The Quest for Active Carbon Adsorbent Substitutes: Inexpensive Adsorbents for Toxic Metal Ions Removal from Wastewater

Due to overgrowth in population, industrialization and civilization, demands for water are increasing geometrically. Therefore, alternative sources of water are required and wastewater treatment and recycling may serve this purpose. Among various water treatment technologies, adsorption onto activated carbon is in the front line due to its universal nature. Activated carbon is the best adsorbent able to capture inorganic, as well as organic, pollutants that contaminate water resources. Inorganic pollutants, especially metal ions, are more dangerous due to their toxic and possibly carcinogenic natures. Also they are most often persistent and difficult to biodegrade. The present article describes the quest to find an economically viable substitute to active carbon adsorbent to remove toxic metal ions. A brief discussion of design of batch and column adsorption experiments, development of inexpensive adsorbents, and experimental conditions of metal ions removal by batch and column procedures is included. Efforts have also been made to differentiate adsorption versus speciation of metal ions.