Our thoughts and comments on the carpet cleaning industry.
Wednesday, July 24, 2019
What Do the Terms “Alkali,” “Alkaline,” “Acid,” “Acidity,” “Saponification,” “pH” Mean?
The Terms “Alkali,” “Alkaline,” “Acid,” “Acidity,” “Saponification,” “pH” as Related to Carpet Cleaning
You may have run into words like "acidic," "alkaline" and "pH” in your carpet cleaning business, but what do they really mean.
What does the the term “alkali” have to do with carpet cleaning?
An alkaline substance has a pH above 7.0 in water.
Alkalinity is neutralized by acids. Neutralization is the reaction between an acid and a base, producing a salt and neutralized base; for example, hydrochloric acid and sodium hydroxide form sodium chloride and water.
Alkaline liquids turn red litmus paper blue.
Most water-based cleaning solutions are alkaline because (1) most soils are acids and (2) because greasy soils such as fats, oils and proteins which are saponified by alkali for easier removal by cleaning.
High-alkaline cleaners also help destroy microorganisms.
The more alkaline the detergent (higher the pH), the more corrosive the cleaner and the more damage it will do to pH sensitive fibers and dyes.
ALL OTHER THINGS BEING EQUAL, the more alkaline or the higher the pH, the better the cleaning.
Alkaline liquids have a bitter taste.
They have soapy or slippery feel because they react with the fatty esters on your skin and turn them into soap by saponification!
Some common alkali are:
Sodium hydroxide – often called “caustic soda.”
Potassium hydroxide – commonly called “caustic potash.”
Lye – generic term for sodium or potassium hydroxide
Some alkali commonly used in carpet cleaning detergents:
Potassium hydroxide is sometimes used in heavy-duty liquid detergents, but is usually too corrosive and dangerous to use.
Soda Ash (Sodium Carbonate):
Most powdered cleaning agents contain high levels of soda ash because it’s cheaper than most water-soluble alkaline builder.
But, Soda ash reacts with calcium water hardness to form Calcium Carbonate scale. This scale can clog nozzles, scale up the stator (resulting in failure) and leave the carpet fibers dull from a hazy film.
Soda ash is primarily used to cut costs and absorb liquid ingredients such as surfactants.
There is no soda ash added to PCA Formula 5 or Formula 4.
Sodium Bicarbonate (baking soda):
Sodium bicarbonate is sometimes used in milder, near neutral powdered detergents is needed. This is seldom used in carpet cleaning detergents.
Borax:
While borax may be found in some laundry detergents, I’ve never seen it used in carpet detergents because it’s not very soluble in water.
Sodium Metasilicate:
Sodium Metasilicate has a very high pH (over 12) and imparts corrosion inhibition to aluminum.
It is commonly used to make the detergent effective against cooking grease by saponifying the grease (turning it into soap).
There is no silicate added to PCA Formula 5, PCA Formula 4, Preface® traffic lane spotter or Olefin Preconditioner.
But it is a very important ingredient in Super LCA™ and TLS® 2000 for greater effectiveness against heavily soiled carpet and greasy restaurant carpets. TLS 2000, a liquid high-pH pre-spray, contains sodium metasilicate and a solvent to help cut through cooking grease in restaurants. The pH of TLS 2000 at its recommended concentration is about 13, so it is definitely not intended for use on stain-resist residential nylon or on upholstery. However, it is extremely effective in cutting through the stubborn oils so often attached to olefin (polypropylene) fibers. We specifically designed TLS 2000 to restaurant carpets with heavy grease and other problem commercial carpets.
But, Sodium Metasilicate has some drawbacks. It reacts with water hardness to form a scale similar to that from soda ash, but it is much finer and not easily removable with acid. Affected parts and nozzles frequently must be replaced rather than simply cleaned. It dissolves very slowly which can lead to clogging of the unit.
Potassium Silicates may be found in some liquid detergents because it is much more soluble in water.
Phosphates:
Trisodium and disodium phosphate are very soluble high pH builders and grease cutters that also increase cleaning power to powdered carpet cleaning detergents.
Polyphosphates such as sodium tripolyphosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate are frequently used as alkaline builders and water softeners (sequestering agents / chelating agents) in detergents.
What is meant by the term saponification as related to carpet cleaning?
Saponification, in carpet cleaning, is a chemical reaction between the detergent and certain fatty, oily soils such as cooking grease in the carpet.
These oils are vegetable/animal fat and oil from cooking, body oils, etc. Oils like these will react with alkali to form soap.
An example of saponification is how soap was made in the frontier days. The mother would heat up a kettle of bear grease in a big kettle with water. The grease would just melt and float on the water because it hates water. She then added lye or wood ash (alkali), and the fat was turned into soap, which not only dissolves in water but also is a detergent!
Saponification is another reason that higher pH usually results in better cleaning.
The alkaline grease saponifiers in highly alkaline TLS® 2000 are highly alkaline materials that chemically react with cooking grease to actually convert the insoluble grease and fats to soluble soaps.
Emulsification is the process of removing those oils that do not saponify; i.e., they don’t react with alkali and turn into soap. These are motor oils, exhaust fumes, common pollution oils, lubricants, silicones, furniture polish, sun tan lotion, tobacco smoke residue, lubricating grease, oils from skin and pet hair, etc.
What are acids and what do they have to do with carpet cleaning?
Definition of acid from my old freshman chemistry class textbook: An acid is a chemical species that donates protons or hydrogen ions and/or accepts electrons. ... The higher the concentration of hydrogen ions produced by an acid, the higher its acidity and the lower the pH of the solution.
An acid is a chemical substance that neutralizes alkalis, dissolves some metals and turns litmus red.
Acids taste sour, conduct electricity when dissolved in water, and react with metals to produce hydrogen gas. Certain indicator compounds, such as litmus, can be used to detect acids.
Strong acids are corrosive to most metals.
Examples of strong mineral acids include sulfuric (used in car batteries), nitric, hydrochloric (often called muriatic acid) and phosphoric acids.
Examples of weak acids include acetic acid, boric acid, citric acid and carbonic acid.
Boric acid is commonly used in eye wash products.
Oxalic acid and hydrofluoric acid (both very hazardous and poisonous) are used in some rust removers.
Vinegar is diluted acetic acid, which is what gives salad dressings and pickled vegetables their tart taste.
Oranges, lemons and limes contain citric acid, which gives them their sour taste.
Carbonated water (carbonic acid) is one of the most common acid additives that is widely added in soft drinks.
What does the term “acid rinse” of carpet after cleaning mean?
We often read the term “acid rinse” in various carpet cleaning publications, but what does it actually mean and how is it done and why? And, should we use the term “acid rinse”?
Strictly speaking, "acid rinse" simply means that, after extraction cleaning the carpet, an acid-based product is run through the machine to rinse out detergent residue in the carpet, rug or upholstery and to decrease the pH by neutralizing the alkaline components of the cleaning compound used.
Historically, when carpets were constructed with jute backing, the jute would often bleed out brown lignin resulting with a “browning” residue on the tips of the carpet fibers. Additionally, in the “old days,” high-pH detergents were often used to clean carpet, leaving a high pH residue on the surface. An acid product or browning agent had to be applied to prevent browning and chemical yellowing and also to stabilize the carpet or rug dyes.
We recommend the use of what some call an acid rinse but what we call a Brown Out rinse or Brown Out flush, which is used by adding 2 or more ounces of Brown Out® per gallon of water (no detergent) through the base unit only when we need to get the pH down, have detergent residue of ice melt track-in or a lot of detergent residue from previous cleanings. In this procedure, extraction clean with the Brown Out solution using plenty of vacuum-only strokes to leave carpet as dry as possible.
We never use the word “acid rinse”in front of a customer! The term “acid”, in the minds of the customer, signals “danger - poison”! Instead, we call it a Brown Out rinse or Brown Out flush.
Some preach prespraying and then using an “acid rinse” to neutralize the detergent and leave no residue. I continue to be amazed that anyone actually believes that an acid leaves no residue or that an acid will somehow magically “zap” the prespray and make it disappear into thin air! Acetic acid (vinegar) will evaporate, but the salt formed when it neutralizes alkali does not evaporate. Some use hydroxyacetic acid, but its evaporation rate is slow and its salts also don’t evaporate. Additionally, acetic acid and hydroxyacetic acid, have an odor that is objectionable to most customers.
What is pH, how is it related to alkalinity and acidity and how is it related to carpet cleaning?
There is nothing magical about the term “pH”. It is the chemist’s shorthand for “Potential of Hydrogen”. It is the measurement used to determine the relative alkalinity, acidity or neutrality of a solution.
Please note the upper pH limit of 10 for stain-resist nylon carpet. Yet, all other things being equal, the higher the pH, the better the cleaning.
Also, note that there is a 10-fold increase in alkalinity or acidity for each pH unit change. In other words, a solution at a pH of 14 is 10,000,000 times as alkaline as one at a pH of 7.
Substances with a pH of lower than 7 register as acidic. Each sequential decreasing number is 10 times more acidic than the number before it. So a substance with a pH of 5 is 10 times more acidic than a substance with a pH of 6.
Note the very low pH of vomit. Because of its low pH, any staining agent in vomit will be MUCH more difficult to remove, because the lower the pH, the more set a dye will be. Just a pleasant thought before dinner!
Detergents with a pH of 7 or nearing 7, register as neutral. These substances do not fall under either acidic or alkaline.
Detergents with a pH of higher than 7 register as alkaline. Each sequential increasing number is 10 times more alkaline than the preceding number. So a pH level of 11 represents 10 times the alkalinity of a level of 10.
When cleaning or treating stains on carpets made from natural fibers, carpet cleaners usually choose neutral or slightly alkaline products.
TLS® 2000 Heavy-Duty Carpet Cleaning Prespray / Traffic Lane Spotter.
Free Bane-Clene Information Package
Free packet of information about Bane-Clene can be obtained by calling toll-free 1-800-428-9512 (U.S. ONLY!). Your information packet will include a full color catalog and price addendum. Packets will arrive in approximately 2 weeks through standard United States Mail.
Free packet of information about Bane-Clene can be obtained by calling toll-free 1-800-428-9512 (U.S. ONLY!). Your information packet will include a full color catalog and price addendum. Packets will arrive in approximately 2 weeks through standard United States Mail.
“A to Z” Alphabetical Index to the Bane-Clene Web Site
Bane-Clene Home Page
