Fast and efficient removal of Reactive Black 5 from aqueous solution by a combined method of ultrasound and sorption...

Removal of Reactive Black 5 (RB5) from aqueous solutions was carried by the sorption process in the presence and in the absence of ultrasound. Sorption of the dye on the solid phase was investigated in a series of batch sorption experiments to determine the influence of different parameters such as contact time, amount of sorbent and concentration of pollutant on the removal efficiency of RB5 with and without ultrasound. The experimental data were fitted properly to the Freundlich model and the isotherm constants were 28.2 and 7.4 for k(f) and 0.13 and 0.38 for 1/n in the presence and in the absence of ultrasound (20 kHz) respectively. The data were analyzed with different sorption kinetic models and were better fitted with a pseudo-second-order kinetic model. Two ultrasonic generators at 20 and 500 kHz were used for sonication of the system. This investigation also reveals that RB5 can be removed by higher frequency apparatus (500 kHz) without sorbent in about 60 min sonication. The rate of removal was higher at the higher frequency than at the lower one.