Research Of Scale And Corrosion Inhibition Of Polyaspartic Acid Graft Copolymer Containing Sulfo, Hydroxy And Heteroaromatic Groups

Now green water treatment agents are hotspot of research and development in internationaland domestic academics. Polyaspartic acid (PASP) has become one of representative in this agentsas it not only possesses outstanding scale inhibition performance for CaCO3and CaSO4scale, butalso biodegradable and environmental-friendly. Nevertheless, its corrosion inhibitor and inhibitorperformance for Ca3(PO4)2are not prominent, which limits use of PASP. In order to improve itsthe comprehensive performance, we modified the PASP by the special structure and excellentwater treatment performance of functional groups. And the influence of groups on performance ofits scale inhibition corrosion inhibition was discussed. The main research content is as follows:1. Polysuccinimide (PSI) was synthesized with maleic anhydride and urea by thermalpolycondensation. The polyaspartic acid/aminomethanesulfonic acid (PASP/ASA), polyasparticacid/2-amino-2-methyl-1,3-propanediol (PASP/TRIS), polyaspartic acid/5-aminoorotic acid(PASP/5-AOA) and polyaspartic acid/3-amino-1H-1,2,4-triazole-5-carboxylic acid hydrate(PASP/3-AT-5C) graft copolymers were synthesized by open-loop modification to PSI. The graftcopolymers were characterized by infrared spectroscopy (IR), ultraviolet spectrum (UV) and1H-NMR spectrum (NMR).2. The PASP/ASA, PASP/TRIS, PASP/5-AOA and PASP/3-AT-5C graft copolymers’performance of scale inhibition against CaCO3, CaSO4and Ca3(PO4)2were measured by staticscale inhibition method. The results showed that these copolymers possessed excellent inhibitionability against them. The inhibition efficiency was close to100%against CaCO3scale when their concentration was up to1mg/L. The inhibition efficiency was close to100%against CaSO4scalewhen their concentration was up to4.5mg/L. The inhibition efficiency was close to100%againstCa3(PO4)2scale when their concentration was up to10mg/L,16mg/L,13mg/L and12mg/L,severally. But the inhibition efficiency of PASP was only about25%when its concentration wasup to16mg/L.3. The graft copolymers’ performance of corrosion inhibition was measured by rotarycoupon weight loss test. The results showed that PASP/5-AOA and PASP/3-AT-5C graftcopolymer possessed good corrosion inhibition ability. Their inhibition corrosion efficiency canreach to75%, PASP just45%when inhibitor concentration is16mg/L.4. The structure of scales crystal was studied analysis by scanning electron microscopy(SEM). The results showed the grain size CaCO3, CaSO4and Ca3(PO4)2scales became small andthe form of crystals turn into loose and flower shape, when these grafted copolymers were addedto solution. This is beacause the grafted copolymers disturb effectively growth of crystal nucleus,destroying crystal habits, and resulting in the crystal distortion.