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A Deeper Dive into Aqueous Ozone 

Author | Xu Simon, PhD, MBA

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What is aqueous ozone?

Many of us are familiar with gaseous ozone. We usually think of it as the component of the stratosphere that protects us from ultraviolet (UV) light from the sun. In fact, we’re so familiar with gaseous ozone that we usually just call it “ozone” (O3).  But there’s also aqueous ozone (AO). Aqueous ozone is still ozone (O3), but it is dissolved in water rather than a gaseous component of the atmosphere. 

There’s an analogous situation with oxygen (O2). We usually think of oxygen as the component of air that we extract for metabolism when we breathe in, but oxygen can also be dissolved in water. In fact, water normally has about 10 parts per million (ppm) dissolved oxygen. This dissolved oxygen is such a fundamental aspect of water composition that aquatic organisms such as fish have evolved gills to use the dissolved oxygen for their own metabolism. Gills don’t break water (H2O) into distinct hydrogen and oxygen atoms. Gills separate dissolved oxygen from water so that the oxygen can be used for metabolism. 

Because ozone gas is usually not present in the troposphere, the atmospheric layer that touches the earth’s surface and that contains the air we breathe, we usually do not see aqueous ozone in natural or municipal water sources. Instead, it is produced in a range of concentrations from 0.1 ppm up to about 10 ppm (0.00001% – 0.001%) by using industrial methods. Furthermore, it quickly reverts back to oxygen, meaning that within minutes, an aqueous ozone solution turns right back into water. There is no chemical residue or hazardous waste generated. 

How does aqueous ozone work?

Ozone is a potent oxidizing agent, meaning it can break strong chemical bonds. Ozone works against microbes in one of two ways. Firstly, it can react with the cell membrane, disrupting its structural integrity and leading to cell lysis. In cell lysis, a cell cannot contain its components within its membrane, so its components leak or explode out from the cell, killing it. Alternately, ozone can react with nucleic acids, disrupting their structure and preventing cell proliferation.  

Furthermore, ozone has the potential to amplify its killing effect through a chemical chain reaction. In addition to reacting directly with cells, one ozone molecule can react with certain other molecules in solution, activating these molecules as new oxidizers themselves. This means that ozone can inactivate some compounds and organisms that are present even at higher concentrations than ozone itself. 

This process of ozone oxidation does not affect humans and animals in the same way as it affects microorganisms. There are two reasons for this difference. First, humans and animals have defense mechanisms against oxidizing agents. The most visible of such defense is skin, which is a protective covering of cells specialized to absorb environmental stresses. Second, humans and animals are multicellular, meaning that even if a small number of cells sustain damage, other cells are available to regenerate the damaged cells and to do their work.  

What is aqueous ozone used for and what are its advantages?

Aqueous ozone is a potent antimicrobial cleaner and sanitizer with a wide variety of applications. It is used for sanitization of hard non-porous surfaces, food contact surfaces, potable water, and swimming pools. It has also been used for wastewater treatment and in food service and agriculture industries. It is even approved for use in organic agriculture and has been shown to remove pesticides used in traditional agriculture. It neutralizes odors and removes stains. It is used in the paper and textile industries, and applications are emerging in the medical field for handwashing and for sanitization of medical tools. 

Ozone has several advantages over other cleaning and sanitizing agents.  First, it reacts with a broad spectrum of compounds, including both organic (carbon-containing) and inorganic ones. For this reason, it not only kills microbes, but it also removes odors, colorants or stains, surfactants, and some suspended solids. It works both on surfaces and within the water itself. 

Chemically, ozone has a high redox potential, meaning its mechanism of action against a typical mixture of organisms and compounds is faster than that of most common harsh chemicals.  Because of its fast action, aqueous ozone also decays rapidly. This means it leaves no residue on surfaces and does not need to be wiped or rinsed. 

Aqueous ozone is safe to use. It has a Generally Regarded as Safe (GRAS) designation from the U.S. Food and Drug Administration (FDA) and unlike certain chemicals and antibiotics, it does not contribute to antibiotic resistance.  It does not create hazardous by-products. Aqueous ozone is easy to keep away from sensitive areas such as lungs. 

Technology to create aqueous ozone is not new; it emerged well over a century ago.  However, aqueous ozone, its many industrial applications, and its advantages are not yet front of mind when thinking of ozone. The next several years are expected to provide exciting applications for maturation, scaling, automation, and wide-scale adoption of aqueous ozone technology.

About Enozo and our aqueous ozone

Enozo products create aqueous ozone on-demand using a patented Active Diamond Electrolytic Process Technology™ (ADEPT™) technology.  With ADEPT, potable tap water from the bottle reservoir is sent into a chamber. From there, the water passes through a solid diamond electrode and encounters a direct electrical current. This causes an electrochemical reaction to split some of the water molecules, creating ozone directly from water. The water now has freshly-created aqueous ozone. 

Enozo creates aqueous ozone directly from water. By using ADEPT technology, Enozo concentrates the ozone it generates into the water stream that will be used directly as an antimicrobial solution. Other technologies for creating aqueous ozone rely on making a high concentration of ozone gas and transferring gaseous ozone to water by using tanks, injectors, or bubblers. These technologies don’t capitalize on the safety and the efficiency of the Enozo ADEPT technology.   

Author | Xu Simon, PhD, MBA

Author | Xu Simon, PhD, MBA

Enozo Chief Technology Officer