Synthesis and Performance of Modified Polyaspartic Acid

A new nitrogen-free and phosphorus-free scale-inhibitor,modified polyaspartic acid,was synthesized in the water system.It contains hydroxyl,sulfonic acid groups and carboxyl groups.The optimum synthetic conditions were ascertained as follows:the mole ratio of n(maleic anhydride)∶ n(ammonia)∶ n(citric acid)∶ n(2-amino-ethanesulfonic acid) is 1∶ 2.8∶ 0.12∶ 0.075;reaction time is 3 hours;the thermal polycondensation temperature is 190 ℃;the polymerization time is 1 h.The product′s structure was characterized.A conclusion is drawn that the scale inhibition rate of the agent is 82.9% when the dosage reaches 24 mg/L.The new antiscalant is significantly better than the traditional productions.