Removal of an Anionic Reactive Dye by Chitosan and its Regeneration

Chitosan, a waste from the food industry, was employed for the removal of Reactive Black 5, a water-soluble anionic dye, from aqueous solution. Adsorption of this dye onto chitosan was studied with respect to pH, contact time and dye concentration. Optimum pH was ranging from 1 to 3. The addition of chitosan to dye solution strongly affected the pH of solution and sorption efficiency. To avoid this pH variation, the initial pH was set at 2.3 (no change in final pH). Reactive Black 5 was efficiently adsorbed on chitosan. The maximum sorption capacity was close to 480 mg g(-1). The aim of this study was also to screen a variety of nontoxic desorbing agents, in order to find out possible application in multiple sorption-desorption cycles. Sorption and desorption experiments have been carried out in batch system, at room temperature. Desorption studies showed that the dye adsorbed on chitosan could be effectively desorbed using diluted KOH and NaOH solutions (0.01 M). The successive sorption-desorption studies using NaOH, indicated that chitosan could be regenerated and reused several times.