Reduction of Cr(VI) in simulated groundwater by FeS-coated iron magnetic nanoparticles

Yanyan Gong; Longshuang Gai; Jingchun Tang; Jie Fu; Qilin Wang; Eddy Y Zeng

doi:10.1016/j.scitotenv.2017.03.282

Reduction of Cr(VI) in simulated groundwater by FeS-coated iron magnetic nanoparticles

Sci Total Environ. 2017 Oct 1:595:743-751. doi: 10.1016/j.scitotenv.2017.03.282. Epub 2017 Apr 11.

Authors

Yanyan Gong¹, Longshuang Gai², Jingchun Tang³, Jie Fu⁴, Qilin Wang⁵, Eddy Y Zeng¹

Affiliations

¹ School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China.
² 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.
³ 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. Electronic address: tangjch@nankai.edu.cn.
⁴ Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
⁵ Advanced Water Management Centre, The University of Queensland, St Lucia, Queensland 4072, Australia.

PMID: 28407591
DOI: 10.1016/j.scitotenv.2017.03.282

Abstract

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 Fe⁰ inhibited the aggregation of Fe⁰ and that Fe/FeS at a S/Fe molar ratio of 0.207 possessed a large surface area of 62.1m²/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 Fe⁰, Fe²⁺, and S^2- were synergistically involved in the reduction of Cr(VI) to nontoxic Cr(III), which further precipitated as (Cr_xFe_1-x)(OH)₃ 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 Fe⁰. 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.

Keywords: Cr(VI) removal; Fe/FeS nanoparticles; Groundwater; Remediation.