Activated carbons fall into different categories based on the conditions subjected to carbon. Here are quick facts about activated carbon that you will find interesting.
The acid-washed activated carbon is made through the washing of activated carbon with acid to remove any available water-soluble wash. Washing of activated carbon with acid lowers the total ash content that makes up the carbon. Acid washed activated carbon being effective is often preferred by many for the treatment of water for drinking as well as for food-grade processing applications. The acid-washed activated carbon is not only used in water treatment plants but also by food processing companies, breweries as well as in distilleries among other applications.
Activated carbon is preferred as a filtration medium because it is cost-effective. The carbon is often available in pelletized, powdered, and granular forms which are derived from materials like coconut shell, coal, and wood. To achieve this raw charcoal is superheated to create a huge internal pore structure for organic contaminants to adsorb into. Activated carbon finds applications in both water and air purification. Adsorption refers to the tendency of a molecule to stick to the surface of the activated carbon.
There are many large internal pore structures in activated carbon which offers a larger surface area for the molecules to stick to the surfaces of these pores. Ash content of the activated charcoal plays a role in its effectiveness. When making activated carbon products, the emphasis is put on the reduction of the ash content. The water-soluble ash can easily be washed away by water. In most cases, activated carbon which is meant for food-grade applications is acid washed to get rid of the water-soluble ash content and no acid should be left behind in the process.
The other concept is the backwashing of the activated carbon. There are initial and periodic backwashes. The first backwash is used to remove the fines and dust that is created when activated carbon is being handled. For proper backwashing of the filter, you need to start the process slowly as you gradually speed it up. This way the carbon can expand gently. It is not advisable to start the process quickly as this is likely to push the carbon higher up. You can backwash for about 20 minutes and should be done periodically to remove particles that might get stuck in the carbon pores. For instance, many car wash customers have lots of soap going through the filter and that is why they need to occasionally backwash the filter to get rid of the soap which could be blocking the activated carbon pores.
The other important aspect of activated carbon is capacity. This refers to the amount of space available to capture contaminants. For instance, activated carbon might capture say one gram of contaminant for a given amount of activated carbon resulting in a particular activated carbon percentage on the weight capacity. There is also the aspect of contact time and features of granular activated carbon you should look at.