Preparation And Application Of The Cationic Starch With High Degree Of Substitution

The literatures of cationic starch were reviewed. The synthesis of 2,3-glycigyl tri-methyl ammonium chloride cationics was studied. After that, the preparation and application of cationic starch were discussed.2,3-glycigyl trimethyl ammonium chloride is one of important functional cationics-es. The methods to synthesize it were discussed. The gaseous phase process was compared with the aqueous phase process and the methylbenzene solvent process.It was found that comparatively satisfying product could be got under the terms of icing bath by the gaseous phase process. The same product could be got by the methylbenzene solvent process,but the cost of the gaseous phase process was lower and gaseous phase process was easy to be industrialized. 2,3-glycigyl trimethyl ammonium chloride was easy to absorb water. It had the ring-opening nature. It could be conserved for a long time in acetone solvent and its every index could be kept intact. The epoxide number of the product was 0.650 mol/kg, close to the theoretical number 0.690 mol/kg. The purity of the product by this process was high. Finally,the structure of the product was proved by the infrared spectrum.The cationic starch with high degree of substitution was prepared from corn starch with 2,3-glycigyl trimethyl ammonium chloride as cationic agent and NaOH as catalyst by a dry process, and the dispersing agent was the mixture of water and alcohol. The effects of reaction temperature, reaction time, amount of dispersing agent, NaOH and GTA on the substitution of cationic starch were studied and discussed carefully. When the amount of corn starch was 5.5g, the optimal reaction conditions were: water-alcohol 21%, NaOH 0.08g, reaction temperature 80℃, GTA 3.0g and reaction time 2.5h. The degree of substitution was 0.56. The reaction efficiency was 89%.In the end, the application of cationic starch in printing and dyeing waste water and coal-dressing waste water was studied. It was found that:(1) The coagulation effect for cationic starch, ferric sulfate and Polyacrylamide to treatprinting and dyeing waste water was good. It was economical effective method to treat waste water with low cost and simple methodology, the optimal conditions were: ferric sulfate addition 40mg/L, cationic starch addition 30mg/L, Polyacrylamide addition 4.0mg/L. The removal rate of chromaticity was 95%.(2) The settling rate of flocculate for cationic starch, calcium chloride and Polyacryl -amide to treat coal-dressing waste water was high with good coagulation effect and low cost. pH of the treated water was about 7.0. It needn't adjust with acid. Experimental results showed that the optimal conditions were as follows: in 500mL coaldress-ing waste water 0.1% cationic starch solution addition was 9.0mL, 0.1% Polyacrylamide solution addition was 1 .OmL and 2% calcium chloride solution addition was l.OmL. The settling rate of flocculate was 0.7995mm/s, SS and COD of the coal-dressing waste water treated with the method was up to the standard of discharging waste water in China.