- What Is Ethanol?
Ethanol is a type of alcohol and an organic solvent used for sterilization and disinfection, as well as for a wide range of other purposes. It is highly volatile and must be sealed in a container and stored in a cool, dark place.
Uses of Ethanol
Ethanol is used in a wide variety of applications. Specific examples are as follows:
1. Disinfection
As a rubbing alcohol, ethanol is used to disinfect skin, medical instruments, surgical sites, and hospital walls and floors. Consumption has increased dramatically, especially since the outbreak of the Coronavirus pandemic.
Disinfectant ethanol generally contains about 30% water in addition to ethanol. This concentration is considered adequate to effectively disinfect bacteria and viruses. The mixture of water makes it less volatile and increases the time that the disinfectant ingredients remain at the disinfection site, thereby enhancing the disinfection effect.
2. Solvent in Industrial Applications
Ethanol is used as a diluent for synthetic resin paints and coatings. In addition, anhydrous ethanol, with an ethanol concentration of 99.5% or higher, is sold at drugstores as a cleaning detergent, and can be purchased and used by the general public.
3. Food Additives
Fermented ethanol made from natural raw materials is used for food preservatives and seasonings such as mirin. Ethanol is also one of the main ingredients in alcoholic beverages, although this is not one of the uses of ethanol.
Ethanol is found in beer, wine, whiskey, sake, etc. It is produced through fermentation in the process of manufacturing alcoholic beverages.
Properties of Ethanol
Ethanol is a clear, colorless, flammable liquid with the chemical formula C2H5OH and molecular weight of 46.07. It has a low melting point of -114.1°C and a boiling point of 78.5°C. Its high volatility makes it easily vaporize even at room temperature. This property is useful when used in disinfectants and hair sprays.
Ethanol is also easily miscible with water and can be easily made into an aqueous solution. This property is important when ethanol is used as a base material for disinfectants and mouthwashes.
Its flash point is low at 12.0℃, and it ignites and burns at room temperature in the presence of an ignition source such as a spark. Even disinfectant ethanol (a 70% aqueous solution of ethanol), which is widely used in homes and public places, has a flash point of 21°C and must be handled with care.
Types of Ethanol
Ethanol can be classified into two types based on differences in raw materials and manufacturing methods: synthetic ethanol and bioethanol.
1. Synthetic Ethanol
Synthetic ethanol is ethanol synthesized from fossil fuels such as petroleum and natural gas. Unlike bioethanol, synthetic ethanol is produced without using renewable raw materials, and its environmental impact can be problematic.
Synthetic ethanol is made from fossil fuels and has the advantage of lower production costs and easier adjustment of production volumes compared to bioethanol.
However, there are concerns about its environmental impact in terms of CO2 emissions. In addition, fossil fuel reserves are limited, which limits its use as a sustainable fuel.
2. Bioethanol
Ethanol is produced by fermenting plant-derived raw materials (biomass). By using biomass, bioethanol is attracting attention as an environmentally friendly fuel that does not rely on fossil fuels.
Ethanol itself has the same properties, but because the raw materials used in its production are derived from plants, bioethanol has lower CO2 emissions than fossil fuels and is considered to be more environmentally friendly. In addition, since biomass is a renewable resource, it is one solution to the problem of fossil fuel depletion.
However, there are some challenges: harvesting and processing biomass requires energy, and the energy needed to produce bioethanol is dependent on fossil fuels.
Other Information on Ethanol
How Ethanol Is Produced
Synthetic ethanol is produced by reacting ethylene obtained from natural gas or petroleum with water.
C2H4 + H2O → C2H5OH
In this reaction equation, ethanol (C2H5OH) is produced by the reaction of ethylene (C2H4 ) and water (H2O). This reaction proceeds in the presence of an acid catalyst such as phosphoric acid or sulfuric acid immobilized on silica. The resulting ethanol is obtained as a mixture with water and byproducts, and can be purified through distillation, separation, and other processes to produce high-purity ethanol.
Bioethanol is produced by fermentation of plant-derived raw materials (biomass). Typical examples of biomass include sugarcane, corn, potatoes, sugar beets, and wood.
These raw materials are crushed to extract the fiber and sugars, and then fermented with yeast and other microorganisms. In this process, the sugars are converted to ethanol. From there, ethanol is concentrated through distillation and further purified to obtain bioethanol.