Preparation and characterization of macroporous pure alumina capillary membrane using boehmite as binder for filtration application

Macro-porous pure alumina membrane was prepared from boehmite sol having a pH of 3.6 as a binder with alumina powder in different concentrations in weight percentage (2.5, 4 and 7 %) to make extrudable ceramic paste. The pastes were extruded by a plunger type extruder to 3/2 mm (outer/inner diameter) capillary tube. The capillaries were dried in a roller drier and subjected to retarded sintering at 1350 °C for 2.5 h. Prepared membrane were characterized and compared with each other and membrane prepared with Methocel as organic binder for pore size, porosity, mechanical strength and clean water flux. The pore size of 7 % boehmite sol based membrane was found to be 400 nm when compared to 1.3 μm for membrane prepared with Methocel. The boehmite act as sintering agent and carry out the retarded sintering of alumina at 1350 °C in place of 1700 °C to form porous alumina membrane. Boehmite membrane was used for treatment of contaminated tannery wastewater and compared with membrane prepared from conventional organic binder. About 99 % removal in total organic carbon was obtained in case of boehmite membrane and chemical oxygen demand (COD) was reduced to 100 mg/L from an initial value of 6600 mg/L whereas in case of Methocel membrane COD was only reduced to 390 mg/L.