The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation

Shaoqi Zhou; Sabereh Nazari; Ahmad Hassanzadeh; Xiangning Bu; Chao Ni; Yaoli Peng; Guangyuan Xie; Yaqun He

doi:10.1016/j.ultsonch.2022.105965

The effect of preparation time and aeration rate on the properties of bulk micro-nanobubble water using hydrodynamic cavitation

Ultrason Sonochem. 2022 Mar:84:105965. doi: 10.1016/j.ultsonch.2022.105965. Epub 2022 Feb 25.

Authors

Shaoqi Zhou¹, Sabereh Nazari², Ahmad Hassanzadeh³, Xiangning Bu⁴, Chao Ni¹, Yaoli Peng¹, Guangyuan Xie¹, Yaqun He²

Affiliations

¹ Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education), China University of Mining and Technology, Xuzhou 221116, China; School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China.
² School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China.
³ Maelgwyn Mineral Services Ltd, Ty Maelgwyn, 1A Gower Road, Cathays, Cardiff CF24 4PA, United Kingdom; Department of Geoscience and Petroleum, Faculty of Engineering, Norwegian University of Science and Technology, Trondheim, Norway.
⁴ Key Laboratory of Coal Processing and Efficient Utilization (Ministry of Education), China University of Mining and Technology, Xuzhou 221116, China; School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China. Electronic address: xiangning.bu@cumt.edu.cn.

Abstract

Fundamental research on bulk micro-nanobubbles (BMNBs) has grown rapidly due to the demand for their industrial applications and potential role in interfacial sciences. This work focuses on examining properties of such bubbles, including the number, concentration, zeta potential, and surface tension in water. For this purpose, BMNBs were generated by the hydrodynamic cavitation (HC) mechanism. Distilled water and air in the experiments were the liquid and gas phases, respectively. The characterization of bulk microbubbles (BMBs) and bulk nanobubbles (BNBs) were performed through focused beam reflectance measurement (FBRM) and nanoparticle tracking analysis (NTA) techniques, respectively. Zeta potential and surface tension of aqueous solutions were measured at different time and aeration rates. The results showed that aeration rate and preparation time had an important role in the properties of BNBs (concentration, bubble size, and surface charge) and BMBs (number, and bubble size). The instability of BMBs led to the rapid changes in the dissolved oxygen (DO) content in the water. The number of BMBs decreased when preparation time and aeration rate increased, but their size remained constant. By enhancing the preparation time and aeration rate, the concentration of BNBs improved first and then reduced. Additionally, the surface tension of an aqueous solution containing BNBs was significantly lower than that of pure water.

Keywords: Aeration rate; Bubble concentration and size; Bulk microbubbles (BMBs); Bulk nanobubbles (BNBs); Dissolved oxygen (DO) content; Preparation time.