Efficient Removal of Dyes from Aqueous Solution by Mesoporous Nanocomposite Al2O 3/Ni 0.5Zn 0.5Fe 2O 4 Microfibers

A novel mesoporous, nanocomposite, magnetically separable adsorbent, namely activated alumina (γ-Al₂O₃)/ferrite (Ni₀.₅Zn₀.₅Fe₂O₄) microfibers have been successfully prepared by the sol–gel process. These nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers are formed after calcination of the precursor at 450 °C for 3 h, and characterized with high aspect ratios and uniform diameters of 1–10 μm. In the nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers, the spherical γ-Al₂O₃particles are homogeneously embedded on the microfiber. Their specific surface areas and magnetic properties are significantly influenced by the γ-Al₂O₃content and calcination conditions. With the designed γ-Al₂O₃mass fraction of 0.2 and the calcination temperature of 550 °C, the γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers possess a high specific surface area of 118.3 m²/g and saturation magnetization (Mₛ) of 20.4 Am² kg⁻¹, respectively. The adsorption behaviors of the nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers were examined using the Congo red and methyl blue dyes as the adsorbate. The adsorption kinetics, effects of the adsorbent dosage and solution pH, adsorption isotherms, and regeneration of the microfiber adsorbents were investigated. The pseudo-second-order model can be used to describe the adsorption kinetics. The resultant isotherm data are well fitted by the Temkin model, implying that the dyes adsorption on the γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers is a multilayer adsorption combined with some degrees of chemical interactions. Considering the simple synthesis process, high adsorption and unique magnetic property, these mesoporous, magnetic, nanocomposite γ-Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers can be used as a highly efficient, fast, and convenient adsorbent for dyes removal.Highlights The magnetic mesoporous Al₂O₃/Ni₀.₅Zn₀.₅Fe₂O₄microfibers were synthesized. Adsorption kinetics and adsorption isotherms were investigated. The separation, regeneration, and adsorption efficiency were enhanced.