Optimizing the synthesis of Fe/Al (Hydr)oxides-Biochars to maximize phosphate removal via response surface model

Highly efficient and cost-effective adsorbents for phosphate (P) recovery are the key to control eutrophication and recover phosphorous from waste streams to enhance food production . This study assembled waste biomass (corn stalk, almond shell, and dairy manure)-derived biochars with Fe/Al (hydr)oxides through co-precipitation method. The fabricated biochar composites presented excellent performance for the adsorption of P due to good amounts of surface area, pore volume, and reactive surface hydroxyl sites. Response surface methodology (RSM) was applied to optimize the production conditions of the Fe–Al (hydr)oxides-biochars for maximizing the P removal. The effects of three key independent variables, i.e. , Fe 3+ concentration (0.2–1.0 mol L −1 ), Al 3+ concentration (0.2–1.0 mol L −1 ), and mass-to-volume ratio (0.05–0.20 g mL −1 ) on the P removal were investigated. The synthesized composites outperformed other sorbents for the P removal, suggesting the synergistic effects of Fe/Al (hydr)oxides and biochar support. These results offer valuable insights to develop high-performance biochar-based composites for green and sustainable environmental remediation.