Interlayer-assisted fabrication of polymer-supported organosilica membranes for enhanced pervaporation dehydration of N, N-dimethylformamide

An interlayer regulates organosilica deposition on porous polymer supports. • A 150 nm organosilica layer was obtained after two spray cycles. • The membrane achieved a flux of about 1.0 kg m⁻² h⁻¹ for DMF dehydration. • The membrane maintained relatively stable performance over 50 h. Pervaporation dehydration of N,N-dimethylformamide (DMF) is challenging because low-viscosity organosilica sols can penetrate porous polymer supports during selective-layer deposition. In this work, a polyarylate (PAR) interlayer was introduced onto a porous poly(ether ether ketone) (PEEK) support by interfacial polymerization to regulate the deposition of a bis(triethoxysilyl)ethane (BTESE)-derived organosilica layer by ultrasonic spray coating. Cross-sectional SEM observations showed that the PAR interlayer reduced BTESE-sol penetration into the porous PEEK support and facilitated the formation of a relatively thin BTESE-derived layer. The selected membrane prepared with two spray-coating cycles exhibited a BTESE-layer thickness of approximately 150 nm. For a 90 wt% DMF/water feed at 50°C, the membrane achieved a total permeation flux of approximately 1.0 kg m⁻² h⁻¹ with a separation factor of 3–4. During 50 h of continuous operation, the permeation flux decreased initially and subsequently remained relatively stable, while the separation performance showed no pronounced deterioration under the tested conditions. Additional pervaporation experiments with NMP/water and DMAc/water mixtures showed different permeation and separation behaviors. Overall, the results indicate that the PAR interlayer can regulate BTESE-sol deposition on the porous PEEK support and facilitate the fabrication of a thin organosilica composite membrane for pervaporation dehydration under the investigated conditions. Download: Download high-res image (287KB) Download: Download full-size image