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| Activated Charcoal is a Proven Water Purifying Agent |
By:
Thelma Oliver |
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A charcoal filter is a common part of most gravity fed and many force-fed water filters. Charcoal is the product of the destructive distillation of wood. This process yields wood alcohol, acetic acid, several burnable gases, and a few other products. The solid residue that results from this process is what we know as charcoal.
Charcoal is a black, brittle solid that is very porous. It is also odorless and tasteless. Though denser than water, charcoal can float! It does this because it is able to adsorb solids and gases so well. When charcoal has the opportunity to adsorb enough gases, they make it float.
Filters use a form of carbon called activated charcoal, coal, or carbon. Activation is a process to make the charcoal extra porous. Consider this: just one gram of activated carbon has a surface area of from 500 m to 1500 m! Since it takes 454 grams to make one pound and a tennis court has 260 m, it is clear that this charcoal is porous indeed! By having a greater surface area, more impurities are sure to come in contact with the charcoal.
Charcoal is able to filter because of its ability to adsorb. What is adsorption (note: not absorption)? "Adsorption is the concentration of a gas, liquid, or solid on the surface of a liquid or solid with which it is in contact." To show how good charcoal is at this, consider the fact that one cubic centimeter of charcoal can adsorb 90 cc of ammonia gas. It adsorbs other substances even better.
Pollutants in the water pass through the filter and come in contact with the activated charcoal. These substances are attracted to the charcoal by what is called van der Waals forces. Wiki says, "In physical chemistry, the van der Waals force is the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules."
It gets more technical that that but, suffice it to say, molecular forces bind some compounds to the charcoal. Activated carbon does not bind well with some chemicals. These include alcohols, glycols, ammonia, strong acids and bases, metals and most inorganics, such as lithium, sodium, iron, lead, arsenic, fluorine, and boric acid.
his is good news and bad news. It is good news because our bodies need the minerals in water. We don't want them filtered out. Fluorine is said to be good for dental health so many don't want that filtered either. However, others on the list above are unwanted and the filter must have other substances to remove these.
In conclusion, water and contaminants pass through the activated charcoal filter and, because of the filter?s porosity, the substances will likely come in contact with the carbon. The van der Waals forces will cause the substances to be attracted to the charcoal where they will remain until the filter is washed or replaced. For the contaminant, it is dead end road. For the person drinking the water, it is refreshing and healthy.
Berkey Filters are the best line of activated charcoal filter we are aware of. Check out the Big Berkey Water Filters or another model. One amazing feature is that each set of filters they ship with can be re-cleaned to purify up to 6,000 gallons of drinking water. |
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