Ozone oxidizing degradation of alkali wheat straw lignin and application of the modified lignin

The study indicated that alkali wheat straw lignin was degradated by O3/H2O2 oxidizing, the optimum conditions of the O3/H2O2 oxidizing were: H2O2 dosage 2.5%, ozone charge 5%, pH 7 - 8, temperature 20°C. The contents of Ph-OH and -COOH of the water insoluble lignin increased obviously after degradation by O3/H2O2 oxidizing. 0.95 mmol/g and 0.62 mmol/g were increased respectively compared with the oxidation only with ozone. After the analysis of molecular weight distribution of the degradated wheat straw lignin in different O3/H2O2 oxidizing conditions, it was found that comparing the ozone oxidizing without H2O2, the proportion of the molecular weight greater than 2000 of insoluble lignin increased obviously, at the same time, the degree of homogenization and molecular weight distribution were further improved. In the optimum conditions of O3/H2O2 oxidizing and Na2SO3 dosage was 5 mmol/g, the pulp had the highest flowage value which was up to 153 mm. At the same time, the surface activity was good.