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FACTS ABOUT HOUSEHOLD CLEANING
In household cleaning formulations, the surfactant (surface active agent) is often the most important single component. One or more surfactants are present in most all-purpose and specialty products. Other ingredients soften water, provide alkalinity, bleach, destroy microorganisms, and provide a wide variety of specific cleaning and aesthetic functions. Surfactants are organic compounds whose molecules consist of two parts: a water-hating (hydrophobic) part and a water-loving (hydrophilic) part. When a surfactant molecule is introduced into water, the water-hating part tries to escape by attaching itself to any available surface other than water. At the same time, the water-loving part tries to remain in water. As a result, surfactants tend to strongly "adsorb" or cling to many surfaces, such as fabric, soil, glass, and where the water and air meet (the water/air interface).
Anionic surfactants have a negative charge. Anionic surfactants are effective in removing particulate (dirt, dust, etc.) and oily soils. In hard water, they react with positively charged water hardness minerals, such as calcium and magnesium. Soap is the original anionic surfactant. In hard water it combines with calcium and magnesium salts to form an insoluble soap film or scum. In general, anionic surfactants tend to generate higher suds levels than other classes of surfactants. Cationic surfactants have a positive charge. In hard surface cleaners, they can be used as effective antimicrobial agents. Nonionic surfactants do not have an electrical charge. Because of this, they tend to be less seriously affected by water hardness. In general, they are low foaming and are especially useful in products which are designed to require little rinsing. The major surfactants in cleaning products are biodegradable. This means that in sewage treatment facilities they are broken down by bacteria, first to smaller molecules and ultimately to carbon dioxide, water and minerals. Builders follow surfactants in importance as ingredients in household cleaners, particularly in all-purpose cleaners. The most basic function of builders is to tie up the hardness minerals in water so they do not interfere with the cleaning action of the surfactants - they soften water. Some builders also aid in keeping soil particles in suspension, thus assuring that cleaned surfaces remain clean. There are three types of builders. A sequestering builder is, in many ways, the most effective type. Sometimes also referred to as a chelating agent (from the Greek word for crab's claw), this type of builder forms a tightly bound, water-soluble complex with calcium or magnesium ions. These water hardness ions are then removed in the rinsing operation. Some builders also tie up the ions of heavy metals, such as iron and manganese. Heavy metal ions can form colored products when oxidized by air, oxygen or bleaches. Their inactivation thus contributes to good cleaning results. Complex phosphates, ethylene diamine tetraacetic acid (EDTA) and sodium citrate are common sequestering builders. Precipitating builders also remove hardness ions. They do so by forming insoluble calcium compounds. In the cleaning process, this precipitate needs to be removed along with the other soils on the surfaces being cleaned. Sodium carbonate and sodium silicate are examples of precipitating builders. Ion exchange builders function by trading electrically charged particles. Sodium aluminosilicate (zeolite) is an ion exchange builder. Other ingredients are present in household cleaners to varying degrees, depending on the job the product is formulated to perform. Abrasives contribute to the mechanical effectiveness of scouring cleansers. In general, abrasives consist of small particles of minerals. Among other properties, they are distinguished by their hardness, a property that is measured on the Moh scale. This scale ranks substances by their relative ability to produce a scratch. Diamond, with a value of 10 on the Moh scale, can scratch almost anything. Glass, on this scale, has a value of 7. The following are among the minerals used in scouring cleansers in order of decreasing hardness: silica (7), feldspar (6) and calcite (3). Acids can dissolve calcium and metal salts and find use in tub, tile, sink and toilet bowl cleaners. Phosphoric acid is a common ingredient in such formulations. Hydrochloric acid is a strong acid used in some toilet bowl cleaners. As an organic acid, hydroxyacetic acid is milder than hydrochloric or phosphoric, but one which provides a measure of sequestering effectiveness. Vinegar (acetic acid) is the weakest acid in this series. Alkalis ensure that pH is maintained at a desirably high level during cleaning. Sodium hydroxide and sodium metasilicate are strong alkalis which not only maintain a high pH, but also play a primary role in removing solid grease. Sodium carbonate, in addition to providing a moderately high pH, provides buffering to maintain pH levels when a product is diluted. It can also precipitate out water hardness ions and, thereby, provide some building function. Sodium bicarbonate (baking soda) provides alkalinity at a somewhat lower pH. It is useful for buffering formulations which will contact the skin and for other uses where mildness is important. Silicates perform additional useful functions. They provide corrosion protection, particularly on "white" metals like aluminum. They are also helpful in suspending fine particles and reducing the redeposition of soil that has been removed from surfaces. Ammonia is a particularly useful alkali in floor wax removers. Antimicrobial agents can destroy bacteria and viruses by interfering with their metabolism or destroying their cell walls. Different chemical structures can serve this purpose, including alcohol, sodium hypochlorite, iodine, pine oil, phenolic and quaternary ammonium compounds. Such molecules act as disinfectants in household cleaning product formulations. Disinfecting products must be registered with the Environmental Protection Agency before they can be sold. Bleaching agents act as soil and stain removers. They attack soil chemically, breaking it down to smaller units. Colored soils and stains are oxidized to a colorless, more easily removable form. The most commonly used bleaching agent is sodium hypochlorite, which is prepared from chlorine gas and a solution of sodium hydroxide. Sodium hypochlorite is an effective, relatively indiscriminate oxidizing agent. Not only does it attack soil, but it is also a disinfectant capable of attacking and destroying bacteria, viruses and mold. It is an important component in many tile and grout cleaners. Colorants are present in most products. They provide a product with an individual characteristic and an appealing appearance. Often, they also act as tracers. In certain toilet bowl cleaners, for example, the disappearance of color indicates the product is exhausted. In other products, the tracer indicates the location of product and helps assure uniform product application, as in certain floor cleaners. Enzymes break down soils into simpler forms that can easily be removed by the cleaner. They are proteins that are classified by the type of soil they break down: amylase works on starch soils, lipase on fatty and oily soils and protease on protein soils. Fragrances cover the base odor of the chemicals used in cleaning products. They may also counteract any malodor inherent in soil itself and leave a pleasing scent after cleaning. Polymers are compounds whose molecules are very large, compared to most of the other materials found in household cleaners. The molecules are made up of many (up to millions) smaller molecules, which may be identical or which may be of two, and sometimes three, kinds. Linking the smaller molecules to each other is a process referred to as polymerization. When polymers dry, they form films, much in the same manner in which paint dries to a thin film. This is particularly helpful in floor care products where the film protects the surface and may provide a shine as well. Polymers can also be used as builders and can assist as thickening agents. Processing aids are added to keep the product homogeneous under varying storage conditions, and to provide desirable dispensing characteristics. Such aids include clays, polymers, sodium silicate and sodium sulfate. Preservatives protect the product against the natural effects that occur when a product ages _ decay, discoloration, oxidation and bacterial attack. Preservatives include ingredients such as butylated hydroxy toluene, ethylene diamine tetraacetic acid and glutaraldehyde. Solvents (organic) have a specific place in products where grease removal and cleaning without leaving a residue is important: window cleaners and products for removing finger marks on walls, for example. Since such products are generally liquids with water as the main ingredient, useful solvents must not only be able to dissolve grease, but must also be compatible with water. Organic compounds make up the solvents of choice in these products. |
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