Effect of thermal treatment on adsorption–desorption of ammonia and sulfur dioxide on palygorskite: Change of surface acid–alkali properties
2011
Chen, Tianhu | Liu, Haibo | Li, Jinhu | Chen, Dong | Chang, Dongyin | Kong, Dejun | Frost, Ray L.
Thermally activated Palygorskite (Pg) has been found to be a good adsorbent material for ammonia (NH₃) and sulfur dioxide (SO₂). This research investigated the effect of thermal treatment on pore structure and surface acid–alkali properties of Pg through the adsorption–desorption of NH₃ and SO₂. The results showed that, up to 200°C, the adsorption of NH₃ on Pg was significantly higher than SO₂. This was due to NH₃ being adsorbed in the internal surface of Pg and forming hydrogen bonds (H-bonds) with coordinated water. The increase in thermal treatment temperature from 150 to 550°C, showed a gradual decrease in the number of surface acid sites, while the number of surface alkaline sites increased from 200 to 400°C. The change of surface acidity–alkaline sites is due to the collapse of internal channels of Pg and desorption of different types of hydroxyls associated with the Pg structure.
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