Comparison Between the Efficiency of Plain GAC and Supported GAC With Manganese Oxide for Toluene Adsorption From Waste Air Stream

Objectives Type of adsorbent is the most important parameter to adsorb volatile organic compounds (VOCs) from the air stream. Application of a selective adsorbent could lead to the higher efficiency and lower costs in the adsorption processes. The current study aimed at investigating the efficiency of manganese oxide impregnated on GAC support (MnO/GAC) to remove toluene from air stream. The efficiency of MnO/GAC and GAC absorbents for toluene removal were compared at the same experimental conditions.
Methods The MnO/GAC preparation method was Sol-gel. Retention time (0.5, 1, 1.5, 2, and 4 seconds), inlet toluene concentration (100, 200, 300, and 400 part per million, by volume) and the temperature of the air stream (25, 50, 75, and 100˚C) were examined as the main functional parameters in the adsorption process.
Results Breakthrough time of MnO/GAC adsorbent in comparison to that of the plain GAC increased 6% to 11% at the retention time of 0.5 to 4 seconds. Adsorption capacity of GAC and MnO/GAC increased 67.9% and 61.1% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. Breakthrough time of GAC and MnO/GAC decreased 57.9% and 59.6% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. Breakthrough time of GAC decreased from 41 to 26 hours by increasing the temperature of the air stream from 25˚C to 100˚C. Direct air temperature increase affected the MnO/GAC efficiency for toluene adsorption and the breakthrough time increased from 46 to 57 hours.
Conclusion Results of the current study showed that MnO/GAC could be applied as a good substitution for GAC in the adsorption of VOCs from air streams.