Chitosan adsorbent reinforced with citric acid modified beta-cyclodextrin for highly efficient removal of dyes from reactive dyeing effluents

摘要

A simple and convenient method for preparing a porous bio-absorbent for treating reactive dyeing effluents was developed. Chitosan adsorbent reinforced with citric acid modified beta-cyclodextrin (CA-CD) was prepared via room temperature amidation followed by freeze-drying. Using reactive blue 49 as the model adsorbate, optimum adsorption (up to 500 mg g(-1)) was achieved with the adsorbent containing 20 wt% CA-CD. The adsorption process was pH-adjustable, so that more efficient dye removal could be achieved by decreasing the pH and regeneration was possible vice versa. Salts and surfactants commonly used in reactive dyeing were found to have moderate negative influence on the adsorption efficiency. The adsorbent was also demonstrated to be generally effective for common reactive dyes including C.I. Reactive Blue 49, Reactive Yellow 176, Reactive Blue 14, Reactive Black 5, and Reactive Red 141, which varied in size and structure. The removal rate of C.I. Reactive Blue 49 was almost 80% even after six adsorption-desorption cycles, confirming the reusability of the adsorbent. Owing to the use of simple and mild preparation conditions, and bio-based chemicals, we believe that this work provides a foundation for the development of environment friendly bio-absorbents for the treatment of reactive dyeing effluents.