Chitosan-coated sand and its application in a fixed-bed column to remove dyes in simple, binary, and real systems.

Adsorption of tartrazine yellow food dye, in a fixed-bed column, was carried out using a single system, a binary system (in the presence of sunset yellow food dye), and in a real effluent provides from an ice cream industry. Chitosan was used to coat sand particles by the dip-coating technique, and these particles were applied in fixed-bed adsorption. The assays were performed in flow rates of 3 mL min and 5 mL min. The best performance was reached at 3 mL min. In this flow rate, for single and binary systems, the breakthrough time was 95 min and 65 min, and the maximum capacity of the column was around 595 mg g and 497 mg g, respectively. In the assay conducted with the real effluent, the breakthrough time was 10 min, and the maximum adsorption capacity of the column was reduced to 191 mg g for tartrazine dye. The dynamic models of Thomas and Yoon-Nelson were used, and both were suitable to represent the breakthrough curves.