)的去除。连续固定床柱研究表明，具有 Fe/FeS 的模拟可渗透反应屏障（PRB）对地下水中 Cr(VI)的原位去除非常有效。本研究表明，Fe/FeS 在水中、地下水和土壤中对 Cr(VI)的固定具有很高的潜力。
