Batch and column adsorption of reactive dye by eggshell powder–chitosan gel core-shell material

In this study, eggshell powder-chitosan gel (EPCG) material was synthesized and tested as an adsorbent for two commercial reactive dyes in batch and dynamic modes. The EPCG material was a novel core-shell material in which the eggshell core particles were coated by a thin layer of chitosan. SEM images of dried EPCG powder showed a porous structure of the surface. In adsorption batch tests, Langmuir and Freundlich equations well described the adsorption isotherms with a maximum capacity of 2.3 mg/g at pH 4 and equilibrium time of 60 min (r 2 > 0.98). The adsorption process followed pseudo-second-order kinetics. Adsorption behaviour of EPCG toward the reactive dyes in fixed-bed adsorber was better described by the Clark model (r 2 > 0.92) than by the Bohart – Adam model (r 2 > 0.82). These results suggest that EPCG, as an environment-friendly material produced from waste eggshell, is very promising for wastewater treatment applications.