The role of surface functionality of sustainable mesoporous materials Starbon® on the adsorption of toxic ammonia and sulphur gasses

The interest in adsorbing toxic gases nowadays is primarily due to their short- and long-term adverse health effects. It is generally accepted that the pore morphology and the surface nature play key roles in the adsorption mechanism of any molecules. The interactions between the adsorbate and adsorbent are affected by their polarity, where nonpolar surfaces would be attracted to a non-polar adsorbate, while polar surfaces have a higher affinity for polar molecules. The primary issue is access to a controllable set of materials with multiple functionalities that provide both polar and nonpolar surfaces for adsorption, which would present an advantage over single-phase adsorbents. Recently this has become available thanks to a novel class of bio-based carbonaceous materials (Starbon®). The functionality of these materials can be easily controlled by their temperature of preparation. The present work studies the nature of the surface chemistry and porosity of bio-based mesoporous materials Starbon and the role this plays in the adsorption of toxic volatile molecules such as ammonia, as a basic adsorptive and two acidic gasses (hydrogen sulphide and sulphur dioxide) using an InfraSorp optical calorimeter. Both hydrogen sulphide and sulphur dioxide adsorb better onto a hydrophobic surface, while ammonia adsorbs best onto a hydrophilic surface. The results showed that in both cases, Starbon significantly outperformed the industrially available powdered Norit® activated carbon (AC) and reacted chemically with the gasses to some extent.