Since the beginning of the industrial revolution, emission of a number of pollutants into the atmosphere was an inherent element of operations of any type of industry. We have managed to effectively handle some of those substances. However, the atmosphere absorbs the most carbon dioxide generated by fossil fuel burning. At the verge of the circular economy era, CO2 may also be somehow recycled.
Fumes as the source of gypsum
A classic example of utilising harmful emission is the wet flue gas desulphurization technology. Fumes from furnaces in power plants or other installations in special devices react, for example, with calcium hydroxide suspension and solutions of sodium, potassium, aluminium, and ammonium salts. These are highly-efficient methods which allow extracting virtually all the sulphur dioxide from fumes and produce a valuable side product – calcium sulphate, or gypsum, also known as plaster of Paris. This is a material widely used in construction and industry. Most of the plaster used today comes from the process of desulphurization of industrial fumes.
What was fairly easy with sulphur is much more difficult with carbon dioxide. This is primarily due to its huge amounts in fumes. The scale of the entire process must therefore be much greater, which also requires appropriately bigger amounts of energy. However, the very reaction of extracting carbon dioxide using amines has been known for years but used at a smaller scale.
A different approach was adopted by a Canadian company called Carbon Engineering, which started to extract CO2 directly from the atmosphere. Huge fans blow the air through a special solution, fixing the dioxide molecules. Afterwards, subsequent physical and chemical processes and reactions produce clean CO2, which may be used for other purposes. Unlike past attempts, this time the Canadians managed to develop a cost-effective solution which is now operating in British Columbia. The cost of extracting a ton of carbon dioxide from the air totals 94 to 232 dollars.
Carbon dioxide and what’s next?
Effective extraction of CO2 is one thing, but using the gas further is a different issue. An interesting technology is being developed by American SkyMine. Unlike Carbon Engineering, SkyMine focuses on the products of burning, contained in industrial fumes, i.e. CO2, SO2, but also potassium compounds.
In subsequent processes, the extracted substances may be used for producing a number of other substances – soda, bleach, lime used in construction or synthetic marble. The primary task here is to trap carbon dioxide in crystals.
An interesting idea for utilising pollution was presented by Air-Ink, which manufactures printer toner out of car exhaust fumes. The company installs specialist catalytic converters in car exhaust systems. Afterwards, the utilised module is sent to the company that recycles extracted toxins into toner for printers. The residue deposited on the filter for 2,500 hours of car driving may produce 150 litres of printer toner. In practice, this solution works as a much more precise diesel particulate filter currently installed in most diesel vehicles.
The significance of extracting toxins from the atmosphere has also been spotted by the consumer market, particularly the developing segment of home air purifiers. Here, the goal is not to reuse the grasped substances and pollutants but to eliminate them. This is most often achieved by using carbon filters and HEPA filters, popular in vacuum cleaners, which once fully utilised, are disposed of.