Efficient and rapid adsorption of iodide ion from aqueous solution by porous silica spheres loaded with calcined Mg-Al layered double hydroxide

In this study, magnesium and aluminum ion was firstly inhaled into the silica sphere by low-vacuum impregnation technique, and subsequently hydrotalcite (Mg-Al-LDH) was synthesized inside the silica-based mesoporous material using in-hole precipitation method. Metal composite oxide (Mg-Al-LDO) was the calcined product by calcining Mg-Al-LDH at 450 degrees C and the composite material Mg-Al-LDO/SiO2 was the main absorbent for absorbing iodine ion (I-) in this study. The characteristics of SEM inner-morphology, FT-IR spectroscopy and X-ray diffraction strongly demonstrated hydrotalcite admirably grew in the channel of silica matrix. The influence of composite material dosage, pH values of aqueous solution, and initial concentration of I-on adsorption capacity was investigated in detail. The batch experiment results showed that Mg-Al-LDO/SiO2 had an excellent adsorption performance on I-and the removal efficiency reached 99.81% from a 30 mg/L I- solution in 5 min, with a dosage of 0.05g/100 ml. The adsorption kinetics was fitted well by pseudo-second-order model. The column experiment data demonstrated that the application of Mg-AI-LDO/SiO2 in a column model for the continuous treatment of iodine ion effluents exhibited optimum breakthrough curves by adjusting the bed heights. The experimental breakthrough curves were correlated with Thomas, Adams-Bohart and Yoon-Nelson models. (C) 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.