One of the primary factors organizations must consider when selecting disposable protective clothing involves a product’s ability to prevent liquid penetration. Employers and safety purchasers must understand the different types of sorption in order to select the right protective clothing for their worksite’s hazardous liquids or gases.

Understanding the science and technical terms surrounding personal protective equipment (PPE) and disposable clothing sometimes leaves safety officials unsure. To help industry leaders make the right choice for their employees, the following discussion about types of sorption and protective clothing highlights the subtle yet important distinctions.

What is Sorption?

In many ways, sorption is a catch-all term that speaks to the process of one thing attaching to another, typically molecules. It has two subcategories — absorption and adsorption — which refer to specialized types of attachments.

The naturally occurring process of sorption and protective clothing products’ ability to slow or prevent molecular adhesion is critical in terms of preventing the health risks associated with hazardous liquids or gases making skin contact.

For example, disposable protective coveralls are often designed to deter a chemical from touching the torso or extremities. When a spill occurs or liquids splash on a staff member, the product must possess the ability to stop sorption. It’s also important to understand that PPE may not be able to prevent molecules from attaching indefinitely. That’s one of the reasons for stockpiling disposable personal protective clothing.

What is Absorption?

The term absorption refers to a type of molecule diffusing or dissolving into a bulky material. For the purpose of this discussion, we’ll focus on absorption and protective clothing. What proves problematic in this context is that once the hazardous agent has bonded with the bulky material, removing or separating it from the garment is difficult.

Let’s use the example of the common household paper towel. Wide-reaching advertisements promote a given product’s ability to absorb spills quickly and effectively. Some show beverages such as wine, Kool-Aid, and other liquids known to leave stains. One swipe of a paper towel and the liquid and its color are absorbed.

After the successful absorption, the absorbent paper towel has changed color. And, we understand it’s nearly impossible to remove the beverage from the paper towel. Even if we run it under water and attempt to squeeze out the colored liquid, the stain remains. The same holds true of absorption and protective clothing.

What is Adsorption?

The adsorption process involves the molecules of a potentially hazardous substance adhering to the surface layer of the protective clothing item’s material. The liquid typically forms a thin patina on the surface without necessarily penetrating the outer layer.

To illustrate this point, consider a candle that drips hot wax on a smooth surface, such as a pair of work boots. When the liquified wax lands on the leather or rubber material, it doesn’t usually penetrate. The wax rests on the surface and bonds, hardening as it cools.

Unlike the absorbent paper towel, you can scrape off the wax relatively easily. Any residue left on the surface can usually be scrubbed away. That’s because adsorption does not involve deep penetration and bonding.

What is Desorption?

Picking up from the example of removing candle wax from work boots, desorption is the process of releasing molecules from a surface. The exact opposite of sorption, it can occur when prominent conditions change.

To continue with the candle wax illustration, if the temperature rose high enough, it would convert the hardened wax back to a liquid. Then, it might simply trickle off the outer layer. That would be a loose example of desorption. There are a variety of conditions that can bring about desorption.

Absorption vs Adsorption

The absorption vs adsorption difference boils down to material penetration, which makes a significant difference when selecting PPE and disposable safety clothing. The combination of absorption and protective clothing leads to coveralls, lab coats, gloves, head coverings, and protective footwear becoming saturated with potentially harmful liquids. Once the substance soaks into the bulk material, it would press against a worker’s skin.

By contrast, safety garments that allow only limited adsorption insulate people from immediate contact with hazardous waste, flammable liquids, and other health dangers. While the substance may linger on the surface of protective wear, workers are not necessarily in harm’s way. However, desorption can unravel the defenses provided by some personal protective clothing.

Desorption and Protective Clothing

Desorption appears conducive to protective clothing products that keep the substance on the surface. The adsorbed chemicals should merely dribble off the outer layer if temperature or other environmental conditions change. Unfortunately, desorption may also aid hazardous liquids that have been absorbed by the PPE, allowing them to seep through the materials and make skin contact. These are ways in which desorption plays a critical role in PPE.

  • Permeation: Consider utilizing a protective clothing product that allows a chemical agent or hazardous liquid to nearly soak its material. There may be time for a worker to strip off the PPE in a safe location, wash, and change. Should conditions such as temperature change, desorption would facilitate skin contact, leading to injury or illness.  
  • Contamination: Doffing soiled PPE poses a secondary risk to workers and their loved ones. Once liquid hazards have made their way through the outer layer via desorption, the risk of cross-contamination escalates. Either from skin transfers or tainted undergarments, the threat can easily leave the worksite.

Absorption, adsorption, and desorption are also reasons why safety-conscious organizations select disposable protective clothing over reusable products. The chances of seepage and cross-contamination are exponentially greater when corporations attempt to recycle PPE. What’s more, protective coatings on reusable protective clothing can degrade over time due to repeated laundering.

Absorption, Adsorption and Desorption in Protective Clothing Solutions

The two types of sorption and desorption remain crucial elements of personal protective clothing that determine effectiveness in real-life situations. Knowing whether substances can cling to the surface, soak into the materials, or be released due to changing conditions is essential when selecting the best safety clothing for your workforce.

It’s also important to educate employees regarding the capabilities of particular PPE and demonstrate proper donning and doffing steps.