Preparation and evaluation of nonphosphate terpolymer as scale inhibitor and dispersant for Ca3(PO4)2, BaSO4, and Iron (III) hydroxide scales

The polymeric scale inhibition and dispersion agents (PAYS) were prepared by graft copolymerization of acrylic acid, allylpolyethoxy carboxylate (APEY) and 2-acrylamido-2-methyl-propanesulfonic acid by using ammonium persulfate as a radical initiator in aqueous solution, among which APEY was synthesized in laboratory. Structure of PAYS was characterized by Fourier transform infrared spectroscopy. Experimental data showed that the terpolymer was a high-efficient chelate sorbent, and it exhibited excellent ability for calcium orthophosphate, with approximately 96% efficiency at the dosage of 4 mg/L, as well as high efficiency toward barium sulfate scales nearly 80% inhibition. The effectiveness of PAYS depends on the agent concentration, temperature and the ratio of the reactant. The formation of Ca3(PO4)2 and BaSO4 precipitates was characterized by scanning electron microscopy. It appeared that the crystal shape, size, and the morphology of scale changed apparently at the dosage of 4 and 15 mg/L, respectively. In addition, it has good effect on controlling iron (III) scaling. This study was also devoted to the understanding of the action mechanism of these inhibitors in suppressing the crystal nucleus formation and preventing the crystal growth. Based on the contrast experiment of scale formation, the supposing mechanism diagram was also delineated and analyzed in detail. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41546.