2.2 Experimental procedure
The uniform mixture of 2 g MTA (MT or P-25)
and 10 g water glass (about 25% of SiO2) was coated
on one side of four clear glass plates (the total effective
illumination area about 331 cm2
), drying in a vacuum
drier at 100 °C for 2 h, then the four plates were placed
into a photo-reactor (SGY-1, Nanjing Sidongke Electric
Equipment Co.) as can be seen in Fig. 1, which is a
1200 ml quartz cylindrical vessel with a water-cooled
jacket and a fan in the bottom. Certain amount of organic
compound was injected into the reactor, which
was kept in dark for 60 min to ensure a sufficient
volatilization and the establishment of gas adsorption/
desorption equilibrium. Irradiation was provided by a
300 W high-pressure mercury lamp (effective arc length
125±10 mm, stabilization time 5 min) with major
emission at 365 nm. By sampling (0.1 ml) gaseous
mixture from photo-reactor at 20 min intervals, the
concentration of organic compounds can be calculated from the analytical results of GC (9800TFP, Shanghai
Kechuang Chromatograph Instruments Co., China).