Synthesis Of Cationic Modified Poly(?-Glutamic Acid)and Research Of Its Flocculation Performance

In recent years,the microbial flocculanthas have a broad development prospect in water treatment agent and has become a hot research topic at home and abroad with the characteristics of safety and efficiency,biodegradability and environmental friendliness.The?-polyglutamic acid contains a large number of carboxyl active groups,which can be chemically modified to obtain cationic modified gamma glutamic acid flocculants.Cationic modified?-polyglutamic acid flocculant is an environmentally friendly flocculant,it not only has excellent flocculation effect on seawater,but also is prone to biodegradation.The flocculation effect on seawater is obviously improved when the inorganic flocculant and cationic modified?-polyglutamic acid flocculant are combined.The research contents of this paper are as follows:At first,the cationic modified?-polyglutamic acid flocculant was obtained by etherification of?-polyglutamic acid and etherification agent.The synthesis process of cationic modified?-polyglutamic acid flocculant was optimized and its flocculation efficiency was characterized and the results showed that when the substrate was 1 g?-polyglutamic acid,the optimal synthetic process conditions are listed below:the amount of the etherification agent is 0.07mol,the molar ratio of thesodium hydroxide and the etherification agent is 1:1.3,the reaction temperature is 50?and the reaction time is 5h.The turbidity removal rate and COD removal rate are 84%and 85%respectively when the addition amount of the cationic modified?-polyglutamic acid flocculant in seawater is 2mg/L and the results are further confirmed by Zeta potential detection.Secondly,the cationic modified?-glutamic acid flocculant was obtained through the Manihi reaction.The synthesis process of cationic modified?-polyglutamic acid flocculant was optimized and its flocculation efficiency was characterized and the results showed that when the substrate was 1 g?-polyglutamic acid,the optimal synthetic process conditions are listed below:the addition amount of the diethanol amine and the formaldehyd are 0.04mol and 0.05 mol,the reaction temperature is 70?and the reaction time is 4h.The turbidity removal rate and COD removal rate are 86%and 87%respectively when the addition amountof the cationic modified?-polyglutamic acid flocculant in seawater is 2mg/L and the results are further confirmed by Zeta potential detection.Finally,the cationic?-polyglutamic acid flocculant modified by etherification agent was mixed with FeCl₃ and its flocculating properties were characterized.The results showed that the removal rate of turbidity is up to 98%when the dosage of FeCl₃ flocculant is 2mg/L and the amount of cationic modified?-polyglutamic acid flocculant is 2mg/L.The TSS removal rate and COD removal rate of seawater are 97%and 92 respectively when the dosage of FeCl₃ flocculant is 2mg/L and the amount of cationic modified?-polyglutamic acid flocculant is 2.5 mg/L.The results are further confirmed by Zeta potential detection.