Interaction between protonated waste biomass of Corynebacterium glutamicum and anionic dye Reactive Red 4

The protonated waste biomass of Corynebacterium glutamicum discharged from an industrial lysine fermentation plant was used as a new type of biosorbent for the removal of anionic dye Reactive Red 4. The dye uptake increased as the solution pH was decreased and at pH >7, the uptake was negligible. The maximum uptake of dye was estimated to be 104.6 ± 8.7 mg/g at pH 1. To identify the binding sites in the biomass, the biomass was potentiometrically titrated. As a result, three types of functional groups were present in the biomass, which was confirmed by FTIR analysis. Among functional groups, primary amine groups (–NH2) were likely the binding sites for anionic Reactive Red 4. The proton dissociated constant pKH and molar content of the protonated amine groups were 9.14 ± 0.07 and 0.68 ± 0.02 mmol/g, respectively. It was also found that carboxyl and phosphonate groups played a role in electrostatic interference with the binding of dye molecules.