Ozone destroys plastic, rubber, metal, creating toxic byproducts. How do you make sure the ozone you create does not contain these potentially toxic byproducts? A scientific review of the options.
There is a tremendous amount of interest in ozone gas these days in the areas of medical / dental research, sterilization, and Ozone Therapy. The ozone utilized for these scientific research applications needs to be manufactured by a machine called an ozone generator. Inside each of these ozone generators is a component called an "Electrode" where the ozone is made. This is where energy comes into contact to create the ozone. It needs to be a sealed chamber, and there are a variety of ways build that sealed chamber.
The overall question that will be answered by this article is what is the best material to use to make this Electrode, Glass or "Ceramic"? Only one is a winner, and you are about to find out which one....
1. We Can’t Compromise Purity (Purity is a Must)
First and foremost it is worth emphasizing that in order for ozone to be used for Ozone Therapy, the one overriding aspect of the ozone itself that can’t be compromised, is that it must be absolutely “UltraPure Contaminant Free”. Just like you don't want contaminants such as plastics and metals in your water, you also don't want them in your ozone.
This need for ultrapure contaminant free ozone originally placed the ozone industry in a tough spot. The reason is that ozone is such a strong oxidant it oxidizes (destroys) virtually every material that is used today to manufacture consumer electronics. For example, ozone destroys plastics and rubber, to the point where they literally dissolve and fall apart. Ozone also oxidizes metals to dust, like rust on a car. The byproducts of these reactions between ozone and these materials are added to the ozone and thereby contaminate the ozone so that it is no longer pure. So what do we need to do to enable us to make ultrapure contaminant free ozone?
When one considers the oxidative destructive potential of ozone upon these materials, it is clear that the only way to create ultrapure contaminant free ozone is to ensure that when the ozone is made it never comes into contact with materials it can destroy, such as the metal, plastics, and rubber mentioned above. To guarantee ozone purity, we have to identify and use materials that are ozone resistant, and make sure the ozone only touches those ozone resistant materials when it is being created.
Two such ‘ozone resistant’ materials are being considered as possible answers to this challenge. Both Quartz Glass and “Ceramic” can be described as ozone resistant, but which one is the wiser choice?
This article will provide you with detailed information as to which of these materials is actually the only choice for the creation of UltraPure Contaminant Free Ozone.
2. The Ozone Electrodes, where the magic happens
When considering a material for making ozone, consider where and how it will be utilized.
Ozone gas is created by exposing pure contaminant free oxygen (O2) to an energy field. This energy causes some of the O2 to split apart and reconnect together as O3, “Ozone”. In order for this process to be successful the feed gas ‘oxygen’, the energy, and the product gas ‘ozone’ must all be contained within some sort of a chamber. This chamber is referred to as an “ozone electrode”. All ozone generators have some sort of an ozone electrode within them. It is the key component in any ozone generator.
Ozone electrodes come in all different sizes, but with regard to ozone electrodes designed to accept pure oxygen as the feed gas the shape remains basically the same => a “double walled” cylinder. The walls of the cylinder are hollow, and the space between the walls provides the channel through which the oxygen travels the length of the electrode and where some of it will turn into ozone.
We discussed above how ozone can only be pure and contaminant free if it is allowed to touch only materials that are ozone resistant (that the ozone cannot break down). It follows that any chamber that we use to create the ozone must be made of, or completely lined with, the ozone resistant material.
Consider Quartz Glass
Quartz Glass is 100% completely impervious to the oxidative effects of ozone. Quartz Glass is therefore a material that is truly, Ozone Proof. The unique aspect that makes Quartz Glass and excellent choice is that it can be melted and molded to any shape. Glass pieces can be ‘welded’ together with liquid glass that then hardens to seamlessly create a one piece glass product made completely of glass. This attribute that glass can be molded, above all, is why Quartz Glass is an outstanding choice for use as an electrode in an ozone generator. Not only is Quartz Glass 100% ozone proof, completely impervious to the oxidative effects of ozone, but it can be molded and worked and shaped to become the entire ozone electrode! Double walls, entry, exit, all glass.
This creates a remarkable and unique 100% Quartz Glass Electrode with no other materials in contact with the ozone or oxygen. Electrical components that are necessary to create the plasma energy field are attached to the outside of the glass electrode. While they do their job of creating the energy field, the oxygen and ozone travels through the energy field within the quartz glass tube, completely isolated from any and all other materials.
Most of us have seen intricate glass sculptures, vases, bottles and other artwork that displays this amazing attribute that is unique to glass. Quartz Glass has these properties too, but with the added bonus that it is extremely strong and durable, lead free, and therefore far superior to standard glass.
Think of it! Oxygen enters the glass electrode through a glass ‘nipple’ entry channel. The oxygen moves along through the electrode between two walls of glass, being exposed to the energy field within and as such, turns into ozone. The product gas ozone remains in contact with only glass, for its entire journey through the electrode, and even exits the glass electrode through an exit port referred to as a glass ‘nipple’.
The entire ozone generating process is started and completed with the ozone only ever touching quartz glass; the ozone never touches any material that could add potentially toxic byproducts to the ozone. And since quartz glass is 100% ozone resistant, the ozone exits the glass electrode as the purest most contaminant free ozone possible. It is this ultrapure ozone that is required for sensitive scientific studies, medical research applications, and ozone therapy.
It is for this reason that the International Scientific Committee for Ozonotherapy (ISCO3.org), a committee of 21 of the world's leading ozone experts, stated in their report "Guidelines and Recommendations for Medical Professionals Planning to Acquire a Medical Ozone Generator" on Page 5, Paragraph 6:
"The material from which these electrodes are made must be of highest quality, so as to be able to withstand long term and frequent exposure to the high electric energy as well as the oxidation which may be caused by ozone. The most recommended material for these electrodes is Quartz Glass".
Is ceramic seen in the same light? Read on and find out …
Fact: At the present time (2015) there is no such thing as a 100% “Ceramic” electrode. You can't make the entire electrode from ceramic. You must use metal, plastic, rubber, glues or resins, and that is the key to the problem with ceramic.
"Ceramic" is a word that can describe a wide variety of materials comprised of many different metals and compounds. For the purposes of this discussion when we say ceramic we mean Aluminum Oxide (Al2O3). As you would assume, Al2O3 is a compound of Aluminum. While it is true that this ‘ceramic’ could be considered an ozone resistant material, one cannot ignore the fact that ceramic cannot be molded, shaped with intricate corners, or bonded to itself like Quartz Glass can. It is this simple fact that prevents it from being able to form the entire ozone electrode.
The design and shape of the ozone electrode therefore requires the use of other materials in addition to ceramic. Since ceramic cannot be molded into complex shapes and it cannot be bonded to itself like glass can, “pieces” of ceramic must be used instead. Unfortunately you can’t create a whole double walled electrode with ceramic.
It is for this reason that most ceramic electrodes use a single ceramic surface as the inner wall of the cylindrical ozone electrode but not for the outer surface. Remember in the design of an ozone electrode the ozone/oxygen travels between two ‘walls’ of the electrode. In the case of the so called ‘ceramic’ electrode, the second wall which is the exterior wall is usually metal. This is why ceramic electrodes on the internet look like they are made out of metal; because they are. A small space is created between the inner ‘ceramic’ surface, and the outer metal surface to allow the passage of oxygen and ozone through the electrode and it is within this space that the energy is supplied to the oxygen to turn it into ozone. The ozone is therefore in contact with both ceramic, and metal.
But wait, how do we seal the ends of the tubes so the oxygen/ozone remains contained within the electrode? Since you can’t bond or weld the inner ceramic surface to the metal exterior tube, some other material needs to be utilized to create this seal. In many electrode designs a plastic cap is used at the ends, in others a metal cap. Some manufacturers searching for a simpler option have found that it is easiest to simply plug the ends with bathroom sealant. (Some refer to it as 'silicone resin' or 'silicone glue' but the reality is that it is simple bathroom sealant). The important factor to remember is that these non-ozone resistant materials need to be incorporated into the overall design.
As you can see the fact that ceramic cannot be bonded to itself (welded), or shaped, means that ‘ceramic’ electrodes are not, and cannot, be completely made of ‘ceramic’. Other materials such as metal, plastic, glues and resins need to be utilized in order to seal the tube to create the ozone chamber within and to prevent the ozone and oxygen from leaking out and they are in contact with the ozone, are oxidized by the ozone, and the resulting byproducts contaminate the ozone. This is a serious issue that is never addressed by the manufacturers of ozone generator that use ‘ceramic’ ozone electrodes.
Summary: Ceramic electrodes by the shear fact that ceramic can’t be molded into complex shapes, contain materials that can be oxidized by the ozone, resulting in the production of the contaminants that we so need to avoid.
These two examples clearly display the advantage and superiority of Quartz Glass and identify it as currently the only material known that can truly provide ultrapure contaminant free ozone. It is not only the Optimal choice, it is the Only choice.
3. Case Closed?
We could stop here. However there is a document circling the internet that was written about ceramic and Quartz Glass electrodes that contains inaccurate, misleading, and/or intentionally falsified information. So we will continue with some categories utilized by that other document in order to clarify these topics, correct the inaccuracies, and shed some light on this topic.
One article on this topic of electrodes discusses the the comparative "Hardness" of ‘ceramic’ (Al2O3) to Quartz Glass (SiO2) by referring to a ‘scratch test’ called Moh’s Scale of Hardness. Both materials score quite well on the hardness scale. While this data is interesting it has essentially has nothing to do with products the ozone electrodes within an ozone generator. Also keep in mind that as discussed in section 3. ‘ceramic’ comprises only a small portion of a so called ‘ceramic’ electrode (usually just a single layer). The other materials differ from manufacturer to manufacturer, and can consist of aluminum (metal), steel, or stainless steel. These materials however need to be held together with plastic caps, glues, resins, and/or epoxy sealants. So the question is, is this reference to ‘hardness’ relevant to the discussion of ozone electrodes, especially since Quartz Glass and ‘Ceramic’ are so close to each other in the ‘hardness’ scale? Does anyone know how ‘hard’ an electrode really needs to be? How 'hard' are the components inside your TV or stereo?
The reality of the situation is that electrodes are mounted inside a protective cabinet and will therefore experience no blunt trauma or force. Unless the company making the ozone generator has made an error on how the electrode is mounted, both electrodes will fare well.
The second consideration is that in modern Quartz Glass ozone electrodes, the electrode is shaped into a double walled cylinder, in essence multiplying its structural strength. Quartz Glass is already a ‘hard’ material, and the Quartz Glass electrodes already have tremendous structural integrity. These are then mounted to a structural plate within the ozone generator, and secured in this location. Due to the high quality and strength of the electrodes, and the professional mounting of the electrode within the cabinet, Quartz Glass electrodes are designed to function flawlessly for a lifetime, and have proven to do just exactly that over the past 30 plus years that they have been on the world market.
Heat Retention, Temperature Changes, and Heat Retention and Conduction
Both Ceramic and Quartz Glass are incredibly heat tolerant, due to their high melting termperatures. The melting temperature of Quartz Glass is over 3000 degrees F, while ceramic is about 3700 degrees F. While a discussion of heat tolerance is interesting in that Quartz Glass and ceramic are both quite heat tolerant, one has to consider that Ozone is destroyed by heat. Since ozone is destroyed by heat the goal of every ozone generator manufacturer first and foremost should be to produce an ozone generator that produces as little heat as possible. In fact, the interior temperature of the ozone generator should not exceed room temperature.
Thermal Shock (Cracking):
A discussion about "Thermal Shock" is usually reserved for discussions about materials that can be exposed to extreme swings in temperature, high heat to sudden cold. For example, in the construction of roads, buildings, building foundations, etc, very cold temperatures can shrink the materials while hot temperatures can expand the materials. Heating and then rapdily cooling a material could also place the material under an extreme condition called "Thermal Shock" which could cause the material to crack.
Due to the fact that ozone generators are typically utilized indoors and are therefore almost always used at room temperature, you might think that discussing what would happen if temperatures wildly swung from extreme hot to extreme cold is a bit out of place in a discussion about ozone generator electrodes. If designed properly they should remain at the same operating temperature throughout their lifespan.
But think of it this way. When the temperature swings rapidly from hot to cold, whether the material 'cracks' or not could be considered as an indicator of the strength (structural integrity) of the material.
In this regard Quartz Glass shines above most other materials. As described in a wide variety of professional articles:
“Quartz Glass has a tremendous resistance to “Thermal Shock”. And further, “...it has a remarkable ability to undergo tremendous temperature changes without cracking”. 
This is because, when heated, Quartz Glass hardly expands at all. It has what is referred to as a very low Thermal Coefficient of Expansion. As a result, quartz glass can be heated to 1000C (over 2000F) and then plunged into cold water without breakage.
Clearly then Quartz Glass is extremely resistant to ‘thermal shock’ and cracking. This proves it has tremendous structural integrity and is therefore the perfect material from which to create a dielectric electrode for ozone generators.
Heat Retention, Heat Conduction, Heat Reflection:
All materials are rated for their "Thermal Conductivity". This simply means how well they conduct heat. If you place a cast iron frying pan on the stove and turn on the element, the handle (which is not in contact with the element) will become hot. This is because the iron frying pan 'conducts' heat quite well.
So let's compare the “Thermal Conductivity” of both Quartz Glass and Ceramic. There is a scientific way to do this, because every material is 'rated' for their ability to conduct heat. The rating scale units are referred to as "Watts per meter Kelvin" or w/mk. The higher the rating, the better the material is at conducting heat.
Thermal Conductivity of Ceramic (Al2O3) = 30 w/mk
Thermal Conductivity of Quartz Glass = 1.3 w/mk
Quartz Glass is such a poor conductor of heat that it scores only a 1.3 w/mk. However Ceramic conducts more heat and scores 30 w/mk, 23 times more heat conductive than Quartz Glass. When discussing a material that is being use in a electrode that would ideally remain cool, this is bad news for Ceramic, but great news for Quartz Glass.
So we have discovered that Ceramic conducts heat better than Quartz Glass. The next question on the list is this: The Ceramic is sealed inside an electrode, with metal on the outside. What is it going to do with that heat?
Let’s take this step by step…
1. If you are producing heat inside an ozone electrode, then the ceramic will actually absorb and conduct the heat.
2. Ceramic not only absorbs heat but it also has a capacity to reflect heat back to its source, which is why it is useful in heat shielding for spacecraft that are re-entering Earth’s atmosphere.
3. If heat is generated inside the ozone electrode, it will be generated in the middle of the electrode where the energy field is. The ceramic will then reflect this heat right back into the center of the electrode, destroying the ozone that is being created.
Quartz Glass on the other hand does not reflect heat back into the electrode as ceramic does. This is why Quartz Glass electrodes are described as “Cold Corona Discharge”, because a Quartz Glass electrode has the capability of remaining far ‘cooler’ than the ‘ceramic’ electrode. This property is one of the reasons why Quartz Glass electrodes are capable of creating not only high levels of ozone gas, but also very predictable, precise, and stable concentrations of ozone gas.
If one considers the characteristics of how a material handles 'heat' then Quartz Glass would again be the preferred material from which to create an ozone electrode.
The rapidly expanding demand for Glass Ozone Electrodes
Ceramic Ozone Electrodes are extremely easy and inexpensive to build. Because of this factor, they are being exported by the Chinese by the millions and millions each year. For the low cost of between $10 and $100 any person and any company can cut corners by simply purchasing cheap ceramic electrodes, install them in a cabinet, and thereby create a cheap ozone generator that can be sold for thousands of dollars. You don't need engineers, a factory, or anything other than a vague knowledge of electronics and a garage in order to create a ceramic electrode ozone generator. This is the only real value to a ‘ceramic’ electrode.
But here is the bad news. Since the inherent design of a ceramic ozone electrode allows the ozone to contact many materials that are not ozone resistant, including metals, rubber, plastics, glues and resins. The substances produced by those reactions, many of them toxic, are considered contaminants in the ozone. These ozone generators then, may be fine for industrial ozone applications and possibly air purification but ceramic electrodes clearly are not suitable where the intended application requires “UltraPure Contaminant Free Ozone” like Ozone Therapy.
As described in this paper, Quartz Glass Electrodes are the only electrodes currently on the market that completely prevent the ozone and oxygen from contacting any and all oxidizable materials. Quartz Glass electrodes therefore remain the only technology available today that is capable of producing this ‘purest’ form of ozone. The superiority of the Quartz Glass and the fact that they have proven reliable over a 30 year period, has firmly entrenched Quartz Glass Electrodes as the only method and the preferred method of producing UltraPure Contaminant Free ozone, worldwide.
If is for this reason, that professionals who need pure contaminant free ozone, as well as the largest and best research corporations and universities who need pure ozone, are all seeking out and using ozone generators with Quartz Glass Electrodes.
Amongst the list of professionals using Quartz Glass Electrodes are such Research and development corporations such as:
NOAA – National Oceanic and Atmospheric Administration,
NIST – National Institute of Standards and Technology,
Rutger’s New Jersey Medical School,
MIT – Massachusetts Institute of Technology,
Brookhaven National Laboratory (US Department of Energy),
CalTech – California Institute of Technology,
University of Detroit Mercy
Kent State University
Washington State University
North Carolina State University
Colorado State University
...and many others all use ozone generators that contain Quartz Glass Electrodes. They require pure contaminant free ozone, and Quartz Glass is undeniably the best material from which to build the electrode if your goal is to obtain pure contaminant free ozone.
Materials in Contact with the Ozone:
If after reading this article you are still tempted to consider a purchase of an ozone generator that contains a ‘ceramic’ electrode, ensure that you first contact the company selling the ozone generator and ask them for a list of all of the materials that the ozone will be in contact with while it is inside the electrode (including metals, plastics, rubber, resins, and glues) so that you can make a fully informed decision.
Professionally Made or "Home Made"?:
Also ask the company selling the ozone generators with Ceramic Electrodes if the product has a Safety and Quality Approval like CSA, UL, ETL, or QAI. All professionally manufactured products do; just check the back of your TV, computer monitor, computer, microwave, etc. These Safety and Quality Approvals are only available if the product is high enough quality to pass the rigorous laboratory testing these companies put it through, and only available if the product is produced by professionals. If the product does not have one of these approvals, it is clear that it is either too low in quality to pass the testing, or it is home made (or both home made and poor quality).
- Perry, R. H.; Green, D. W., eds. (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill. Table 1–4. ISBN 978-0-07-049841-9.
- T. J. Lue; N. A. Fleck (1998). "The Thermal Shock Resistance of Solids" (PDF). Acta Materialia 46 (13): 4755–4768.
(1000C to cold water with no breakage)
- CRC Handbook of Chemistry and Physics, 96th Edition (15 June 2015)