Carbon-based adsorbents for removing pharmaceuticals from wastewater: A critical review

Pharmaceutical contamination of aquatic environments is a growing global concern due to the extensive use and persistence of pharmaceuticals through conventional wastewater treatment. These emerging pollutants, even in trace amounts, cause ecological disruption, including antibiotic resistance and endocrine effects, and pose human health risks via drinking water. This review analyzes the adsorptive removal of pharmaceuticals using carbon-based adsorbents, including activated carbon (AC), carbon nanotubes (CNTs), and graphene-derived substances. Adsorption is a promising strategy due to its simplicity, cost-effectiveness, and efficiency without generating toxic by-products. AC is valued for its high porosity and large surface area, but faces challenges related to regeneration and competitive adsorption. CNTs (single-walled and multi-walled) exhibit exceptional adsorption capacities due to their unique structures and high specific surface areas; their tunable surface chemistry, achieved through functionalization, enhances selectivity and mitigates hydrophobicity. Graphene-derived substances possess an extraordinary theoretical surface area, mechanical robustness, and versatile chemistry, making them highly effective for sequestering a diverse range of pharmaceuticals. Dominant adsorption mechanisms include π-π interactions, hydrogen bonding, and electrostatic forces. The review highlights the promising application of these advanced carbon adsorbents in mitigating pharmaceutical water pollution, discusses ongoing research to optimize performance scalability, and addresses their long-term environmental fate for sustainable water resource management.