Adsorption behavior of cationic and anionic dyes on magadiite-chitosan composite beads.

In this paper, the composite beads were obtained by the encapsulation of a lamellar polysilicate magadiite in chitosan. The composite beads were tested as adsorbents for the removal of anionic Congo red (CR) and cationic methylene blue (MB) dyes. The obtained material was characterized by different methods such as XRD, SEM, TGA and zeta potential analysis. The adsorption mechanism of both dyes was supported by UV-vis and (FTIR) spectroscopy. The results reveal that the magadiite was immobilized in the chitosan matrix by hydrogen bond and electrostatic interactions. The influence of contact time, adsorbent dose and initial concentration of dye were investigated. The adsorption kinetics of CR onto composite beads followed the linear form of pseudo-second-order model and their equilibrium data were fitted well to the linear Langmuir model as confirmed by the calculated values of R2, RMSE and SD. The adsorbed quantity registered for CR and MB dyes are 135.77 and 45.25 mg/g, respectively.