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Abstract
Chitosan films (CF) are an interesting way to remove heavy metals from aqueous solutions. The effluents containing vanadium is highly toxic from environmental viewpoint, then, the aim of this work was to evaluate the vanadium adsorption onto CF. The films were prepared by casting technique and characterized (tensile strength, elongation, and thickness). The vanadium adsorption was optimized as a function of the pH and film dosage by response surface methodology. The equilibrium isotherms were obtained and the thermodynamic parameters were estimated. The vanadium–CF interactions were elucidated, and also regeneration studies were performed. The more suitable adsorption conditions were in pH 6 and film dosages of 100 and 300 mg L−1, under these conditions, the vanadium removal percentage and adsorption capacity were of 50.3% and 251.4 mg g−1, respectively. The BET model showed best fit for the experimental equilibrium data. The adsorption process was spontaneous, favorable, and endothermic. Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed the presence of vanadium on CF after adsorption. Desorption was possible with 0.01 mol L−1 NH4Cl solution. The CF maintained the structural characteristics and adsorption capacities after six cycles of regeneration.
Acknowledgment
The authors would like to thank CAPES (Brazilian Agency for Improvement of Graduate Personnel) and CNPq (National Council of Science and Technological Development) for the financial support.