Response Surface Methodology for Biochar Performance Optimization: A Comprehensive Bibliometric Review

Biochar, as a widely available and environmentally friendly porous carbonaceous material, holds broad application prospects in fields such as environmental remediation, soil improvement, and carbon sequestration. Its performance is highly dependent on the precise control of preparation processes and modification conditions. Traditional single-factor experiments and orthogonal designs cannot systematically reveal the interaction effects among multiple factors; they suffer from limitations such as a large number of experiments, low optimization efficiency, and a tendency to overlook global optimal solutions. Response surface methodology (RSM), which integrates experimental design, mathematical modeling, and parameter optimization, is an effective tool for solving complex optimization problems involving multiple factors and levels. Based on 1468 valid publications screened from the Web of Science Core Collection (2010-2025), this paper systematically reviews the development trajectory and research landscape of this field using bibliometric methods. The results show that the annual number of publications in this field increased from 4 in 2010 to 312 in 2025, with a compound annual growth rate of 33.7%. Research hotspots were concentrated in three major areas: optimization of adsorption performance, control of pyrolysis preparation processes, and chemical modification. Central composite designs and Box-Behnken designs were the most prevalent experimental approaches, accounting for 56.8% and 35.5%, respectively. Building on this foundation, this paper elucidates the basic principles of RSM and the applicability limits of commonly used design methods. It examines the optimization effectiveness and the value of analyzing interaction effects of RSM from three dimensions-biochar adsorption performance, preparation processes, and modification processes-in conjunction with typical application scenarios such as heavy metals, organic compounds, and non-metallic inorganic compounds; it also provides an in-depth analysis of core issues in current research, including limitations in secondary model fitting, inadequacies in multi-objective optimization, and significant extrapolation risks. Finally, the paper outlines future research directions, aiming to provide a systematic theoretical framework for the precise R&D and engineering applications of biochar materials.