A concentrate-and-destroy technique for degradation of perfluorooctanoic acid in water using a new adsorptive photocatalyst

WATER RESEARCH

卷:185

Article

Li, Fan¹  Wei, Zongsu¹  He, Ke²  Blaney, Lee²  Cheng, Xinquan³  Xu, Tianyuan¹  Liu, Wen^4,5  Zhao, Dongye¹ 

[1] Auburn Univ, Dept Civil Engn, Environm Engn Program, Auburn, AL 36849 USA

[2] Univ Maryland Baltimore Cty, Dept Chem Biochem & Environm Engn, Baltimore, MD 21250 USA

[3] Auburn Univ, Dept Chem Engn, Auburn, AL 36849 USA

[4] Peking Univ, Coll Environm Sci & Engn, Key Lab Water & Sediment Sci, Minist Educ, Beijing 100871, Peoples R China

[5] Peking Univ, Beijing Innovat Ctr Engn Sci & Adv Technol BIC ES, Beijing 100871, Peoples R China

关键词: Per- and polyfluoroalkyl substances;    Perfluorooctanoic acid;    Adsorption;    Photocatalysis;    Concentrate-and-destroy;   

DOI  :  10.1016/j.watres.2020.116219

来源: Elsevier

【 摘 要 】

Per- and polyfluoroalkyl substances (PFAS) have emerged as a major concern in aquatic systems worldwide due to their widespread applications and health concerns. Perfluorooctanoic acid (PFOA) is one of the most-detected PFAS. Yet, a cost-effective technology has been lacking for the degradation of PFAS due to their resistance to conventional treatment processes. To address this challenge, we prepared a novel adsorptive photocatalyst, referred to Fe/TNTs@AC, based on low-cost commercial activated carbon (AC) and TiO2. The composite material exhibited synergistic adsorption and photocatalytic activity and enabled a novel concentrate-&-destroy strategy for rapid and complete degradation of PFOA in water. Fe/TNTs@AC was able to adsorb PFOA within a few minutes, thereby effectively concentrating the target contaminant on the photoactive sites. Subsequently, Fe/TNTs@AC was able to degrade >90% of PFOA that was preconcentrated on the solid in 4 h under UV irradiation (254 nm, 21 mW cm(-2)), of which 62% was completely mineralized to F-. The efficient photodegradation also regenerated Fe/TNTs@AC, eliminating the need for expensive chemical regenerants, and after six cycles of adsorption/photodegradation, the material showed no significant drop in adsorption capacity or photocatalytic activity. Simulations based on the density functional theory (DFT) revealed that Fe/TNTs@AC adsorbs PFOA in the side-on parallel mode, facilitating the subsequent photocatalytic degradation of PFOA. According to the DFT analysis, scavenger tests, and analysis of degradation intermediates, PFOA decomposition is initiated by direct hole oxidation, which activates the molecule and leads to a series of decarboxylation, C-F bond cleavage, and chain shortening reactions. The innovative concentrate-&-destroy strategy may significantly advance conventional adsorption or photochemical treatment of PFAS-contaminated water and holds the potential to degrade PFOA, and potentially other PFAS, more cost-effectively. (C) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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