Everyday, we use various substances that eat away unwanted stuff like mold and mildew. Various industries use these chemicals as catalysts for chemical reactions or to quickly dissolve unwanted materials.
Despite their ominous terminology, corrosive chemicals are actually very useful substances. However, we need to identify its hazards so we could establish ways on how to handle them safely. This is the objective of this article.
Corrosive Chemicals Definition
Corrosive chemicals are exceptionally reactive compounds that can damage or destroy living tissue. Corrosive reactions can be initiated through direct contact and chemically breaking up tissue. However, corrosion can also occur indirectly such as inhaling corrosive gasses.
According to the Occupational Safety and Health Administration (OSHA), particularly 29 CFR 1910.1200 App A, a corrosive chemical is described as:
“A chemical that produces destruction of skin tissue, namely, visible necrosis through the epidermis and into the dermis, in at least 1 of 3 tested animals after exposure up to a 4-hour duration. Corrosive reactions are typified by ulcers, bleeding, bloody scabs, and by the end of observation at 14 days, by discoloration due to blanching of the skin, complete areas of alopecia, and scars. Histopathology should be considered to discern questionable lesions.”
Sometimes, the word “caustic” is also used as a synonym for “corrosive.” A corrosive chemical is referred to as an “irritant” if it is mild or at low concentrations.
Etymologically, the word “corrosive” stems from the Latin verb “corrode,” meaning “to gnaw.” This indicates how corrosive chemicals appear to eat through flesh or other materials.
Corrosive elements may also include chemicals or factors that dissolve or deteriorate the structure of a non-living object such as metals. The rusting of iron on a bridge, for example, is an example of corrosion on a non-living object. Such corrosion can happen instantly or can take a long time.
There are many people who mistake calling corrosive chemicals as poisons. Both substances can harm the human body, but they work in technically distinct ways. A corrosive substance is immediately dangerous and damaging to tissues upon direct or indirect contact. On the other hand, a poison causes a systemic toxic effect that may take some time to take effect.
Chemicals that cause rapid corrosion of skin and metals are marked by a unique hazard pictogram in the international system of symbolic chemical labels. These symbols are included in the internationally agreed-upon standards of the Globally Harmonized System of Classification and Labeling of Chemicals (GHS).
Corrosion on living tissue is typically caused by acid-base reactions. Proteins, which are the main components of cells that make up tissues, are torn down via amide hydrolysis. Lipids, which are fatty molecules that help store cellular energy, are decomposed via ester hydrolysis. The result is protein denaturation, a biochemical process wherein the protein molecules lose their quaternary, tertiary, and secondary structures.
Although technically not poisons, ingesting corrosive chemicals can cause severe damage as the substance dissolves linings and tissues in the gastrointestinal tract.
Corrosive chemicals are also incredibly dangerous to eyesight. Even a single drop of strong corrosive material can cause blindness within 2 to 10 seconds. Opacification or instantaneous destruction of the cornea can happen when such a chemical is introduced to the eye.
Corrosive chemicals may be dangerous, but they are also incredibly useful for household, commercial, and industrial uses. For example, drain cleaners have corrosive acids or alkalis that can dissolve grease and mineral deposits that can clog up pipes. Bathroom cleaners also contain corrosive elements needed to dissolve mold and mildew.
They are also valued in industrial processes where high chemical reactivity is needed or desired. For example, sulfuric acid (a powerful corrosive) is often used as a catalyst to initiate the alkylation process in an oil refinery.
After using, a corrosive chemical may be discarded, recycled, or neutralized. If discarded, however, it has to undergo certain treatments as untreated or accidentally discarded corrosives can cause environmental and health problems.
The corrosivity characteristics of such substances can be found in the Environmental Protection Agency’s (EPA) Corrosivity Characteristic Background Document.
Types of Corrosive Materials & Examples
Acids and bases form the most common and widely used corrosive chemicals. Some examples include:
Acids
- Weak but concentrated acids such as acetic acid, phosphoric acid, and formic acid
- Strong acids such as nitric acid, hydrochloric acid, and sulfuric acids
- Superacids are substances with higher acidity than 100% sulfuric acid. These include perchloric acid, hydrogen fluoride, and fluoroantimonic acid. Super-acids are often used as catalysts in the petrochemical industry.
- Lewis acids including boron trifluoride and aluminum chloride. A Lewis acid is a kind of chemical species that contains an empty non-bonding orbital. That orbital can accept an electron pair from a Lewis base to form a Lewis adduct. An adduct is a single-reaction product caused by adding multiple dissimilar molecules.
Bases
- Caustics and alkalis including potassium hydroxide, calcium hydroxide, and sodium hydroxide
- Alkali metals in their metallic forms such as elemental sodium
- Hydrides of alkali or alkaline earth metals such as sodium hydride
- Alkalized salts of weak acids such as trisodium phosphate
- Super-bases such as metal amides and alkoxides
- Organometallic bases such as butyllithium
- Weak but concentrated bases such as ammonia
In addition to acids and bases, there are other substances that are considered as corrosive chemicals. Some of which are enumerated below:
- strong oxidizers such as hydrogen peroxide
- electrophilic halogens including bromine, chlorine, and elemental fluorine
- electrophilic salts including sodium hypochlorite and chloramine-T
- alkylating agents including dimethyl sulfate, ethylbenzene, and linear alkylbenzene sulfonates for detergents
- phenol
- dehydrating agents such as calcium oxide, phosphorus pentoxide, and zinc chloride
Special Considerations for Corrosive Gases
Corrosive chemicals can come in different physical states: solid, liquid, and gaseous. Corrosive gases, however, present special problems that need to be considered.
Health hazard
When inhaled or ingested, leaking corrosive vapors and gases can potentially burn, damage, or destroy organic tissue. Extremely sensitive organs such as the eyes and the respiratory tract are especially susceptible to permanent and severe injury. If the corrosive toxins enter the bloodstream, they could permanently damage major organs such as the liver and kidneys.
Equipment damage
Leaking corrosive gases can corrode metals, concrete, and other materials, causing damage and diminishing the lifespan of various equipment. Corrosion in electrical systems can cause circuit breakers to fail, creating an electrical fire hazard.
Environmental hazard
Untreated corrosive gases can damage local vegetation and fauna. These are especially hazardous to aquatic environments.
Physicochemical hazards
Ruptured, cracked, or overheated cylinders that hold corrosive gases can explode, cause fire, and contaminate the entire area.
Because of the dangers of escaping corrosive gases, special care is needed to properly handle them. Facilities and workplaces that use or store such gases in cylinders are required to abide by specific guidelines.
Handling Tanks and Cylinders that Hold Corrosive Gases
- When handling materials that pose an inhalation ingestion and hazard, you should use a chemical fume hood to minimize exposure.
- Always don on the appropriate personal protective equipment (PPE). Check the PPE for any tears, holes, and wear and tear that could expose skin surfaces with corrosive gases.
- Make sure you use the right respiratory protection equipment. That equipment must be in good working order.
- The valves and regulators of cylinders or tanks holding corrosive gases must be in good condition and closed when not in use. After using, these valves and regulators should be purged with dry air, nitrogen, or some other inert gas.
- Corrosive gases should be discharged into a liquid, check valve, trap, or vacuum break equipment. This prevents unsafe reverse flow as well as untoward dissipation in the environment.
- Corrosive gas cylinders must be stored at least 3 meters away from personnel workstations, gas tanks, and other combustible materials. If this is somehow impractical or impossible, use a screen wall made of a non-combustible material. That screen should be at least 1 meter higher than the tallest cylinder.
- Corrosive gas cylinders must be secured properly so that they don’t get knocked over or fall down. Secure them with chains, bars, or brackets.
- Corrosive gas cylinders should be located at least 1 meter away from doors, vents, ducts, windows, and other building openings.
- Corrosive gas cylinders must be stored far away from equipment that generates heat such as furnaces, radiators, boilers, incinerators, and more.
- Potential ignition sources such as cigarette lighters, burners, and welders as well as devices that could generate static electricity must be kept away from gas cylinders.
Other Special Handling
When handling corrosive chemicals, extreme caution must be observed. By following these guidelines, you can reduce personal risk and minimize environmental exposure to these hazardous substances
Safety shower and eye-wash station
It’s highly recommended that facilities handling corrosive chemicals should have a safety shower and eye-wash station within easy access. A first-aid kit as well as an emergency PPE container should be easily accessible as well.
Eye and Face Protection
Corrosive chemicals can do untold damage to the eyes. Thus, when handling such substances, make sure you wear industrial safety glasses that meet the ANSI Z.87.1 1989 standard. Safety glasses should enclose the entire eye area. It should also have side shields if there is a risk of flying particles such as glass shards or plastics.
If the handling process has a potential of splashing, additional eye and face protection should be worn. Safety goggles, face shields, or even a self-contained breathing apparatus (SCBA) may be required.
Note that sunglasses, prescription glasses, or hobby magnifiers cannot provide sufficient protection.
Skin Protection
At the very least, nitrile gloves should be worn when handling standard corrosive chemicals in a general laboratory setting. However, if the task requires higher risk or prolonged exposure, you should check your workplace’s material safety data sheet (MSDS) for specific information about the occupational health and safety requirements of handling such substances.
It is also recommended that you wear a protective apron or lab coat for extra safety. Wear the proper protective footwear; you shouldn’t use open-toe footwear.
Finally, additional shielding and protection may be required if there is a high risk of explosion, exposure, or contamination. Fume hoods, respirators, and portable shields are just some of the protective equipment that you may need.
Important Storage Pointers
- Avoid storing containers of corrosive liquids above eye level or in an open shelf. You could accidentally knock the containers and risk being splattered by the liquid.
- Keep the containers tightly closed or sealed.
- When storing acids and bases, always separate them in different storage areas.
- Always store corrosive chemicals away from oxidizers, heat generators, and water sources.
- Do not tamper, vandalize, or remove the manufacturer’s labels.
Mixing chemicals
- Work with corrosive chemicals in a well-ventilated place.
- When mixing corrosives, always add the acids or bases to water. Never do the reverse to reduce the risk of a chemical reaction.
- If you are adding solid corrosive chemicals to water, add the chemical slowly to the water. While doing so, stir the mixture continuously while adding. Depending on the nature of the substances, you may need to do it with a cooling process such as an ice bath.
Dealing with Emergencies
Facilities handling corrosive chemicals should always have readily available and appropriate equipment for containing corrosive chemical spills and leakages. At the very least, the facility should have a number of acid and base spill kits within easy reach.
Personnel assigned for this task must be properly trained and protected. Do not attempt to spill or contain any spill or leakage if you’re not trained to do so. Notify the assigned department if such an accident happened. It is also a good idea to contact your local emergency service or the Department of Environmental Health and Safety.
Disposing Corrosive Chemical Wastes
The dangerous nature of corrosive chemical wastes means that they shouldn’t be disposed of together with solid waste. They should be treated and disposed of as hazardous wastes under the guidelines of the Environmental Protection Agency (EPA), specifically in 40 CFR section 261.22 in this electronic code.
You can, however, dispose of corrosive aqueous solutions that are between pH 6.0 to 10.0 down the sink. Other than that, you should contact your local government regarding disposing other chemicals down the sink.
Disposing corrosive chemicals require special training. Service providers such as ACT Enviro offer reliable high hazard substance management, cleanup, transportation, and disposal. Their extensively trained personnel use high-quality, duly-certified equipment to handle the task safely and securely.
Conclusion
Many of the substances we use, from ordinary household cleaners to industrial-strength super-chemicals, are corrosive. While they are practical in a lot of ways, they also pose a hazard if carelessly handled. We hope that this short guide will give you a glimpse of the dangers of using them as well as safety protocols on how to mitigate that danger when handling them.
