Degradation of dye solution by an activated carbon fiber electrode electrolysis system

Degradation of 29 dyes by means of an activated carbon fiber (ACF) electrode electrolysis system was performed successfully. Almost all dye solutions tested were decolorized effectively in this ACF electrolysis process. Internal relationships between treatment mechanisms and chemical composition of the dye have been discussed in this paper. Generally, it is shown that higher solubility leads to greater degradation in the process. Dyes with many -SO(3)(-), COO(-), -SO(2)NH(2), -OH, hydrophilic groups, and azo Linkages are susceptible to reduction. However, dyes with many -C=O, -NH- and aromatic groups, and hydrophobic groups, tend to be adsorbed. For dyes with -SO(3)(-), -COOH and -OH groups, if their molecules linearly spread in solution and have a significant tendency to form colloids by hydrogenous bonding, they also tend to be adsorbed and flocculated. Typical dynamic electrolysis of dye Acid Red B, Vat Blue BO and Disperse Red E-4B shows how the two major mechanisms, degradation and adsorption, act differently during treatment. Reduction occurs evenly during treatment. During the dominant adsorption process, after certain amount of iron is generated, colloid precipitation occurs and TOC and color are rapidly removed. (C) 2001 Elsevier Science B.V. All rights reserved.