# Micro-Nanobubble Technology in Surface Cleaning and Defouling
## 3 Advanced Applications of NBs in Precision Surface Cleaning
### NBs in Membrane Cleaning
Bubble size and concentration determine the effectiveness of MNBs, and maximizing these variables may increase their wider use. Future studies should examine how MNBs affect membranes  
Figure 7: The figure illustrates the intensity of turbulence and gas bridge effects exerted by micro- and NBs on a ceramic membrane over time. Reproduced with permission from [34], Copyright © 2024, Published by Elsevier B.V.  
over the long run, the distinct functions of each mechanism in preventing fouling, and how to regulate the bubble size for best results. [PERSON] et al. [57] intended to increase the cleaning effectiveness of membrane fouling mitigation in MBRs through the use of sodium hypochlorite (NaClO) in the NB water during NB-assisted backwashing. Both NBs and NaClO worked in concert to remove the fouling layer, whereas NaClO chemically broke down its constituent parts. The effectiveness of this method was strongly influenced by pH; the optimal outcomes were observed at pH 4, followed by pH 8.5 and pH 12. The strong oxidation power of NaClO and the advantageous qualities of NBs greatly increased the cleaning effect at acidic pH. This study showed that combining NBs with chemical reagents such as NaClO can enhance fouling control in MBRs, providing a viable approach for widespread use. However, further investigations are required to examine additional chemical agents and maximize the long-term performance. [PERSON] et al. [58] reported the hydrothermal synthesis of several morphologies of MnO\({}_{2}\)-modified ceramic membranes (MnO\({}_{2}\)@CMs) in which the morphological evolution of MnO\({}_{2}\) on the ceramic membranes was affected by the concentration of K\({}^{+}\) and H\({}^{+}\). To remove pollutants, an H\({}_{2}\)O\({}_{2}\)/MNB/MnO\({}_{2}\)@CM system was developed using MnO\({}_{2}\)@CMs. The maximum catalytic activity was shown by the sheet-like MnO\({}_{2}\)@CM, which removed 73.07% of the TOC and 99.45% of the methylene blue hue. With its outstanding stability, reusability, and minimal manganese leaching, the system demonstrated exceptional effectiveness in reducing membrane fouling. According to a mechanistic study, MNbs produced ROS upon exposure to H\({}_{2}\)O\({}_{2}\), which improved the MnO\({}_{2}\)@CM's catalytic activity. Furthermore, MnO\({}_{2}\)@CM's surface underwent a Fenton-like reaction, which further enhanced pollutant degradation. This system has excellent potential for wastewater treatment because of its effective pollutant removal, strong antifouling capability, and minimal environmental impact. [PERSON] et al. [59] aimed to alter the surface of PA membranes by employing branched bis- and tris-quaternary assemblies (BQTEs and TQTEs, respectively), which are produced via a quaternization reaction. The development of NBs within the PA matrix was induced by grafting these assemblies onto immature PA membranes. The loose PA film was the result of the modification mitigating Donnan exclusion and reducing the negative charge. With a water permeance of 9.7 L\(\cdot\)m\({}^{-2}\)\(\cdot\)h\({}^{-1}\)\(\cdot\)bar\({}^{-1}\) and a NaCl/tetracycline selectivity of 42.5, the PA-BQTE and PA-TQTE membranes demonstrated exceptional antibiotic desalination performance. Improved antifouling properties and increased chlorine resistance were also demonstrated for the modified membranes, which are suitable for real-world water treatment applications.