Activated charcoal is a remarkable material that has many uses in industry and medicine. It is an effective and readily available tool for water purification, cleaning up chemical spills and waste, and in medicine for removing poisons and drugs from the stomachs of humans and animals.
How it is produced
Production of activated charcoal can either be achieved through physical activation by exposing carbonized material to an oxidizing atmosphere at high temperature, or chemical activation with a strong acid or base at a lower temperature. The source material plays a part in determining the end product’s properties, and anything from nut shells, to peat or petroleum byproducts can be used to produce the activated charcoal.
The individual particles of activated charcoal made through these processes are only about 0.1 millimeters wide, yet have a surface area of several square meters, making it extremely porous. A single gram of the material can have a total surface area of anywhere between 300-2000 square meters, giving it excellent adsorption qualities. This high adsorption is what makes the activated charcoal useful, as it is able to adsorb unwanted material that becomes trapped in the many pores.
The science behind activated charcoal’s function
Activated charcoal is essentially pure carbon, and it is the attraction of the carbon atoms which allow it to absorb other molecules through London dispersion forces, in a similar way to gravitational forces between planets. The electrons in a molecule tend to move around, giving the molecule positive and negative charges at opposite ends called a temporary dipole, and the electrons of the carbon are attracted to the negative poles, trapping the molecule on the surface of the activated charcoal.
Larger molecules have more electrons, and it is more likely for them to form temporary dipoles, and thus activated charcoal is more effective at removing larger molecules, and has The way the charcoal is activated and the carbon source are important in determining how effective it is at adsorbing a particular contaminant and it may also be impregnated with other elements, such as silver to give it antimicrobial properties and make it more effective for use in purifying water.
Improving activated charcoal for specific functions
The addition of elements such as iodine and sulfur make the activated charcoal able to adsorb inorganic chemicals it otherwise wouldn’t, such as mercury, due to a process called chemisorption where chemicals trapped in the charcoal react with the inorganic chemical and bind to it. In this way it is also possible to form activated charcoals that are able to neutralize certain chemicals and poisons in the case of spills and accidents, making it a valuable technique for cleaning up waste.
Due to the way activated charcoal works to adsorb molecules, eventually it reaches a maximum concentration of foreign material and all the pores are filled. When this happens the activated charcoal can either be replaced, or regenerated through high heat or chemical treatment to remove the adsorbed organic matter.
