Alginate-chitosan beads were used asudadsorbent to remove two azo anionic textile dyes, DirectudBlue 78 and Direct Yellow 106, from aqueous solutions.udBatch mode experiments of dyes adsorption wereudperformed and the effects of various parameters such asudcontact time, adsorbent dosage, initial dye concentration,udpH and temperature were examined.udSuccessively, the dyes have been desorbed from theudadsorbent and were recycled to dye a cotton fabric.udThe maximum efficiencies in dye removal, performed atudpH 6, 298 K and with 0.5 g of adsorbent, were found to beudabout 97% for Direct Blue 78 and about 86% for DirectudYellow 106, respectively. The adsorption isotherms fittedudthe Freundlich’s model, the adsorption kinetics followedudthe pseudo-second order model and experimental dataudindicated an exothermic adsorption process. Moreover,udthe dyes desorption experiments from the alginatechitosanudbeads demonstrated that about 50% of dyes wereudreleased in distilled water at high temperature (368 K)udand the colored solutions obtained were so reused inuddyeing tests.udThe results demonstrated that the alginate-chitosan beadsudare very efficient systems able not only to remove dyesudfrom wastewater, but also to recycle and reuse them inudfurther dyeing processes.
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