| Abstract: | This study uses a waste iron oxide material (BT3), which is a by-product of the fluidized-bed Fenton reaction (FBR–Fenton), for the treatment of a fluoride (F?) solution. The purpose of this study is to investigate a low-cost sorbent as a replacement for the current costly methods of removing fluoride from wastewater. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) are used to characterize the BT3. Contact time, F? concentration (from 0.75 to 6 mmol L?1), and temperature (from 303 to 323 K) are used as operation parameters to treat the fluoride. The highest F? adsorption capacity of the BT3 adsorbent was determined to be 1.17 mmol g?1 (22.2 mg g?1) for a 6 mmol L?1 initial F? concentration at pH 3.9 ± 0.2 and 303 ± 1 K. Adsorption data were well described by the Langmuir model, and the thermodynamic constants of the adsorption process, ΔG°, ΔH°, and ΔS°, were evaluated as ?1.63 kJ mol?1 (at 303 K), ?1.75 kJ mol?1, and ?52.4 J mol?1 K?1, respectively. Additionally, a pseudo-second-order rate model was adopted to describe the kinetics of adsorption. BT3 could be regenerated with NaOH, and the regeneration efficiency reached 95.1% when the concentration of NaOH was 0.05 mol L?1. |
