Porous carbon spheres: Recent developments and applications

Activated or porous carbon is a carbonaceous material which has excellent adsorption capacity. Activated carbon has many applications including heavy metal and toxic gas removal as well as air and water filter applications. Microporous activated carbon in spherical shape (activated or porous carbon spheres) is a variant of activated carbon which has high compressive strength and low ash content. Pitch, polymeric (phenolic and sulfonated polystyrene resins) and other precursor materials (carbohydrate and seeds) have been generally used for production of activated carbon spheres employing carbonization and activation processes. Various parameters viz. carbonization temperature, heating rate, activation time and temperature, and activation media affected the performance and quality of end product. Generally activation by physical and chemical means is used for activated carbon spheres preparation. The use of polymeric precursors yielded better compressive strength and minimal ash content in comparison to other precursors. Activated carbon spheres produced using these processes has been successfully utilized as adsorbent materials for removal of heavy metals, organic dye, carbon dioxide, volatile organic chemicals, support for catalyst, gas and energy storage and also in chemical protective clothings. In present review, we discuss latest developments in activated carbon spheres and its use as adsorbent materials for removal of toxicants and various other applications.