The Research Of Improvement And Pollution Control During The Synthesis Of Polyaspartic Acid Under Microwave Irradiation

Polyaspartic acid(PASP)is a kind of polymer with good biodegradability and excellent scale inhibition and dispersion performance. It is an kind of green scale inhibitor with no phosphoric and toxic in its molecular,and it can be used in industry substitute for polyacrylic acid.As one kind of new green environmental protection water treatment agent,more and more attention to its research in recent years.The synthesis of PASP is firstly raw materials are condensed and polymerized into polysuccinimides(PSI),then,PASP is produced by PSI hydrolysis. Nowadays PSI is mainly obtained through two methods, one is the thermal condensation polymerization of L–aspartic acid, and the other is the polymerization of maleic anhydride and ammonia in liquid phase. There are both some pollution problems in the traditional way of the two synthesis processes during the PASP synthesis technology.This article seeks the low cost non-pollution green environmental protection synthesis method of the PASP through the research trial, and research the main pollutant control during the synthesis of polyaspartic acid.This article through the mechanism research of polyaspartic acid,synthesis the polyaspartic acid under microwave irradiation,and control the main pollutant which comes from the synthesis. The optimum condition of microwave synthesis is: ammonia: maleic anhydride=1.2:1,output power 900W,irradiation 3min.Controls the pollutant comes from the synthesis of PASP acid under microwave irradiation,and using maleic anhydride recycling the ammonia during the synthesis. The ammonia comes from the microwave synthesis can be all absorbsed under the conditions of gas flow rate was the 0.6 L·min-1 and ammonia anhydride=1.2. This method eliminated the ammonia pollution of the synthesized process of the PASP which with the maleic anhydride as raw material.The catalyst pollution problems can be successful solution with the methods of the synthesis of polyaspartic acid in monomer polymerization under the microwave irradiation. The polyaspartic acid yield ratio reach 96.3% under the conditions:output power 900W,irradiation 4min. In this method the used amount of phosphoric acid is 0,it can eliminates the phosphoric acid catalyst pollution from source. Finding a new green cleaner production method of synthesis PASP during the researche of eliminates the catalyst pollution process. It is ues L-aspartic acid as the raw materials to synthesis the PASP under the microwave irradiation.Polyaspartic acid was synthesized by monomer polymerization with L-aspartic acid as raw materials under microwave irradiation. The optimum condition of synthesis is: ammonia: output power 900W, irradiation 4.5min. It is characterized to determination for Polyaspartic acid.The efficiency of scale inhibition under the two methods was assessed by static scale inhibition tests. The result shows that scale inhibition rate of the polyaspartic acid can reach 100% for [Ca2+]=300mg/L.The efficiency of scale inhibition of PASP is equals to PAA. Research the influencing factors of the PASP scale inhibition performance,The optimum condition for PASP as a water treatment agent is: pH below 8.3, water temperature is 80℃, constant temperature time is 20h.The comparison of several synthetic methods for PASP is to find out the optimum methods. Through the comparison with the traditional method, the method of microwave radiation has more advantages. And compare the two synthesis method under microwave, the synthesis with maleic anhydride, ammonia as raw material method is prices cheaper,and the L-aspartic acid synthesized by monomer polymerization method without any contaminants.