Effect of single and binary mixed surfactant impregnation on the adsorption capabilities of Chitosan hydrogel beads toward RhodamineB.
The adsorption of cationic xanthene dye RhodamineB (RhB) on pure Chitosan (CS), single surfactant (SDS, Brij30 and DTAB) and binary surfactant (SDS-Brij30 and DTAB-Brij30) modified Chitosan beads has been investigated. While the adsorption capacity of CS/SDS and CS/Brij30 beads were enhanced at all concentrations of SDS (0-4mM) and Brij30 (0-1mM), however the increase in the concentration of DTAB above 1mM in the CS/DTAB beads reduced the adsorption capacity of the beads significantly. Furthermore, the adsorption studies were carried out in the mixed surfactant impregnated CS beads. The adsorption capacity of CS/SDS-Brij30 beads increases with increase in mole fraction of SDS and in CS/DTAB-Brij30 the adsorption capacity increases upto mole fraction of DTAB=0.4, beyond which it decreases with further increase in DTAB mole fraction. The mixing of surfactants in the CS beads had a synergistic effect on the adsorption capability of these beads which is important from environmental point of view and cost effectiveness in the manufacture of such beads. The equilibrium adsorption data were analyzed using Langmuir, Freundlich, and Temkin adsorption isotherm models. The results showed better agreement with the Langmuir model and hence indicated a homogeneous adsorption process. The maximum Langmuir adsorption capacity of CS and surfactant modified CS follows the order: CS<CS/DTAB<CS/DTAB-Brij30<CS-Brij30<CS/SDS-Brij30<CS/SDS. After comparing with the literature, the SDS and SDS-Brij30 modified CS beads exhibited significantly higher adsorption capacities ≈1000 mg/g more adsorbent for the effective removal of Rh B than reported so far.