Inhibition of calcium carbonate and sulfate scales by a non-phosphorus terpolymer AA-APEY-AMPS

The inhibition of calcite crystal growth by acrylic acid-allylpolyethoxy carboxylate-2-acrylamido-2-methyl-propanesulfonic acid (AA-APEY-AMPS, PAYS for short) was investigated in the cooling-water system. The terpolymer was prepared via the copolymerization of acrylic acid (AA), allylpolyethoxy carboxylate (APEY) and 2-acrylamido-2-methyl-propanesulfonic acid (AMPS), whose structures were characterized by FTIR and 1H NMR. In this study, we have investigated the effect of the agent concentration and the ratio of the reactant. The experimental results show that AA-APEY-AMPS is an effective chelating scale inhibitor and it has high efficiency toward scales and nearly 90% for calcium carbonate and 100% for calcium sulfate. The produced crystals were characterized by using scanning electron microscopy and X-ray diffraction methods. It appears that the crystal shape, size, and the morphology of scale have changed apparently at the dosage of 5 mg/L. Based on the contrast experiment of the problem of scale formation, this paper analyses the mechanism of scale formation and the advantage of PAYS. The supporting mechanism of scale formation was also described and analyzed briefly.