The influence of preparation methods and surface properties of activated carbons on Cr(III) adsorption from aqueous solutions

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Abstract
Activated carbons were prepared from eucalyptus wood, by using three different “physical” activating methods: air and CO2 partial gasification of wood char (2 hr, 400°C and 800°C, respectively), and direct CO2 partial gasification of wood sawdust. The three activated carbons were then oxidized with HNO3 for increasing the surface concentration of oxygenated functions, and Cr(III) aqueous solution adsorption isotherms were determined for each oxidized carbon. Characterization of the carbons were done through elemental analysis, N2 adsorption, and Fourier transform infrared spectroscopy spectra. Results show that oxidized activated carbons prepared from air gasification have the higher Cr(III) adsorption capacity. Conclusions about chemical functions formed onto the carbon surface and the relationship with Cr(III) adsorption are exposed.