Copolymerization modification of poly(vinyltriethoxysilane) membranes for ethanol recovery by pervaporation

Abstract

In this study, a copolymerization modification method is used to modify the rigid structure of a high-flux poly(vinyltriethoxysilane) (PVTES) membrane, which was prepared from VTES monomers in our previous work, to further enhance its separation factor. A value of R/Si, which could characterize the density of organic groups and the chain flexibility in membrane materials, is introduced here to guide the selection of modification chemicals. Modifiers with different polymerization degree but the same flexible chain unit (DMDES, HSO and PDMS) are chosen to be copolymerized with PVTES. Analysis results show that the PVTES-HSO membrane possesses lower thickness, higher amount of hydrophobic groups, and an inner structure with greater chain flexibility and lower crystallinity, leading to the best pervaporation (PV) performance among these modified membranes, which is much better than the original PVTES membrane. Furthermore, PVTES-HSO membranes with different R/Si values are prepared to optimize their PV performance. And the optimal PVTES-HSO membrane (R/Si ¼ 1.4) shows the best performance with the separation factor of 6.6 and flux up to 8160 g m À2 h À1 when separating 9 wt% ethanol aqueous solution at 35 C.

High flux and ultra‐thin poly‐dimethyldiethoxysilane/poly(vinylidene fluoride) composite membrane for alcohols recovery from aqueous solution by pervaporation

“…Obviously, broad and diffuse peaks were found on both polymers, indicating that the amorphous substances with larger area of noncrystalline and tiny area of crystalline regions existed in selective layers. 21,52 The diffusion in membrane was related to the crystal structure of membrane, in details, the components can only pass through non-crystalline regions or defects of crystalline regions, except for crystalline regions. 21 The intensity of PDMDES's peaks was larger than that on PDMS pattern inferred from Figure 6, indicating that the crystalline region in PDMDES polymer was larger than PDMS.…”

“…21,52 The diffusion in membrane was related to the crystal structure of membrane, in details, the components can only pass through non-crystalline regions or defects of crystalline regions, except for crystalline regions. 21 The intensity of PDMDES's peaks was larger than that on PDMS pattern inferred from Figure 6, indicating that the crystalline region in PDMDES polymer was larger than PDMS. The peaks appearance on two polymers' patterns were also observed, where PDMDES polymer's pattern had two peaks appearing with the first one at 2θ = 8.92 , while PDMS polymer's pattern had only one at 2θ = 11.53 .…”

“…Furthermore, defects on the membrane surface, which is caused by uneven distribution of polymers at low viscosity, can be prevented by using monomer in membrane preparation. 21 It is available to prepare ultra-thin selective layer in a simple fabrication method through introducing monomer into polymerization. In addition, the trade-off between total permeation flux and separation factor is obvious in PDMS composite membranes, and the total flux is insufficient to meet the actual demands.…”

Membranes for bioethanol production by pervaporation

“…% ethanol aqueous solution at 35 °C. As summarized in Table 3 , it appeared that PVTES, PVTES-DMDES, and PVTES-HSO membranes showed great potential for in situ recovery of ethanol [ 161 ].…”

Novel Silica Functionalized Monosodium Glutamate/PVA Cross-Linked Membranes for Alkali Recovery by Diffusion Dialysis

“…The characteristics sharp peak at 1723 cm −1 is attributed to stretching vibration of carbonyl (−C=O) group from GMSG/VMSG [46,47], the intensity of which increases with the increase of GMSG/VMSG contents in the membrane matrix. The small peak at 1645 cm −1 is attributed to the stretching vibration of C=C [48]…”