TABLE OF CONTENTS Richard D.Brady
Richard Brady & Associates
San Diego, California
Activated carbon is an adsorbent material that provides a surface on which ions or molecules in the liquid or gaseous phase can concentrate.
The use of activated carbon in water treatment in the United States has been limited primarily to removing taste- and odor-causing compounds, pesticides, and other organic contaminants.
Activated carbon has a random structure that is highly porous, with a broad range of pore sizes ranging from visible cracks and crevices down to molecular dimensions. Intermolecular attractions in the smallest pores create adsorption forces. These forces cause large and small molecules of dissolved contaminants to be condensed and precipitated from solution into the molecular-scale pores. Activated carbon is an effective adsorbent because it provides a large surface area on which the contaminant chemicals can adhere.
Activated carbon is available in two different forms: powdered (PAC) and granular (GAC). Adsorptive properties of GAC and PAC are fundamentally the same because they depend on pore size, the internal surface area of the pores, and surface properties independent of overall particle size. Each brand of commercially available PAC or GAC has properties making it most suitable for particular applications. Besides adsorptive capacity and selectivity in removal, these properties include the ability to withstand thermal reactivation and resistance to attrition losses during transport and handling. Powdered activated carbon is added to water, mixed for a short time, and removed. Adsorption of molecules occurs while the PAC is in contact...
