| Abstract [eng] |
Recently, the synthesis, structure, and applications of calcium aluminate –mayenite have received considerable attention in the scientific literature. All methods currently used for the synthesis of mayenite can be divided into three broad groups. Two-stage production methods such as the synthesis of calcium hydroaluminate precursors of mayenite and the heat treatment of the resulting products to form the target synthesis product are the least studied. This technology has been applied to the synthesis of mayenite, but the scientific literature provides only fragmentary data. The aim of the dissertation is to determine the influence of two-stage synthesis conditions on the formation and properties of mayenite derivatives and propose rational areas of applications. Researched that increasing the combustion temperature (from 350 to 900°C) increases the specific surface area and pore volume of the mayenite derivatives almost threefold. The additive of mayenite derivatives, irrespective of the temperature at which it is obtained, modifies the hydration process of Portland cement: promotes calcium sulphate dihydrate reacting, the formation of ettringite, and increases the total amount of heat released. The adsorption of Cu2+ and SO42- ions is a major focus of this work, it was determined that the total adsorption capacity of synthetic mayenite derivatives for Cu2+ and SO42- ions increases with increasing combustion temperature of the mayenite derivatives and the initial concentration of copper sulphate solution. For the first time, it has been shown that, after thermal activation, mayenite derivatives can be used for the re-adsorption of Cu2+ and SO42- ions from aqueous solutions. It has been investigated that the products obtained after two cycles of adsorption and additional heat treatment can be used as accelerators for the hydration process of Portland cement. |
