SIMULATION OF SMALL-ANGLE X-RAY-SCATTERING BEHAVIOR OF ACTIVATED CARBON-FIBERS ADSORBING WATER

Small-angle X-ray scattering (SAXS) measurements have been carried out in order to investigate the size of micropores in activated carbon fibres (ACF) and the apparent change in size for different relative humidities. The scattering intensity at smaller angles and the gyration radius R(g) increase at first with increasing relative humidity and then decrease. To interpret this anomalous behaviour, a simulation study has been carried out by considering the change in the effective sizes of micropores and carbon grains caused by adsorption of water. The observed behaviour of the SAXS intensity and the R(g) value can be explained by the increase in the effective grain-size due to the adsorption of water molecules around the carbon grains in ACF.