Study On Synthesis Of Polyaspartic Acid By Imidazole Ionic Liquid And Its Scale Inhibition Performance

In order to improve the synthesis condition of polyaspartic acid in traditional organic solvent, a kind of imidazole ionic liquids with heat stability, organic compounds solubility and catalytic was used for the synthesis of polyaspartic, and the synthesis process of polyaspartic acid (PASP) in imidazolium ionic liquids([Bmim]Cl,[Bmim]Br and [Hmim]HSO4)was studied to determine the optimal reaction system. Then optimize synthesis contration of PASP in [Bmim]Br ionic liquids, the inhibiton scale performance of the products to different condition was evaluated. At last, the mechanism of L-Asp polymerization in Imidazolium ionic liquids was analyzed.The results showed that PASP can be synthesized in three kind of imidazolium ionic liquid. Polymers synthesised in the [Bmim]Br exbitited the highest yield,74%proportion of β-bonded PASP in polymer could be achieved. The optimal conditions of polymeric reaction are reaction temperature is155℃, reaction time is2.0hour, L-Asp mass present and product yield were33.3%and66.31%, repectively. At the same time,94.66%scale inhibition rate was obtained and molecular was up to3506. While when the catalyst H3PO4concentration of reactants accounted for25%, the product scale inhibition rate was up to96.50%, and molecular was4725. Compared with traditional organic solvents, as a reaction solvent,[Bmim]Br ionic liquid can make solution temperature of L-Asp decreased35℃, and reaction temperature changed from180℃to155℃, inhibition rate increased5%. H3PO4can reduce the reaction temperature to135℃, inhibition rate increased from6to7%. The best inhibit calcium carbonate scaling apply conditions are that PASP dose is4mg/L, reaction time is6h, solution temperature is80℃, calcium is250mg/L. The drawing electron group of anion Br in [Bmim]Br play as a catalytic role, can charged more carbonyl carbon electropositive in the process of of L-Asp polymerization, which will help nucleophiles amino attack on the carboxyl and cause dehydrate and condensate reaction.