EARTH

[1801-09-03] Facile synthesis and characterization of aluminum-based mixed (hydr)oxides as adsorbents for fluoride removal

○Shunqi Tian¹, Qiongzhi Tang¹, Yajun Ran¹, Weichun Yang^1,2 (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman：Mayumi Ito（Hokkaido University)

Keywords:Fluoride removal, adsorption, aluminum-based mixed (hydr)oxides

Various aluminum-based mixed (hydr)oxides including Mn-Al (hydr)oxides, Zn-Al (hydr)oxides, Cu-Al (hydr)oxides, Ce-Al (hydr)oxides, La-Al (hydr)oxides have been synthesized in single-step without high energy consumption. The possibility of fluoride removal by these mixed (hydr)oxides has been examined. The observations reveal that the adsorption for the various aluminum-based mixed (hydr)oxides decreased with the increase of the electronegativity of the metals contained in the aluminum-based mixed (hydr)oxides. And Ce-Al (hydr)oxides and La-Al (hydr)oxides have better potential of fluoride removal from aqueous solution. The characterization of Ce-Al (hydr)oxides and La-Al (hydr)oxides was undertaken by scanning electron microscopy (SEM)with an energy dispersive X-ray spectroscopy (EDX), Zeta potential measurement, X-ray powder diffractometer (XRD)and N₂ adsorption/desorption analysis. The effects of initial fluoride concentration, contact time and pH on the fluoride adsorption were investigated. Kinetic study results indicated that the fluoride adsorption over the Ce-Al (hydr)oxides, La-Al (hydr)oxides follows a pseudo- second-order kinetic model. The Ce-Al (hydr)oxides composites showed high fluoride removal efficiency over a wide range of pH (4-11). The calculated adsorption capacities of Ce-Al (hydr)oxides and La-Al (hydr)oxides for fluoride by Langmuir model were 15.5 and 86.48 mgg^-1, respectively. Fourier transform infrared spectroscopy (FT-IR) analyses confirmed that both Ce and La ions can act as a bridge between adsorbed fluoride and adsorbents surface. The results of this study indicate that the Ce-Al (hydr)oxides composites could be used as an effective adsorbent for fluoride removal from aqueous solution.