Polysulfone-immobilized Corynebacterium glutamicum: A biosorbent for Reactive black 5 from aqueous solution in an up-flow packed column

Polysulfone-immobilized Corynebacterium glutamicum was employed as a biosorbent, for the continuous removal of Reactive black 5 (RB5) from aqueous solution, in an up-flow packed column. The biosorbent performance was evaluated with different bed heights (8-10 cm), flow rates (0.5-1 ml/min) and initial dye concentrations (50-100 mg/l). Favorable conditions for RB5 biosorption were observed with the highest bed height (10 cm), lowest flow rate (0.5 ml/min) and lowest initial dye concentration (50 mg/l); at which the RB5 uptake and % removal, 88.9 mg/g and 61.8%, respectively, were recorded. Mathematical modeling of experimental data was performed, using a non-linear form of the Thomas, modified dose-response and Yoon-Nelson models, to simulate the breakthrough curves. Very favorable results were obtained with the Thomas and Yoon-Nelson models, which described the experimental data well, with very high correlation coefficients. In an attempt to regenerate the exhausted biosorbent for possible reuse in multiple cycles, 0.1 M NaOH was employed as elutant. Due to continuous usage of polysulfone-immobilized C. glutamicum in three sorption-desorption cycles, a decreased breakthrough time, increased exhaustion time, broadened mass transfer zone, flattened breakthrough curve and decreased RB5 uptake were observed with progressive cycles. Linear regression of the breakthrough, uptake and critical bed length revealed that the sorption zone would reach top of the bed after 18 cycles, with the column bed completely exhausted after 35 cycles. The elutant, 0.1 M NaOH, provided uniform elution efficiencies greater than 99.2% in all three cycles.