Study On The Synthesis Reaction And Application Of Carboxymethyl Starch Graft Polyacrylamide

Carboxymethyl starch itself is abundant, cheap and easy to get. And it has been widely used in the food, medicine, oil, and other industries. If carboxymethyl starch is modified by grafting reaction, it will not only give new performance, but also does not damage its inherent excellent properties. The graft of polyacrylamide onto the maternal carboxymethyl starch will get a new type of organic polymer flocculant which is the main application in the industrial production.In this paper, about the polyacrylamide grafted into the maternal carboxymethyl starch by graft reaction and its application were studied as follows.(1) Through the experiments four different kinds of initiators of ceric ammonium nitrate, potassium permanganate, potassium persulfate, mixed initiator potassium persulfate and anhydrous sodium sulfite were studied,and finally I selected mixed initiator as the better initiator. The molar ratio of the potassium persulfate and anhydrous sodium sulfite was3:1.(2) In single factor experiment, the grafting ratio and graft efficiency were indexes. The dosage ratio of carboxymethyl starch and polyacrylamide, the concentration of potassium persulfate and anhydrous sodium sulfite, reaction time and reaction temperature were the main factors impact on grafting reaction through the single factor experiment.(3) Based on single factor, I designed orthogonal test with graft rate, grafting efficiency and the molecular weight as indexes. By orthogonal test, the best condition of carboxymethyl starch and polyacrylamide graft reaction were:the concentration of potassium sulfate at a concentration of5.76×10-4mol/L (keep the molar ratio of potassium persulfate and sodium sulfite anhydrous3:1), reaction time4h, the dosage ratio of carboxymethyl starch and polyacrylamide1:4, reaction temperature55℃.(4) Grafting reaction occured at the surface of carboxymethyl starch which was find from the SEM photos. The grafting reaction was progressed again by IR. From the TG curve, CMS-PAM copolymer was more stable if it was compared with polyacrylamide. Compared with CMS and PAM, CMS-PAM copolymer was more viscous and it had high molecular weight fom the results of viscosity analysis.(5) On the basis of experiment, the relationship of Rg and the concentration of each reactants was:Rg=K[AM]1.0[CMS]0.50[K2S2O8]0.53[Na2SO3]0.53.(6)On the basis of experiment, according to Rg=Ae-Ea/RT,the reaction activation energy of this graft copolymerization was18.36KJ/mol.(7) By beaker coagulation experiment, when the CMS-PAM copolymer as a flocculant dealed with reactive black wastewater, decolorization rate was82.06%.And better condition were:the quantity of material0.008g/300mL, initial pH8, the temperature of flocculation35℃, the time of flocculation50min.(8) By beaker coagulation experiment, when the CMS-PAM copolymer as a auxiliary flocculant dealed with kaolin wastewater simulated, turbidity removal rate was86.25%. And better condition were:the quantity of material0.002g/300mL, initial pH7, the temperature of flocculation30℃, the time of flocculation40min.