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High-flux nanofiltration membranes tailored by bio-inspired co-deposition of hydrophilic g-C₃N₄ nanosheets for enhanced selectivity towards organics and salts

journal contribution
posted on 2019-01-01, 00:00 authored by W Ye, H Liu, F Lin, J Lin, Shuaifei ZhaoShuaifei Zhao, S Yang, J Hou, S Zhou, B Van Der Bruggen
This journal is © The Royal Society of Chemistry. Surface modification with advanced nanomaterials (i.e., 2D nanosheets) can be used to strategically tailor membrane properties, providing improved solute permselectivity to targeted molecules. In particular, 2D graphite-like carbon nitride (g-C3N4) nanosheets are a promising alternative for membrane modification, due to their exceptional physicochemical properties and facile synthesis. Herein, high-flux nanofiltration (NF) membranes were designed using bio-inspired co-deposition of hydrophilic g-C3N4 nanosheets with a polydopamine (PDA)/polyethylenimine (PEI) layer onto porous ultrafiltration (UF) substrates. The g-C3N4 nanosheets created additional nanochannels in the PDA/PEI layer to facilitate water molecule transport, resulting in high permeability (28.4 ± 1.2 L m-2 h-1 bar-1). Particularly, the bio-inspired layer structure was tailored from the UF to the NF (592 Da) scale by incorporating g-C3N4 nanosheets, thereby breaking through the permeability-selectivity trade-off effect. The tailored NF membrane enabled ultrahigh retention of three reactive dyes (610-630 Da, >99.3%) and low salt rejection (2.9% for NaCl; 7.6% for Na2SO4), significantly promoting the fractionation of dyes and salts for dye desalination. Additionally, the hydrophilic g-C3N4 nanosheets with oxygen plasma treatment further enhanced the wettability of the membrane surfaces, resulting in a superior antifouling performance. This study indicates the promise of g-C3N4 nanosheets to engineer high-flux NF membranes with desirable fractionation performance for sustainable treatment of highly saline wastewater.

History

Journal

Environmental science: nano

Volume

6

Issue

10

Pagination

2958 - 2967

Publisher

Royal Society of Chemistry

Location

Cambridge, Eng.

ISSN

2051-8153

eISSN

2051-8161

Language

eng

Publication classification

C1 Refereed article in a scholarly journal