Surface engineering approaches for the design of magnetic biochar-composites for removal of heavy metals: A comprehensive review

Engineered magnetic biochar (EMB) is a multifunctional material that has gained increasing attention in environmental and industrial applications. This review explores various synthetic methods, and diverse applications of EMB, focusing on its enhanced potential for environmental remediation, and water treatment. The incorporation of metal, various functional groups along with magnetic nanoparticles into biochar matrices provides EMB with unique properties, enabling efficient adsorption of heavy metals, organic contaminants, and pollutants from aqueous solutions. There are extensive literature reports on the development of such engineered magnetic biochar adsorbents for effective and selective removal of a wide range of inorganic pollutants including heavy metals and inorganic ions from water. This article encompasses all the techniques which have been utilized for the engineering of the pristine magnetic biochar and its application specifically in heavy metal removal from water and summarizes the latest innovative research and knowledge in this field. Due emphasis has been shed on elaborating the mechanisms involved in the adsorption of inorganic pollutants, specifically heavy metals by these efficient materials. Until now, to the best of our knowledge, no review on tailored magnetic biochar covering the surface engineering techniques and adsorption mechanisms has been penned. In addition to shedding light on the fundamental aspects, this article also provides a critical comparison of these adsorbents with the literature reported ones which clearly highlight their efficacy and offers insights into the current advancements, challenges, and future prospects of EMB, emphasizing its potential to address environmental and agricultural sustainability challenge.