The comparison of Se(IV) and Se(VI) sequestration by nanoscale zero-valent iron in aqueous solutions: The roles of solution chemistry

Yankai Xie; Haoran Dong; Guangming Zeng; Lihua Zhang; Yujun Cheng; Kunjie Hou; Zhao Jiang; Cong Zhang; Junmin Deng

doi:10.1016/j.jhazmat.2017.05.053

The comparison of Se(IV) and Se(VI) sequestration by nanoscale zero-valent iron in aqueous solutions: The roles of solution chemistry

J Hazard Mater. 2017 Sep 15:338:306-312. doi: 10.1016/j.jhazmat.2017.05.053. Epub 2017 May 29.

Authors

Yankai Xie¹, Haoran Dong², Guangming Zeng¹, Lihua Zhang¹, Yujun Cheng¹, Kunjie Hou¹, Zhao Jiang¹, Cong Zhang¹, Junmin Deng¹

Affiliations

¹ College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082, China.
² College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082, China. Electronic address: dongh@hnu.edu.cn.

PMID: 28578232
DOI: 10.1016/j.jhazmat.2017.05.053

Abstract

The sequestration of Se(IV) and Se(VI) by nanoscale zero-valent iron (NZVI) particles were compared under different solution conditions. Firstly, the comparison was conducted at three pH values (4.0, 6.0 and 8.0) in deionized water. Generally, the removal of Se(IV)/Se(VI) by NZVI was more rapid under acidic conditions and the removal efficiency of Se(IV) was much higher than that of Se(VI). Moreover, the pH variation exhibited much larger influence on the sequestration of Se(VI) than that of Se(IV) by NZVI. The spectroscopic analysis showed that both the Se(IV) and Se(VI) were reduced to Se⁰ and Se^2-, while NZVI was transformed into iron (hydr)oxides. When the selenium-NZVI reactions occurred in synthetic groundwater, all the reaction systems were inhibited in varying degrees. The individual effects of humic acid (HA) and typical inorganic ions were also examined. It seems that HA could substantially hinder the sequestration of Se(IV) compared with that in deionized water, while sulfate (SO₄^2-) and bicarbonate (HCO₃^-) inhibited the Se(VI) removal significantly. Notably, the presence of cations (i.e., Na⁺ or Ca²⁺) ions did not cause obvious interference to the Se(IV)/Se(VI) removal by NZVI, while the presence of Ca²⁺ could alleviate the adverse effect of HA on Se(IV) removal to some degree.

Keywords: Groundwater; Humic acid; Nanoscale zero-valent iron; Reduction; Selenium removal.