Scale inhibition mechanism of itaconic acid-sodium methacrylate sulfonate on calcite: Quantum chemical calculation and molecular dynamics simulation

Abstract

In order to explore the scale inhibition mechanism of green scale inhibitor-itaconic acid-sodium methacrylate sulfonate (IA-SMAS) on calcium carbonate (CaCO3), the scale inhibition characteristics of IA-SMAS were studied by quantum chemical calculation and molecular dynamics simulation. The charge distribution, electrostatic potential distribution, geometric matching degree and frontier molecular orbital energy of IA-SMAS were analyzed by quantum chemical calculation. It was found that IA-SMAS molecules have the ability to bind to Ca2+ at the micro level, occupy the growth active sites of crystal during the growth of calcite crystal planes, and inhibit the normal growth of crystal. Based on the molecular dynamics simulation method, the effects of IA-SMAS concentration on the adsorption configuration, radial distribution function and interaction energy in the binding process of IA-SMAS with calcite crystal planes were analyzed. The results show that the area of calcite crystal planes covered by IA-SMAS molecules, the peak value of radial distribution function and the binding energy increase with the increase of IA-SMAS concentration. However, the relative concentration of water molecules near the calcite crystal planes decreases, and the trend of water molecules moves away from the crystal planes of calcite. It indicates that the high concentration of IA-SMAS molecules can occupy the position of water molecules, and enhance the scale inhibition efficiency. Therefore, the scale inhibition performance of IA-SAMS increases with the increase of its concentration in a certain range, and an appropriate increase in IA-SMAS concentration can effectively inhibit the growth of scale.