High‐performance PDMS membranes for pervaporative removal of VOCs from water: The role of alkyl grafting

Abstract

To improve the pervaporation performance of PDMS membrane, alkyl groups with different chain length were grafted into PDMS matrix. The prepared membranes were characterized by ATR-IR, DSC, TGA, PALS, and tensile testing. The effects of alkyl grafting on pervaporation performance of PDMS membrane were investigated in separation of ethyl acetate/water mixture. Experimental results show that the separation factor of PDMS membrane is largely improved by alkyl grafting because of the enhanced preferential sorption of ethyl acetate, and this improvement depends on alkyl grafting ratio and alkyl chain length. The total flux of PDMS membrane reduces after alkyl grafting owing to the decreased free volume. When grafting ratio is above 6.9%, membrane grafted with shorter alkyl groups is preferred for pervaporation. The best pervaporation performance is achieved by 9% octyl grafted PDMS membranes with a separation factor of 592 and a total flux of 188 gm 22 h 21 in separation of 1% ethyl acetate/water mixture at 40 8C. Moreover, this octyl grafted PDMS membrane also exhibits excellent separation performance in removal of butyl acetate, methyl-tert-butyl ether, and n-butanol from water.

Industrial Membrane Processes for the Removal of VOCs from Water and Wastewater

“…Second, alkyl modified PHMS was cross-linked and grafted homogenously into vinyl terminated polydimethylsiloxane. The results confirmed that alkyl grafted PDMS separation performance depends on both the alkyl grafting ratio and alkyl chain length [20]. Investigations on the effect of alkyl grafting on both separation factor and total flux have been discussed in previous studies.…”

“…Flux rates were associated with the free volume that is explained by the solubility and diffusivity of EA and water in membranes based on the solution-diffusion model. The octyl grafted PDMS membrane (C8-PDMS) showed an improved separation performance in removal of BA, MTBE, and BuOH from water [20]. Fig.…”

“…In other words, branches can be distributed homogeneously or heterogeneously based on the reactivity ratio of the terminal functional group on the macromonomer and the low molecular weight monomer [18,19]. Zhou et al (2016) studied the role of alkyl grafting in enhancing the separation of VOCs from water in which ethyl acetate (EA) in a water mixture was selected for the study. Preparation of the alkyl grafted PDMS membranes was completed by different alkyl chain length through two single steps.…”

Preparation of Poly(ethylene‐co‐acrylic acid) Grafted with Aliphatic Quaternary Ammonium Salts as Antibacterial Polymers

“…43 In addition, the decomposition rates of DDHAC from PGD135, 165, and 185 were 9, 16, and 23 wt %, respectively. This was attributed to the better thermal stability in comparison to non-grafted PEAA.…”

The potential of polymers of intrinsic microporosity (PIMs) and PIM/graphene composites for pervaporation membranes

“…The first reported use of PV for VOC removal was in 1970 by Cole et al [46], with numerous reports since then showing further developments in the field [45]. A great number of PV membranes investigated for the removal of VOCs have been formed from organophilic materials such as poly[1-(trimethylsilyl)-1-propyne] (PTMSP), polydimethylsiloxane (PDMS), poly (ether-block-amide) (PEBA), and polyvinylidene fluoride (PVDF) [47][48][49][50][51][52][53][54], with many of these polymers and their derivatives being used in industrial settings [55][56][57][58]. The removal of organics from water is also of interest for industrial biotechnology, in particular for the recovery of products such as ethanol, butanol and acetone from fermentation broths, where the concentration of organics is low because of their toxicity towards the microorganisms used for fermentation [59,60].…”