Effect of the form and deacetylation degree of chitosan sorbents on sorption effectiveness of Reactive Black 5 from aqueous solutions

The article presents the impact of a chitosan sorbent form (flakes/hydrogel granules) and the degree of its deacetylation (DD = 75%/DD = 85%/ DD = 90%) on the effectiveness of sorption of a popular textile dye Reactive Black 5 (RB5). The effect of pH on dye sorption effectiveness was examined as well as RB5 sorption kinetics and RB5 sorption capacity of the chitosan sorbent were tested. The highest sorption capacity (1559.7 mg/g) was obtained for the chitosan hydrogel in the form of granules (DD = 90%). Due to a loose structure and an easy access to sorption centers, chitosan hydrogel granules may ensure up to 224% higher sorption capacity (Q(DD75%) = 1307.5 mg/g) than chitosan in the form of flakes (D-DD75% = 403.4 mg/g). The sorption effectiveness of the tested dye was observed to increase in the range of DD = 75% < DD = 85% < DD = 90%. The deacetylation degree of chitosan had a particularly large impact on RB5 sorption effectiveness by chitosan in the form of flakes. The effectiveness of adsorption on the flakes with a deacetylation degree DD =90% was 1049.6 mg/g and was by 160% higher than on the flakes with DD = 75%. (C) 2016 Elsevier B.V. All rights reserved.