Abatement efficiency and fate of EPA-Listed PAHs in aqueous medium under simulated solar and UV-C irradiations, and combined process with TiO2 and H2O2

Abstract

Photolytic degradation of dissolved compounds of 16 EPA-Listed PAHs in aqueous medium, exposed to ultraviolet/ titanium dioxide (UV-C/TiO2), xenon light/ titanium dioxide (Xe/TiO2), xenon light/ hydrogen peroxide (Xe/H2O2) and ultraviolet/ hydrogen peroxide (UV-C/H2O2) was studied. The compounds which detected above detection limit of applied analytical method and instrument include: naphthalene (Nap), acenaphthylene (Acy), acenaphthene (Ace), fluorene (Flu), fluoranthene (Fln) and pyrene (Pyr) survived. A time-course experiment (0, 1, 2, 5, 12 min) was performed to determine the fate of PAHs profile along treatments. After accomplishment of the removal process ∑6 PAHs ranked as follow: UV-C/TiO2 > Xe/TiO2 > UV-C > Xe > Xe/H2O2, and UV-C /H2O2 with estimated values of 76.38, 23.02, 22.55, 2.78, 0.00 and 0.00% of the concentration values at the beginning of the treatment, respectively. High efficiency of Xe/H2O2 treatment process (100.00%) at the end of treatment and the structure of residual PAHs which changed to the lighter compounds (2,3-ringed PAHs) before accomplishment of the removal process were proven. Generally, low resistance of Fln to all treatment conditions was observed. Total removal of Nap was considered to be a characteristic PAH compound for completion of the removal of PAHs. Mutate of parent PAH compounds and intermediates were analyzed by gas chromatography-mass spectrometry (GC-MS) and the results suggest the evaluating the toxicity of the treated water due to by-product formation concerns.