Recent Advances on Application of Modified Biochar for the Removal of Pharmaceutical Compounds from Wastewater

The widespread use of pharmaceutical compounds (PCs) has led to their extensive contamination in aquatic environments. Biochar, a carbon-rich and porous material, offers a promising solution for the remediation of PCs, particularly when modified. Modification methods can be physical (ball milling, steam activation, and CO₂ activation) or chemical (acid/alkali treatment, oxidation, surface functionalization, metal impregnation, and nano structuring). These treatments enhance biochar's structural properties including pore size, pore volume, surface area, and surface functionality, thereby increasing its affinity for PCs and improving removal efficiency. Modified biochar enables multiple adsorption mechanisms, including pore diffusion, electrostatic interactions, hydrophobic effects, hydrogen bonding, and π-π interactions, which act synergistically to remove PCs from water. This review critically discusses various biochar modification techniques, their efficacies, and key parameters influencing their performance. It also highlights adsorption mechanisms, regeneration strategies, and the importance of biochar stability for economic and environmental feasibility. Additionally, life cycle and techno-economic analyses are discussed to evaluate the financial and technical viability of using modified biochar for PCs' remediation. Finally, the review outlines the major challenges associated with modification techniques and provides insights into future research directions to enhance the removal of PCs from aqueous environments.