Design of activated carbon–clay composites for effluent decontamination

Adsorption offers an efficient technology for removing volatile organic compounds (VOCs) from air pollution sources. Often activated carbons (ACs) are employed owing to their large specific surface areas, high micropore volumes, rapid adsorption capabilities and selectivity towards organic molecules compared to water vapour or air. However, when large volumes of gas are to be treated pressure drop limitations may arise from the use of conventional powder adsorption beds. For these applications conformation of the activated carbon as open channel honeycomb monoliths can take advantage of the almost null pressure drop caused by these structures. Similarly, conformation as extrudates or tubes although increasing the pressure drop due to the turbulent gas flow can improve any diffusion limitations that the open channel monoliths can suffer. Conformation of the AC as a ceramic composite also improves the handling characteristics. By the use of a silicate clay binder a commercially available AC, was conformed in three different monolithic geometries; changing the channel width and the wall thicknesses and as solid extrudates and tubes. The textural and mechanical properties of these conformed composite structures were determined and the results analysed along with their dynamic adsorption capacities towards toluene at 30 °C, used as a probe molecule to establish criteria by which the most suitable structure for industrial use could be selected.

Graphical abstractBy the use of a silicate clay binder a commercially available AC, was conformed in three different monolithic geometries; changing the channel width and the wall thicknesses and as solid extrudates and tubes. The textural and mechanical properties of these conformed composite structures were determined and the results analysed along with their dynamic adsorption capacities towards toluene at 30 °C, used as a probe molecule to establish criteria by which the most suitable structure for industrial use could be selected.Breakthrough curves for the dynamic adsorption of toluene at 30 °C on Pansil 100/Fluesorb B 50/50 conformed materials heat-treated at 500 °C of various geometries: wide channel/thick wall monolith (black), narrow channel/thick wall monolith (red), narrow channel/thin wall monolith (green), cylinder (orange) and tube (pink).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Design of activated carbon–clay composites for effluent decontamination. ► Fabrication of composites from clay and activated carbon for gas decontamination. ► Development of textural and mechanical characteristics of the conformed materials. ► The dynamic adsorption capacity of toluene is described. ► Geometric shape in relation to the adsorption capacity under dynamic conditions.