Preparation Of Ceramic Support With Adsorption Function And Coating Process Research

Currently, commercial porous ceramic supports are mainly made of industrial grade alumina, existing problems of high raw material cost and high energy consumption. So the development of new mineral raw materials with low cost is needed. The application of ceramic membrane in traditional film processing techniques, such as wastewater treatment, only its retention function is considered. Thus the smaller the MWCO is, the smaller the membrane pore size should be, so does the membrane flux and the processing efficiency. This paper provides new ideas by designing calculation from the point of chemical composition of raw materials for selecting raw materials for ceramic supports. And the membrane separation technology and adsorption technology are combined to get a kind of ceramic membrane with dual function.Conventional ceramic support materials including kaolin, talc, attapulgite, clay and fly ash are remixed in accordance with the chemical composition, getting several kinds of raw material power with a big gap between the main chemical components. The corresponding ceramic supports are prepared by half dry pressing molding process. Particle size distribution of raw materials, average pore size, pore size distribution, XRD and compressive strength of supports are respectively characterized. Results show that:the performance of supports is closely related to the chemical composition of raw materials. The content of A12O3decides the compressive strength of supports. SiO2and MgO contents have effects on the pore size and pore size distribution of supports. Fe2O3and some other minor components play the role of sintering additives. According to the comprehensive survey of performance and cost, clay and fly ash are determined to be taken as raw material to make porous ceramic supports.Effects of raw materials adsorption, raw material ratio, sintering temperature on the performance of ceramic supports are studied. The optimum preparation conditions are determined:the mass ratio of clay and fly ash is8:2, the heating rate is1℃/min, the sintering temperature is900℃. Under these conditions, the porosity of ceramic support is36.75%, pore size distribution range in5-1000nm, pure water flux is52.89L/m2·h, the compressive strength is17.92MPa. The good treating results of simulated dyeing wastewater、 phosphate and iron ions wastewater prove that the ceramic support not only has good interception function for macromolecules, but also has good adsorption function for small molecules smaller than its aperture.For further improving the pore size distribution of clay-fly ash support, the coating process of electrophoretic deposition and solid particles sintering method are attempted. Results show that the solid sintering method can get complete membrane on the support. The pore size distribution of attapugite membrane made by solid sintering method is5-17nm, film thickness is20μm and has good adsorption for phosphate and iron ions wastewater.