Amphoteric Starch Synthesis And Applied Research

3-chloro-2-hydroxypropyltrimethylammonium chloride was prepared by reacting epichlorohydrin with an excess mol of trimethylamine hydrochloride and the tree amine at room temperature. The effects of various factors on product purity were studied. And possible reaction mechanism was discussed. Besides, instead of traditional vacuum distillation, carrier distillation was applied for purifying the product. The proper technology parameters for the process were obtained by orthogonal test: the concentration of hydrochloric acid was 36%, the pH was 8, the molar ratio of epichlorohydin to trimethylammonium chloride was 0.95. Under the reaction condition, qualified product was obtained, containing 69% 3-chloro-2-hydroxypropyltrimethylammonium chloride, epichlorohydrin ^ 0.0004%, and l,3-dichloro-2-propanol^0.0018%.Instead of traditional wet reaction, amphoteric starches with low DS were prepared using above etherifying reagent by hemi-dry process in two steps. The effect of some factors on the reaction efficiency, such as amount of alkaline, reaction time, reaction temperature, and water content in system were discussed. The result showed that cationization efficiency reached 99-84.2%, while anionization 40-99% when achieving DSO.01~0.08. Crosslinked amphoteric starches with DSO. 1-0.3 were prepared by the same process. And the reaction efficiency of reached 68.9-90% when DS of cationic group (DSc) was 0.1-0.5, while 80-44% when DS of anionic group (DSa) was 0.1-0.5.Adsorption process was studied between crosslinked amphoteric starches and heavy metal ion, as well as dye wasterwater. The result indicated that crosslinked amphoteric starches were effective in removing heavy metal anion and cation. The adsorption efficiency reached up to 90% when SOmg/LC^O?2", Fe(CN)6~were treated by adding 0.6g/L amphoteric starch, the adsorption followed the Langmuir isotherm. The thermodynamic study indicated that the adsorption process was exothermic. While the dose was 0.8g/L, the adsorption efficiency for Cu2+ reached 80%, the adsorption followed the Freundlich isotherm. The decoloring experiment for lOOmg/L acid yellow 11 and acid red FG showed the decoloring efficiency reached up to 95% when the dose was 0.6g/L.By a series of moisture preservation and adsorption studies on amphoteric starch with DSa=0.23, DSc=0.3, it was proved that amphoteric starch had better moisture preservation and adsorption ability.