Equilibrium and kinetic studies on the adsorption of surfactant, organic acids and dyes from water onto natural biopolymers

In order to improve the mechanical property of chitosan beads, the powder of loofah fiber was added in chitosan/acetic acid slurry to prepare composite beads with and without freeze-drying. The former was called the dried bead and the latter was the wet bead. The equilibria and kinetics for adsorption of linear alkylbenzene sulfonate, tannic acid, humic acid, and three dyes (reactive, acidic, and basic) onto these two beads were compared at 30 °C. It was shown that the adsorption capacity with the wet bead was generally higher than that with the dried bead. Lumped kinetic analysis indicated that the pseudo-first-order equation could well describe the adsorption processes. On the other hand, the better fit of kinetic data by the Elovich equation instead of by intraparticle diffusion model suggested the significance of chemisorption mechanism during the processes. The parameters of these kinetic models were also evaluated and discussed.