Identification of adsorption or degradation mechanism for the removal of different ionic dyes with iron-carbon micro-electrolysis process

Abstract

The Fe-C micro-electrolysis materials (Fe-C MEM) are thought to be a good candidate in dyes removal. In this work, two Fe-C MEM (M1 and M2) with different physiochemical properties were compared in the dyes removal. Three cationic dyes (Three cationic dyes (malachite green (MG), crystal violet (CV), methylene blue (MB)), as well as two anionic dyes (methyl orange (MO), sunset yellow (SY)), were chosen in the study. The results showed that the M2 exhibited a better porosity with higher ZVI content, contributing to a higher dyes removal efficiency for all five dyes. Meanwhile, the cationic dyes had a higher dyes removal efficiency than anionic dyes. When the dyes were mixed together, CV had a higher removal efficiency than MG, although MG was the highest in the single dye solution. The removal mechanism of the five dyes was different. The two cationic triphenylmethane dyes (CV and MG) could be degraded while the two anionic azo dyes (MO, SY) were not degraded but adsorbed on Fe-C MEM. MB was removed mainly based on adsorption and coagulation.