Electro-Degradation of Sodium Lignosulfonate

Abstract

The electro-degradation of sodium lignosulfonate was conducted in an electrolytic cell equipped with PbO₂ membrane electrode as the anode and stainless steel gauze as the cathode. Sodium lignosulfonate was degraded into substances with relatively low molecular weights. Some high molecular weight fractions were also formed during the reaction demonstrating that the condensation occurred simultaneously with degradation. The distribution and the characteristics of the products were greatly affected by the voltage, the electricity consumption, the current density, and the pH. Degraded lignosulfonate gave much lower surface tension and oil–water interfacial tension than unreacted lignosulfonate did in aqueous solution.

Keywords:

• Electro-degradation
• Lignosulfonate
• Condensation
• Ring cleavage

Acknowledgments

The financial support from the Guangdong Provincial Natural Science Foundation of China (Project No. 994572) and the State Key Laboratory of Pulp and Paper Engineering, South China University of Technology is gratefully appreciated.