Kinetic studies on bioadsorption of arsenate from aqueous solutions using chitosan

Arsenic, one of the most toxic and dangerous elements in the environment affecting millions of people around the world, is associated with several diseases. In this pilot study, we investigated removal of arsenate from aqueous solutions using chitosan under the influences of initial arsenic ion concentrations, pH, contact time, and adsorbent dosages of chitosan. In order to assess the sorption mechanism and the potential rate of controlling steps, the pseudo-first and pseudo-second order kinetic models and the Langmuir and Freundlich isotherm models were used. The obtained results showed that the removal of As (V) by chitosan was found to be pH dependent, with optimum sorption occurring at pH = 4. The kinetics of arsenate adsorption on chitosan is well described by the pseudo-second order model. Furthermore, As (V) sorption isotherm was developed at optimal conditions and sorption equilibrium data were fitted to the Freundlich isotherm model.