Dye Sorption from Mixtures on Chitosan Sorbents

This article presents studies on the sorption of the anionic dyes Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84) from solutions of single dyes and from dye mixtures onto three chitosan sorbents–chitin, chitosan DD75% and chitosan DD95%. In this work, the influence of pH on sorption efficiency, the sorption equilibrium time for the tested anionic dyes and the sorption capacity in relation to the individual dyes and their mixtures were determined. It has been found that the sorption process for both dyes was most effective at pH 3 for chitin and chitosan DD75 and at pH 4 for chitosan DD95%. The obtained results were described by the double Langmuir equation (Langmuir 2). The obtained constants made it possible to determine the affinity of the tested dyes for the three sorbents and the sorption capacity of the sorbents. For RB5, the highest sorption capacity for chitosan DD95% was achieved with sorption from a single solution-of 742 mg/g DM and with sorption from mixed dyes-of 528 mg/g DM. For RY84, the highest efficiency was also achieved for chitosan DD95% and was 760 mg/g DM for a single dye solution and 437 mg/g DM for a mixture of dyes.