[Preparation and evaluation of Fe-La composite oxide nanoadsorbent for As(III) removal from aqueous solutions]

In this study, a Fe-La composite oxide nanoadsorbent was synthesized via a facile co-precipitation process. This adsorbent was well characterized with various techniques and its As (III) adsorption performance was investigated. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) analyses indicate that the Fe-La composite oxide is formed with nanoparticles (20-200 nm). X-ray powder diffraction (XRD) analysis shows that the Fe-La composite oxide is similar to the crystal structure of La (OH)3. The specific surface area of Fe-La composite oxide is 99. 3 m2 x g(-1) and the isoelectric point is 7.8. The prepared Fe-La composite oxide nanoadsorbent is effective for As(III) removal from water. The isotherm data is well fitted with the Langmuir model (R2 = 0.95) with a maximal As(III) adsorption capacity of 58.2 mg x g(-1) at pH 7.0. The adsorption of As(III) is very fast and over 80% of the equilibrium adsorption capacity is obtained within 240 min. Elovich model (R2 = 0.97) is more suitable to describe adsorption kinetic data. The As(III) adsorption is dependent on solution pH. The effect of coexisting anions on As(III) adsorption increases in the order of SO4(2-) < CO3(2-) < SiO3(2-) < PO4(3-).