Carboxylate-terminated double-hydrophilic block copolymer as an effective and environmental inhibitor in cooling water systems

In an attempt to control Ca 3 (PO 4 ) 2 , CaCO 3 , and CaSO 4 deposits in industrial recycling water systems, an acrylic acid (AA)-allyloxy poly(ethylene glycol) polyglycerol carboxylate (APEG-PG-COOH) copolymer was synthesized as a nonphosphorus inhibitor. The synthesized polymer was characterized by 1 H NMR. The performance of PAA/APEG-PG-COOH on inhibition of Ca 3 (PO 4 ) 2 , CaCO 3 and CaSO 4 precipitation was studied through static scale inhibition tests. It was shown that PAA/APEG-PG-COOH exhibited excellent ability to control inorganic minerals, with approximately 100% CaSO 4 inhibition and 99.89% Ca 3 (PO 4 ) 2 inhibition at levels of 3 and 6   mg/L PAA/APEG-PG-COOH, respectively. PAA/APEG-PG-COOH also displayed ability to prevent the formation of CaCO 3 scales. The effects on formation of Ca 3 (PO 4 ) 2 , CaCO 3 and CaSO 4 were investigated with combination of Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM), and X-ray powder diffraction (XRD) analysis, respectively.