Magnetite/carbon nanocomposites prepared by an innovative combustion synthesis technique-Excellent adsorbent materials

摘要

Magnetite nanoparticles embedded within a matrix of activated carbon were prepared for the first time using a simple and effective combustion synthesis technique. The resulting nanocomposites had a magnetite/carbon ratio varying between 1/1 and 1/10 and exhibited a ferrimagnetic behavior. As the magnetite/carbon ratio decreased from 1/1 to 1/10, the BET surface area increased from 360 m~2/g to 814 m~2/g and the saturation magnetization decreased from 34.1 emu/g to 7.8 emu/g. The removal efficiency of phenol and p-chlorophenol increased as the magnetite/carbon ratio decreased. Using an adsorbent mass of 2 g/L, magnetite/carbon nanocomposites showed a removal efficiency ranging from 89% to 98% for p-chlorophcnol. For the same adsorbent mass, the removal efficiency of phenol varied between 59% and 91 %. The experimental data for phenol and p-chlorophenol adsorption on magnetite/carbon nanocomposites were best fitted by the Sips isotherm and showed a significant increase of the maximum adsorption capacity with the increase of the carbon content. The unique combination of enhanced adsorption capacity, excellent separation capability and the short time span for reaching equilibrium indicates that the as-prepared magnetite/carbon nanocomposites are excellent adsorbent materials.