Abstract :
This study investigates the Mn-Ti-incorporated mesoporous silicate (Mn-Ti-MPS) as a photocatalyst for highly concentrated toluene removal in
a plasma–photocatalytic hybrid system. Various Mn-Ti-MPS [Ti/Si molar ratio = 1/4, Mn/Ti molar ratio = 0.01/1 (1 mol%), 0.05/1 (5 mol%) and
0.1/1 (10 mol%)] photocatalysts were successfully synthesized using a common hydrothermal method without causing any structural damage. In
the X-ray diffraction (XRD) pattern, the main peaks of the TiO2 anatase structure and MnO did not show. All samples displayed hexagonal specific
peaks at 2.58 (d1 0 0 plane), 4.18 (d1 1 0 plane) and 4.78 (d2 0 0 plane). This indicates that the Ti ions and Mn ions were well substituted into the Si ion
sites in the framework of MCM-41. Their surface areas decreased compared with that of pure MCM-41, while the hexagonal straight pore size was
distributed in a range of 2.5–3.5 nm. In the Mn-Ti-MPS, much more water and toluene molecules were absorbed compared to the Ti-MPS. From the
X-ray photoelectron spectroscopy (XPS) result, it was determined that the hydrophilicity of the Mn-Ti-MPS was stronger than that of the Ti-MPS.
Photocatalytic decomposition for highly concentrated toluene of 1000 ppm increased in the Mn-Ti-MPS when compared with the Ti-MPS, while
toluene decomposition on 5 mol% Mn-Ti-MPS was remarkably enhanced to 80% in the plasma system. The conversion to CO2, however, did not
improve in the case of the plasma-only system. Nonetheless, in the plasma–photocatalytic hybrid system, the conversion to CO2 for 5 mol% Mn-Ti-
MPS reached 43% (in an 800 ppm toluene conversion).
