Synthesis Of Polyaspartic Acid Under Microwave Irradiation And The Study Of Properties

Polyaspartic acid(PASP) is a kind of scale inhibitor which has attracted much attention of domestic and international researchers.There is no phosphor in PASP,it is not poisonous and can be totally biologic decomposed in the environment.Its use is very extensive,involving the industry water processing,agrochemical,medicine, day chemicals etc.In this work the preparation and its influencing factors were studied.The product was characterized and the static scale inhibiting performance was studied in detail.The scale inhibiting mechanism of PASP were introduced by SEM,FT-IR and XRD.The main research is as follows:1.Polyaspartic acid was synthesized by catalytic polymerization with L-aspartic acid as raw material in the medium of propylene carbonate under microwave radition. The best condition for the synthesis of PASP is:the dosage of the activator is 8%; the microwave power is 325W,the hour of the reaction is 4min,the solvent amount used is 15mL(regarding 10g L-ASP).2.The IR test were carried out for the product synthesized on above condition. The characteristic peaks indicated the product was PSI.3.Its properties of scale inhibition to CaCO₃,CaSO₄ was examined by static scale inhibition method.The study of water conditions effect on the performance of PASP indicates that the performance decreased with higher pH and temperature,longer heating time,lower value of Ca²⁺ / HCO₃^- and higher calcium ion concentration.PASP had excellent efficiency of scale-inhibiting to CaSO₄ for water treatment and have dispersedness effect to Fe₂O₃.4.The scale inhibition of combination of PASP and ATMP was discussed with static scale inhibition method in different condition.The effects of scale inhibitor concentration,time,water bath temperature,Ca²⁺ concentration as well as HCO₃^-concentration on scale inhibiting performance were studied.As a result,the optimum dosage of the combination is1:1,When the dosage of the compound scale inhibitor is 4 mg/L,its scale inhibition efficiency is 86%.Temperature,time and HCO₃^-concentration have less effect on the scale inhibitors of combination,while Ca²⁺ concentration has biggish influenced on it.The economical appraisal of compound scale inhibitor is also carried on.The result shows that the compound scale inhibitor can reduce the cost.5.Mechanism of scale inhibition of PASP was also studied through instruments,such as SEM,IR and XRD.It was found that PASP has complexing effect,crystal lattice distortion effect,agglomeration and dispersedness effect and threshold effect.