Nanobubbles are extremely small gas bubbles that have several unique physical properties that make them very different from normal bubbles. These properties make nanobubbles a superior aeration method for a number of applications around the world.
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Nanobubbles have a typical mean diameter of roughly 80nm based on extensive testing through independent laboratories using Malvern's NanoSight Nanoparticle Tracking Analysis software. Bubbles this size lack enough buoyancy to reach the surface and instead follow Brownian motion. The net effect is that nanobubbles will remain suspended in water for months until they dissolve, traveling randomly throughout the body of water and efficiently aerating the entire water column. Subsequently, dissolved oxygen (DO) measured at the deepest parts of a tank or pond will match the DO recorded near the surface. This unique behavior enables nanobubbles to provide a homogenous distribution of oxygen throughout an entire body of water.
All bubbles naturally possess a surface charge. The smaller the bubble, the stronger the surface charge. Nanobubbles have a high zeta potential, which is the electro kinetic potential in colloidal dispersions. Through the testing done with zeta-sizers, it has been shown that the strong negative charge of nanobubbles limits their coalescence, meaning the integrity of the bubble is preserved at any depth for extended periods of time. Additionally, the negative charge combined with their high concentration improves separation efficiency in flotation processes by increasing collision probability. This unique property allows wastewater, Oil and Gas and Mining operators to float more suspended matter than through conventional methods.
The neutral buoyancy and negative surface charge of nanobubbles allows them to remain in suspension for months at a time. This occurs even after the solution reaches oxygen saturation. In this capacity, the nanobubbles act as a gas reserve in the solution. As oxygen is consumed from the water by biology, chemistry, or off-gassing, the nanobubbles rapidly diffuse more oxygen into the water, maintaining elevated dissolved oxygen levels until the nanobubbles are depleted. This additional gas reserve, estimated up to 20% over the saturation point, enables industries to utilize gases more cost effectively than ever before.
Oxygen Transfer Efficiency
A key requirement of any aeration application is efficient oxygen transfer into the body of water. Conventional aeration systems transfer only 1% to 3% of oxygen per foot of water due to their size and corresponding rapid rise rate. This makes conventional aeration highly inefficient. As a result, aeration is estimated to consume between 1 and 2% of the world's energy, almost all of it going toward treating wastewaters. Moleaer's technology leverages the unique properties of nanobubbles and delivers an industry-leading oxygen transfer efficiency (OTE) of over 85% per foot of water. The nanobubbles' longevity in water, together with their high surface area per volume, makes them the most efficient aeration method on the market today and allow operators to significantly reduce operating costs.
Zeta potential is a key indicator of the stability of colloidal dispersions. The higher the zeta potential, the more stable the behavior of the colloidal particle. Nanobubbles have a high zeta potential, meaning their interaction with surrounding colloidal particles is stable compared to larger bubbles. The higher zeta potential also causes excess ions to be formed and the creation of free radicals. Free radicals are atoms with an odd number of electrons that can be formed when oxygen interacts with certain molecules. Free radicals are important to processes such as combustion, atmospheric chemistry, polymerization, plasma chemistry, biochemistry and other chemical reactions.
Nanobubbles are the smallest bubble size known, 500 times smaller than a microbubble, or about the size of a virus. At this scale, far more nanobubbles can fit in the same volume of water compared to other bubbles. They also have several unique characteristics directly related to their miniature size that includes neutral buoyancy, a strong electric charge, and a high transfer efficiency. Larger bubbles do not possess these characteristics, making them less beneficial in a number of applications when compared to Moleaer's nanobubbles.
Michael Stenstrom, the foremost aeration industry expert and distinguished professor at UCLA, said, "Moleaer's nanobubble generators provide the highest oxygen transfer efficiency of any aeration technology I have tested so far."
Additionally, the size and concentration of Moleaer’s nanobubbles are measured using Nanoparticle Tracking Analysis (NTA) performed by a NanoSight instrument. You can read the NanoSight report here.