Development and Evaluation of an Environmentally Friendly Calcium Carbonate and Calcium Sulfate Scales Inhibitor

Abstract

Abstract The precipitation of CaCO3 (calcite, vaterite, aragonite and calcium carbonate hydrates) and CaSO4 (calcium sulfate anhydride, calcium sulfate dihydrate and calcium sulfate hemihydrates) scale on pipe surfaces widely occurs in numerous industrial processes. For the control of CaCO3 and CaSO4 scales, a novel environmentally friendly scale inhibitor, maleic anhydride (MA)-allypolyethoxy carboxylate (APEM9), was synthesized. MA-APEM9 was characterized by Fourier transform infra-red spectroscopy (FT-IR) and 1H-NMR. The inhibitor property of the MA-APEM9 copolymer towards CaCO3 and CaSO4 in the artificial cooling water was studied by static scale inhibition tests. The effect on formation of CaCO3 and CaSO4 was investigated with a combination of scanning electronic microscopy (SEM) and transmission electron microscopy (TEM) analysis. The observation showed that MA-APEM9 was a much better inhibitor both for CaCO3 and CaSO4 compared to the commercial inhibitors. An inhibition mechanism is proposed. It shows that the interactions between calcium and allyl-terminated PMA are the fundamental impetus to restrain the formation of the scale in cooling water systems. The MA-APEM9 Inhibitor can be used safely in cooling water systems.