Preparation and characterization of chitosan-zirconium(IV) composite for adsorption of vanadium(V)

• Chitosan-zirconium(IV) composite was prepared and used for removal of V(V).
• The maximum capacity was as high as 208 mg g−1 for V(V) adsorption.
• The adsorption was dependent on the solution of pH and temperature.
• Mechanism for V(V) adsorption on chitosan-zirconium(IV) composite was elucidated.

In this present study, an inorganic-biopolymer composite based on chitosan-zirconium(IV) was prepared and investigated as a biosorbent for the removal of vanadium(V) ions from aqueous solution. The resulting composite before and after adsorbed V(V) were characterized by using FT-IR, XRD, SEM and EDS, respectively. Various relevant parameters affecting the adsorption capacity such as pH, initial concentration, contact time, temperature and co-existing ions were evaluated. The results demonstrated that the optimum pH was found to be 4.0 and the equilibrium was achieved after 4 h for V(V) adsorption. The Langmuir isotherm model could be well described the adsorption of V(V), with the maximum adsorption capacity of 208 mg g−1 at 30 °C. The kinetics data were well fitted to pseudo-second-order equation, indicating that chemical sorption as the rate-limiting step of adsorption mechanism. The calculated thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated that the adsorption process was feasible, spontaneous and endothermic in nature. Moreover, co-existing ions including nitrate, chloride and sulfate had a certain effect on the uptake of V(V). The V(V) loaded chitosan-zirconium(IV) composite could be regenerated by 0.01 mol L−1 sodium hydroxide, with efficiency greater than 95%.