Ions and ozone, let’s clean the air
At Aerisa we are constantly asked what is the difference between Ions and Ozone and how does your systems clean the air and improve overall indoor air quality? In this post we hope to explain what Ions and Ozone are and how they work.
Ozone is a chemical that contains three oxygen atoms, one more than the oxygen that we breathe. Ozone is a neutral molecule (one without any overall charge).
An atom is a basic unit of matter containing a nucleus (containing protons and neutrons), surrounded by electrons.
Protons are positively charged; neutrons are neutral; and electrons are negatively charged.
A molecule is a group of two or more atoms held together by covalent bond(s), which is when atoms share electrons. Generally molecules, by definition, are neutral.
An ion is an atom or molecule that has either a positive or a negative charge.
A charge is created when the total number of electrons is not equal to the total number of protons, such that there is a net difference of charge.
Only electrons can transfer from an atom or molecule, the number of protons and neutrons is fixed (except for radioactive decay). Individual atoms within one molecule share electrons in order to balance the charges and create a neutral molecule, such as ozone, water, dioxygen, or molecular nitrogen. Dioxygen and molecular nitrogen make up the majority of the air we breathe.
An ion can consist of a single atom, such as monatomic oxygen with a single negative charge; or, it can consist of multiple atoms, such as an oxygen molecule that has attracted an extra electron, or a nitrogen molecule that has lost an electron.
Charged objects are attracted to objects with the opposite charge, positive to negative and vice versa; conversely, they are repelled by objects with the same charge. This is illustrated by the attraction and repellant forces observed with magnets. A charged object can also attract something that is neutral, such as a charged balloon to a neutral wall.
These charge characteristics also are the force that allows current (electrons) to flow through conductive materials in order to generate electricity. The shock one feels from static electricity starts with the build-up of a charge on two surfaces (shoes and carpet) that are then separated (and thus contain opposite charges). The shock occurs when the built-up charge comes into contact with a second (oppositely) charged or conductive surface. This contact allows the charge to neutralize by flowing excess electrons from one surface to another and creates a shock as the discharge occurs.
Ions, Ozone and Aerisa
Ions typically exist at a much lower concentration than ozone in normal air. Aerisa technologies produce ions through the use of electricity, high voltage, dielectrics (non-conductive material), and conductive materials. A byproduct of this technology can be ozone. Even with Aerisa increasing the density of ions in the air a hundred-fold, ions still exist at a relatively low concentration when compared to ozone and other contaminants. The charged nature of ions allows them to be much more effective than ozone at the expected concentrations produced by Aerisa technology. This effectiveness is due to the different behaviors of ions and ozone, specifically, their different reaction mechanisms (or how they interact and react with other molecules) and reaction speeds.
The effectiveness of ions is due to the uniqueness of gas-phase ion reactions. In gas-phase reactions, an ion’s charge cannot be destroyed (except for collisions with an oppositely charged ion) because charge must be conserved. The charge can be transferred but not destroyed.
Notice the positive charge transfers, but does not disappear. The same would occur for a negatively charged ion.
Thus, an ion can participate in a reaction and survive in a modified form to participate in another reaction. In such a manner, an ion (or rather the ion’s charge) can participate in thousands of reactions, and each reaction can be up to 1 million times faster than ozone.
Ozone, by contrast, works through chemical reactions, and is more reactive than oxygen. Because ozone is not a charged molecule, when ozone reacts with a contaminant in the air, it goes through a reaction that produces different molecules that are not typically charged. These products are usually more stable than ozone, and may be able to react with another molecule if the conditions are right. Because there is no charge to conserve, an ozone molecule can only generate 1 up to 5 gas-phase reactions, and thus is used up much more quickly than ions. While ozone is not a charged molecule, it is polar, meaning that the electrons are shared unequally which creates a charge on one side and an opposite charge on another side. This polarity allows ozone to react easily with other molecules. Ozone will decay back to the more stable form of dioxygen.
Ions do not behave the same when they come into contact with a surface. In this case, the charge can be ‘absorbed’ by the surface; whereby the solid properties of the surface cause the charge to either be transferred through the solid and out to ground or it may charge the surface slightly if it is a less conductive material. When the surface is charged, it will eventually find a mode to disperse and become neutralized. Due to the absorption and neutralization of the charge by the surface, ions are able to react once and are done. Ozone is depleted similarly when contact is made with a surface.
Ions in gas-phase reactions also can attract particles (both oppositely charged and neutral) in the air together through their charges. This allows the particles to become heavier / larger in size and cause them to drop out of the air and either be cleaned through normal housekeeping duties, or get filtered out through return air system filters.
Ions are very effective in improving indoor air quality through removal of dust particles from the air stream, and by breaking down odors and contaminants into less offensive molecules.