O-(Carboxymethyl)-chitosan Nanofiltration Membrane Surface Functionalized with Graphene Oxide Nanosheets for Enhanced Desalting Properties

Abstract

A novel O-(carboxymethyl)-chitosan (OCMC) nanofiltration (NF) membrane is developed via surface functionalization with graphene oxide (GO) nanosheets to enhance desalting properties. Using ring-opening polymerization between epoxy groups of GO nanosheets and amino groups of OCMC active layer, GO nanosheets are irreversibly bound to the membrane. The OCMC NF membranes surface-functionalized with GO nanosheets are characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, contact angle analyzer, and zeta potential analyzer. The membranes exhibit not only higher permeability but also better salt rejections than the pristine membranes and the commercial NF membranes; besides, the desalting properties are enhanced with the concentration of GO nanosheets increasing. Furthermore, the transport mechanism of GO-OCMC NF membranes reveals that the nanoporous structure of GO-OCMC functional layer and size exclusion and electrostatic repulsion of water nanochannels formed by GO nanosheets lead to the membranes possessing enhanced desalting properties.

Graphene Oxide‐Based Polymeric Membranes for Water Treatment

“…The first approach enables the good dispersion and strong attachment of the nanomaterial on the membrane surface and enhances the long‐term stability of the nanomaterial. Functionalized graphene has been reported to modify a wide range of membrane types, including MF, UF, NF, RO, and FO membranes, via this approach. For instance, Wang et al modified a PSf membrane surface by cross‐linking GO/epichlorohydrin (ECH) with O‐(carboxymethyl)‐chitosan (OCMC), where GO bound covalently to the amino groups of OCMC.…”

Incorporation of Graphene-Related Carbon Nanosheets in Membrane Fabrication for Water Treatment: A Review

“…Ring opening polymerization reaction was used to stably immobilize epoxy groups of GO to amino groups of an active layer of O -(carboxymethyl)-chitosan on a PSf membrane support. The GO nanosheets were immobilized on the surface, and again increase in negative charge was seen with rejections of >97% for Na 2 SO 4 and >60% for NaCl, with fluxes of >20 LMH [48]. Loose NF membranes with zwitterionic GO grafted with poly(sulfobetaine methacrylate) brushes (GO-PSBMA) were prepared by phase inversion of mixtures of GO-PSBMA and PES [49].…”

High‐speed CO2 transport channel containing carboxymethyl chitosan/hydrotalcite membrane for CO2 separation

“…Therefore, it is very necessary to identify a compatible polymer matrix for the development of a MMM. Carboxymethyl chitosan (CMC), a water‐soluble derivative of chitosan is one of the versatile polymers, which has been widely accepted as the matrix for MMMs as it comprises of ample carboxyl, hydroxyl, and amine groups in the skeletal [Figure (b)], which offers possible sites for metal ion interaction . CMC already has attracted a large number of researchers from the field of biomedical application due to its exceptional physical and chemical properties .…”

“…Carboxymethyl chitosan (CMC), a watersoluble derivative of chitosan is one of the versatile polymers, which has been widely accepted as the matrix for MMMs as it comprises of ample carboxyl, hydroxyl, and amine groups in the skeletal [ Figure 1(b)], which offers possible sites for metal ion interaction. [22][23][24] CMC already has attracted a large number of researchers from the field of biomedical application due to its exceptional physical and chemical properties. [25][26][27] Lately, CMC has been proven to be an effective CO 2 selective membrane as experimented in our previous work.…”