Kinetic mechanisms of organophosphine compounds on calcium carbonate crystal growth: Cruising effect and Spatial matching

Abstract

Calcium carbonate (CaCO3) is a common mineral in industrial water systems. Organophosphate is a widely used scale inhibitor with 100% inhibition of thousands of mg/L of calcium (Ca2+) ions at concentrations below 10 mg/L. However, chelating agent EDTA is hundreds of times more effective in achieving the same inhibitory effect. Our study explored the significant difference in CaCO3 growth inhibition by these compounds. Through experiments combining molecular dynamics simulations and quantum chemical calculations, we have found that organophosphines dynamically capture and release Ca2+ ions, enhancing the solubility of Ca2+ ions and impeding CaCO3 growth through a mechanism known as the “cruising effect”. Simultaneously, the lattice distortion induced by “spatial matching” was employed to inhibit the growth of CaCO3. On the other hand, chelating agents exhibited robust coordination forces, particularly with ligand atoms (O and N), showcasing superior chemometric characteristics. These findings illuminated the distinct mechanisms of CaCO3 growth inhibition.