The role of H3PO4 in the preparation of activated carbon from NaOH-treated rice husk residue

The preparation of activated carbon from rice husk residue using H3PO4 as activation agent was studied. The samples were characterized by elemental analysis, N-2 adsorption-desorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), temperature programmed decomposition-mass spectra (TPD-MS), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The role of H3PO4 in the activation process was discussed. A maximum surface area of 1016 m(2) g(-1) was obtained under the optimized conditions, that is, a base treated solid material to H3PO4 mass ratio of 1 : 2, an activation temperature of 500 degrees C and an activation time of 1 h. H3PO4 might act as a catalyst which facilitates the release of CO2, an oxidant which reacts with carbon after dehydration, and a reagent which enters AC through C-O-P bonds.