Preparation and desalination performance of porous planar cordierite membranes using industrial solid waste as main silica source

Silica is a main component of cordierite ceramic, in the present work, industrial solid waste was used as main silica source to prepare porous planar cordierite membranes by a solid-phase sintering process with starch as pore-forming agent. It is shown that the concentration of starch plays a critical role in the pore structure and mechanical property and the cordierite membranes with a starch concentration of 40 wt% (M-40) have a desirable pore structure and flexural strength after sintering at 1300 degrees C for 5 h. After grafted with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS, C-8), the ceramic membranes were used for desalination by vacuum membrane distillation (VMD). The results show that the membranes(M-40) possess an average flux of 11.43 kg/m(2) h, a high salt rejection of 99.9% under the following operation conditions: a NaCl concentration of 3.5 wt%, a feed rate of 300 ml/min and a temperature of 80 degrees C. After desalination for 120 h, the water contact angle decreases to 130 degrees. The cordierite membranes exhibit poor resistance to thermal acid/alkali solution(boiling, pH = 1 and 14, respectively, soaked for 8 h) but excellent resistance to ambient temperature acid/alkali solution (25 degrees C, pH = 1 and 14, respectively, soaked for 120 h).