Pig bone-derived biochar from food industry waste for heavy metal remediation: Sustainable consumption and production

• Pig bone biochar was produced via slow pyrolysis at 300–500°C under O₂-limited conditions. • Biochar at 500°C exhibited a high Cu²⁺ adsorption capacity (59.4 mg/g) and surface porosity. • Fractal-like kinetic and Toth isotherm models best describe adsorption behavior. • Thermodynamics confirmed spontaneous, endothermic Cu²⁺ adsorption with high reusability. • Life-cycle evaluation revealed a low cost (1 USD/kg) and a positive social return (SROI = 1.56). This study investigates the sustainable conversion of abattoir waste into pig bone-derived biochar(PBC) through slow pyrolysis at temperatures of 300 °C, 400 °C, and 500 °C under oxygen-limited conditions. Biochar produced at higher temperatures showed improved surface area, porosity, and hydroxyapatite crystallinity, as confirmed by BET, SEM-EDX, FTIR, and XRD analyses. PBC prepared at 500°C demonstrated the highest Cu 2+ adsorption capacity (59.4 mg/g, Toth isotherm model). Kinetic studies revealed that the Fractal-like Pseudo-First-Order (FL-PFO) model best described the adsorption process (R 2 >0.999), outperforming conventional models. Equilibrium data fit the Toth isotherm most accurately, indicating heterogeneous surface energy, while Langmuir, Freundlich, and Redlich–Peterson models provided secondary insights. Thermodynamic analysis confirmed spontaneous and endothermic adsorption, with entropy increases suggesting interfacial structural changes. Desorption tests confirmed high reusability. Economically, PBC production is low-cost (∼1 USD/kg) with carbon-neutral to negative emissions under renewable energy use and a favorable social return on investment (SROI = 1.56). The study highlights the potential of biochar as an efficient, renewable, and low-cost adsorbent for decentralized wastewater treatment, especially in regions with significant livestock waste and limited treatment infrastructure. This work demonstrates a practical path toward waste valorization, environmental remediation, and socio-economic impact within a circular economy framework.