Sustainable wastewater purification with crab shell-derived biochar: Advanced machine learning modeling &...

Detoxifying ecologically persistent dyes is vital for environmental and human well-being. Herein, crabshell waste is transformed into porous carbon (CB900) through pyrolysis, achieving a remarkable removal rate of 90.5% (CR-RR) and adsorption capacity (∼256.36 mg g^-1, q_CR). Employing XGBoost modeling, with a robust R² ∼0.996, proved its superiority over others in predicting CR adsorption. PSO-XGB optimization led to an optimal configuration: 0.051 g adsorbent, 460.56 mg L^-1 CR concentration, pH 3.16, and a 94.01 min contact time, resulting in 68.39% CR-RR and 822.15 mg g^-1 q_CR, simultaneously; sensitivity analysis unveiled the pivotal role of pH and adsorbent dose. CB900 exhibited physical, spontaneous, endothermic following both Langmuir and Freundlich isotherms. Remarkably, CB900 effectively eliminated various contaminants, including chromium and sulfasalazine antibiotic. Pilot-scale CB900 production cost via pyrolysis was $8.5/kg, a fraction of commercial powdered activated carbon, underscoring its economic viability and potential as a sustainable solution for the elimination of toxic contaminants from aqueous environments.