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

Abstract

The preparation of activated carbon from rice husk residue using H₃PO₄ as activation agent was studied. The samples were characterized by elemental analysis, N₂ 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 m² 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 °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.