非催化条件下H_2O_2对淀粉的氧化降解行为

在非催化条件下,H2O2可以有效地对淀粉进行氧化降解。H2O2用量由2 mL增加至12 mL的过程中,淀粉的粘度下降百分率由3.49%增加至57.91%,继续增加H2O2的用量,淀粉的粘度下降百分率不再明显变化。对降解时间的研究表明,最佳反应时间为120 min,延长反应时间,淀粉的粘度反而有所增加。在18~70℃的范围内,H2O2对淀粉的氧化降解性能先增加后减弱,在60℃时达到最好,淀粉的粘度下降百分率为52.36%。在H2O2的作用下,淀粉中羟基部分被氧化为羧基或醛基,另外淀粉分子链中的1,4位的环间苷键也可能被打断,从而使淀粉的粘度下降。

Study on oxidative degradation of amylum caused by H2O2 without catalytic condition

The oxidative degradation of amylum could be carried out effectively by using H2O2 as an oxidant.The decreasing ratio of viscidity of amylum reached 3.49% from 57.91% when the amount of H2O2 increased from 2 mL to 12 mL.The decreasing ratio of viscidity of amylum did not change obviously while the amount of H2O2 increased continuously.The effect of reaction time showed that the optimal reaction time is 120 min.However,the viscidity of amylum increased by prolonging the reaction time continuously,The oxidative degradation capability of H2O2 increased at first and then decreased when the temperature ranged from 18 ℃ to 70 ℃.The best reaction temperature is 60 ℃ and the decreasing ratio of viscidity of amylum is 52.36%.The hydroxyls in the molecular structures of amylum were oxidized to be carboxyl or aldehyde groups,and the cleavage of 1,4-glucoside bonds also occurred in the presence of H2O2.Therefore,the viscidity of amylum decreased.