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.
Highlights
Throughout the world, rapid industrial development from photo-electrochemical cells, papers, plastics, textiles, pharmaceuticals, etc. has brought about serious water contamination
Based on the evaluation of the World Health Organization (WHO), 1.1 billion people could face a shortage of clean drinking water
The development of novel technology to remove the contamination of salts, dyes or proteins from wastewater is essential in both theoretical and practical studies [6]
Summary
Throughout the world, rapid industrial development from photo-electrochemical cells, papers, plastics, textiles, pharmaceuticals, etc. has brought about serious water contamination. According to World Water Council reports, the ‘water scarce’ population will increase to 3.9 billion people by 2030 [3]. In this context, several researchers are focusing on salt/dye/protein/oil-effluents water treatment, targeting the emission standard of wastewater [2]. Various scientific techniques including adsorption, ion exchange, chemical oxidation, flocculation and photocatalytic degradation are established to separate contaminated effluents from wastewater [4, 5]. Based on these methods, many technical reports were established for the possible treatment and processing of drinking water. The development of novel technology to remove the contamination of salts, dyes or proteins from wastewater is essential in both theoretical and practical studies [6]
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