Development of water vapor recovery membrane for efficient recycling system

Abstract

Abstract In wastewater treatment at semiconductor plants separation operations are currently conducted mainly by distillation. Membrane distillation using ceramic surface-treated membranes is expected to provide more efficient separation. In this study, we investigated the improvement of acid resistance of surface-treated ceramic membranes by using four silicon alkoxides, Hexamethyldisiloxane(HMDS), Dimethyldimethoxysilane(DMDMOS), 3,3,3-Trifluoropropyltrimethoxysilane (TFPrTMOS), Tetramethoxysilane(TMOS) were used as surface treatment and it was performed in the gas phase. The water vapor permeance of the TFPrTMOS surface treated membrane was 2.35✕10−6 [mol m−2 s−1 Pa−1], and it maintained its functionality after immersion in a 10 wt% sulfuric acid solution under 60°C for 170 h. The membrane with multiple surface treatments with TFPrTMOS showed an increase in acid resistance to 491h, indicating that unreacted alkoxide affected the degradation. The water vapor permeance of the TFPrTMOS-DMDMOS treated membrane combined silicon alkoxides was 2.85✕10−6[mol m−2 s−1 Pa−1] and the acid resistance was 687 h. It is possible that DMDMOS acted as a cross-linker in modifying the unreacted alkoxide portion of the membrane, leading to improved resistance.