Ceramic Substrates for Filtration Membranes Based on Fine Fly Ash Microspheres

Abstract

A procedure has been proposed for producing ceramic substrates for filtration membranes based on a narrow fraction of fine fly ash microspheres using cold uniaxial pressing followed by high-temperature firing. It has been shown that increasing the sintering temperature from 1000 to 1150°C leads to a decrease in open porosity from 40 to 24%, a decrease in the average pore size from 1.60 to 0.34 μm, and an increase in the compressive strength from 9.5 to 159 MPa. The resulting substrates are characterized by water permeability values of 1210, 310, 240, 170 L m⁻² h⁻¹ bar⁻¹ at sintering temperatures of 1000, 1050, 1100 and 1150°C, respectively. Experiments on filtration of aqueous suspensions of fine microspheres (d_av = 2.5 µm) and microsilica (d_av = 1.9 μm) through a substrate produced at a sintering temperature of 1150°C have shown the rejection close to 100%. The proposed methodology for using ash waste in the production of membrane materials promotes the development of technologies for the integrated processing of thermal energy waste.