Recent progress in the development and application of magnetic biochar for the adsorption of potentially toxic metals from aquatic systems: A review

The growing concern over environmental pollution by potentially toxic metals, resulting from the intensification of industrial processes, has driven the search for effective and sustainable remediation solutions. In this context, magnetic biochar has emerged as a promising adsorbent for the removal of these contaminants from aquatic systems, owing to its high adsorption capacity, simplified operation, and ease of magnetic separation. This review details the methods for obtaining magnetic biochar, encompassing both direct and multistep approaches, and discusses the adsorption mechanisms involved, such as complexation, ion exchange, and electrostatic interactions. Practical examples of magnetic biochar applications in the remediation of various metals, including Cr, Pb, Cu, Cd, Zn, and Ni, in aqueous matrices are explored. Magnetic biochar exhibits competitive performance and offers significant advantages compared to traditional adsorptive methods, particularly in simplifying sample preparation and reducing costs. However, challenges such as pore blockage, aggregation of magnetic nanoparticles, and large-scale production costs persist, requiring optimization of synthesis processes and validation of sustainability through long-term field studies.