Chemical’s and pHHow does pH affect cleaning?

PWNA 2015

Presentation given by Linda Chambers

Brand and Sales Manager

for Soap Warehouse

As a cleaning contractor there is a lot you need to know and think about when it comes

to the chemical products you are using in your business, for yourself, your employees

and your clients or customers.

What chemicals are in the products we are using?

Are any ingredients hazardous?

What soil type am I trying to remove?

What chemical should give the best results?

Some times cleaners work and some times they don’t

But Why?

Understand and use pH information when cleaning.

Whether you are cleaning carpet, tile, concrete, or any other surface, the pH of the products you use can have a major effect on how well the job is done, as well as whether you may damage the surface or not.

pH was first described by Danish biochemist Soren Sorensen in 1909 as “the power of hydrogen”, where the “p” is short for power and the capital “H” is for the element hydrogen as it is represented on the elementary table.

pH is a logarithmic measure of the hydrogen ion concentration of an aqueous (water based) solution. pH = -log[H+]

The scale runs from 0 to 14, with 7 as the neutral mid point. For each whole value above or below the 7 it is 10 times higher or lower in value.

Value’s under 7 are Acids, while those over 7 are Bases or also known as Alkalis.

So when we talk about pH, we are really talking about whether a solution is acid or alkaline. And for everyone that has had acid-indigestion, then you already know why maintaining a proper pH is as important to your stomach as it would be when stripping a wood deck you are preparing to stain.

You want your stomach as well as the wood surface to get to as neutral a pH as possible.

How can pH help or hinder cleaning?

Most soil is acidic in nature, averaging between a 4 to 5 pH, that is because it is a combination of dirt, dust and/or oily substances. To remove it you will need to neutralize this soil with an alkaline cleaner. The degree of alkalinity required will depend on the soils composition and the amount of build up. Since fats, oils and grease when mixed with an alkaline form soap, most cleaning agents are alkaline.

Conversely, alkaline substances, such as lime, mineral scale, rust and hard water deposits will require an acid cleaner to dissolve them to get a surface clean.

There are also various subtypes of soils:

Inorganic: Matter that was never alive and thus contains no carbon.Scale and lime deposits, rust, corrosion, oxidation, and mineral.

Organic: Matter that once lived and thus does contain carbon.Body oils, animal fat, carbohydrates, proteins, mold, yeast, bacteria and animal waste.

Petroleum: Any product made from petroleum, oils, grease, wax and gums. These contain no water in fact they repel water and thus they have no pH because they contain no Hydrogen.

These stains most often require another petroleum based solvent to remove them. No amount of soap is going to completely do it.

Last is Combination soils: these can be any number of % of inorganic, organic and/or petroleum substances. These are the hardest to remove since they are harder to identify and may require a combination cleaner or succession of alkaline, solvent or acid to completely remove them.

Types of Soils

Physical Change vs. a Chemical ReactionMost cleaning involves a physical change not a chemical

one. An example of a physical change is when oils and soluble soils are removed by dissolving them and extracting or rinsing the solution from a surface.

Just like when salt is dissolved into water. The salt is still there and can be visible again once the water evaporates.

So the oils and dirt are still in the waste water and is why for waste water management you filter out the oils and debris before discharge.

The most common type of physical changing cleaners contain emulsifiers. They break up fat, oils and grease into microscopic droplets that become suspended in water so that they can be extracted.

A chemical reaction is different. It means that molecules of one kind are actually changed to molecules of something different. For example when we use bleach. Natural stains, molds, algae and mildew contain chromophore. Chromophore is the part of a molecule that absorbs light at different wavelengths that cause color. When chlorine bleach reacts with water is produces hydrochloric acid and atomic oxygen.

The oxygen is what actually molecularly removes a part of the chromophore and eliminates the structure that made the color. The natural stains are still there, but you just do not see them since they no longer have color.

This then is a chemical reaction, there is no way this can be reversed even if the water was removed, like you could with a physical change.

And this is why for house and roof washing you need to use a true soap along with the bleach to actually remove the soil’s once you have removed the stains color. It may look clean with bleach alone but it isn’t.

The main reason to use bleach is to remove exposed algae, mold and mildew. Bleach may not kill all molds but it is the best thing we have.

Things Bleach KillsAccording to the CDC in Atlanta and Clorox.com bleach kills numerous bacteria, fungi, and

viruses-• Staphylococcus aureus  (Staph infection)• Salmonella choleraesuis  (Salmonella poisoning)• Pseudomonas aerugenes   (bacterial infection)• Streptococcus pyogenes  (pneumonia)• Escherichia coli 0157:H7  (E. coli)• Shigella dysenteriae   (Dysentery)• Methicillin Resistant Staphylococcus aureus    (MRSA)• Trichophyton mentagrophytes    (Athlete’s Foot, Ringworm, Jock Itch)• Candida albicans  (yeast infection, Thrush)• Rhinovirus type 37  (common cold)• Influenza A   (Bird Flu)• Hepatitis A virus  (effects liver, found in bad water, fecal matter)• Rotavirus  (infectious diarrhea, especially in babies)• Respitory Syncytial virus   (RSV- bronchitis/pneumonia in babies/children)• HIV-1  (STD leads to AIDS)• Herpes simplex type 2   (mouth, face, lip, eye blisters)• Rubella virus  (German measles)• Adenovirus type 2    (Conjunctivitis/Pink Eye, stomach flu, ear infection, croup)

No where on this list is Mold mentioned. Bleach helps remove mold but not kill it.

“Green” or Neutral Cleaners

Cleaners that may be called “Green” or Neutral have a pH between 6-8 and are usually meant to be used for repeated daily cleaning of surfaces with a film of light soil or small particles.

There is no chemical way a neutral cleaner will be able to remove a highly acid or alkaline material completely no matter how long it stays in contact with it. The pH difference will just not allow it.

Now adding heat to the equation will increase the effectiveness of a cleaner no mater the pH, as will higher water volumes or physical pressure that may help bridge the gap in some cleaning tasks.

“Green” or Neutral Cleaners

Enzymatic cleaners also fall into the “Green” category because they have a pH range from 5.5 to 7.5 but they are also considered a Natural cleaner because they contain living organisms found in nature.

But do not confuse Natural with Neutral or “Green” since many natural things that can be used for cleaning yet will not be neutral. Take for instance vinegar. This was the very first natural cleaner for man yet it is acidic with a pH between 2.5 to 5 depending on the type of vinegar.

Parts of a Cleaner

• Solvent• Surfactant (detergent or soap)• Penetrating and wetting agents• Chelators• Saponifiers• Builders

Cleaners will contain a combination of ingredients to let them to their job. They may contain just a few or even all of them in one cleaner.

Each of these below parts may be in a cleaner in different amounts with different pH combinations some that will add to each other and others that will cancel or balance each other out.

A product must create a set series of events to give an effective clean.

A cleaner needs to wetten, loosen, break up, suspended, dissolve, disperse and prevent the soil from redepositing itself back onto the surface being cleaned long enough for the solution to be removed by some means from the surface, whether it be rinsed, wiped, mopped, sucked, or blown off.

A cleaner must also be made so that the pH is the correct level and strong enough to remove the soil yet not too strong as to harm the surface being cleaned.

This can be a fine blanching act when dealing with particularly sensitive surface but a hard soil, like effervescence on soft stone.

How do you know the pH of a stain?

• Check with a pH strip– You can purchase paper strips– Add water (pH neutral) to the stain, only enough to

wet it so the strip will read.– Be careful not to touch the strip with your fingers

• Use a pH meter (flat tip model)– These run around $100 and are much more sensitive

and give better results than eye balling the color change on a paper strip. Plus many men are color blind.

What else should you know?

As previously mentioned, solvents do not ionize in aqueous solutions and therefore do not have a pH content to register a pH, however, due to their chemical properties, even at low concentrations some acids (like sulfuric) are much more aggressive than others used at higher concentrations (such as phosphoric).

Even with similar pH cleaners can react differently when asked to clean the same thing.

Remember, pH does not measure the corrosiveness of an acid product. Alkaline cleaners, on the other hand, usually go through the four phase process I mentioned of wetting, penetration, emulsification and soil suspension to clean. Varying degrees of effectiveness in each of the four phases of cleaning often separate alkaline cleaners even further apart. So two alkaline cleaners with the exact same pH may still give you different results.

For example, the standard butyl degreaser you use has outstanding penetration properties as it reduces the viscosity of the oily part of soil but the newer so called "non-butyl degreasers" have engineered surfactant systems which make them excellent emulsifiers.

pH on an SDS can help you to compare cleaning products, but remember that there are other considerations as well. Total percentage of active ingredients (that can usually tell you how far the product may be diluted), surfactants and builders are just a few of the other important features that won’t necessarily show up on a SDS. While pH will give you a good yardstick for comparing chemical products - it is by no means the only measurement to consider.

Keeping good records of your successes and failures can be your best resource.

Thank you for your attention and I will try to answer any of your questions.