Low-Cost Solvothermal Synthesis of Hierarchical Structure γ-AlOOH and its Application to Remove Cr (VI), Methyl Orange and Congo Red from Contaminated Water

Leaf-like hierarchical γ-AlOOH was prepared by a facile template-free solvothermal method at 150°C for 6 h, using aluminum nitrate (Al (NO₃)₃9H₂O) as aluminum source and a mixed water/ethanol solution as solvent. The obtained sample was characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption/ desorption technique. Experiment results indicated that the obtained leaf-like hierarchical γ-AlOOH exhibited a BET surface area of 190.3 m²/g and an average pore widths of 18.82 nm. The hierarchical γ-AlOOH showed excellent removal efficiency for Cr (VI), Methyl orange and Congo red with maximum adsorption capacity of 7.4 mg/g, 59.9 mg/g and 99.0 mg/g, respectively.