Application of ‘treating the waste with waste’: Fabrication of hierarchically hollow structures of <scp>AlOOH</scp> / <scp> Al ₂ O ₃ </scp> as adsorbents for the high efficiency removal of methyl blue

Abstract Hierarchically hollow structures of AlOOH and Al 2 O 3 were hydrothermally fabricated employing Al 2 (SO 4 ) 3 obtained from the aluminium residue in zinc hydrometallurgy, which exhibited the excellent removal capacities and rates for methyl blue. The unique hollow spherical structures composed of numerous nanosheets offer the high specific surface areas. the adsorption begins, equilibrium can be reached within 10 min. The maximum adsorption capacities are 224.85 and 415.53 mg · g −1 on hollow structures of AlOOH and Al 2 O 3 , respectively. The adsorption conforms to the pseudo‐second‐order model and can be described by the Redlich–Peterson model. In addition, the two hollow spherical structures have good regeneration performance. Hollow spherical structures have the advantages of low cost, simple synthesis, fast adsorption rates, and large capacities, and are the qualified alternatives for the dyes removal.