Exfoliated biochar activates soil microbial metabolism and demonstrates immobilization potential toward toxic metals and metalloids

Biochar is widely recognized for its potential to enhance soil microbial activity and immobilize toxic heavy metals. However, its large-scale adoption is limited by inconsistent performance and high market costs (320 to 800 € m−3). Here, we present a cost-competitive strategy for the industrial-scale production of exfoliated biochar from phytowaste feedstock and its robust validation in soil–microbial systems. Exfoliated biochar was continuously manufactured at pilot-to-industrial scale and evaluated across multiple independent trials using representative agricultural soils. Its performance was systematically benchmarked against virgin biochar in terms of microbial metabolic activation and immobilization of environmentally relevant heavy metals (Cu2+, Cr6+, and As3+). Across all validation sets, exfoliated biochar consistently promoted higher microbial metabolic activity and superior metal adsorption efficiency, demonstrating both reproducibility and process robustness. These enhancements are attributed to increased surface area, optimized pore architecture, and improved accessibility of reactive functional groups introduced during exfoliation. Molecular dynamics simulations combined with radial distribution function analyses revealed distinct adsorption mechanisms, including preferential interactions of hydroxyl (–OH) groups with Cr6+ ions and pyridinic nitrogen sites with Cu2+ ions. Complementary spectroscopic analyses further identified aliphatic hydrocarbons, aromatic domains, aromatic C=C bonds, and hydrogen-bonded –OH groups as major contributors to adsorption performance. Overall, this study demonstrates that industrially scalable exfoliation, coupled with targeted structural and functional optimization, enables reproducible enhancement of biochar–microbe–metal interactions. This approach provides a robust, systems-oriented pathway for sustainable soil remediation and biomanufacturing-relevant environmental applications.