When you next walk through a health food store or even through your local CVS, take a look around and you will see an array of charcoal or carbon based products. Those products range from Soap and toothpaste to activated charcoal for indigestion.
My own exposure to activated charcoal began when a pediatric emergency room patient presented with an accidental overdose of the parents Digoxin, a drug used to treat heart conditions. We placed a small tube into the child’s stomach, suctioned it out and then mixed powdered activated charcoal mixed with water down the tube to prevent absorption of the drug. It worked and the patient did well.
Activated charcoal has a fascinating history. As far back as 3750 BC the Egyptians found that charcoal burned hotter than wood and used charcoal fires to melt metals and by 1500 B.C. we find the first recorded use of activated charcoal for medicinal purposes. The Egyptians and also the Phoenicians and the ancient Hindu’s of India all began using activated charcoal to stop the odors coming from contaminated wounds and found that the charcoal not only stopped odors but also had antimicrobial properties which also helped to clean the wounds. Another thousand years passed and the valuable benefits of activated charcoal continued to be discovered. Around 400 BC, we find records that sailors would char the inside of water barrels to purify and preserve their water for long ocean voyages. The charcoal formed on the inside of the barrel would keep the water from becoming stagnant and prevent the growth of dangerous mold, bacteria or parasites.
Hippocrates, often called the father of modern medicine, was the first physician to be credited for his belief that disease was caused by natural causes, and environmental circumstances, rather than as a punishment from the gods. Hippocrates used charcoal to treat epilepsy (seizures), indigestion and even bacterial diseases such as anthrax. However, the value of charcoal to medical treatments accelerated much more quickly once methods of activation of the charcoal were developed in the early 19th century when it was found to absorb multiple poisons such as strychnine and arsenic.
In the 19th century a French pharmacist proved to an audience of medical doctors the benefits of activated charcoal in preventing poisoning. It was widely believed that Alexander the Great had been killed by being poisoned with Strychnine and many prominent people of that era feared being poisoned. Strychnine is a highly toxic, colorless but bitter poison that comes from the seeds of the Strychnos tree. The French pharmacist Monsieur Touery, took ten times the lethal dose of strychnine in front of a meeting of the French Academy of Medicine. To prevent his own illness and death Monsieur Touery also took 15 grams of activated charcoal. To the amazement of the audience, Monsieur Touery remained calm, healthy, and walked out of the room with no evidence of any ill effect.
In 1881, an important term was coined by physicist Heinrich Kayser. Kayser used the word “adsorption” to describe the process of atoms or molecules from a gaseous, liquid or dissolved solid substance attaching themselves to a surface and creating a film on thesubstance. Kayser started using the term to describe how charcoal could “adsorb” gases and he has been credited with this description of the mechanism by which activated charcoal filters or purifies gases and liquids. Adsorption is a distinct process where organic compounds in the air or water react chemically with the activated carbon, which causes them to stick to the filter. The more porous the activated carbon is, the more contaminants it will capture. These filters are most notably used to remove hazardous compounds in home air purification systems.
By the beginning of the 20th century, the commercial manufacture of activated carbon was prevalent. Common uses in this time period included carbon solutions used for food and chemical decoloration and the use of activated carbon in gas masks to protect soldiers from chemical weapons.
Activated charcoal and activated carbon are synonyms. It is an organic product that is formed by subjecting wood, bamboo, or coconut fibers to high heat and combustion without enough oxygen to allow it to burn up completely. The resulting charcoal forms with deep crevices and porosity that creates an amazing surface area. One gram of activated charcoal can have a surface area, due to these pores, of five thousand and four hundred square feet (5,400 sq ft).
Now when you walk into that health food store you will likely be breathing air that is passed through air filters that use activated carbon fibers to purify the air.
Fig. 1 Electron microscope photos of the pores in activated carbon
Activated charcoal is typically produced as powder or crystals. Activated Carbon fiber or fabric is created when the activated charcoal is treated and then spun into fabric to be used in air and water purification and filtration. The Charcoal works for filtration through a process called adsorption where the activated charcoal binds to the impurities passing through. It works immediately and within seconds purifies air or liquid.
Coconut shell or bamboo charcoal is the raw material used in the manufacture of some of the best activated carbon, creating a sustainable material. This process utilizes only high quality coconuts or bamboo with origins in Vietnam, Indonesia, China and the Philippines.
The process of manufacturing activated carbon begins with the carbonization of coconut shell carbon to create the charcoal. Any carbon material such as coconut shell, wood, or paddy husk can be used in this process, but the activated carbon manufactured from coconut shell or fine quality bamboo is considered superior to other sources. The small macrospores structure in these products renders it very effective for the adsorption of gas / vapor.
The process of making activated carbons consists of crushing the coconut shell in a hammer mill to the required size, and then pulverizing it in a ball mill. The shell powder is digested with zinc chloride. The mass is then activated at elevated temperature, quenched and leached and dried in a tray drier. In the steam treatment activation process, the fully matured, dried, and cleaned wood fibers are burned in the presence of a limited supply of oxygen, it is this burning without oxygen that produces the carbonization. This is a non-graphite form of carbon, and it tremendously increases these important adsorption properties.
Activated carbon is used as a natural fiber enhancer that adds new performance qualities to blended yarns. Typically, 40% to 50% of activated carbon in a blended yarn is adequate to create the activated carbon absorption benefits.