Recovery of alcohols from water using polydimethylsiloxane–silica nanocomposite membranes: Characterization and pervaporation performance

Abstract

Different polydimethylsiloxane (PDMS) nanocomposite membranes were synthesized by incorporating various contents of nanosized silica particles to improve the PDMS pervaporation (PV) performance. A uniform dispersion of silica nanoparticles in the PDMS membranes was obtained. The nanocomposite membranes were characterized morphologically by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that surface roughness increases by incorporating silica, and this decreases absorption of penetrants on the membrane. Swelling studies showed that the presence of silica nanoparticles into the PDMS membranes decreases degree of swelling, which can be attributed to rigidification of the PDMS matrix. Additionally, the results revealed that helium permeability decreases through the nanocomposite membranes, due to the more polymer chains packing. Effects of silica on recovery of isopropanol (IPA) from water mixtures were also investigated. Based on the results, incorporating silica nanoparticles promotes significantly the PDMS membrane selectivity because the polymer chains are rigidified and also the polymer free volume decreases. However, permeation flux decreases as diffusion of the penetrants reduces in the presence of silica nanoparticles within the PDMS membranes. As PV performance depends on operating conditions, effects of feed composition, and temperature were also studied. Moreover, recoveries of IPA, ethanol, and methanol from water mixtures were compared using the PDMS-silica nanocomposite membranes. The results demonstrated that polarity and solubility of alcohols affect permeation flux and selectivity resulting in the higher permeation flux and selectivity for IPA.

Preparation and characterization of Silicalite‐1/PDMS surface sieving pervaporation membrane for separation of ethanol/water mixture

“…[22][23][24] At choice of nanoporous molecular sieving materials, studies have been focused of choosing different nanomaterials or zeolite with special feature to prepare the PDMS MMMs to enhance the performance of the membranes. [25][26][27] Hydrophobic Silicalite-1 zeolite was added into polymer membranes for pervaporation separation of ethanol-water mixture. [28][29][30][31][32][33] Yi et al 29 improved the affinity between Silicalite-1 and PDMS by modifying the Silicalite-1 particles with vinyltriethoxysilane (VTES).…”

Nanocomposite materials based on zinc sulfide nanoparticles reinforced chlorinated styrene butadiene rubber

“…Hybrid nanocomposites are relatively new types of composite materials. The nanoparticles incorporated polymer shows excellent properties, such as enhanced mechanical strength, fire retardant, thermal stability, solvent, and gas barrier properties . The large surface area of nano‐fillers with a high aspect ratio produces good reinforcement in polymers even at very low filler loading (<15%) as compared to conventional fillers, which require much larger quantities of filler (>30%).…”

Pervaporation of Ethanol/Water Mixtures Through a High-Silica MFI Membrane: Comparison of Different Semi-Empirical Mass Transfer Models

“…The reported total fluxes, however, are typically relatively low, mostly below 1 kg m -2 h -1 [3,[5][6][7][8]. The modification of PDMS membranes with fillers such as hydrophobic zeolites, referred to as mixed matrix membranes, has also been studied [9][10][11]. In many cases, the ethanol-water separation factor using such membranes has been increased, up to as high as 59, with the total flux remaining mostly below 1 kg m -2 h -1 [12].…”