LAUSR

Abstract This paper examines the influence of pressure on the crystalline properties of CaCO3 precipitate from drinking water and model aqueous solutions. Seven different evaporation models were examined. Evaporation was performed with a rotary evaporator, pressure vessel, and evaporation at atmospheric pressure at 373K. Evaporation was also performed with a pressure vessel using a model aqueous solution in the presence of Mg2+ ions, which are CaCO3 inhibitors. Measurements of absorbency, turbidity, pH value, zeta potential and particle size were performed at different time units after the precipitation of CaCO3 from a model aqueous solution and tap water. The precipitated crystals were determined by XRD and SEM. It can be concluded that pressure affects the properties of CaCO3, but not immediately after CaCO3 precipitation. The changes began after 15 minutes of model sample processing. Calcite was precipitated in all experiments, except in one with Mg2+ ions when aragonite was found. The treatment of tap water in a pressure vessel favoured aragonite precipitation, although later the aragonite modified into calcite.