Anionic And Cationic Modification Of Inulin And Their Application Properties

Considering that the modified inulin could have some extra properties besides theoriginal biodegradability, renewability and non-toxicity of native inulin, the modified inulinwould be applied in many fields. This thesis studied the preparation of carboxymethylinulinand cationic inulin by using sodium chloroacetate and glycidyl trimethyl ammonium chloride(GTA) as etherification reagents respectively, and their application properties were alsoinvestigated. A new method for analysing the degree of substitution (DS) ofcarboxymethylinulin was established, that was spectrophotometric titration. The DS obtainedby spectrophotometric titration was the same as that of traditional method.The carboxymethylinulin (CMI) was prepared by reacting pure or impure inulin withsodium chloroacetate in alkali medium using microwave method. The effects of reactionconditions to DS and reaction efficiency were researched. The suitable reaction conditionswere as follows: alkalization time was 2.5 min, etherification time was 30 min, the amount ofNaOH was 0.40 g, the volume of isopropyl alcohol solution (φ(isopropyl alcohol)=90%) was2 mL, the power of microwave oven was 90 W and the dosage of inulin and sodiumchloroacetate were 2.70 g and 1.70 g respectively. Under these conditions, when pure inulinwas used as substrate, the DS and reaction efficiency of CMI reached 0.5t and 57.7%respectively, while when impure inulin was used as substrate, the DS and reaction efficiencyof CMI was 0.46 and 52.1% respectively.Anti-scale properties of CMI and chelation of Cu²⁺ and CMI were also studied, pH shiftmethod was used to evaluate the anti-scale properties of CMI. The anti-scale ratio was 99.6%when 3 mL solution of CMI(2 mg/mL), which DS was 0.51, was mixed with 150 mLexperiment solution. UV spectrophotometry method was used to measure the chelation ofCMI and Cu²⁺. The minimum concentration of Cu²⁺ detected was 0.4×10^-4 mol/L. When CMI(DS=0.51) was used as adsorbent of Cu²⁺, the maximum chelate ratio could achieve 92.5%, and the maximum adsorption capacity could achieve 1.00 mmol/g.The cationic inulin was prepared via reacting inulin with GTA in the presence of NaOHin water. Many factors affected DS and reaction efficiency. The suitable reaction conditionswere as follows: the reaction time was 4 h, the reaction temperature was 60℃, the dosage ofNaOH was 0.40 g, the volume of water was 5 mL and the dosage of inulin and GTA were 5.00 g and 3.50 g respectively. Under these conditions, the DS and reaction efficiency of CMIreached 0.54 and 72.6% respectively.The moisture absorption, moisture retention properties and antibacterial properties ofcationic inulin were studied. When the relative humidity(RH) was 81%, moisture absorptionratio of CMI(DS=0.65) was 65.0%, and then, when the RH was 43%, moisture retention ratiocould reached 50.8% after 48 h. Cationic inulin also has better selectivity to gram-negativebaeteria-E.coil. For cationic inulin (DS=0.65), the minimum inhibitory concentration(MIC)was 2.5 mg/mL, in which the quanternary ammonium salt content was 0.47 mg/mL. And theminimum bactericidal concentration (MBC) was 5.0 mg/mL after it. had been acted on thebacillus for 5 h.