Synthesis and characterization of novel polyaspartic acid/urea graft copolymer with acylamino group and its scale inhibition performance

A novel green scale inhibitor, polyaspartic acid/urea graft copolymer (PASP/Urea), was synthesized by polysuccinimide (PSI) and urea. PASP/Urea was a non-toxic, non-phosphorus, biodegradable acylamino copolymer. The structure of PASP/Urea was characterized by Fourier transform infrared spectroscopy (IR), ¹H nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC) analysis. Its scale inhibition performance was estimated with static scale inhibition methods. The influence of PASP/Urea on formation of CaCO₃, CaSO₄ and Ca₃(PO₄)₂ was investigated using scanning electronic microscopy (SEM). The PASP/Urea exhibited more excellent scale inhibition property against CaCO₃, CaSO₄ and Ca₃(PO₄)₂ than the PASP and the comprehensive scale inhibition property of PASP/Urea is much better than the property of PASP. The scale inhibition efficiency of PASP/Urea against CaCO₃ was 93% when the dosage of PASP/Urea was 10 mg/L. The inhibition efficiency against CaSO₄ increased to 97% in the PASP/Urea concentration of 4 mg/L. The inhibition efficiency against Ca₃(PO₄)₂ reached up to 100% in the concentration of 12 mg/L. The results of SEM indicated that the scale crystals became irregular and distorted and the formation of scales was inhibited when the PASP/Urea was added.