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アントラセンとベンゾアピレンの混合物を超微量レベルで光分解し、消毒を目的とした天然水中での光分解
Photolysis of a mixture of anthracene and benzo[a]pyrene at ultra-trace levels in natural water with disinfection purposes.
PMID: 32430135 DOI: 10.1016/j.jes.2020.02.002.
抄録
多環芳香族炭化水素(PAH)であるアントラセン(AN)とベンゾ[a]ピレン(BaP)の光分解を表層水中の超微量レベルで調査し、複数の照射量と放射線の種類による挙動を明らかにした。その結果、紫外C(UVC)照度0.63mW/cmの照射では、15分後に99%以上の除去効率が確認され、ランプの発光束とスペクトルがANとBaPの分解に重要な役割を果たしていることがわかった。一方、紫外線A（UVA）ランプはUVCランプに比べて高い照射量を示したが、目的とするPAHの分解には効率的ではなかった。これらの知見を裏付ける除去速度試験では、最適な運転条件での表層水中のAN除去率が脱イオン水中よりも高いことが確認された。消毒能力も測定した。水質中に自然に含まれている全大腸菌群の量から見て、処理後15分以内に迅速な微生物負荷の不活化が確認された。しかし、暗所での24時間後には再増殖が観察された。さらに、親化合物よりも毒性の高い光分解生成物が検出され、処理時間を延長しても除去されなかった。このことから、消毒を目的としたANやBaPの除去に対するUVC光の単独作用は効率的な治療法ではなく、他の種類の治療法との併用が必要であると結論づけられる。
The photodegradation of anthracene (AN) and benzo[a]pyrene (BaP), two priority polycyclic aromatic hydrocarbons (PAHs), was examined at ultra-trace levels in surface water to elucidate their behaviour under several irradiance values and types of radiation. The emitting flux and the spectrum of the lamps were found to develop a crucial role in AN and BaP degradation since removal efficiencies of the target contaminants higher than 99% were found after 15 min of irradiation under an ultraviolet C (UVC) irradiance of 0.63 mW/cm, corresponding to a fluence of 560.25 mJ/cm. On the other hand, although ultraviolet A (UVA) lamps exhibited a higher irradiance compared to that of UVC lamps, they were not efficient for degrading the target PAHs. The removal kinetic studies corroborated these findings, being the AN elimination rate in surface water higher than that in deionized water at optimal operating conditions. Disinfection potential was also measured. A rapid microbial load inactivation, in terms of total coliforms naturally contained in the water matrix studied, was evidenced within 15 min of treatment for the fluence referred. However, after 24 hr in the dark, a regrowth was observed. Additionally, photolysis products more toxic than the parent compounds were found, which were not removed even by extending the treatment time. In this regard, it can be concluded that the individual action of UVC light for removing AN and BaP with disinfection purposes is not an efficient treatment; therefore, the use of radiation in combination with other kinds of treatments is required.
Copyright © 2020. Published by Elsevier B.V.