Evaluation of fluoride adsorption in solution by synthetic Al2O3/CeO2: A fixed‐bed column study

• Published in: Water environment research Vol. 93; no. 11; pp. 2559 - 2575
• Main Authors: Chen, Fenfei, Lv, Fengjin, Li, Huabin, Xu, Ling'e, Wei, Jun, He, Yuxuan, Qian, Jin, Gao, Pan
• Format: Journal Article
• Language: English
• Published: Alexandria Blackwell Publishing Ltd 01-11-2021
• Subjects: Adsorption; Aluminium; Aluminum; Aluminum oxide; Analytical methods; Anions; Binding; Cerium oxides; Coefficients; Coordination compounds; Correlation coefficient; Correlation coefficients; Electron microscopy; fixed‐bed experiment; Flow velocity; fluoride; Fluorides; Influents; Infrared spectroscopy; Metals; Microscopy; modified Al2O3; Photoelectron spectroscopy; Photoelectrons; Regeneration; Regeneration (biological); Removal; Scanning electron microscopy; Spectrum analysis; Transmission electron microscopy; Wastewater; X ray photoelectron spectroscopy
• ISSN: 1061-4303; 1554-7531
• DOI: 10.1002/wer.1601

A highly efficient fluoride adsorbent Al2O3/CeO2 was synthesized in this work and used it to fluoride removal in the fixed‐bed adsorption through changing the different experimental conditions (influent F− concentration, flow velocity, and bed heights). The adsorption capacity was 9.72 mg/g. In addition, the Adams–Bohart and Thomas models were used to fit and evaluate the column breakthrough curve of fluoride removal process by Al2O3/CeO2, and the correlation coefficients (R2) of the Thomas model were close to 1 under all experimental conditions. The structure of Al2O3/CeO2 and the adsorption mechanism were confirmed by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), N2 adsorption and desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray photoelectron spectroscopy (XPS). Moreover, the adsorption of fluoride (F−) was mainly through metal binding (MF) and hydroxyl binding (AlOH⋯F) on the surface of the Al2O3/CeO2. Furthermore, the regeneration and coexisting anions studies of Al2O3/CeO2 were carried out, and the efficiency of adsorption was still above 70% after five cycles.
Practitioner Points
Removal of fluoride was studied by fixed‐bed experiment, and the adsorption capacity of composite Al2O3/CeO2 was 9.72 mg/g.
The metal complex played important role in fluoride removal and reusability makes a long‐term application for fluoride adsorption.
Fluoride wastewater is pumped to the fixed‐bed column, and fluoride ions are absorbed by Al2O3/CeO2 through fluoride metal complex and aluminum hydrofluoride.
A highly efficient fluoride adsorbent Al2O3/CeO2 was synthesized and used it to fluoride removal in the fixed‐bed adsorption to simulate the water treatment process in practical engineering application. Fluoride solution entered from the bottom of the fixed‐bed column and went out from the top by pumping. The adsorption of fluoride by Al2O3/CeO2 could be divided into three pathways, which were fluoride metal complex (Ce–F or Al–F), aluminum hydrofluoride (Al–OH⋯F), and fluoride metal covering (MFN). The effective adsorption capacity implies the availability of Al2O3/CeO2 for flowing fluoride‐containing wastewater.