Carbon dioxide is a chemical compound with the chemical formula CO2. It is made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature, and as the source of available carbon in the carbon cycle, atmospheric CO2 is the primary carbon source for life on Earth. In the air, carbon dioxide is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. When carbon dioxide dissolves in water, it forms carbonate and mainly bicarbonate, which causes ocean acidification as atmospheric CO2 levels increase.
Dry ice colloquially means the solid form of carbon dioxide. It is commonly used for temporary refrigeration as CO2 does not have a liquid state at normal atmospheric pressure and sublimes directly from the solid state to the gas state. It is used primarily as a cooling agent, but is also used in fog machines at theatres for dramatic effects. Its advantages include lower temperature than that of water ice and not leaving any residue (other than incidental frost from moisture in the atmosphere). It is useful for preserving frozen foods (such as ice cream) where mechanical cooling is unavailable.
Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water. Clothes are instead soaked in a water-free liquid solvent. Perchloroethylene is the most commonly used solvent, although alternative solvents such as hydrocarbons, and supercritical CO2 are also used.
Steelmaking is the process of producing steel from iron ore and/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur, and excess carbon are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon, and vanadium are added to produce different grades of steel.
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is added to replenish the amount metabolised by the user. This differs from open-circuit breathing apparatus, where the exhaled gas is discharged directly into the environment. The purpose is to extend the breathing endurance of a limited gas supply, while also eliminating the bubbles otherwise produced by an open circuit system. The latter advantage over other systems is useful for covert military operations by frogmen, as well as for undisturbed observation of underwater wildlife. A rebreather is generally understood to be a portable apparatus carried by the user. The same technology on a vehicle or non-mobile installation is more likely to be referred to as a life-support system.
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is sublime, or less preferably, sublimate. Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly is called critical sublimation point, or simply sublimation point. Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating.
A supercritical fluid (SCF) is any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid. It can effuse through porous solids like a gas, overcoming the mass transfer limitations that slow liquid transport through such materials. SCFs are superior to gases in their ability to dissolve materials like liquids or solids. Also, near the critical point, small changes in pressure or temperature result in large changes in density, allowing many properties of a supercritical fluid to be "fine-tuned".
A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator.
Supercritical carbon dioxide is a fluid state of carbon dioxide where it is held at or above its critical temperature and critical pressure.
Parts cleaning is a step in various industrial processes, either as preparation for surface finishing or to safeguard delicate components. One such process, electroplating, is particularly sensitive to part cleanliness, as even thin layers of oil can hinder coating adhesion.
Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants. A pressurised fluid, typically compressed air, or a centrifugal wheel is used to propel the blasting material. The first abrasive blasting process was patented by Benjamin Chew Tilghman on 18 October 1870.
A fire extinguisher is a handheld active fire protection device usually filled with a dry or wet chemical used to extinguish or control small fires, often in emergencies. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user, or otherwise requires the equipment, personnel, resources or expertise of a fire brigade. Typically, a fire extinguisher consists of a hand-held cylindrical pressure vessel containing an agent that can be discharged to extinguish a fire. Fire extinguishers manufactured with non-cylindrical pressure vessels also exist but are less common.
Martian geysers are putative sites of small gas and dust eruptions that occur in the south polar region of Mars during the spring thaw. "Dark dune spots" and "spiders" – or araneiforms – are the two most visible types of features ascribed to these eruptions.
The planet Mars has two permanent polar ice caps of water ice and some dry ice (frozen carbon dioxide, CO2). Above kilometer thick layers of water ice permafrost slabs of dry ice are deposited during a pole's winter, lying in continuous darkness, causing 25–30% of the atmosphere being deposited annually at either of the poles. When the poles are again exposed to sunlight, the frozen CO2 sublimes. These seasonal actions transport large amounts of dust and water vapor, giving rise to Earth-like frost and large cirrus clouds.
CryoJet / IceJet is a derivative of the machining process called abrasive waterjet (AWJ) machining. CryoJet/IceJet technology uses ice particles made of water coming from a running water or freshwater system to cut material. While the ice particles are cutting material, they melt and go into the water tank of the machine. The pressurized water acting as a cutting jet can be re-used, with adequate filtering, creating a closed water circuit. However, the majority of users do not re-use the water. If more widely used, CryoJet may produce a drastic reduction in the amount of abrasive waste spill currently produced during the water jet cutting process, as no mineral abrasive is used by this technology.
Heather D. Willauer (born 1974) is an American analytical chemist and inventor working in Washington, D.C., at the United States Naval Research Laboratory (NRL). Leading a research team, Willauer has patented a method for removing dissolved carbon dioxide (CO2) from seawater, in parallel with hydrogen (H2) recovered by conventional water electrolysis. Willauer is also searching to improve the catalysts required to enable a continuous Fischer–Tropsch process to recombine carbon monoxide (CO) and hydrogen gases into complex hydrocarbon liquids to synthesize jet fuel for Navy aircraft.
Joly is an impact crater on Mars, located at 74.7°S latitude and 42.7°W longitude in the Mare Australe quadrangle. It measures 79.9 kilometres (49.6 mi) in diameter and was named after Irish physicist John Joly (1857–1933). The name was approved in 1973, by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN).
Carbon dioxide cleaning (CO2 cleaning) comprises a family of methods for parts cleaning and sterilization, using carbon dioxide in its various phases. Due to being non-destructive, non-abrasive, and residue-free, it is often preferred for use on delicate surfaces. CO2 cleaning has found application in the aerospace, automotive, electronics, medical, and other industries. Carbon dioxide snow cleaning has been used to remove particles and organic residues from metals, polymers, ceramics, glasses, and other materials, and from surfaces including hard drives and optical surfaces.
Ice blasting is a form of non-abrasive blasting where frozen water particles are combined with compressed air and propelled towards a surface for cleaning purposes. Ice is one of several different media commonly used for blast cleaning. Another common method of non-abrasive blasting is dry ice blasting, which uses solid carbon dioxide as a blast media. Other forms of abrasive blasting use mediums such as sand, plastic beads, and baking soda.
The dry ice color show is a demonstration of the chemical formation of carbonic acid by the dissolution of dry ice in water. The dry ice color show is usually performed in classrooms to demonstrate the properties of acids and bases, their effect on pH indicators, and the sublimation of dry ice. Setup is simple and generally involves only minor hazards, the main one being the low temperature of dry ice, which can cause frostbite upon skin contact. The carbonic acid formed in the demonstration is a weak acid and is not hazardous, being present in numerous consumer products including tonic water, soda, and beer.
