Antifreeze ('Tis the Season)
ATRI News - March/April 2014
Antifreeze is an additive that is used to, as the name suggests, prevent water-based liquids from freezing. Mixtures available commercially are also referred to as antifreeze. These mixtures are what recyclers are familiar with – what is recovered from vehicles. Distilled water is used in the cooling systems of internal combustion engines because water alone is a good coolant. Extreme weather conditions, however, make the addition of antifreeze necessary to prevent engine damage caused by expansion when coolant water freezes. Interestingly, antifreeze additives not only decrease the freezing-point, but also increase the boiling-point. This property allows for the coolant water to be effective at both lower and higher temperatures. A number of different alcohols are used as additives including methanol, ethylene glycol, propylene glycol, and glycerol. Ethylene glycol is most commonly used in automotive antifreeze.
Antifreeze mixtures contain other additives including lubricants, buffers, and corrosion inhibitors. Most antifreeze mixtures are proprietary so the exact composition is unknown. Common antifreeze stabilizers include sodium silicate, disodium phosphate, sodium molybdate, sodium borate, and dextrin. The mixtures also contain dyes – that are often highly toxic. Many of the additives are capable of causing adverse effects on both humans and the environment. Ethylene glycol, for instance, is poisonous and causes diarrhea, vomiting, and potentially death when ingested. It also tastes sweet – a dangerous combination for both children and animals. Once antifreeze has contacted the cooling system in combustion engines it, like used oil, can become contaminated by heavy metals from the engine, benzene from traces of fuel, and over time acidic breakdown products can form. Antifreeze, like many automotive fluids, therefore has the potential to be substantially more toxic once it is used. Releases of antifreeze to the environment could not only result in adverse effects to human health and the environment, but could also necessitate costly environmental remediation projects for property owners. Once antifreeze is reclaimed from end-of-life vehicles, it is crucial to exercise proper storage techniques. Properly labeled containers, tightly sealed lids, and secondary containment are great ways to prevent a release of antifreeze to the environment. Antifreeze should never be dumped on the ground or down drains. Spills should be contained and cleaned up immediately. It is no news to any of you that antifreeze can be recycled. But, it may be interesting to know that ethylene glycol, the most common antifreeze additive, is produced from natural gas. That’s why fluids recyclers want it! It is nonrenewable and has value. Used antifreeze can be reconditioned at a significantly lower cost than producing new antifreeze. The recycling process removes secondary contaminants like heavy metals through filtration, distillation, reverse osmosis, or ion exchange methods. The recycling process allows used antifreeze to be returned to use as antifreeze, although some original equipment manufacturers do not approve the use of recycled antifreeze in their vehicles.
The Indiana Department of Environmental Management (IDEM) published a Guidance Document (2 pages long) on the Classification of Used Antifreeze on January 18, 2000. This is an excellent document to have on hand or even hang on the wall in the area where you remove/store fluids. It explains the benefits of management practices, as recommended by IDEM, and explains the advantages of recycling antifreeze. This document is available online.