https://www.sciencedirect.com/science/article/abs/pii/S2213343725023334

• Dissolved ozone in the nanobubble solution was 2.7 times

higher than conventional ozone.

• Nanobubbles’ mass transfer coefficient was one order

of magnitude higher than conventional ozone.

• Nanobubbles are detectable in solution at 39 °C

after 4 h without additional gas infusion.

• Nanobubbles clean acrylic and PVC surfaces up to

2.4 times better than conventional ozone and tap water

Nanobubbles enhance gas–liquid mass transfer, particularly in gas-limited

or diffusion-restricted systems, owing to their minuscule sizes and high

interfacial surface areas. However, their potential to enhance ozone mass

transfer in heated aqueous systems for removing abiotic fouling in sanitary

applications remains understudied. This study simulated application

conditions for a typical sanitary system to evaluate ozone nanobubbles’

efficacy for surface cleaning. First, 71 × 10⁶ nanobubbles/mL were produced

by circulating 120 L of tap water at 39 °C with 0.5 LPM ozone-air flow rate

(target ozone = 1.5 mg/min) for 2 h. This resulted in a dissolved ozone

concentration of 5.6 µg/L i.e., 2.7 times higher than the conventional ozone

(micro-macrobubble). Ozone nanobubbles exhibited a more rapid increase

in oxidation-reduction potential and dissolved oxygen than conventional ozone.

Although dissolved ozone was depleted within 1 h, 12 × 10⁶ nanobubbles/mL

remained in suspension after 4 h. The minimal decline in ORP over this period

suggests that the residual nanobubbles continued to release ozone and/or oxygen

, sustaining the oxidative environment in the absence of external ozone input.

Nanobubbles significantly enhanced fouling removal by up to a 2.4-fold on PVC 

and acrylic surfaces than conventional ozone solutions within a 30-minute treatment

period. SEM, FTIR, and XRF analyses expounded the role of enhanced ozone transfer

by nanobubbles in improving surface cleaning, and also revealed potential surface 

interactions between ozone and polymer substrates. The findings here feature the

potential of ozone nanobubbles to enhance cleaning performance in sanitary systems,

offering an effective solution for fouling control.