Synthesis of FeOOH/Al2O3 Composites with Excellent Adsorption Performance and Regenerability for Phosphate Removal from Wastewater

To address the issues of insufficient capacity and difficult regeneration of adsorbents for phosphate removal from wastewater, in this study, FeOOH/Al₂O₃ adsorbents were successfully developed by in situ growing amorphous iron oxyhydroxide (FeOOH) within the pores of alumina (Al₂O₃) using a simple method. The physicochemical properties of FeOOH/Al₂O₃ adsorbents were characterized using X-ray Diffraction (XRD), N₂ adsorption/desorption analysis, and scanning electron microscopy (SEM). Additionally, their phosphate adsorption properties were comparatively investigated. The results revealed that FO-A-3, one of the FeOOH/Al₂O₃ samples prepared with Fe/Al molar ratio of 0.47, exhibited excellent adsorption capacity and a relatively fast adsorption rate, surpassing those of Al₂O₃ and amorphous FeOOH alone. The adsorption process of phosphate using FO-A-3 conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, with a maximum adsorption capacity of 131.00 mg/g. To tackle the problem of poor regeneration performance, this study innovatively proposed a repeatable and simple regeneration strategy. Experiments demonstrated that FO-A-3 maintained a relatively high adsorption capacity after four cycles of regeneration.