Adsorption rate of Reactive Black 5 on chitosan based materials: geometry and swelling effects

The overall adsorption rate of Reactive Black 5 dye (RB5) on chitosan based materials was elucidated using diffusional models. Fundamental aspects, such as, geometry of the adsorbents and swelling effects were considered. Chitosan based materials (powder and film) were prepared from shrimp wastes and characterized regarding to the fundamental features for adsorption. Experimental decay curves were obtained under different conditions of stirring rate and initial dye concentration. The data were modeled according to the external mass transfer and diffusional models. The kL (external mass transfer coefficient), Dep (effective pore diffusion coefficient) and Ds (surface diffusion coefficient) values were estimated. For both adsorbents, it was found that the surface diffusion was the intraparticle diffusion mechanism governing the adsorption rate of RB5, since its contribution was higher than 92 %25 regardless the position and time. The Ds values ranged from 2.85 × 10−11 to 5.78 × 10−11 for chitosan powder and from 4.15 × 10−11 to 12.12 × 10−11 cm2 s−1 for chitosan films. The RB5 adsorption was faster when chitosan powder was used, mainly at higher stirring rates and initial dye concentrations. The swelling effect was most pronounced for the chitosan films, where, provided an increase of about 65 times in the Ds value. © 2016, Springer Science%2bBusiness Media New York.

Chitosan films; Chitosan powder; Mass transfer; Reactive Black 5; Swelling Adsorption; Chitosan; Mass transfer; Surface diffusion; Chitosan film; Chitosan powder; External mass transfer; External mass transfer coefficient; Initial dye concentration; Intra-particle diffusion; Reactive black 5; Reactive black 5 dyes; Swelling

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