Generating Singlet Oxygen Bubbles: A New Mechanism for Gas鈥揕iquid Oxidations in Water

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• 作者：Dorota Bartusik ; David Aebisher ; BiBi Ghafari ; Alan M. Lyons ; Alexander Greer
• 刊名：Langmuir
• 出版年：2012
• 出版时间：February 7, 2012
• 年：2012
• 卷：28
• 期：5
• 页码：3053-3060
• 全文大小：335K
• 年卷期：v.28,no.5(February 7, 2012)
• ISSN：1520-5827

文摘

Laser-coupled microphotoreactors were developed to bubble singlet oxygen [¹O₂ (¹螖_g)] into an aqueous solution containing an oxidizable compound. The reactors consisted of custom-modified SMA fiberoptic receptacles loaded with 150 渭m silicon phthalocyanine glass sensitizer particles, where the particles were isolated from direct contact with water by a membrane adhesively bonded to the bottom of each device. A tube fed O₂ gas to the reactor chambers. In the presence of O₂, singlet oxygen was generated by illuminating the sensitizer particles with 669 nm light from an optical fiber coupled to the top of the reactor. The generated ¹O₂ was transported through the membrane by the O₂ stream and formed bubbles in solution. In solution, singlet oxygen reacted with probe compounds (9,10-anthracene dipropionate dianion, trans-2-methyl-2-pentanoate anion, N-benzoyl-d,l-methionine, or N-acetyl-d,l-methionine) to give oxidized products in two stages. The early stage was rapid and showed that ¹O₂ transfer occurred via bubbles mainly in the bulk water solution. The later stage was slow; it arose only from ¹O₂-probe molecule contact at the gas/liquid interface. A mechanism is proposed that involves ¹O₂ mass transfer and solvation, where smaller bubbles provide better penetration of ¹O₂ into the flowing stream due to higher surface-to-volume contact between the probe molecules and ¹O₂.