Polyethersulfone–Quaternary Graphene Oxide–Sulfonated Polyethersulfone as a High-Performance Forward Osmosis Membrane Support Layer

Abstract

The stability and compatibility of a nanomaterial in a substrate matrix are a tough challenge in preparing thin-film nanocomposite membranes. In this study, we fabricated a ternary nanocomposite membrane substrate consisting of polyethersulfone (PES), quaternary graphene oxide (QGO), and sulfonated polyethersulfone (SPES). First, SPES was blended with the PES substrate, and then different concentrations of QGO were incorporated within this substrate. The effect of QGO on the substrate morphology, hydrophilicity, and porosity was analyzed via scanning electron microscopy, water contact angle measurement, and gravimetric methods, respectively. The optimum loading of QGO significantly enhanced the hydrophilicity, porosity, and water permeability of the PES/SPES support layer. In addition, the effect of QGO on the polyamide rejection layer morphology and performance was thoroughly investigated. The result shows that a thin, smooth, and defect-free polyamide (PA) layer was formed on hydrophilic QGO-based substrates. Intrinsic separation performance data verified these results, where the PA layer formed on the QGO-based substrate presented the highest water permeability. The forward osmosis test also demonstrated the positive impact of QGO incorporation on the performance of membrane substrates. The optimal TFC-QS0.5 (containing 0.5 wt % of QGO) membrane has a water flux of 24.4 LMH in the forward osmosis mode and 32.1 LMH in the pressure-retarded osmosis mode when using a 1 M NaCl draw solution and deionized water feed solution.

Polymer-Grafted Graphene Oxide as a High-Performance Nanofiller for Modification of Forward Osmosis Membrane Substrates

“…In addition, the color change became further observable when the concentration of GP 21 nanoplates increased. In each substrate, the top surface color was darker than that of the bottom surface, which may be linked to the migration of hydrophilic nanofillers toward the substrate top surface during the NIPS process …”

“…In each substrate, the top surface color was darker than that of the bottom surface, which may be linked to the migration of hydrophilic nanofillers toward the substrate top surface during the NIPS process. 39 Characterization of TFC and TFN Membrane. Morphology.…”

“…According to previous work, the bare and modified PSf substrates were fabricated via the conventional NIPS process. 39 In short, a certain quantity of different types of nanofillers (GO or GP) was dispersed into NMP as the single solvent by ultrasonication for 2 h. After adding the PSf polymer into the nanofiller/NMP suspensions, the mixtures were magnetically agitated for 12 h at 60 °C to achieve a stable nanofiller/PSf solution for casting. After that, the obtained uniform dope solutions were sealed and then degassed in a desiccator for 12 h to prevent defect formation during the NIPS process.…”

Whey Recovery Using Nanofiltration-like Forward Osmosis: Optical Coherence Tomography Based Approach to Understanding Fouling Behavior

“…However, it was challenging to identify the contribution of membrane fouling to the flux decline as the effective driving force (i.e., the transmembrane osmotic gradient) could be substantially shortchanged by the polarized concentration profile of the draw solute in the support layer (i.e., the internal concentration polarization, ICP). 11 Indeed, the phenomenon of ICP is, to a great extent, inevitable owing to the nonideal semipermeability of the active layer. In contrast, the study by Wang et al 12 focused on the hydrodynamic conditions associated with the physicochemical properties of the feed of whey.…”

“…For example, Seker et al investigated the flux decline in FO for concentrating a feed solution of whey; the conditions for the feed pretreatment were varied when different membrane orientations were employed by facing the active layer to either the feed solution (ALFS) or the draw solution (ALDS). However, it was challenging to identify the contribution of membrane fouling to the flux decline as the effective driving force (i.e., the transmembrane osmotic gradient) could be substantially shortchanged by the polarized concentration profile of the draw solute in the support layer (i.e., the internal concentration polarization, ICP) . Indeed, the phenomenon of ICP is, to a great extent, inevitable owing to the nonideal semipermeability of the active layer.…”