Laboratory-scale application of fiber optic transflection dip probe (FOTDP) for in situ monitoring of gas phase ozone in unsaturated porous media

A fiber optic transflection dip probe (FOTDP) system was developed for in situ and real-time monitoring of the transport of gas phase ozone in unsaturated porous media. A unique property of this system is the employment of a dip probe, which is inserted within the porous media. At the probe's tip, incoming light interacts with gas phase ozone and is partially reflected back into the probe by a mirror attached to the tip. Calibration of the FOTDP system was successfully carried out with various ozone concentrations using a column packed with glass beads. The ozone breakthrough curves (BTCs) were obtained by converting normalized UV intensities into gas phase ozone concentrations. The FOTDP system worked well for in situ monitoring of gas phase ozone using a column packed with sand under various water saturations in the presence of SOM and reflected the ideal transport phenomena of gas phase ozone for various flow rates.