Synthesis And Scale Inhibitor Performance Of Polyaspartic Acid

This paper studies the optimize synthesizing method of polyaspartic acid (PASP). The structure of synthetic product was by Infrared spectra (IR), and the chemical properties of which was determined on the basis of the chemical industry standard of People's Republic of China HG/T 3822-2006 about< polyaspartic acid (salt)>, at the same time, the static inhibition performance of polyaspartic acid and blends with properties of other scale inhibitors were studied referring to calcium carbonate deposition test.With maleic anhydride and ammonium carbonate for raw materials for the polymerization, with the quality yield of polyaspartic acid and the inhibition rate for calcium carbonate as inspects index, the optimum reaction conditions were obtained by single factor experiment and orthogonal tests:the molar ratio of maleic anhydride and ammonium carbonate was 1:1.2; the polymerization temperature was 180℃, polymerization time was1.5h; hydrolysis reaction temperature was 60℃, the product yield of polyaspartic acid synthesized at these conditions can reach 85%, the average inhibitor rate for calcium carbonate can reached more than 90%.The features groups of polyaspartic acid were observed from infrared spectrum on polymerization products. The molecular weight of polymer measured by limitting stick for legal was between 3,000～6,000. According to HG/T 3822-2006, the determination results on the phychemical properties of synthesized PASP were:the content of solid was 33.35%, the density (20℃) was 1.19 g/cm3, limit sticky number was 0.0595 dL/g, number of pH value (aqueous solution was 10g/L)was 9.00, all of which were within specifications. According to the study of static anti-scaling performance of PASP by calcium carbonate deposition, when dosing amount was 5mg/L, the anti-scaling rate of PASP on calcium carbonate in water is close to 95%, on calcium sulfate is 90%, on calcium phosphate is close to 70%; when dosing amount was 7mg/L, the inhibition rate of PASP on calcium sulfater improve to 95.8%, on calcium phosphate is close to 90%.The blends with test of PASP with other inhibitors showed that polyaspartic acid has good synergy effect blends with divinyl three amine five methylene fork (DTPMP), hydroxyl ethyl fork two phosphate (HEDP),2-phosphonate base-1,2,4 three carboxyl butane (PBTCA), and the best ratio were:PASP:DTPMP=2:1, PASP:HEDP=1:1, PASP:PBTCA=2:0.5.This paper successfully synthesized environment-friendly green polyaspartic acid, polymerization raw material was avirulent, harmless and easy access, operation process is simple, energy consumption is lesser and suitable for large-scale production.