Desorption of reactive dyes from modified chitin.

A study was undertaken to evaluate the efficiency of adsorption and desorption of three reactive dyes on to modified chitin. Black DN from the chlorotriazine group, Scarlet R from the vinylsulfone group of dyes and a chlorovinyl dye, Brilliantorange 3R, were examined. Following adsorption of the dyes at pH 3, their desorption was carried out at pH 11. The results obtained indicated that the highest efficiency of desorption, nearly 100%, was obtained for Brilliantorange 3R, and lower ones for Scarlet R and Black DN, at 89% and 90%, respectively. The highest number of adsorption/desorption cycles, nearly 100, was recorded for Brilliantorange 3R. In the case of Scarlet R the number of subsequent adsorption/ desorption cycles run reached around 25, whereas in the case of Black DN it accounted for 37.