Gravimetric Analysis of CO(2) Adsorption on Activated Carbon at Various Pressures and Temperatures Using Piezoelectric Microcantilevers

Abstract

We investigated the adsorption and desorption of CO2 on activated carbon using piezoelectric microcantilevers. After coating the free end of a cantilever with activated carbon, variations in the resonance frequency of the cantilever were measured as a function of CO2 pressure, which is related to mass changes due to the adsorption or desorption of CO2. The pressure-dependent viscous damping effects were compensated in the calculation of the CO2 adsorption capacity of the activated carbon by comparing the frequency differences between the coated and uncoated cantilevers. The mass sensitivity of the piezoelectric cantilever was found to be better than 1 pg. The fractional coverage of CO2 agreed with a Langmuir adsorption isotherm, indicating that a submonolayer of adsorbed CO2 occurred on the surface of the activated carbon under the experimental conditions. The heat of adsorption was determined using the Clausius-Clapeyron relation and the fractional coverage of CO2 at various temperatures and pressures.