The investigation of reaction parameters on the formation of calcium carbonate (CaCO3) and controlling of morphology

The crystallization of calcium carbonate has been intensely studied because it is important mineral in both industrial applications and biomineralization. It is widely used in various industrial fields as an additive to foods, paper, paint, cosmetic, rubber and plastics. Apart from being used as filler, it is also used in a variety of applications such as sulfur dioxide scrubbing, glass manufacture, waste treatment and heavy metal complexation. Precipitation of calcium carbonate on surfaces is a major problem for industrial equipment.In this work, the kinetics of precipitation of calcite (CaCO3) from aqueous solution in the presence of carboxymethyl inulin (CMI) were studied by constant composition method under strictly controlled temperature, pH, supersaturation ratio (S = 4.8) and ionic strength (I = 0.1 M). The crystal growth of calcium carbonate (CaCO3) was inhibited in the presence of CMI at low concentration.In the second part of the experiments, we were carried out the calcium carbonate crystallization using batch crystallizer with biopolymer. The effect of additive, initial concentration and adding rate of reactant on the crystal morphology, specific surface area and particle size was investigated in the batch crystallizer system. The effect of ultrasound wave on the morphology and crystal size of calcium carbonate was also studied. Samples were characterized with XRD, FT-IR, TG/DTA, BET and SEM analysis. In the presence of CMI, the polymorph of the synthesized calcium carbonate crystals changed from pure calcite to the mixture of vaterite and calcite. The investigation of SEM photographs showed that the mean crystal size reduced in the presence of biopolymer. The calcium carbonate crystals obtained in the absence and presence of biopolymer were used as adsorbent at the removal of Cu+2 from aqueous solutions. The data obtained were defined by the adsorption kinetics models.