Exogenous reactive oxygen species (ROS) produced by nanobubble (NB) water offer a reasonable explanation for NBs’ physiological promotion and oxidation effects. To develop and exploit the NB technology, we have performed further research to identify the specific ROS produced by NBs. Using a fluorescent reagent APF, a Fenton reaction, a dismutation reaction of superoxide dismutase and DMSO, we distinguished four types of ROS (superoxide anion radical (O2·–), hydrogen peroxide (H2O2), hydroxyl radical (·OH), and singlet oxygen (1O2)). ·OH was confirmed to be the specific ROS produced by NB water. The role of ·OH produced by NB water in physiological processes depends on its concentration. The amount of exogenous ·OH has a positive correlation with the NB number density in the water. Here, spinach and carrot seed germination tests were repeatedly performed with three seed groups submerged in distilled water, high-number density NB water, and low-number density NB water under similar dissolved oxygen concentr...

Identification of ROS Produced by Nanobubbles and Their Positive and Negative Effects on Vegetable Seed Germination

Mysteries of bulk nanobubbles (ultrafine bubbles); stability and radical formation

Colorimetric sensing of bithiols using photocatalytic UiO-66(NH2) as H2O2-free peroxidase mimics.

https://hal.archives-ouvertes.fr/hal-02470592/document

Oxygen nanobubbles enhanced photodegradation of oxytetracycline under visible light: Synergistic effect and mechanism

The present study addresses the mechanism of hydroxyl radical (·OH) generation by the collapse of microbubbles in water solution. The influence of gas supply and flow rate, solution pH, and ionic strength on the aeration efficiency, free radical generation, and contaminant removal (take methylene blue as an example) are elucidated. The results showed that the degradation rate of methylene blue by ·OH increased with flow rate as well as in acidic or alkaline solutions compared to that in neutral conditions. ·OH was shown to be produced by the reaction between protons and oxygen radicals generated by the decomposition of O2 rather than water molecules. A greater concentration of O2 or H+ thus promoted the reaction, resulting in effective removal at a high flow rate or low pH. Nevertheless, there was considerable methylene blue removal at high pH, driven by the production of the dye cation through the dissociation of methylene blue and the high electronegativity of bubbles at high pH, thus enhancing interface adsorption and degradation, as well as by the high ionic strength of the solution helping to generate ultrafine bubbles and maintaining them through ionic shielding. The current work provides useful insights into the application of microbubble as a promising technique.

Hydroxyl Radical Generation and Contaminant Removal from Water by the Collapse of Microbubbles Under Different Hydrochemical Conditions

Many scientists have elucidated that characteristics of micro-nanobubbles are distinctly different from those of normal bubbles. However, the physicochemical properties of micro-nanobubble water ha...

ESR Measurement of Hydroxyl Radicals in Micro-nanobubble Water

Cleaning Effect by Fine Bubbles Generated with Gas–Liquid Share Method

Abstract In recent years, it has been defined by the International Organization for Standardization (ISO) that fine bubble of 100 m or less be referred to as fine bubble. Fine bubbles will have specific properties different from bubbles that are seen in everyday life such as millimeter size and centimeter size by refining the gas. For example, the total surface area of a plurality of fine bubbles having the same volume as a single bubble of centimeter size is significantly large, and the chemical reaction, physical adsorption and mass transport at the gas-liquid interface are dramatically improved. Moreover, the fine bubbles have such property that dissolution efficiency of internal gas is improved from a huge total surface area acquired. In this study, cleaning and purification were performed utilizing the specific properties of these fine bubbles. In cleaning, the research was conducted on the removal of oils adhered to polypropylene and the removal of salt fixed to aluminum foil. Regarding the oil removal, the removal effect that relies on the total surface area of fine bubbles was verified. Regarding the removal of fixed salt, the result that by efficiency improvement of the removal of fixed salts is attained from phenomena such as fine bubble dissolution and bubble formation again. On the other hand, in the purification, fine bubbles were supplied to a river model tank containing the actual river sediment, and the changes in the water quality were investigated. As a result, the oxide layer of the sediment was formed from the high dissolution efficiency of the fine bubbles, and the suppression of elution of phosphorus from the sediment was verified.

Research on Cleaning and Purification Using Fine Bubbles

This paper discusses the effectiveness of the new TERAKOYA learning system in remedial education. This system provides both interactive lessons and a small private school environment similar to the 18th-century Japanese basic schools called TERAKOYA. It helps students study actively anywhere on a local area network linking multipoint remote users, and it provides an interactive evening lesson using tablet PCs and custom-built applications both in the dormitory and at home, so students and teachers can stay in their own living spaces. The proposed learning system was implemented in a girl's dormitory with a teacher at home or in a teacher's room on campus over one year. The implementation employed a handwritten electric whiteboard with verbal communication through a headset. After this test was conducted, the effectiveness of the system in helping students study actively and willingly as an example of "right time, right place" learning was verified.

Yusuke Nishiuchi

Papers

ESR Measurement of Hydroxyl Radicals in Micro-nanobubble Water

Cleaning Effect by Fine Bubbles Generated with Gas–Liquid Share Method

Research on Cleaning and Purification Using Fine Bubbles

Evaluation of TERAKOYA Learning System Linking Multi-point Remote Users as Supplementary Lessons

Discrimination of Ultra-fine Bubbles and Solid Nanoparticles Using the Sonoluminescence Effect