Activated carbon, also known as activated charcoal, is usually found in the form of a powder or granules. Among other things, it is used in air and water filters.
There are several substantial advantages to using activated carbon in a fiberous form.
- Fibers can have a greater effective surface area. This allows them to adsorb more contaminants quickly.
- In order to be used in a filter, granules or powder must
be put into a special container that will hold them in place while water or air flows through. Often, these containers can be quite leaky, and some of the carbon gets out.
Originally, the fibers were made from nothing but carbon. Recently, a second-generation active carbon fiber has become available. They are made by coating glass fibers with a phenolic resin, then carbonizing them and activating them in a simple one-step process. The next-generation fibers possess several advantages.
- Their effective surface area is even greater than the first-generation fibers.
- They can be regenerated far more easily.
- They are very inexpensive by comparison to other forms of activated carbon fibers.
- They are far less brittle and thus more durable.
- Their surface chemistry can be tailored so that they are particularly good at adsorbing one particular type of contaminant.
Second-generation active carbon fibers may soon become the dominant technology for military gas masks and protective garments for NBC warfare. Additionally, they may find widespread use for environmental remediation and large scale water purification. Recent research at the University of Illinois has shown that they can be tailored to selectively remove the infamous pollutant MTBE from water.