Preparation and characterization of γ-AlOOH/Fe3O4 for the highly effective removal of Congo red from wastewater

Due to the highly toxic and non-degradable nature of Congo red (CR) in wastewater, how to effectively separate CR from an aqueous solution remains a major challenge in the field of wastewater treatment. Consequently, an γ-AlOOH/Fe3O4 composite was prepared using the sol-gel method under ultrasonic stirring conditions. The structural and surface properties of the magnetic γ-AlOOH/Fe3O4 composite were analyzed in detail using a range of physical and chemical characterization methods. It was shown that the γ-AlOOH/Fe3O4 composite possessed the advantages of its layered structure, high porosity, and positively charged surface, all of which were conducive to improving the adsorption capacity of CR. During our CR adsorption experiments, the maximum adsorption amount reached 1350.11 mg g−1. Simultaneously, the whole adsorption process was more consistent with the pseudo-second order kinetic and Langmuir isotherm model. The adsorption activation energy and thermodynamic data prove that the adsorption process was chemisorption, spontaneous, and endothermic. In addition, the γ-AlOOH/Fe3O4 composite can be easily separated from treated-wastewater upon the application of an external magnetic field and its excellent reproducibility increases its practical application value. Therefore, the γ-AlOOH/Fe3O4 composite synthesized in this study has a wide range of practical applications.