Indexed on: 10 Aug '16Published on: 09 Aug '16Published in: Ceramics International
Amorphous aluminum hydroxide hollow spheres were synthesized and characterized by field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermal gravimetric analysis. The obtained amorphous aluminum hydroxide hollow spheres were an excellent precursor for the fabrication of porous alumina hollow spheres via a simple thermal transformation process. The influence of the calcination temperature on the fluoride removal performance and the concentration of the residual aluminum ions were investigated. With the calcination temperature of 800 °C, the concentration of the residual aluminum ions was low than that of WHO guideline (0.2 mg L−1), and the corresponding adsorption capacity towards fluoride at neutral pH was 16.77 mg g−1. When the calcination temperature lower than 800 °C, both of the fluoride adsorption capacity and the concentration of the residual aluminum ions were increased. Batch experiments were performed to study the influence of various experimental parameters such as contact time, initial concentration, pH value and the presence of competing anions on the adsorption of fluoride on porous alumina hollow spheres prepared with the calcination temperature of 800 °C. The fluoride adsorption can be well described by the Langmuir model, and the kinetic data was well fitted to pseudo-second-order model. The co-existing carbonate and phosphate anions have great influence on fluoride removal. Furthermore, the regeneration and recyclability of the obtained porous alumina hollow spheres were evaluated.