Toluene adsorption from waste air stream using activated carbon impregnated with manganese and magnesium metal oxides

Adsorption is one of the most common methods for VOCs elimination from waste air stream. The study on the application of a selective and cheap adsorbent with high efficiency in VOCs removal is important from economic aspects. In this study, the potential of MnO/GAC and MgO/GAC composites was investigated for toluene adsorption from air stream at lab scale.
Material and The MnO/GAC and MgO/GAC adsorbents were prepared through Sol-gel method and then were characterized using BET, XRF, and SEM analysis. The effect of operational parameters including; retention time (0.5, 1, 1.5, 2, and 4 S), inlet toluene concentration (100, 200, 300, and 400 ppmv) and the temperature of the air stream (25, 50, 75, and 100 ˚C) were examined on the efficiency of both adsorbents. The efficiency of MnO/GAC and MgO/GAC were determined from the breakthrough time and adsorption capacity and the results were compared statistically.
The breakthrough time of MnO/GAC and MgO/GAC adsorbents increased 90% by increasing retention time from 0.5 to 4 S. Adsorption capacity of MgO/GAC and MnO/GAC was increased 39and 61.1% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. Breakthrough time of MgO/GAC and MnO/GAC decreased 65 and 59% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. The efficiency of MgO/GAC and MnO/GAC adsorbents had a direct relationship with the increase of air temperature from 25 to 100 ˚C. Accordingly, the efficiency of MgO/GAC and MnO/GAC was increased 78 and 32% by increasing air temperature, respectively.
The results of the study showed that MgO/GAC and MnO/GAC adsorbents had high efficiency in toluene removal from air stream. The difference between the efficiency of MgO/GAC and MnO/GAC adsorbents was significant and MgO/GAC adsorbent showed higher efficiency than MnO/GAC for toluene adsorption from waste air.