Quantitative structure–activity relationships for the prediction of VOCs adsorption and desorption energies onto activated carbon

The aim of the study is to investigate quantitative relationships to predict the energetic interactions resulting from either adsorption or desorption of volatile organic compounds (VOCs) onto granular activated carbon. For that purpose, an experimental database was first built. Heats of adsorption and desorption were determined onto one activated carbon material for a 40 VOCs panel. The measurements were performed using differential scanning calorimetry coupled to thermogravimetry analysis. Adsorption energies were found to range between 40 and 80 kJ mol−1, whereas the desorption energies appear to be about 16% higher. Multiple linear regressions were afterwards tested in order to relate energies data with VOCs molecular properties. In a first approach, physical and chemical properties of the organic compounds were selected to investigate the best correlations. From the results obtained, the main influence of the ionization potential and of the polarisability were enlightened. In a similar way, connectivity molecular indexes were used. Some additional information were thus provided, which demonstrated the influence of the molecular shape, its branching and the steric hindrance.