Publication

Abstract : Functionalization of activated carbon (AC) enhances its adsorption efficiency, texture, and selectivity for specific pollutants through various physical, chemical, and biological processes. Chemical modifications involve the incorporation of oxygen, nitrogen, and sulfur into AC's surface, employing acids, bases, and salts to improve hydrophilicity and polarity for better adsorption of gases, heavy metals, dyes, PFAS, and pharmaceuticals. Techniques such as oxidation with strong acids (e.g., HNO3, H2SO4) and treatments with strong bases (e.g., NaOH, NH4OH) effectively introduce functional groups like carboxyl, hydroxyl, and phosphate, enhancing catalytic performance and improving the removal of basic pollutants such as ammonia (NH3) and heavy metals. Physical methods—including heating, steam purging, microwave irradiation, and non-thermal plasma—significantly increase AC's porosity and surface area. Microwave treatment, for example, optimizes energy efficiency and enhances adsorption capacity by uniformly heating AC at the molecular level. Similarly, plasma treatments increase surface acidity, facilitating better adsorption of metal ions. Biological refinements leverage microorganisms for surface modification, promoting pollutant removal by degrading organic materials and preventing pore blockage. Additionally, alkaline treatments using metallic salts (e.g., Fe, Cu) and noble metals (e.g., Pt, Pd) improve catalytic activity and create active sites for enhanced reactions. Steam enrichment, an eco-friendly method, promotes gasification at high temperatures to develop a highly porous structure, thereby improving adsorption and catalytic properties. While alternative methods such as coating, ball milling, and sol-gel techniques offer further enhancement, challenges like pore blockage can limit their practical applications. Overall, these functionalization strategies significantly improve AC's effectiveness in environmental remediation, particularly for water treatment, enabling efficient removal of a wide range of contaminants, including heavy metals such as lead, copper, and cadmium.