Grafting Thin Layered Graphene Oxide onto the Surface of Nonwoven/PVDF-PAA Composite Membrane for Efficient Dye and Macromolecule Separations

Abstract

This study investigates the permeance and rejection efficiencies of different dyes (Rhodamine B and methyl orange), folic acid and a protein (bovine serum albumin) using graphene oxide composite membrane. The ultrathin separation layer of graphene oxide (thickness of 380 nm) was successfully deposited onto porous polyvinylidene fluoride-polyacrylic acid intermediate layer on nonwoven support layer using vacuum filtration. The graphene oxide addition in the composite membrane caused an increased hydrophilicity and negative surface charge than those of the membrane without graphene oxide. In the filtration process using a graphene oxide composite membrane, the permeance values of pure water, dyes, folic acid and bovine serum albumin molecules were more severely decreased (by two orders of magnitude) than those of the nonwoven/polyvinylidene fluoride-polyacrylic acid composite membrane. However, the rejection efficiency of the graphene oxide composite was significantly improved in cationic Rhodamine B (from 9% to 80.3%) and anionic methyl orange (from 28.3% to 86.6%) feed solutions. The folic acid and bovine serum albumin were nearly completely rejected from solutions using either nonwoven/polyvinylidene fluoride-polyacrylic acid or nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane, but the latter possessed anti-fouling property against the protein molecules. The separation mechanism in nonwoven/polyvinylidene fluoride-polyacrylic acid membrane includes the Donnan exclusion effect (for smaller-than-pore-size solutes) and sieving mechanism (for larger solutes). The sieving mechanism governs the filtration behavior in the nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane.

Graphene Oxide-Induced Protein Conformational Change in Nasopharyngeal Carcinoma Cells: A Joint Research on Cytotoxicity and Photon Therapy

“…After exfoliation, the GO oxygen content significantly increased to 32%, and the carbon content decreased to 68%, as calculated from deconvolution of the peaks. The higher GO oxygen content further confirms the existence of more hydrophilic groups [ 36 ]. The surface charge of nanometric GO was calculated as -38 mV due to the ionization of carboxylic acid groups and the formation of a stable aqueous dispersion [ 28 ].…”

Flux model development and synthesis optimization for an enhanced GO embedded nanocomposite membrane through FFD and RSM approach

“…The GO dispersed into the substrate or support layer increases the hydrophilic moieties of the TFNC and reduces the interlayer surface fouling. The presence of GO on the PSF substrate induces a more negative surface charge, which is often said as an anti-fouling resistance compared to the non-GO surface [ 12 ].…”

Enhancing the Dye-Rejection Efficiencies and Stability of Graphene Oxide-Based Nanofiltration Membranes via Divalent Cation Intercalation and Mild Reduction

“…This relatively poor rejection rate of the GOM toward RB could have been caused by its neutral charge. In the case of MO, its negative charge could have generated electrostatic repulsion with the negatively charged surface of the GOM (shown in Figure 5B), resulting in a higher rejection efficiency than RB, despite a smaller molecular weight [39,40]. Paradoxically, even for the positively charged MB, which has the smallest molecular weight, the GOM had a higher rejection rate than that for other selected organic dyes.…”