Engineered biochar for simultaneous removal of heavy metals and organic pollutants from wastewater: mechanisms, efficiency, and applications

Organic compounds and heavy metals constitute two major classes of aquatic contaminants. Their prolonged simultaneous presence facilitates complexation reactions, which can generate novel toxicants with enhanced biological hazards. Therefore, developing advanced remediation technologies for the concurrent elimination of these remains imperative. As a carbon-rich material, biochar is considered an environmentally friendly and cost-effective adsorbent. Over the past decade, modification of biochar has emerged as a hot research topic. Strategic architectural and physicochemical modifications enable tailored surface properties and enhanced adsorption mechanisms, substantially expanding potential applications across environmental remediation domains. Despite emerging literature on the simultaneous removal of heavy metals and organic pollutants through engineered biochar, most research still focuses on the removal of single pollutants. This review examines the simultaneous removal of heavy metals and organic contaminants using functionalized biochar. Firstly, remediation efficiency, mechanistic pathways, and practical applications of engineered biochar are investigated for complex pollution matrices in aqueous environments. Secondly, physicochemical processes governing simultaneous contaminant capture through surface-modified carbon architectures are elucidated. Thirdly, performance across diverse wastewater treatment scenarios are evaluated, and environmental deployment viability assessed. This comprehensive analysis not only advances scientific understanding but also facilitates technological implementation of engineered biochar for the simultaneous removal of heavy metals and organic pollutants from wastewater.