Development of chitosan/Spirulina sp. blend films as biosorbents for Cr⁶⁺ and Pb²⁺ removal

Chitosan film, Spirulina sp. film and its blend were developed as biosorbents to remove Cr⁶⁺ and Pb²⁺ ions from aqueous solutions. The kinetic study and the pH effect on biosorption efficiency were evaluated to comprehend the interactions between the ions and biosorbents. The characterization analyses pointed out that occurred interaction between both biomaterials, which resulted in structural alterations through the blend. The Spirulina sp. film exhibited the highest biosorption capacities for Cr⁶⁺ (43.2 mg g^-1) and Pb²⁺ (35.6 mg g^-1) ions, however, its physical integrity was not kept in acid medium. The blend film showed results slightly lower (35.8 mg g^-1 for Cr⁶⁺ and 31.6 mg g^-1 for Pb²⁺), but its physical integrity remained intact in all assays. Chitosan film presented the lower biosorption capacities (15.4 mg g^-1 for Cr⁶⁺ and 20.9 mg g^-1 for Pb²⁺). Elovich and pseudo-second order models were the most suitable to express the kinetic behaviors for Cr⁶⁺ and Pb²⁺, respectively. Therefore, chitosan/Spirulina sp. blend could be a green alternative for Cr⁶⁺ and Pb²⁺ removal, because this biosorbent showed high biosorption capacity obtained from Spirulina sp. and great physical integrity obtained of chitosan.