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Effects of gas saturation and sparging on sonochemical oxidation activity in open and closed systems, Part I: H2O2 generation
Ultrasonics Sonochemistry ( IF 8.4 ) Pub Date : 2022-10-28 , DOI: 10.1016/j.ultsonch.2022.106214
Younggyu Son 1 , Jieun Seo 2
Affiliation  

Cavitational/sonochemical activity can be significantly enhanced or reduced depending on the gases dissolved in the liquid. Although many researchers have suggested the order of importance of dissolved gas conditions that affect the degree of sonoluminescence (SL), sonochemiluminescence (SCL), and compound degradation, the most suitable gas condition for sonochemical oxidation reactions is currently unknown. In this study (Part I), the effects of gas saturation and sparging on the generation of H2O2 were investigated in a 28-kHz sonoreactor system. Four gas modes, saturation/closed, saturation/open, sparging/closed, and sparging/open, were applied to Ar, O2, N2, and binary gas mixtures. The change in dissolved oxygen (DO) concentration during ultrasonic irradiation was measured and was used as an indicator of whether the gaseous exchange between liquid and air altered the gas content of the liquid. Considerable difference in the DO concentration was observed for the gas saturation/open mode, ranging from –11.5 mg/L (O2 100 %) to +4.3 mg/L (N2 100 %), while no significant difference was observed in the other gas modes. The change in the gas content significantly reduced the linearity for H2O2 generation, which followed pseudo-zero-order kinetics, and either positively or negatively affected H2O2 generation. Ar:O2 (75:25) and Ar:O2 (50:50) resulted in the highest and second-highest H2O2 generation for both gas saturation and sparging, respectively. In addition, gas sparging resulted in much higher H2O2 generation for all gas conditions compared to gas saturation; this was because of the significant change in the cavitational active zone and concentrated ultrasonic energy, which formed a bulb-shaped active zone, especially for the Ar/O2 mixtures adjacent to the transducer at the bottom. The sparging flow rate and position also significantly affected H2O2 generation; the highest H2O2 generation was obtained when the sparger was placed at the bottom adjacent to the transducer, with a flow rate of 3 L/min.

In Part II, the generation of nitrogen oxides, including nitrite (NO2) and nitrate (NO3), was investigated using the same ultrasonic system with three gas modes: saturation/open, saturation/closed, and sparging/closed.



中文翻译:

气体饱和度和鼓泡对开放和封闭系统声化学氧化活性的影响,第一部分:H2O2 的产生

根据溶解在液体中的气体,可以显着增强或降低空化/声化学活性。尽管许多研究人员提出了影响声致发光 (SL)、声化学发光 (SCL) 和化合物降解程度的溶解气体条件的重要性顺序,但目前尚不清楚最适合声化学氧化反应的气体条件。在这项研究(第 I 部分)中,研究了 28 kHz 声反应器系统中气体饱和度和鼓泡对 H 2 O 2生成的影响。四种气体模式,饱和/封闭、饱和/开放、喷射/封闭和喷射/开放,应用于 Ar、O 2、N 2, 和二元气体混合物。测量了超声波照射期间溶解氧 (DO) 浓度的变化,并将其用作液体和空气之间的气体交换是否改变了液体的气体含量的指标。对于气体饱和度/开放模式,观察到 DO 浓度存在显着差异,范围从 –11.5 mg/L (O 2 100 %) 到 +4.3 mg/L (N 2 100 %),而在其他气体模式。气体含量的变化显着降低了 H 2 O 2生成的线性度,这遵循伪零级动力学,并且对 H 2 O 2的生成有积极或消极的影响。氩:O 2(75:25) 和 Ar:O 2 (50:50) 分别导致气体饱和度和喷射的 H 2 O 2生成量最高和第二高。此外,与气体饱和度相比,气体喷射导致所有气体条件下产生的H 2 O 2高得多;这是因为空化活性区发生了显着变化,超声能量集中,形成了一个球形活性区,尤其是底部靠近换能器的 Ar/O 2混合物。喷射流量和喷射位置也显着影响H 2 O 2的产生;最高的H 2 O 2当分布器放置在传感器附近的底部时,产生了 3 L/min 的流速。

在第二部分中,使用具有三种气体模式的相同超声波系统研究了氮氧化物(包括亚硝酸盐 (NO 2 ) 和硝酸盐 (NO 3 ))的产生:饱和/开放、饱和/封闭和喷射/封闭。

更新日期:2022-11-01
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