Graphene oxide for high-efficiency separation membranes: Role of electrostatic interactions

Abstract

Graphene oxide (GO) membranes represent a next generation of high-flux, ultra-lightweight and energy-efficient membranes for molecular and ionic separation in aqueous solution. In this work, we fabricate free-standing GO membranes with tunable thickness via facile vacuum filtration process. The effect of electrostatic interaction on the separation performance of GO membrane for organic dyes was demonstrated. It is observed that GO is negatively charged in a wide pH range of 1-12 and its surface charge density significantly varied with pH of aqueous solution. The electronegative GO membrane exhibits much higher rejection rate for electronegative organic dyes than that for electropositive molecules. Furthermore, the rejection rate and the strength of electrostatic interaction are directly related. In addition, the rejection behaviors of GO membranes for inorganic salts with different charge or ionic strength are explored as well. The experimental data are fitted well with the theoretical model based on Donnan equilibrium. Our results indicate that GO membranes could be promising candidate for water treatment and desalination application. And adjusting the surface charge density of GO and filtrated molecules is an effective way to achieve high separation performance (e.g. rejection rate).

Preparation and properties of cellulose membranes with graphene oxide addition

“…The results show that the GO addition facilitates the adsorption of the dye on the composite membranes. Literature reports indicate that bonds can be formed between the negatively charged dye and GO 43 , which may affect dye retention in the membrane, as confi rmed by the results obtained in our experiment. Zhang et al 39 used GO caged in cellulose microbeads to remove another dye -malachite green -from aqueous solutions.…”

“…Moreover, the GO layer is responsible for the transport of the dyes in the described membranes. On the other hand, in our GO/CEL membranes, graphene oxide is dispersed, which makes it diffi cult to compare the results we obtained with the literature 43 . By studying the behavior of the membranes in the presence of FeCl 3 solution, it was observed that iron (III) ions improve the volumetric permeate fl ux parameters for membranes "0", A and B.…”

“…Rui-Hong et al obtained hydrogel by introducing NaOH and urea and cellulose into the aqueous dispersion of GO, followed by mixing it with PVA solution 42 . Liu et al obtained cellulose composite membranes by fi ltration of GO solution on pure cellulose membrane 43 . The paper-making method was used to obtain paper with GO addition in the presence of polyacrylamide 44 .…”

Bioactive Membranes from Cellulose with a Graphene Oxide Admixture

“…The hydrogels were prepared from an aqueous dispersion of GO, NaOH and urea and cellulose, which were combined with a polyvinyl alcohol (PVA) solution [Rui-Hong et al 2016]. Liu et al (2016) obtained cellulose composite membranes in the simplest way possible -by filtration of GO solution on pure cellulose membrane. The paper-making method was used to obtain paper from cellulose, with GO and polyacrylamide addition [Huang et al 2016] or by mixing the suspension of hydrolysed microcrystalline cellulose with a GO dispersion [Kafy et al 2016].…”

Solution-assisted ultrafast transfer of graphene-based thin films for solar cells and humidity sensors

“…Vacuum filtration is widely applied in depositing highly smooth GO films and can generate uniform membranes with controllable thickness [11][12][13]. Since the size of the GO membrane is determined by the wick size of the filtration device, it is convenient to fabricate the GO membrane, especially a large size membrane, by adjusting the area of the filtration wick.…”