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



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Conte, Leandro O. and Cotillas Soriano, Salvador and Sánchez Yepes, Andrés and Lorenzo Fernández, David and Santos López, Aurora (2022) LED visible light assisted photochemical oxidation of HCHs in aqueous phases polluted with DNAPL. Process Safety and Environmental Protection, 168 . pp. 434-442. ISSN 0957-5820

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Official URL: https://doi.org/10.1016/j.psep.2022.10.015


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

Item Type:Article
Additional Information:

CRUE-CSIC (Acuerdos Transformativos 2022)

Uncontrolled Keywords:DNAPL, Lindane Persulfate, Ferrioxalate, LED, Vis-Light
Subjects:Sciences > Chemistry > Chemical engineering
ID Code:75425
Deposited On:17 Nov 2022 08:48
Last Modified:17 Nov 2022 10:07

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