Abstract
The adsorption of organic micropollutants onto activated carbon is a favourable solution for the treatment of drinking water and wastewater. However, these adsorption processes are not sufficiently understood to allow for the appropriate prediction of removal processes. In this study, thermogravimetric analysis, alongside evolved gas analysis, is proposed for the characterisation of micropollutants adsorbed on activated carbon. Varying amounts of carbamazepine were adsorbed onto three different activated carbons, which were subsequently dried, and their thermal decomposition mechanisms examined. The discovery of 55 different pyrolysis products allowed differentiations to be made between specific adsorption sites and conditions. However, the same adsorption mechanisms were found for all samples, which were enhanced by inorganic constituents and oxygen containing surface groups. Furthermore, increasing the loadings led to the evolution of more hydrated decomposition products, whilst parts of the carbamazepine molecules were also integrated into the carbon structure. It was also found that the chemical composition, especially the degree of dehydration of the activated carbon, plays an important role in the adsorption of carbamazepine. Hence, it is thought that the adsorption sites may have a higher adsorption energy for specific adsorbates, when the activated carbon can then potentially increase its degree of graphitisation.
Highlights
The adsorption of organic micropollutants onto activated carbon is a favourable solution for the treatment of drinking water and wastewater
Phosphorus is dominating in the HK 950, indicating chemical activation with phosphoric acid41
Complete pyrolytic removal was achieved on these materials, indicating the presence of fewer complex mechanisms occurring in comparison to that occurring with activated carbon45
Summary
The adsorption of organic micropollutants onto activated carbon is a favourable solution for the treatment of drinking water and wastewater. These adsorption processes are not sufficiently understood to allow for the appropriate prediction of removal processes. Adsorption in the liquid phase has been proven to be much more complicated than adsorption in gas phases, especially in complex water matrices that are governed by the presence of dissolved organic matter, the ionic strength and the pH value. Adsorption in the liquid phase has been proven to be much more complicated than adsorption in gas phases, especially in complex water matrices that are governed by the presence of dissolved organic matter, the ionic strength and the pH value21–23 Both the adsorbate solution and the adsorbent, are mutually influenced. Manufacturer Raw material BET surface area C/H ratio Ash content Si P S K Ca Ti Fe m2 g−1 μ mol g−1 μ mol g−1 μ mol g−1 μ mol g−1 μ mol g−1 μ mol g−1 μ mol g−1
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