Analysis of calcium carbonate polymorphs deposited in water piping system and the effect of tartaric acid additive

Abstract

Calcium carbonate (CaCO3) formed in a water piping system was investigated in the presence of chemical additives tartaric acid (0.00 and 10.00 ppm) and various temperatures ((27 and 50ºC). The flow rate inside pipe (35 ml/min) were selected. Solutions of CaCl2 and Na2CO3 were prepared in water with equimolar to Ca2+ concentration of 3000 ppm. The induction time of scale nucleation varied from 24 min to 44 min. An increasing temperature of the solution resulted in more CaCO3 scale, mass, while the higher tartaric acid made the reduced mass of scales by 90%. SEM/EDS analysis verified CaCO3 with a plate like morphology. Also the XRPD Rietveld method provided the confirmation of a major phase of calcite and vaterite minerals followed by the minor of aragonite in the absence of tartaric acid and at room temperature. However, the presence of 10 ppm tartaric acid yielded the increasing result of calcite, while aragonite precipitation was hampered under the influence of tartaric acid. The presence of tartaric acid at increasing temperature of 50ºC could delay formation of calcite, whereas aragonite could be formed significantly. Thus the study showed the capacity of the tartaric acid in influencing CaCO3 crystallization.