A novel method for synthesis of Co–Al layered double hydroxides and their conversions to mesoporous CoAl2O4 nanostructures for applications in adsorption removal of fluoride ions

• Mesoporous Co–Al LDHs with rodlike and nanosheet-like morphologies were synthesized via micro-emulsion method.
• The calcined Co–Al sample with 10% content of cobalt exhibits the highest specific surface area.
• The calcined samples exhibit higher fluoride removal efficiency than the uncalcined ones.
• Performance of the adsorption decreases with an increase in the cobalt ratio generally.
• The adsorption kinetics and isotherms were also discussed.

Facile micro-emulsion methods have been developed to synthesize mesoporous Co–Al hydroxide carbonates with rodlike and hexagonal sheetlike morphologies. A series of samples with different molar ratio of cobalt/aluminum were prepared to investigate the impact of cobalt content. Employing transmission electron microscopy, X-ray diffraction analysis and Fourier transformed infrared spectra, the morphology, structure and composition of the products were investigated. Characterized by gas-sorption measurements, the specific surface area of the calcined S-10 sample with the rodlike morphology was as high as 379 m2/g, which provided this material porosity properties and outstanding fluoride removal efficiency as high as 95.6%. The sorptive removal capacity of fluoride from aqueous solutions by the precursors and their corresponding annealed products was investigated in a batch mode. Also, the adsorption kinetics and isotherms were discussed.

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