Preparation of the ECTFE/SiO2 Hybrid Membrane and Its Application in Membrane Condensation

Abstract

As a new separation technology, membrane condensation requires simple equipment and mild operating conditions and has wide application potential and value in the process of water vapor recovery and chemical concentration and recovery. In this paper, we have proposed a new application process to incorporate nano-SiO₂ into ECTFE membranes and apply them in the membrane condensation process. The fabrication of ethylene-chlorotrifluoroethylene copolymer (ECTFE)/SiO₂ hybrid membranes is performed by incorporating hydrophobic nano-SiO₂ during ECTFE membrane preparation, with varying ECTFE/SiO₂ compositions achieved through SiO₂ dosage adjustments. It can be found that SiO₂ can change the structure of membrane during the process; hence, the impact of SiO₂ removal after membrane formation on membrane performance was evaluated. SiO₂ removal was conducted using a 1 mol/L hot alkali solution with continuous agitation for 24 h. A maximum water recovery rate of 24% (adequate for industrial water self-sufficiency) was attained at 2 wt % SiO₂. Compared with the original membrane, the addition of hydrophobic nano-SiO₂ significantly enhances the condensation performance of the ECTFE membrane.