Synthesis And Application Properties Of New Cationic Starches

Cationic modified products of starch and their derivatives have good physical and chemical properties, they are widely used in paper making, wastewater treatment, petroleum exploiting, printing and dyeing, etc, and they show promising application prospects in various areas. In this thesis, novel tertiary amine cationic starch (TCS) and quaternary ammonium cationic starch (QCS) were designed and synthesized using hydroxymethyl dimethylamine hydrochloride (sulfate) and chloro-choline chloride (CCC) as etherification agents, the process of preparation and application of the cationic starches (CS) were investigated detailedly, which contributed to the development of lower cost, wider synthesis and application range of CS.According to Mannich reaction, cationic reagent hydroxymethyl dimethylamine hydrochloride (sulfate) was prepared with formaldehyde, dimethylamine and hydrochloric acid (sulfuric acid), and then new tertiary amine cationic starch-starch-methylene dimethylamine hydrochloride (SMMAHC) with degree of substitution (DS) of 0.79, reaction efficiency (RE) of 96.3%, and starch-methylene dimethylamine sulfate (SMMAS) with DS of 0.84, RE of 84% were prepared from the reaction of corn starch with cationic reagents by using solvent-free method. The structures of TCS were characterized by 13C NMR spectroscopy.A novel quaternary ammonium cationic starch was prepared by using chloro-choline chloride as an etherification agent. Effects of wet method, dry method and the application of catalyst on DS and RE of QCS were discussed. In wet process, isopropanol/water and DMSO were adopted as solvent, sodium hydroxide as catalyst, then QCS with maxima of DS 0.14 and 0.23 were prepared with isopropanol/water and DMSO were adopted as solvent, respectively; in dry method, sodium hydroxide with strong basicity and calcium carbonate with weak basicity were used as catalysts, when using calcium carbonate as acid-binding agent, DS of QCS got to 0.48, RE got to the maximum of 80%. The structure of QCS was characterized by 13C-NMR.The moisture-adsorption and retention ability of TCS (SMMAHC, SMMAS) and QCS were investigated at different relative humidity (RH). The results showed that the moisture-adsorption and retention ability of TCS and QCS increased with the increase of DS. When compared with traditional humectants, SMMAHC with DS of 0.70 combined the advantages of both moisture-adsorption and retention of glycerol and HA. Kinetic studies showed that moisture adsorption of cationic starch was consistent with pseudo second order kinetics model and linear correlation coefficients reached more than 0.999.The cross-linked SMMAHC (C-SMMAHC) and cross-linked QCS (C-QCS) were used to investigate the flocculation ability for dyestuff (brilliant red KE-3B) waste water. The results showed that the suitable pH value range for using C-SMMAHC was 3-5, while C-QCS was suitable in a wider pH value range of 1-7. The higher the DS is, the higher the flocculation value is. Under the optimal conditions, the color removal rates were all more than 94.8%. The comparison of the cost of etherification reagents showed that:the cost of the new etherification reagents for preparing per ton new cationic starches were much lower than that of traditional quaternary ammonium cationic starches.