Nanobubbles are tiny gas bubbles with diameters generally less than 200 nanometers.
Due to their small size, they exhibit unique physical and chemical properties compared to larger bubbles, such as higher stability in liquids, increased surface area, and enhanced reactivity. Nanobubbles are used in water treatment, environmental remediation, agriculture, aquaculture, medical and cleaning and sterilization applications.
The study also involved predicting and analyzing nanobubble stability by calculating the total potential energy between two bubbles based on the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. This approach helps understand the interactions governing nanobubble stability and coalescence under different conditions.
In the paper entitled, “Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water,” researchers studied the long-term stability of various gas nanobubbles, which are significant for numerous applications. The research involved preparing five types of nanobubbles—N2, O2, Ar + 8% H2, air, and CO2—in both deionized water and salt aqueous solutions using hydrodynamic cavitation. Key measurements included the mean size via dynamic light scattering and zeta potential via electrophoretic light scattering of the nanobubbles, obtained through the NanoBrook Omni light scattering instrument (Brookhaven Instruments, Nashua, NH USA.)
Key findings include:
- pH and IEP Variations: The isoelectric points (IEPs) of nanobubbles differed among gases, with CO2 nanobubbles reaching the highest pH value of 5.7.
- Stability in Deionized Water: N2, O2, Ar + 8% H2, and air nanobubbles remained stable for 60 days, though their sizes fluctuated due to Ostwald ripening, explained through potential energy calculations with extended DLVO theory.
- CO2 Nanobubbles Instability: CO2 nanobubbles dissolved within five days in deionized water, likely due to HCO3− formation reducing potential energy and destabilizing the bubbles.
- Salt Water Effects: In 1 mM salt solutions, N2, O2, Ar + 8%H2, and air nanobubbles became unstable, coalesced, and disappeared within 7 to 14 days. Conversely, CO2 nanobubbles in salt solutions were more stable, maintaining 200–300nm sizes for two weeks, thanks to ionic interactions.
- Bubble Size and Buoyancy: Bubbles smaller than 1μm exhibit extremely low terminal velocities, preventing buoyancy-driven floating, which influences their stability and potential applications.
This comprehensive study highlights how gas type, solution chemistry, and nanobubble size influence stability, with potential implications for their use in various fields such as water treatment, medicine, and nanotechnology.
Brookhaven Instruments, with a legacy of pioneering in light scattering and zeta potential analysis, is committed to advancing its technology to provide reliable and innovative solutions that support modern scientific breakthroughs in nanotechnology, pharmaceuticals, and materials science.
Contact us today to learn more about our light scattering solutions for particle size and zeta potential analysis.