Biosorptive decolorization of reactive orange 16 using the waste biomass of Corynebacterium glutamicum

The protonated waste biomass of Corynebacterium glutamicum discharged from an industrial lysine fermentation plant was used for the removal of Reactive Orange 16 (RO16). The maximum sorption capacities of the biomass were as high as 186.6 +/- 7.1 and 154.8 +/- 2.8 mg g(-1) at pH 1 and 2, respectively, which are comparable to those of commercial sorbents such as activated carbons and ion-exchange resins. As the solution pH decreased, the dye uptake increased and, under neutral conditions, it was negligible. Because the RO16 molecule has two negatively charged sulfonate groups, it is likely that the dye cannot be bound to a negatively charged carboxyl and/or phosphonate sites of the biomass. Instead, positively charged amine-occurring protein molecules seem to be dye binding sites. The uptake of RO16 was not significantly affected by a high concentration of salts, and the biomass could be repeatedly reused up to eight times per sorption/desorption cycle, reflecting that the biomass wastes deserve to be a potential regenerable biosorbent for dye removal.