LED visible light assisted photochemical oxidation of HCHs in aqueous phases polluted with DNAPL

This work focuses on removing hexachlorocyclohexanes (HCHs) found in groundwater polluted with dense non-aqueous phase liquids (DNAPLs) by photo-oxidation hydrogen peroxide or persulfate using LED visible light and ferrioxalate as the catalyst. Single oxidation tests were also performed to evaluate contribution of LED-vis HCHs removal. Results show that it is possible attain degradation up 85% 420 min persulfate, whereas percentages lower than 40% are obtained when peroxide. Using both oxidants presence promotes generation hydroxyl sulfate radicals under circumneutral pH values, which main responsible species for Specifically, an oxidant conversion higher 50% was achieved during photochemical treatment oxidants, conversions below 20% absence irradiation. On other hand, DNAPL produced liquid residuum lindane production contains chlorinated organic compounds (COCs), susceptible being oxidized radicals, generating competitive reactions. The final chlorbenzenes reaches values close 100% only effectively removed used oxidant. better performance indicates should be carried out ensure removal more dangerous COCs. confirms excellent ability C-Cl bond breakdown. • Persulfate leads efficiencies Different mechanisms radicals. Other COCs eliminated light. attack favours dechlorination.