Negatively-charged nanofiltration membrane and its hexavalent chromium removal performance

Xiu-Zhen Wei; Zhi-Qiang Gan; Yu-Jie Shen; Ze-Lin Qiu; Li-Feng Fang; Bao-Ku Zhu

doi:10.1016/j.jcis.2019.06.051

Negatively-charged nanofiltration membrane and its hexavalent chromium removal performance

J Colloid Interface Sci. 2019 Oct 1:553:475-483. doi: 10.1016/j.jcis.2019.06.051. Epub 2019 Jun 17.

Authors

Xiu-Zhen Wei¹, Zhi-Qiang Gan¹, Yu-Jie Shen², Ze-Lin Qiu², Li-Feng Fang³, Bao-Ku Zhu⁴

Affiliations

¹ College of Environment, Zhejiang University of Technology, Hangzhou 310014, China.
² Department of Polymer Science and Engineering, ERC of Membrane and Water Treatment (MOE), Key Laboratory of Macromolecular Synthesis and Functionalization (MOE), Zhejiang University, Hangzhou 310027, China.
³ Department of Polymer Science and Engineering, ERC of Membrane and Water Treatment (MOE), Key Laboratory of Macromolecular Synthesis and Functionalization (MOE), Zhejiang University, Hangzhou 310027, China. Electronic address: fanglf@zju.edu.cn.
⁴ Department of Polymer Science and Engineering, ERC of Membrane and Water Treatment (MOE), Key Laboratory of Macromolecular Synthesis and Functionalization (MOE), Zhejiang University, Hangzhou 310027, China. Electronic address: zhubk@zju.edu.cn.

PMID: 31229866
DOI: 10.1016/j.jcis.2019.06.051

Abstract

To enhance hexavalent chromium (Cr(VI)) removal performance under acidic conditions, the nanofiltration (NF) membrane with enhanced negative charge was fabricated via introducing 2, 5-diaminobenzenesulfonic acid (DABSA) into polyamide layer. The control membrane (NF-P) was directly prepared from piperazine and 1, 3, 5-benzenetricarbonyltrichloride. Surface chemical compositions, morphology, surface charge, pore size, permeability and pH-dependent separation performance of the fabricated membranes were characterized. The membranes showed the similar water permeance (∼11.5 L m^-2 h^-1 bar^-1) and Na₂SO₄ rejections (∼98%) under neutral environments. The DABSA introduced NF membrane (NF-PD) was negatively charged in the pH range of 2.5-11, while the isoelectric point for NF-P was ∼pH 4.0. Cr(VI) removal ability was then evaluated under various concentrations and pH environments. The results indicated that NF-PD showed the better Cr(VI) rejection performance in all tested conditions than NF-P, especially under acidic environments (e.g., pH 4 and pH 5). Moreover, there was a fluctuation of the rejection with the increase of Cr(VI) concentration under acidic environments, which was mainly caused by the formation of Cr₂O₇^2- species. The harmful Cr(VI) was efficiently removed by the NF membrane with enhanced negative charge under acidic environments, which indicated the wider application range of the NF membrane.

Keywords: 2, 5-Diaminobenzenesulfonic acid (DABSA); Donnan exclusion; Hexavalent chromium Cr(VI); Nanofiltration; Negative charge.