Piezoelectric porous α-quartz membrane by aqueous gel-casting with enhanced antifouling and mechanical properties

Porous α-quartz ceramics with improved mechanical strength were fabricated by using silica sol as a bonding agent in an aqueous gel-casting process. α-quartz dispersion was prepared with a solid load of 75 wt% and a viscosity of 1.66 Pa·s. α-Al₂O₃ particles were added to promote dispersion of the bonding agent. The optimum amounts of amorphous silica and α-Al₂O₃ were 10 % and 8 % of the mass of α-quartz powder, respectively. The thermal treatment of α-quartz green bodies was optimized for mechanical and permeation properties. Electrical fields up to 1 kV/mm were applied to the green bodies to accomplish α-quartz grains orientation and hence piezoelectric response. This caused an increase of piezo-acoustic response by 58 % at an excitation frequency of 200 kHz. In-situ mitigation of fouling was obtained by applying an alternating voltage of 60 V, during TiO₂ suspension filtration, which resulted in an increase of the stationary flux by 23 %.