Abstract
Tetraethylorthosilicate (TEOS)-crosslinked poly(vinyl alcohol) (PVA) solution was prepared and treated with benzaldehyde 2 sulphonic sodium salt acid (B2SA) for sulfonation. Different contents of graphene were incorporated into B2SA-grafted PVA–TEOS hybrid membrane to improve the membrane stability, mechanical strength, and overall pervaporation performance of the membranes. Membranes were fabricated using the casting technique. Developed membranes were then analyzed for their physicochemical changes by means of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), contact angle analysis (CA), and mechanical strength. The lower d-spacing value observed in WAXD was evidence for the decreased inter-chain distance between the polymer chains. DSC exhibited the enhanced thermal stability of the developed membranes compared to the plane PVA membrane with enhancement in Tg value (106 °C), which was well above the pervaporation experimental temperature. Incorporation of graphene induced higher mechanical strength to the fabricated membranes. Further, the membranes were tested for the pervaporation separation of bioethanol. All the membranes were stable throughout the pervaporation studies, with M-2 G showing the total permeation flux of 11.66 × 10−2 kg/(m2 h) at 30 °C.
Highlights
Bioethanol is one of the attractive renewable fuels that are produced from biomass [1,2,3]
A small peak at around 730 cm−1 appeared in the sulfonated poly(vinyl alcohol) (PVA)–TEOS and graphene-loaded sulfonated PVA–TEOS membranes, which was due to the presence of the benzaldehyde 2 sulphonic sodium salt acid (B2SA) content as the peak indicated aromatic alkene out of plane bending
The broad intensity peak appearing at 3318 cm−1 was enhanced systematically, which was due to the presence O–H groups of water molecules present in the channels created due to the adhesion (Van der Waals force of attraction) between the graphene and the silane group of TEOS
Summary
Bioethanol is one of the attractive renewable fuels that are produced from biomass [1,2,3]. The materials must encompass properties such as film-forming ability, high selectivity, higher permeation flux, good mechanical strength, and good shelf life. Research in this direction has shown that hydrophilic materials are always suitable for the dehydration of alcohols, and many such membrane materials have been studied for dehydration of alcohols [10,11,12,13]. Dharupaneedi et al prepared chitosan nanocomposite membranes with embedded functionalized graphene sheets and subjected them to isopropanol and ethanol dehydration via pervaporation In the study, they revealed that functionalized graphene sheets enhanced the water permeation and decreased the alcohol permeation through the membrane [29]. The effect of graphene loading on the PV separation of azeotropic aqueous bioethanol was broadly studied
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