Issue 45, 2019, Issue in Progress

Performance of selenate removal by biochar embedded nano zero-valent iron and the biological toxicity to Escherichia coli

Abstract

The application of nano zero-valent iron (nZVI) in water environment was limited by its easily aggregation and potential biological toxicity. In this study, biochar embedded nZVI (BC-nZVI) was prepared by carbon-thermal reduction method, and the SEM-EDX mapping results showed that nZVI was successfully embedded on biochar. Meanwhile, BC-nZVI with the optimal Fe/C of 2/1 showed a similar Se(VI) removal efficiency to pure nZVI. Effects of pH, BC-nZVI loading, and initial Se(VI) concentration were studied. Se(VI) removal rates (at 30 min) by BC-nZVI at pH 4.0 and 5.0 were 98.2% and 95.9%, respectively. But Se(VI) removal rate (at 30 min) was sharply decreased to 25.8% at pH 6.0. With the increase of BC-nZVI loading from 0.5 g L−1 to 1 g L−1, Se(VI) removal rate (at 30 min) significantly increased from 25.5% to 95.9%. And the continuous increase of BC-nZVI loading to 2 g L−1 did not improve Se(VI) removal rate. Se(VI) less than 3 mg L−1 was completely removed by BC-nZVI in 30 min, but Se(VI) more than 6 mg L−1 only was removed about 25.9% at 30 min. Optimal parameters were pH 4.0, 2 g L−1 BC-nZVI, and 1.5 mg L−1 Se(VI). Variation of calculated amount, SOD activity, and protein content of Escherichia coli with nZVI and BC-nZVI indicated that nZVI and BC-nZVI both produced negative effects on the growth of E. coli. But the amount and SOD activity of E. coli with pure nZVI was lower than that with BC-nZVI. Moreover, E. coli with nZVI released more protein than that with BC-nZVI. So modified nZVI by biochar was less harmful to E. coli than nZVI.

Graphical abstract: Performance of selenate removal by biochar embedded nano zero-valent iron and the biological toxicity to Escherichia coli

Supplementary files

Article information

Article type
Paper
Submitted
17 Jun 2019
Accepted
14 Aug 2019
First published
21 Aug 2019
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2019,9, 26136-26141

Performance of selenate removal by biochar embedded nano zero-valent iron and the biological toxicity to Escherichia coli

L. Liang, Y. Xue, G. Tian, Q. Mao, Z. Lou, Q. Wu, Q. Wang, J. Du and X. Meng, RSC Adv., 2019, 9, 26136 DOI: 10.1039/C9RA04535J

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