Aspartic Acid - Glutamic Acid Synthesis Method And Performance Research

Polyaspartic acid is a new type of environment-friendly water treatment agent with superior scale inhibition performance and biodegradability. The high reaction temperature and non-uniform heating of the reactants results in low scale inhibition and high energy consumption, therefore, how to improve the scale inhibition efficiency has become the focus of water treatment researches. In this paper mixed samples was prepared by solution evaporation and chemical co-precipitation, Poly-aspartic-glutamate copolymer was synthesis by thermal polycondensation, structure and shape of the samples was characterized. At last, PAG scale inhibition performance was discussed by static scale inhibition. The scale inhibition mechanism is also investigated by CO2 aeration process.The results show, the samples with lower crystallinity and smaller particle size can be produced by chemical co-precipitation varying in a wide range of stoichiometry. The optimum thermal polycondensation conditions is confirmed, that is:n (GLU):n (ASP+GLU)=0.1, reaction temperature 180℃, reaction time 4h. PAG scale inhibitor optimum process conditions is dose of 8mg/L, constant time 6h, solution temperature of 80℃, calcium 250 mg/L. In solution CaCO3 tends to form vaterite with coordination number is 12 by the macromolecular template effect of PAG. Because of the interaction between CaCO3 crystals of different types, small-particled precipitation with irregular surface is formed to achieve the purpose of scale inhibition.The experimental result suggests, chemical co-precipitation by doping small dose glutamate component into aspartic acid, is efficiently improving the scale inhibition of PAG. PAG is suitable to be used in circulating cooling water system with high temperature and low concentration of calcium ion.