Investigation of Scale Inhibition Mechanisms Based on the Effect of HEDP on Surface Charge of Calcium Carbonate

Abstract

Abstract 1-Hydroxyethylidene-1,1-diphosphonic acid is a widely used CaCO3 scale inhibitor. To probe its inhibition mechanisms, the effect of 1-Hydroxyethylidene-1,1-diphosphonic acid on surface charge and crystalline form of CaCO3 scale was investigated. The results show that CaCO3 originated from the equimolar mixture of Ca2+ and CO3 2 − is negatively charged and 1-Hydroxyethylidene-1,1-diphosphonic acid has no obvious effect on the zeta potential of CaCO3. Analysis of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction indicated that the crystalline form of CaCO3 was altered in presence of 1-Hydroxyethylidene-1,1-diphosphonic acid. With the increase of the scale inhibition efficiency, more vaterite appeared in the particle. So a conclusion was drawn that the formation and transformation of the metaphase was inhibited by 1-hydroxyethylidene-1,1-diphosphonic acid, then the whole process of CaCO3 precipitating was slowed greatly.