Application Technology - Odor Control - Fundamentals and Applications
In today´s time more and more attention is paid to the quality of the air that we breathe. The main reason for this increased awareness is the rapidly growing number of people with allergies. Simply due to the fact that an ever increasing number of substances end up in the air and the human body that are of a synthetic nature, that is created by man, reactions occur in the human body that may assert themselves in the form of an allergy.
On average we spend over 90% of our time indoors. As a result indoor air quality (IAQ) plays an important role as it will have the biggest influence on our healthy disposition and well-being. In addition to this comes the fact that indoor space is insulated more and more for economic reasons, that is, to reduce energy costs. The breathing process of the building is inhibited or even suffocated as a result. This has only recently entered our awareness! How the IAQ of buildings can be improved and how damages caused by increased humidity and the resulting bacterial and fungal growth can be alleviated is the topic of this discussion.
In order to maintain or improve IAQ maintenance cleaning and odour neutralization play an important role. The possibilities for odour neutralization and the individual actions that can be taken as well as the effect they have on the IAQ are discussed below.
Smell is a sensation that is triggered by specialized cells in our nose. Depending on the configuration and size of the odour molecule different cells are triggered. The triggered cells transmit a signal to the brain, and these signals are connected to a comparable signal, in order for us to be able to express this sensation in words. Whether that means we can give the smell a name, for example like roses or can simply describe it as bad, pungent or sweet is not as important as the fact that our nose registers this smell. Since we are all individuals that differ from each other this means that the sensation of each individual faced with the same smell underlies a certain subjectiveness. In the same way some have a more sensitive nose than others, which means that the threshold for the perception of a smell differs for each individual. Most important, however, is the fact that the perception through our nose depends on the odour molecule itself. The cells in our nose react to a change of the odour molecule and thereby determines whether the odour problem has been removed or at least reduced. This behaviour is the basis for odour neutralization.
There are different methods of odour neutralization. These are described in detail in the following paragraphs. Each method has a different working mechanism and different situations demand a decision as to which method should be applied.
Currently, there are eight different methods of odour neutralization being used. The first method is adsorption through a so called adsorber. These adsorbers are solid in form and scrub the air free from odour molecules by binding the molecules to the solid by means of the physical process of adsorption. One has to differentiate between adsorption and absorption (see Figure 1). Whereas absorption leads to the integration of one substance in another, adsorption results in the physical binding of the substance on the surface of the adsorbing material. Effectively, this binding results in withholding the odour causing molecule from our noses which means that it can no longer perceive this substance as an odour. Examples of materials that are used as adsorbers are active charcoal, alumina, and molecular sieves. This method is especially suited for odours in carpets and smoke odour.
The second type of odour neutralizer are biocides. These kill odour causing microorganisms like mold or mildew and /or prevent their growth (biostatic action). In this case the killing prevents the microorganisms natural digestive process whose result can cause the odour. In the case of mold it is not only odour neutralization that is of concern but also the prevention of the setting-free of spores which are a big cause of allergies and which can, in individual situations, actually be fatal, especially where infants are concerned.
Encapsulation is another way to neutralize odours. Here the odour causing molecules are enveloped by the encapsuling agent. A barrier is created between the odour causing molecule and the atmosphere. The most common mechanism of encapsulation is based on surfactants or emulsifiers that are fogged in a water- or solvent-based medium. These surfactants encapsule the odour molecule (by forming a micelle) and the mentioned barrier is created in this manner. In addition these products generally contain a higher concentration of perfume that has a short-term masking effect as not all molecules are encapsuled right away. CEBE has two products on this basis, one water-based, Wet Fog, the other solvent- based, Dry Fog.
Wet Fog may also be used as an additive in water-based paints, in order to avoid smoke odours from penetrating. Wet Fog and Dry Fog are available in six different scents.
A relatively recent method of odour neutralization is based on the natural process of digestion. Just like there are odour causing microorganisms, as mentioned in the section on biocides, so there are microorganisms that do not emit odours as part of their digestive process. These microorganisms work twofold: they digest odour-causing molecules and break them down into smaller molecules that do not smell. They are also very adaptive which means that they can digest a wide variety of nutrients and thus multiply quickly. By doing so, they deprive the odour-causing microorganisms of food leading to their starving and thus dying off. In effect, the same result is achieved as with a biocide. CEBE´s BioLine contains a number of products that have this characteristic: some examples are BioFresh as an odour neutralizer and stain remover, BioSeptic which is especially effective for water-damage associated odours, and BioBreeze, especially effective against urine odours.
Molecular modifiers also achieve a neutralization of odours. This is accomplished by the attachment of the modifier to the odour molecule, thereby altering its physical structure and thus its properties as well. A successful modification almost always leads to an elimination of the smell. CEBE has a product, OdourEx, which is constructed on this basis. This product has the ability to modify odour molecules like smoke, sulphur, ammonia and other organic molecules and thereby neutralize their odour. OdourEx can be sprayed on textiles, carpets or simply into the air in order to neutralize the odours.
Oxidation is, aside from the digestion by microorganisms, the most complete process of odour neutralization, since the odour molecules are broken down into small parts, most often water and carbon dioxide. The fastest method of oxidation is achieved with an ozone generator. Here we offer the well-proven Sonozaire® generators as well as the compact but powerful CEBE®zon generators. The fact that odour molecules are broken down quickly and effectively by ozone, an active form of oxygen, without residues (ozone that has not reacted breaks down into normal oxygen) makes this form of odour neutralization especially attractive.
Neutralizers achieve exactly that: they neutralize a chemical reaction that causes odours. Neutralization of a sulphuric acid reaction results in elimination of the associated sulphur odours. A further example is treatment of a urine stain with an acidic product. By treating this slightly alkaline stain with an acidic product bacterial growth and thus odour development is prevented. CEBE developed a product especially for this purpose: Acidic Pre-Spray.
Masking agents are true to their name: they fight strong, bad odours with a stronger odour, usually pleasant to the majority, by covering, that is masking it. The cause is not fought with this type of odour neutralization, rather it is a treatment of the symptom by trying to hide it. Thus masking agents have more of an assisting function in odour neutralization, that bridge the time before the above mentioned methods battle the actual cause of the odour, by creating a short-term pleasant atmosphere. CEBE uses masking agents in exactly this function: they are incorporated in the other types of products in order to use this step at the same time as the odour is actually being neutralized, saving an additional step in the process of odour neutralization.
As can be seen in the above discussion of the various types/methods of odour neutralization, CEBE has many years of experience in this area and the products to go with it in order to be able to achieve the best possible results when combatting odours. For a successful odour neutralization it is of paramount importance to determine not only the source but also the cause of the odour problem. Once these have been identified it is only a matter of choosing the right method for a successful odour neutralization. The CEBE® Kill Odor Line Brochure can help you. It lists the most common odour problems and the methods most successful in combating them effectively.
The impact on IAQ can be summarized easily after the above discussion: oxidation, treatment with biocides and treatment with microorganisms have the largest positive effect on IAQ, since these methods effectively remove, or kill the odour sources. Adsorption removes the odours from the atmosphere and thereby improves IAQ. When using the method of neutralization it is important to remove the neutralized residues completely in order to improve IAQ. Encapsulation and the use of molecular modifiers also have a positive effect on the IAQ, but these methods are not always successful or of lasting duration, as external influences may influence the conditions in a negative manner, breaking down the encapsulation or the modified molecule. Use of masking agents has no positive effect, as the odour remains in the air and additional substances are released which may actually have a negative effect on us. Thus one can say that IAQ is actually made worse.