Fabrication of Chitosan-Reinforced Zr_xAl_1-xOOH Nanocomposites and Their Arsenite and Fluoride Depollution Densities from Single/Binary Systems

The unique and versatile adsorbents zirconium oxyhydroxide (ZrOOH), aluminum oxyhydroxide (AlOOH), zirconium-aluminum oxyhydroxide (Zr_xAl_1-xOOH) and chitosan-supported zirconium-aluminum oxyhydroxide (CS@Zr_xAl_1-xOOH) were synthesized via a simple co-precipitation method. CS was used as a pillar-like support to reinforce the Zr_xAl_1-xOOH, the resulting material was capable of simultaneously adsorbing both F⁻ and AsO₃ ³⁻ because the functional groups of CS facilitated the formation of both ZrOOH and AlOOH nanoparticles. Interestingly, Zr_xAl_1-xOOH and CS@ Zr_xAl_1-xOOH had better F⁻ adsorption capacities at pH<7, whereas better AsO₃ ³⁻ removal was observed at pH>9. The Langmuir maximum adsorption capacity of CS@Zr_xAl_1-xOOH was 0.655 and 0.983 mmol g⁻¹ for AsO₃ ³⁻ and F⁻, respectively and the performance was superior to that of previously reported metallic oxide and chitosan-based sorbents. In addition, the presence of coexisting anions revealed that the CS@Zr_xAl_1-xOOH material selectively removed AsO₃ ³⁻ over F⁻ in a binary batch system. The adsorption kinetics of the adsorbents were well fit to the pseudo-second-order model. Due to the simultaneous and quick uptake capacity and cost-effectiveness, CS@Zr_xAl_1-xOOH nanocomposite have potential application in environmental cleanup.