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Thursday, August 30, 2007

Surfactants

Question:
What is a surfactant?

Answer:
Surfactant is short for “surface active agent,” it is an organic molecule with a hydrophobic (water-hating/oil-loving) end and a hydrophilic (water-loving) end. Surfactants are often emulsifiers, wetting agents, and dispersants (see other definitions).

The most common surfactant is sodium Linear Alkylbenzene Sulfonate (called LAS for short). The alkylbenzene portion of the molecule is the hydrophobic/oleophilic end of this surfactant and the negatively charged sulfonate molecule is the hydrophilic end of the molecule. Surfactants are typically classified as anionic, nonionic, and cationic. The class of surfactant determines the class of the cleaner.

Tuesday, August 28, 2007

Water-based Cleaner

Question:
Is a water-based cleaner the same as an aqueous cleaner?

Answer:
Yes! Aqueous means water. A water-based or aqueous cleaner is a cleaner that increases the ability of water to clean. An aqueous cleaner uses blends of detergent compounds with surface active agents together with other cleaning chemicals that use detergency to lift soil from a surface by displacing it with surface active materials that have a greater affinity for the surface than for the soil.

Water, considered by many to be the "universal solvent," is an important component of aqueous cleaners because it dissolves many types of soils. Water-municipal tap water, deionized or distilled water depending upon the cleaning application-also functions as a carrying medium for detergent compounds. But, while water is capable of dissolving many inorganic and some organic contaminants, not all residues dissolve readily in water. For this reason, aqueous detergent cleaners are complex mixtures specifically formulated to create greater chemical and mechanical cleaning action.
Water is a polar solvent. Being polar is the characteristic that makes it good at dissolving a wide range of polar residues, contaminants and/or soils. Water has a unique V shaped structure with two hydrogen atoms at the top of the V and an oxygen at the bottom. One can think of the oxygen as being a large, dense electron rich atom.

This gives the entire water molecule an overall net negative, electron-rich end at the base of the V (d-) and an electron poor positive end (d+) of the molecule towards the hydrogen top of the V. This directional net-negative charge towards the base of the V is called a dipole moment. Polar molecules such as water have a dipole moment.
Alconox, Inc manufacturers a full line of aqueous cleaners widely used in a range of industries, including pharmaceutical and medical device.

Thursday, August 16, 2007

Aqueous Cleaners

Question:
What is an Aqueous Cleaner?

Answer:
Alconox, Inc manufacturers a full line of aqueous cleaners widely used in a range of industries, including pharmaceutical and medical device. An aqueous cleaner is a blend of ingredients designed to enhance the cleaning ability of water. Typically an aqueous cleaner contains a surface active agent (surfactant) and builders to help the surfactant. The surfactant acts as a wetting agent to allow the cleaning solutions to penetrate into crevices and around and under soils. The surfactant will usually also act as an emulsifier to help form emulsions with water in soluble oils. The builders usually react with dissolved metal ions in the water to help stop them from interfering with cleaning.

Tuesday, August 14, 2007

Inhibited Cleaner for Aluminum

Question:
Specifications for indicate that "Solujet is inhibited for Aluminum. Corrosion testing is advisable." What does this mean?

Answer:
Solujet contains sodium metasilicate which acts as a corrosion inhibitor to stop alkaline attack on aluminum. Solujet would not cause alkaline attack on aluminum as long as the bath is not overused and the metasilicate depleted.

There are galvanic (forming a battery) attacks on aluminum that involve interactions with other metals that may be dissolved in the cleaning solution from prior use, or that may be present as metal in the tank or part being cleaned, and this form of attack will happen with just about any detergent solution including Solujet. Ideally you should not clean other metals in baths used to clean aluminum and should not have other metals that have significantly different galvanic potential than aluminum present in the cleaning solution. If there is any concern that there may be other metals involved, then some testing may be advisable. If the aluminum parts being cleaned are very high value parts, then some testing would be advisable.

Certainly Solujet is designed to clean aluminum safely. Aluminum is a reactive metal, especially if it has been recently machined, cut or tooled so that there is exposed, freshly cut aluminum that has not had a chance to form a protective passive layer of alumninum oxide, which happens naturally with exposure to air. If the protective passive layer is not formed then you can get all sorts of strange galvanic reactions that are not technically corrosion, but which will result in discoloration due to deposits of whatever the other metal or metal oxide on the surface of the aluminum.