ABSTRACT
Activated carbon or activated charcoal (AC) is a porous and nongraphitizable form of carbon and considered as an efficient adsorbent due to its high porosity and large surface area per unit volume. AC can be prepared from various carbon-rich natural and synthetic precursors, agricultural byproducts, food wastes, domestic wastes, petrochemical products, and fruit shells through a two-stage process, that is, (i) carbonization of carbonaceous precursors and (ii) activation of the carbonized precursors by physically or chemically. Depending upon the starting raw materials and product selectivity, the selective activation process is required. Based on the physical characteristics, shape, and size of particles, activated carbons are broadly classified into various categories which have specific applications. ACs can adsorb a wide range of chemicals, organic compounds, and heavy metal ions and can be operated at a wide range of temperatures and humidity conditions. Specific surface area, pore size distributions, hardness, and iodine index are the major physical properties which qualitatively measure the adsorption efficiency of AC. Activated carbons show a wide range of applications such as water or air purifications, metal extractions, catalysis, gas storage, trapping heavy metal ions from wastewater, odor removal, gas storage, and many other industrial and medical applications.
