Conversion of food waste to biochar via pyrolysis: Production processes, material properties, and environmental...

Food waste generation has reached 1.3 billion tons annually, contributing to global greenhouse gas emissions and placing considerable strain on conventional waste management systems. Though pyrolysis-mediated conversion of food waste to biochar is a suitable thermochemical approach within circular economy frameworks, a rigorous, quantitative mapping of this research domain has been lacking. This study bridges this gap by presenting the first bibliometric review with an in-depth qualitative synthesis. A systematic literature search was conducted using the Scopus database, guided by the PRISMA framework, and analyzed using Bibliometrix (RStudio) and VOSviewer. A total of 543 publications from 2010 to 2025 were examined to map publication trends, collaboration networks, and thematic structures. The findings show an exponential growth in research output, with an annual growth rate of 29.08% and strong international collaboration (34.62%). China, the United States, and South Korea are the major contributors. However, contributions from Sub-Saharan Africa remain limited. Thematically, the research domain is focused on production optimization, environmental remediation (e.g., heavy-metal and pollutant adsorption), and agricultural applications (e.g., soil amendment). Feedstock characteristics exerted a stronger influence on biochar performance than pyrolysis conditions. Emerging areas include co-pyrolysis, machine learning optimization, and multifunctional biochar composites. The study highlights critical knowledge gaps in pore formation mechanisms, contaminant-selective adsorption, and regional research disparities. The findings provide actionable insights for researchers to prioritize future studies, for policymakers to design circular-economy strategies, and for industry stakeholders to optimize scalable biochar production and application pathways.