Chemists discovered what stabilizes gas nanobubbles in liquids.

Gases play a crucial role in many chemical reactions, and one way to retain them in solutions is by forming bubbles. Compared to larger bubbles, nanobubbles, which are smaller than a human hair, can trap gas for a longer duration—up to months. This provides more time for chemical reactions to occur.

“When we need to introduce gas into a solution on an industrial scale, we want to minimize its losses and maximize its use for chemical reactions. Our primary goal is to keep the gas in the solution for as long as possible, ideally indefinitely, so that it does not escape and the bubbles do not burst,” explained the group’s interest in the research, Dr. Hamidreza Samouei.

A team of researchers from Texas A&M University studied the factors contributing to the stability of nanobubbles. The results of their work were published in the journal The Journal of Physical Chemistry.

The scientists discovered that the stability of nanobubbles is largely determined by their electrical charges and the interaction of these charges with the solvent. The stability of the bubbles is also affected by additives present in the solution. The authors presented data on nanobubbles of nitrogen, oxygen, helium, n-butane, and carbon dioxide.

The chemistry team experimentally confirmed the viability of their concept. The results demonstrated how the stability of nanobubbles depends on the polarity of the solvent, the magnitude of the dipole charge of the nanobubbles, and the adsorption of additive ions. The interaction of these three factors proved to be critical in determining the likelihood of nanobubbles merging into larger and less stable ones.

The ability of nanobubbles to retain gas in solution makes wastewater treatment, hydroponic plant cultivation, and disinfection possible and efficient. When using nanobubbles in hydroponics, producers achieve higher yields compared to growing the same plants without considering bubble sizes. Nanobubbles increase the oxygen content in water, creating optimal conditions for the growth of many crops.

Understanding the stability of nanobubbles is part of a larger research project. Scientists introduce carbon dioxide into saline solutions to extract various minerals from them. This method, known as brine mining, allows for the extraction of minerals used, for example, in the production of lithium batteries and magnesium fertilizers. Researchers have figured out how to extend the lifespan of nanobubbles, which will help make them a key tool in mineral extraction from brines.