Study of the oxidative modification of calcium lignosulfonate

The oxidative modification process of calcium lignosulfonate (CLS) was studied. The influence of several oxidizers on the properties of CLS was measured. The results showed that the effect of oxidative degradation and polymerization of hydrogen peroxide on CLS was small. Ammonium persulfate could greatly improve the surface activity and dispersion properties of CLS under the optimum conditions that the amount of ammonium persulfate was 4% - 6%, reaction temperature was 80 - 90°C and pH of solution was 8 - 10. The oxidation-polymerization mechanism of CLS was discussed. Under alkaline condition ammonium persulfate causes ionization and dehydrogenation of the lignin phenols to form free radicals and thus promotes the polymerization of CLS.