The structure activity relationship of non-dissolved redox mediators during azo dye bio-decolorization processes

► The dye decolorization rates were enhanced by non-dissolved redox mediators. ► The structure activity relationship of RM was elucidated from three aspects. ► The decolorization rate and reduction potential of RM was liner equation. ► The calculated ρ(rc) based on ATM consistent with its accelerating effects.