Synthesis And Flocculation Performance Of Quaternary Ammonium Type Cationic Hydrolyzed Starch Under Dry Process

A range of different molecular mass of cationic hydrolyzed starches with bearing quaternary ammonium groups was prepared via reaction of different molecular masses of corn starch with glycidyl trimethyl ammonium chloride (GTA) using the dry process. The effect of various factors on the reaction efficiency was investigated in detail. When the ratio of GTA and Starch was0.6:1, the optimal reaction conditions were:reaction temperature80℃, reaction time1.5h, n(NaOH):n(HS)=0.07:1, the water content is18%in the system, the degree of substitution was0.49and the reaction efficiency was81.7%.Amorphous corn starches were synthesized under the protection of ethanol solution, and the quaternary ammonium type cationic amorphous starches were prepared via amorphous corn starch by dry process. The degree of substitution and the reaction efficiency of the products were compared with that which was prepared via corn starch, the results showed that the degree of substitution of the cationic amorphous starches reached0.54and the reaction efficiency reached84.4%which were higher than whose that were prepared via raw corn starch. The cationic amorphous starch had smaller viscosity.With com starch as raw material and HClO4as catalyst, quaternary ammonium cationic starches were prepared. Through the orthogonal experiments we knew when the ratio of GTA and Starch was2:3, the optimum reaction conditions were n(HC104):n(AGU)=0.012:1, reaction temperature80℃, reaction time4h. The degree of substitution was0.3; the reaction efficiency was45%.The cationic hydrolyzed starches were used for treating Kaolin suspension as flocculants and the flocculation effected by their dosage and pH were studied. The results showed that the optimal value of cationic hydrolyzed starches tended to decrease firstly and then increase with the decrease of their molecular weight. When the dosage was the same, the cationic hydrolyzed starch prepared via of corn starch which was degraded when hydrochloric acid solution was0.5mol/L, mass concentration was0.4kg/L, reaction time was2h had the best flocculation performance. When the dosage was the same and the pH was from4to10, cationic hydrolyzed starch with small molecular weight had a wider range of applications of pH. The quaternary ammonium cationic starches were used for treating starch wastewater and dyeing wastewater. The removal rate of turbidity of starch wastewater could reach72%, the rate of decolorization of dyeing wastewater reached as high as88.2%. This verified the high-efficiency flocculation performance of the quaternary ammonium cationic starches.