Magnetic calcinated cobalt ferrite/magnesium aluminum hydrotalcite composite for enhanced adsorption of methyl orange

A novel environment friendly adsorbent, magnetic calcinated cobalt ferrite/magnesium aluminum hydrotalcite composite (CoFe2O4/MgAl-LDO) was prepared through coprecipitation method and employed for methyl orange (MO) removal from aqueous solutions. The physicochemical properties of CoFe2O4/MgAl-LDO were characterized and its adsorption properties for MO removal under different conditions were investigated systematically. The results indicated that the adsorbent exhibited a high MO removal efficiency in a wide range of initial pH of 2.0-12.0 and high selectivity for MO versus common co-existing ions. The MO adsorption rate of the adsorbent was very fast, and the adsorption kinetics followed pseudo-first-order model. The adsorption isotherm could be well fitted in Langmuir model, while the maximum adsorption capacity was found to be 1219.5 mg/g at pH 6.0, which was much higher than the MO adsorption capacity of for most reported adsorbents. Thermodynamics data revealed the exothermic and spontaneous nature of the adsorption process. The regeneration of the adsorbent could be easily achieved through thermal treatment. After three cycles, the MO removal efficiency of CoFe2O4/MgAl-LDO still remained high. The efficient MO removal and easy magnetic separation makes CoFe2O4/MgAl-LDO be a promising adsorbent for effective removal of dyes from aqueous solutions. (C) 2016 Published by Elsevier B.V.