Degradation of calcium lignosulfonate using gamma-ray irradiation

• Published in: Chemosphere (Oxford) 2004-12, Vol.57 (9), p.1181-1187
• Main Authors: Zhang, Shu-Juan, Yu, Han-Qing, Wu, Liang-Xing
• Format: Article
• Language: English
• Subjects: Applied sciences; calcium lignosulfonate; CaLS; Exact sciences and technology; gamma radiation; Gamma Rays; Hydrogen Peroxide - chemistry; Industrial wastewaters; Ionizing radiation; Iron - chemistry; irradiation; Kinetics; Lignin - analogs & derivatives; Lignin - chemistry; Lignin - radiation effects; lignosulfonates; Mineralization; photolysis; Pollution; pulp and paper mill effluents; Spectrophotometry, Ultraviolet; wastewater treatment; Wastewaters; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2004.08.015

Gamma-ray irradiation was proven to be a promising means for the removal of calcium lignosulfonate (CaLS). At a dose rate of 55 Gy min −1, over 90% of CaLS was mineralized to CO 2, H 2O and sulfates within 3-d irradiation. The degradation of CaLS with the initial CaLS concentrations ranging from 40 to 200 mg l −1 followed zero-order kinetics at the dose rates of 16–150 Gy min −1. The zero-order degradation rate constant was functionally related with irradiation dose rate. Experiments performed with or without addition of radical scavengers demonstrated that the role of OH was predominant in CaLS degradation and the reductive species made minor contributions to CaLS degradation. Addition of appropriate amounts of H 2O 2 significantly enhanced the mineralization of CaLS, e.g., addition of 10 mM H 2O 2 at a dose rate of 55 Gy min −1 elevated the mineralization rate constant by five times. The addition of Fenton’s reagent to irradiated CaLS solutions facilitated the degradation of CaLS, but no obviously synergistic effect was observed.