Adsorption of Reactive Dyes by Modified Chitin from Aqueous Solutions
1. U. Filipkowska, 1. E. Klimiuk, 2. S. Grabowski, 3. E. Siedlecka
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1. Faculty of Environmental Sciences and Fisheries
University of Warmia and Mazury in Olsztyn, Poland
2. Faculty of Geodesy and Land Management
University of Warmia and Mazury in Olsztyn, Poland
3. Faculty of Chemistry University of Gdansk, Poland
Pol. J. Environ. Stud. 2002;11(4):315–323
The adsorption of reactive dyes onto chitin (deacetylation degree = 5%) was investigated from aqueous solutions at pH 3. Ten reactive dyes were examined, including 5 dyes from the helactine group, 3 dyes from the polactine group and 2 dyes from the remazol group. The K and b constants were calculated from the Langmuir equation that assumes the presence of two sites of different nature. It was found that the dye adsorption on chitin in type I and II sites differed in both the adsorption affinity and maximum adsorption capacity. Based on the dimensionless separation factor RL it was found that the dye adsorption mechanism in type I sites was an ion exchange, whereas in the case of type II sites it was a physical adsorption. A correlation was found between dye adsorption on chitin and the number of sulfone groups in a dye molecule. However, neither molecular weight nor the number of aromatic rings was correlated with dye adsorption.