School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
Kunshan Hexin Mass Spectrometry Technology Co., Ltd., Kunshan, 215311, China.
Chemosphere. 2020 Jun;249:126215. doi: 10.1016/j.chemosphere.2020.126215. Epub 2020 Feb 14.
Nonthermal plasma (NTP) degradation has been shown to be a promising method for volatile organic compounds (VOCs) removal from air. However, there have been few studies on the degradation of indoor VOCs using NTP, and even less on their reaction kinetics. In this study, NTP degradation of acetone, a representative of oxygenated VOCs, in a closed-loop reactor operating in recirculation mode was investigated. Acetone and organic by-products were characterized in real-time by proton transfer reaction time-of-flight mass spectrometry. The results showed that approximately 85.7% of the acetone degraded within 7.5 h with dielectric barrier discharge treatment at 4.3 W. Methanol, acetaldehyde, formic acid, and acetic acid were observed to be the main organic byproducts with concentrations time-dependent on the order of ppb/ppm. The concentrations of the inorganic by-products O and NO are also time-dependent and can decrease to nearly 0 after a sufficient degradation time. Based on the concentration measurement in real-time, several rate laws were used to fit the concentration variations of acetone and the organic by-products, and it was observed that they strictly followed the simple kinetic reaction rate laws: acetone followed the first-order rate law, and formic acid formation followed the one-half-order rate law, etc. This study provides a good example of characterizing NTP removal of VOCs in airtight spaces and has important theoretical and practical significance in designing a better NTP device, predicting NTP degradation reaction rate, and accelerating the practical application of NTP technology for indoor air treatment.
非热等离子体（NTP）降解已被证明是一种很有前途的去除空气中挥发性有机化合物（VOCs）的方法。然而，利用 NTP 降解室内 VOCs 的研究很少，对其反应动力学的研究就更少了。本研究在循环模式下的闭环反应器中研究了 NTP 对丙酮（一种含氧 VOCs 的代表物）的降解。利用质子转移反应飞行时间质谱实时对丙酮和有机副产物进行了表征。结果表明，在 4.3 W 的介质阻挡放电处理下，约 85.7%的丙酮在 7.5 h 内降解。观察到甲醇、乙醛、甲酸和乙酸是主要的有机副产物，其浓度随时间呈 ppb/ppm 级的顺序变化。无机副产物 O 和 NO 的浓度也随时间变化，在足够的降解时间后可降至接近 0。基于实时浓度测量，使用了几种速率定律来拟合丙酮和有机副产物的浓度变化，结果表明它们严格遵循简单的动力学反应速率定律：丙酮遵循一级速率定律，甲酸的生成遵循半级速率定律等。本研究为在密闭空间中对 NTP 去除 VOCs 的特性提供了一个很好的范例，在设计更好的 NTP 装置、预测 NTP 降解反应速率以及加速 NTP 技术在室内空气处理中的实际应用方面具有重要的理论和实际意义。
