Synthesis and characterization of tubular ceramic ultrafiltration membrane from coal fly ash

In this study, a tubular ceramic ultrafiltration membrane was synthesized using coal fly ash (CFA) along with fuller clay and a small quantity of inorganic precursors by extrusion method. The composition of membrane precursors was varied to prepare the ceramic membranes which were named as CM1, CM2 and CM3. Thermogravimetric analysis (TGA) confirmed high thermal stability nature of the membranes. The insignificant weight loss (<0.5%) of the membranes in a highly acidic and alkaline medium showed the high chemical resistance of the ceramic membranes. Mullite and Quartz was identified as significant phases of synthesized membranes via XRD analysis. The high negative charge of ceramic membranes was observed by Zeta potential analysis. Molecular weight cut-off (MWCO) of CM1, CM2, and CM3 membranes were estimated as 59, 50.3 to 36.6 kDa, respectively. The proportion of fuller clay significantly influenced the membrane properties such as porosity, pore size, and hydraulic permeability. The pure water flux of the membranes was increased with increase of applied pressure from 69 to 345 kPa. The maximum water flux was obtained as 11.7 x 10(-5) m(3)/m(2) s at 345 kPa for CM1. The pore size and porosity of the membranes were decreased from 131 to 96 nm and 57.68% and 44.8% while increasing the fuller clay from 8% to 12% in the membrane (CM1 to CM3), respectively. The results obtained in this study demonstrate that the CM3 tubular ceramic membrane can be successfully used for various ultrafiltration applications.