Surface modification and characterisation of a coal-based activated carbon

Surface modification of a coal-based activated carbon (F400) was performed using thermal and chemical methods. Nitric acid oxidation of the conventional sample produced samples with weakly acidic functional groups and the presence of such groups was confirmed by Fourier transform infra red (FTIR) spectroscopy, pH titration, zeta potential measurements and sodium uptake capacity results. There was a significant loss in microporosity of the oxidised samples which was caused by humic substances that were formed as a by-product during the oxidation process. Thermal treatment produced a carbon with some basic character while amination of the thermally treated carbon gave a sample containing some amino (–NH2) groups and these groups were detected by X-ray photoelectron spectroscopy (XPS) analysis.