Oxidative decomposition and mineralization of caffeine by advanced oxidation processes: The effect of hybridization
| Autor: | Başak Savun-Hekimoğlu, Viktorya Aviyente, Ayşen Erdinçler, Evrim Arslan, Asu Ziylan-Yavas, Ece Ozon, Nilsun H. Ince |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Reaction mechanism
·OH Acoustics and Ultrasonics Radical QC221-246 02 engineering and technology Energy barrier 010402 general chemistry Photochemistry 01 natural sciences •OH Catalysis Sonochemistry Inorganic Chemistry Reaction rate Ultrasound hybridized technologies: A new breathing for Sonochemistry Chemical Engineering (miscellaneous) Environmental Chemistry AOP’s Radiology Nuclear Medicine and imaging QD1-999 Cavitation Chemistry Organic Chemistry Acoustics. Sound Mineralization (soil science) 021001 nanoscience & nanotechnology Decomposition Hybrid 0104 chemical sciences Reagent Synergy index 0210 nano-technology |
| Zdroj: | Ultrasonics Sonochemistry Ultrasonics Sonochemistry, Vol 76, Iss, Pp 105635-(2021) |
| ISSN: | 1873-2828 1350-4177 |
| Popis: | The study consists of a detailed investigation of the degradability of the emerging water contaminant-caffeine by homogeneous and heterogeneous Advanced Oxidation Processes (AOP’s), estimation of a synergy index for each hybrid operation thereof, and proposing the most plausible reaction mechanisms that are consistent with the experimental data. It also encompasses evaluation of the effect of the water matrix represented by carbonate species and humic acids, as strong scavengers of hydroxyl radicals. The results showed that single AOP’s such as sonolysis (577 kHz) and photolysis with H2O2 provided complete caffeine elimination, but they were insufficient for the mineralization of the compound. Hybrid AOP’s were considerably more effective, particularly when operated at a heterogeneous mode using commercial TiO2. The most effective hybrid process was UV-H2O2/TiO2, which provided more than 75% TOC decay at the minimum test doses of the reagent and catalyst. While the addition of ultrasound to the process significantly increased the rate of caffeine decomposition, it reduced the overall degradation of the compound to 64% in terms of TOC decay. The antagonistic effect was attributed to the formation of excess H2O2, and the presence of cavity clouds and/or high density layers that inhibited the transmission of UV light. The effect of natural water ingredients was found to reduce the reaction rates, signifying the major contribution of hydroxyl radicals to the destruction of caffeine. The proposed reaction mechanisms based on OH radical attack and the calculated energy barriers were in good agreement with the experimentally detected reaction byproducts. |
| Databáze: | OpenAIRE |
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