ABSTRACT
Calcium carbonate polymorphs are encountered in water intensive industrial processes and gas and petroleum production operations. The presence of water-soluble polymers at very low concentrations (ppm) is known to affect nucleation and/or crystal growth of calcium carbonate polymorphs. The presence of Mono Ethylene glycol (MEG) in supersaturated solutions has been found to affect both kinetics and the morphology of calcium carbonate. In the present study, the effect of acrylate polymers and copolymers with sulfonic and styrene units on the formation of calcium carbonate, in supersaturated solutions, prepared in mixtures of water-MEG (0-60% v/v MEG). The inhibitors tested included poly acrylic acid (PAA), and a Ter polymer (Polymer acrylic acid sulfonic acid sulfonated styrene at concentrations of 1to 5 ppb. The kinetics of calcium carbonate were measured at constant supersaturation. Rate reduction in the presence of the test inhibitors was comparable or more effective in comparison with the case in aqueous solutions. The initial formation and stabilization of the metastable phases of aragonite and vaterite was identified with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Test inhibitors seemed to retard transformation of the least stable vaterite.
