Photocatalytic degradation of phenol and trichloroethylene: On-line and real-time monitoring via membrane introduction mass spectrometry

Membrane introduction mass spectrometry (MIMS) has been applied to monitor and compare in real time the extent by which three photocatalytic remediati on processes-Fenton's reagent/ UV, ferrioxalate/H2O2/UV, and TiO2/UV-destro y two common water pollutants-phenol and trichloroethylene (TCE). Continuou s MIMS and selected ion monitoring (MIMS-SIM) of both phenol and TCE degrad ation and CO2 production show first-order kinetics for the three processes. Phenol half-life times indicate that Fenton's reagent/UV and ferrioxalate/ H2O2/UV destroys phenol 10 times faster than TiO2/UV, that is, Fenton's rea gent/UV approximate to ferrioxalate/H2O2/UV >> TiO2/UV. For TCE, half-life times for the three remediation processes are ordered as follows: ferrioxal ate/H2O2/UV >> Fenton's reagent/UV > TiO2/UV. For phenol, the extent of min eralization measured via total organic carbon analysis was lower than the e xtent of degradation measured by MIMS-SIM; hence, for the three processes, the intermediate products of phenol photocatalytic degradation are slowly d estroyed. For Fenton's reagent/UV and ferrioxalate/H2O2/UV GC/MS analysis d etected pyrocatechol as the main intermediate of phenol degradation and p-b enzoquinone for TiO2/UV.