PVA-Based MMMs for Ethanol Dehydration via Pervaporation: A Comparison Study between Graphene and Graphene Oxide

Abstract

Two different types of 2D nanosheets, including hydrophobic graphene (GR) and hydrophilic graphene oxide (GO), were filled into poly (vinyl alcohol) (PVA) polymers to prepare mixed matrix membranes (MMMs) for ethanol dehydration via pervaporation. The relationship between the physical/chemical properties of graphene and pervaporation performance of MMMs was investigated by a comparison of GR/PVA and GO/PVA MMMs in microstructure and PV performance. The incorporation of GO nanosheets into PVA reduced PVA crystallinity and enhanced the membrane hydrophilicity, while the incorporation of GR into PVA led to the opposite results. The incorporation of GR/GO into PVA depressed the PVA membrane swelling degree, and the incorporation of GR showed a more obvious depression effect. GR/PVA MMMs showed a much higher separation factor than GO/PVA MMMs, while they exhibited a much lower permeation flux than GO/PVA MMMs and pristine PVA membranes. The huge difference in microstructure and performance between GO/PVA and GR/PVA MMMs was strongly associated with the oxygen-containing groups on graphene lamellae. The higher permeation flux of GO/PVA MMMs was ascribed to the facilitated transport of water molecules induced by oxygen-containing groups and exclusive channels provided by GO lamellae, while the much lower permeation flux and higher separation factor GR/PVA MMMs was resulted from the smaller GR interplanar spacing (0.33 nm) and hydrophobicity as well as barrier effect of GR lamellae on the sorption and diffusion of water molecules. It was presumed that graphene intercalated with an appropriate number of oxygen-containing groups might be a good choice to prepare PVA-based MMMs for ethanol dehydration, which would combine the advantages of GR’s high interlayer diffusion selectivity and GO’s high permeation properties. The investigation might open a door to achieve both of high permeation flux and separation factor of PVA-based MMMs by tuning the microstructure of graphene.

Review on Membrane Materials for Ethanol/Water Separation by Pervaporation

“…According to the solutiondiffusion model, both water and ethanol molecules dissolve at the membrane's feed side surface and then diffuse towards the permeation side of the PVA membrane driven by the concentration gradient. PVA is a hydrophilic polymer [14]…”

Polycrystalline Metal–Organic Framework Membranes for Pervaporation

“…These advantages promoted the development of polycrystalline MOF membranes for PV. Although MOF mixed polymer membranes were also reported, ,− the final membrane performance was strongly determined by the polymer matrix. To focus on one topic, to study the MOF membrane materials well, polycrystalline MOF membranes are reviewed in this work.…”

Novel Polymeric Membranes Preparation and Membrane Process

“…One review article describes the fouling problems in the membrane technology for use in water and wastewater treatment, as well as the methods of both initial treatment and the least-advanced technologies in treatment processes, such as introducing nanochemistry into the area of water treatment [1]. Six research papers illustrated high-performance NF membrane for the lithium recovery from brine [2], molecular dynamics (MD) simulation of gas transporting in polydimethylsiloxane (PDMS) membrane [3], zeolite molecular sieve SAPO-34/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) preparation to recover propane [4], polyvinylidene fluoride (PVDF)-pressurized ultrafiltration membrane on the treatment of steel wastewater and analyzing [5], poly (vinyl alcohol) (PVA)-based MMMs preparation for high ethanol dehydration performance [6], hydrophilizing the polytetrafluoroetylene (PTFE) microfiltration membrane combining of surfactants and cross-linked co-deposition double-layer self-assembly method [7].…”

“…Ethanol dehydration via pervaporation (PV) has attracted increasing attention due to ethanol biofuel's rapid development and application [15]. Xia Zhan et al reported another kind of MMMs for ethanol dehydration via pervaporation [6]. The relationship between the physical/chemical properties of graphene and pervaporation performance of MMMs was investigated by comparison of hydrophobic graphene (GR)/PVA and hydrophilic graphene oxide (GO)/PVA MMMs in microstructure and PV performance.…”