Ice and aircraft are a dangerous combination. On 17 November 2018, a passenger aircraft partially slid off the taxiway at Denver International airport. Fortunately, the plane was not moving too fast when it hit the ice, and none of the 85 passengers or 6 crew were injured. However, the incident highlights just how dangerous it can be for an aircraft to encounter ice on the runway.
When ice is found on runway strips, it forms a major hazard and safety risk. Just like a car can skid and spin on an icy road, the same is true for an aircraft. De-icing technology is therefore crucial to maintaining passenger and crew safety in these conditions. The working principle of de-icers is that they lower the freezing point of water. Instead of forming a solid ice layer, the water then remains liquid, and washes away without affecting the aircraft. Care must be taken to protect the safety of the environment however, as de-icers contain chemicals that may be harmful.
De-icers on the basis of potassium hydroxide (KOH) couple effectiveness with a low environmental impact. As Europe’s number 1 producer of potassium hydroxide, Vynova is a major supplier to the de-icing industry, contributing to safe air travel.
How potassium-based de-icers work
Potassium acetate is made from potassium hydroxide and acetic acid. It is a highly effective de-icer designed to penetrate pavement surfaces and break down ice and snow bonds. It has a freezing point of -60°C. Because of its effectiveness on the runway surface, potassium acetate is often used as an anti-icer. It is applied before snowfall events or ice conditions materialise, thus preventing the build-up of snow and ice in the first place.
Potassium formate is made from potassium hydroxide and formic acid. It lowers the freezing point of water to -51°C when mixed at a concentration of 50%. Once applied to a runway, it becomes diluted by the ice and snow, leading to an effective freezing point of -32°C. The advantage of potassium formate over potassium acetate is that it has a lower Chemical Oxygen Demand (COD). Lower COD means lower environmental impact and lower processing costs through waste water treatment plants.
The main purpose of both potassium acetate and potassium formate is to lower the freezing point of water, therefore preventing the formation of ice. This means that aircraft can take off and land safely, despite adverse weather conditions.
Impact of de-icers on the environment
Both potassium acetate and potassium formate are organic compounds. The process of breaking them down and absorbing them into the environment consumes oxygen. This is potentially hazardous for organic life because it depletes the amount of oxygen available for living organisms. Potassium acetate has a COD of 0.3 g O2 / g, which is lower than glycol- and urea-based de-icers. Potassium formate performs even better, with a COD of 0.11 g O2 / g.
Biodegradability is another important characteristic of de-icers in terms of their environmental impact. Chemicals that biodegrade quickly have a lower impact on the environment. This is because there is a limited accumulation of the chemical in the soil or aquatic system before it is broken down by microbial activity. Potassium acetate has completely biodegraded within 20 days of release into the environment.
Potassium formate is generally considered to have the best environmental performance of current de-icers available on the market. Because potassium occurs in nature, releasing potassium-based materials back into the environment is considered environmentally responsible.
Practical uses for de-icers
De-icing is not only essential for airport runways and aircraft wings, but plays an important safety role wherever icy conditions affect human safety. Public roads become a hazard when ice limits the traction of car tyres on the pavement. Carparks and train station platforms become slip hazards for commuters. Even harbours and warehouses become dangerous when workers are lifting and carrying heavy object in slippery conditions.
Potassium formate is a versatile product that has also found widespread applications in the oil and gas industry. It has physical and chemical properties that make it conducive for use as a drilling fluid.
Potassium hydroxide is the key raw material in manufacturing potassium-based de-icers. Vynova has two independent KOH manufacturing facilities, in Tessenderlo (Belgium), and at our affiliated site of Potasse et Produits Chimiques (PPC) in Thann (France). This makes us the only potassium derivatives producer with two manufacturing sites in Europe, offering our customers unique and flexible logistics solutions, an extensive storage network across Europe and a highly reliable supply. Vynova supplies KOH at various concentrations according to customer demand. Contact our sales team, or find out more about KOH from Vynova here.