Different binding mechanisms in biosorption of reactive dyes according to their reactivity

Various binding mechanisms for the uptake of reactive dyes by the protonated waste biomass of Corynebacterium glutamicum were investigated. As model reactive dyes, Reactive Blue 4 (RB 4), Reactive Orange 16 (RO 16) and Reactive Yellow 2 (RY 2) were used in this study. The solution pH strongly influenced the sorption capacity and the binding mechanisms of reactive dyes by C. glutamicum. At acidic pH, the electrostatic interaction was found to be a major binding mechanism. The maximum uptakes of RY 2, RO 16 and RB 4 at pH 2 were estimated to be 155.0 ± 14.1, 156.6 ± 6.7 and 184.9 ± 16.4 mg/g, respectively. Under alkaline conditions, the binding mechanisms were quite different according to the reactivity of reactive dyes. It was found that chemical bonding existed between the biomass surface and dye molecules under basic pH conditions.