Synergistic effects of magnesium and EDTA on polymorphism and morphology of CaCO3 and its influence on scale

Abstract

Calcium carbonate scale formation in the presence of magnesium ions has been studied between 60 and 100 °C. The samples were characterized using XRD, FTIR and FE-SEM techniques. The effect of EDTA on the polymorphism and morphology of calcium carbonate in presence of magnesium ions also have been reported. The study revealed that both magnesium and EDTA influence the crystallization behavior and morphology of the CaCO3 formed. The study also revealed that the effect need not be same under different temperatures and environments and the morphological transformation need not compulsorily represent the polymorphic transformation. The findings are explained by a two stage mechanism which revealed that the magnesium ions present in the system can favorably or adversely affect the scale inhibition property of the inhibitor depending on the concentration and temperature.