Comparison of different types of redox mediators on the chemical reduction of azo dye by sulfide

摘要

Azo dyes are extensively used in the industry, resulting in the large amount of wastewater. Redox mediators (R.M.) can accelerate the chemical reduction of azo dye by shuttling electrons from primary electron donors such as sulfide to azo dyes. Three different types of R.M. were studied on the enhancement of chemical reduction of Acid Orange 7. The electron shuttle ability of these types of R.M. with 2.5 mM of initial sulfide concentration at pH 7.5, either dissolved or undissolved type, followed in order by riboflavin, humic acid and activated carbon. The potential engineering application of these R.M. lie on the superior catalytic ability for riboflavin, wide existence in the environment for humic acid, and retaining in the bioreactors all the times for activated carbon.