Synthesis And Application Of Quaternary Ammonium Cationic Starch With Low Viscosity

Cationic starches are a kind of starch derivatives obtained by introduction of cationic groups through etherifying,esterifying or grafting reaction of starch.They are widely used in many fields.The researches on developing new cationizing reagents,innovating synthesis process,improving application properties and enlarging application area,becomes intensive topics and focus is mainly made on quaternary ammonium cationic starch because they are stable both in acidic,neutral and basic conditions.In this thesis,synthesis and application of esterified/etherified quaternary ammonium cationic starch were studied.The optimum synthesis conditions of esterified cationic starch—starch betainate by organic solvent method were firstly studied in detail.In view of complicated process, environmental pollution and corrosion of equipment resulted from organic solvent method, eco-friendly dry method was established to prepare starch betainate with dicyandiamide as a dehydrating reagent.Two etherified cationic starches—starch-2-hydroxypropyltrimethylammonium chloride derivative with low viscosity and water-insoluble cationic starch were prepared by dry method.The etherified cationic starch with low viscosity and starch betainate were characterized by FTIR spectroscopy,NMR spectroscopy,X-ray diffraction,scanning electronic microscopy,etc.Conductometric titration was designed to determine the DS of starch betainate with low viscosity,and the results showed that the method was feasible,which was simply,quick and the amount of starch betainate used in titration was small.Starch betainate was applied in flocculation of kaolin suspension.The flocculation efficiency of starch betainate increased with the increase of both DS and molecular weight of starch betainate,which demonstrated that the flocculation was realized mainly by charge neutralization and bridging of the particles.When the dose of crosslinked starch betainate with DS of 0.330 was 3ppm,the removal ratio of turbidity could reach 90.5%,which was similar to the effect of traditional etherified cationic starch.The flocculation efficiency of starch betainate decreased with the increasing amount of salt in the kaolin suspension.Besides. pH of 5-7 was shown reasonable in application.Etherified cationic starch with low viscosity was prepared by cationization of hydrolyzed starch,which was suitable for application in salt-free dyeing.Dye fixation increased along with the increase of DS of etherified cationic starch,and the property of level dyeing was good when decreasing the viscosity of etherified cationic starch.The highest dye fixation for C.I.Reactive Red 2,C.I.Reactive Blue 19 and C.I.Reactive Yellow 145 was 69.4%,73.8% and 75.3%,respectively,and the corresponding concentrations of CHS6 were 30 g/L,22.5 g/L and 17.5 g/L,respectively,which was higher than that of conventional exhaust dyeing by 20.3%,0.9%and 18.4%,respectively.Besides,level dyeing and good wash fastness were achieved by pretreating cotton with cationic starch with low viscosity.Water-insoluble etherified cationic starch was obtained by cationizing crosslinked starch. The adsorption behaviors of water-insoluble etherified cationic starch for C.I.Acid Red 1,C.I. Acid Yellow 4,C.I.Acid Yellow 17 and C.I.Acid Orange 7 were investigated,and this starch derivative was proved to be good adsorbent for acid dyes.The adsorption process was so quick and adsorption reached equilibrium nearly in 15min.The adsorption fit the pseudo-second-order model.The negative△G~θfor the adsorption showed the spontaneous nature of the process.The adsorption equilibrium data correlated well with the Langmuir isotherm model,and the adsorption capacity increased with the increasing DS of water-insoluble cationic starch,which demonstrated that the adsorption mechanism was adsorption of unimoleeular layer and the adsorption was mainly ion exchange adsorption realized by the electrostatic attraction between the anions of the dyes and the cations of the water-insoluble cationic starch.The corresponding maximam of adsorption capacity from the Langmuir isotherm model for C.I.Acid Red 1,C.I.Acid Yellow 4,C.I.Acid Yellow 17 and C.I.Acid Orange 7 were 1.27,1.16,2.44,2.92mmol/g,respectively.The optimum pH rang for the adsorption of the acid dyes with hydroxyl group was wider than that of the dyes without hydroxyl group.