An aminated bacterial biosorbent capable of effectively binding negatively charged pollutants in aqueous solution

The main aim of this work was to enhance the biosorption capacity of Corynebacterium glutamicum for the remediation of wastewaters containing Reactive dyes. Amine groups were found to be responsible for accommodating negatively charged Reactive Red 4 (RR4) molecules via electrostatic interaction. Thus, increasing the number of amine groups on C. glutamicum, via amination, resulted in an enhanced RR4 biosorption capacity. The pH-edge experiments revealed that acidic conditions (pH = 2) favoured the biosorption of RR4 molecules. Isotherm experiments indicated that the aminated C. glutamicum exhibited the highest RR4 uptake, i.e. 133.8 mg/g at pH 2, compared to 96.8 mg/g for raw C. glutamicum. Of the two isotherm models considered, the Toth model provided a better description of the experimental isotherms, with high correlation coefficients and low percentage error values. Kinetic experiments revealed the importance of the initial dye concentration, with equilibrium being rapidly attained after ca. 1 h for all the concentrations examined. The non-linear form of the pseudo-second-order model described the biosorption kinetic data, with high correlation coefficients and low percentage error values compared to the pseudo-first-order model. Desorption was successful achieved at pH 10, with > 90.2% elution efficiencies for both the raw and aminated biomasses.