Attractive technologies such as separation processes, oil exploitation and refining, flotation, mixing processes, wastewater treatment, surface cleaning, nanomaterials in nanotechnology, agronomy, etc. request new tools for increasing their effectiveness. The idea to see deepest what in real happen in the nanolevel of the liquid and colloid systems opened a new field in the area of the physicochemical science. This new field spreads out from the investigation of the nanobubble (NB) creation mechanisms to the study of their properties and the potential applications, from the plants' growth to the medicine. It is not an occasional fact that during the last years the number of the published papers regarding the NB technology increased remarkably. In this chapter gives a general overview regarding the history, the production methods/generators, and the potential applications of the NBs. Particularly, a historical issue from earliest experiments, where the existence of NBs was proved, is described. Following, the issues of the bulk and interface NB production and the information regarding their stability are covered. The properties of NBs are also mentioned and discussed, and finally the group of the suggested application fields is reported. Some emphasis has been given on the effect of the NBs on the biological applications, where new, unpublished, data are provided.

Fundamentals and applications of nanobubbles

Environment-friendly surface cleaning using micro-nano bubbles

Effect of electrolyzed water (EW) produced from sodium chloride solution in a single vessel and carbon dioxide microbubbles (CO2MB) on decomposition of diazinon and its oxidized product, diazoxon, was investigated. Furthermore, these removal by the EW with CO2MB from broccoli-attached diazinon was examined. Diazinon was oxidized to diazoxon by EW, and the oxidative effect increased with increasing EW concentration from 0.1 to 0.6 mol L−1 or electrolyzing time from 1 to 10 min. However, EW concentration more than 0.2 mol L−1 was required to reduce diazoxon. The effect of EW on the decomposition of diazoxon increased with increasing EW concentration, electrolyzing time or reaction time from 10 to 60 min but decreased by generating CO2MB. Furthermore, diazinon concentration in broccoli was significantly decreased by treatment with deionized water or EW for 10 min, and the removal effect was continued by generating CO2MB in EW until 60 min. The diazoxon concentration in broccoli treated by EW decreased after increased up to 30 min, and the removal effect was increased by generating CO2MB. Also, the pH and available chlorine concentration (ACC) of the EW increased with increasing EW concentration or electrolyzing time but decreased and almost unchanged by generating CO2MB, respectively. Therefore, it was revealed that EW had a decomposition effect on diazinon and diazoxon and that CO2MB promoted the effect of EW on the removal of these pesticides in broccoli. Additionally, the decomposition effect of EW on diazinon and diazoxon was suggested to be influenced by high pH and ACC. Practical Application The EW produced from NaCl solution in a single vessel is a safer technique easy to be used than that from HCl. In addition, CO2MB has no harmful effects on the human body. This study demonstrated that the EW was effective for decomposing diazinon, an organophosphorus insecticide, and diazoxon, its oxidized product, and that the removal of these pesticides in broccoli by the EW could be more effectively achieved by generating CO2MB. Therefore, the use of EW with CO2MB can be expected to remove pesticides from fruits and vegetables at food factory. 

Effect of electrolyzed water and carbon dioxide microbubbles on removal of diazinon and diazoxon

3D printing technology has been used to directly produce various actual products, ranging from engines and medicines to toys, especially due to its advantage in producing items of complicated, porous structures, which are inherently difficult to clean. Here, we apply micro-/nano-bubble technology to the removal of oil contaminants from 3D-printed polymeric products. Micro-/nano-bubbles show promise in the enhancement of cleaning performance with or without ultrasound, which is attributed to their large specific surface area enhancing the adhesion sites of contaminants, and their high Zeta potential which attracts contaminant particles. Additionally, bubbles produce tiny jets and shock waves at their rupture, driven by coupled ultrasound, which can remove sticky contaminants from 3D-printed products. As an effective, efficient, and environmentally friendly cleaning method, micro-/nano-bubbles can be used in a range of applications.

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Green Cleaning of 3D-Printed Polymeric Products by Micro-/Nano-Bubbles

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Takahiro Ishizaki

Papers

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