THE EFFECT OF THE TYPE AND CONTENT OF CARBONATES ON THE CHARACTERISTICS OF POROSITY OF CERAMIC MEMBRANES

Abstract

The main issue considered in the work is the creation of a matrix for ceramic membranes, which would be distinguished by low cost and high porosity. In order to reduce the cost of ceramic membranes, a widespread approach was chosen, which is powerfully used by many researchers, namely the use of natural minerals - kaolin and saponite - as the main components of the matrix. Carbonates were used as pore generating agents to achieve the required porosity value. Three series of ceramic membranes (CM) differing in chemical composition were synthesized in the work: KP1, KP2, and KP3 series. The main composition of CM includes: kaolin, saponite, sodium silicate and carbonates. The effect of the type and amount of carbonates (CaCO3, NH4HCO3, (NH4)2CO3) as pore generating agents on the formation of the porous structure of the samples was studied. The type and content of carbonates varied in different samples from 8 wt% up to 40 wt%. The dry pressing method using pressure equivalent to 8 tons and 15 tons was used to form ceramic membranes. The main parameters by which the properties of ceramic membranes were evaluated: water absorption, total and open porosity. Standard methods were used to determine these parameters for synthesized samples. The chemical composition of the dry mixture of the ceramic membrane, for which the porosity is the maximum in the series of manufactured samples, was established. It was established that the addition of calcium carbonate components to the dry mixture increases the porosity of ceramic membranes and water absorption. The chemical composition of a ceramic membrane sample with the best indicators of total and open porosity in the KP2 series is given. The chemical and phase composition of samples of the KP2 series, as well as their structural and adsorption characteristics, were investigated by X-ray fluorescence and diffraction methods of analysis and low-temperature nitrogen adsorption-desorption. The effect of the addition of silicon carbide on the characteristics of the porosity of the samples was determined.