Scalable Chitosan-Graphene Oxide Membranes: The Effect of GO Size on Properties and Cross-Flow Filtration Performance

Abstract

Chitosan (CS)-graphene oxide (GO) composite films were fabricated, characterized, and evaluated as pressure-driven water filtration membranes. GO particles were incorporated into a chitosan polymer solution to form a suspension that was cast as a membrane via evaporative phase inversion allowing for scale-up for cross-flow testing conditions. Morphology and composition results for nano and granular GO in the CS matrix indicate that the particle size of GO impacts the internal membrane morphology as well as the structural order and the chemical composition. Performance of the membranes was evaluated with cationic and anionic organic probe molecules and revealed charge-dependent mechanisms of dye removal. The CSGO membranes had rejections of at least 95% for cationic methylene blue with mass balances obtained from measurements of the feed, concentrate, and permeate. This result suggests the dominant mechanism of removal is physical rejection for both GO particle sizes. For anionic methyl orange, the results indicate sorption as the dominant mechanism of removal, and performance is dependent on both GO particle size and time, with micrometer-scale GO removing 68–99% and nanometer-scale GO showing modest removal of 29–64%. The pure water flux for CSGO composite membranes ranged from 2–4.5 L/m 2 h at a transmembrane pressure of 344 kPa (3.44 bar), with pure water permeance ranging from 5.8 × 10 –3 to 0.01 L/m 2 h kPa (0.58–1.3 L/m 2 h bar). Based on the 41 μm membrane thickness obtained from microscopy, the hydraulic permeability ranged from 0.24–0.54 L μm/m 2 h kPa (24.4–54.1 L μm/m 2 h bar).

Graphene Oxide–Chitosan Composite Material for Treatment of a Model Dye Effluent

“…37 In comparison to the GO and LCTS patterns, cross-linked GO-LCTS shows shifting of the sharp XRD line of GO at 12.5° to a lower 2θ (10.2°) value with an absence of broad LCTS peaks. These changes indicate the exfoliation of LCTS into the GO sheets 38 and an increase in the interplanar distance (0.72–0.87 nm) between GO sheets by the introduction of LCTS. Although the broadening peak in the XRD pattern of GO-LCTS suggests slightly lower crystallinity of the GO-LCTS, shifting of the peak to lower wavenumbers indicates an increase in interlayer distance of GO sheets by 0.15 nm upon cross-linking with LCTS.…”

Recycling performance of graphene oxide-chitosan hybrid hydrogels for removal of cationic and anionic dyes

“…For filtration membrane, Abolhassani et al fabricated GC composite as a film by casting method [35], achieved rejections of at least 95% for cationic methylene blue (MB) during filtration process and suggested that the dominant mechanism of removal is the physical rejection for both GO particle sizes. On the other hand, Qi et al prepared GC sponge-based adsorbent with CTS content of 9% had high adsorption capacity (275.5 mg g −1 ) for MB during a filtration process [36].…”

“…Besides, its adsorption capacity is not broad; the amine and hydroxyl groups of CTS act as active sites to trap anionic pollutions, while its effectiveness towards cationic dyes is rather low due to their adverse electrostatic interactions [34]. However, when evaluated as a composite with GO [35], CTS based material achieved rejections of at least 95% for cationic methylene blue (MB), with the mass balances obtained from measurements of the feed, concentrate, and permeate. The dominant mechanism of removal was the physical rejection for both GO particle sizes.…”

Efficient Chitosan/Nitrogen-Doped Reduced Graphene Oxide Composite Membranes for Direct Alkaline Ethanol Fuel Cells

“…The introduction of graphene oxide (GO) has been identified to improve mechanical stability, prevent fuel crossover and swelling of the membrane, and improve ionic conductivity due to the π–π interaction between the aromatic chain of reduced GO (rGO) and the polymer backbone. Strong hydrogen bonds and electrostatic attraction between negatively charged GO plates and positively charged polysaccharide CS groups make CSGO a stable nanocomposite with excellent mechanical and thermal properties [ 10 ].…”