Optimization and comparative performance of Jatropha Curcas extracts for turbidity removal in water treatment

This study assesses the coagulation potential of Jatropha Curcas leaf, shell, and kernel extracts for removing turbidity from synthetic water. Process optimization was conducted using Response Surface Methodology with a Central Composite Design, focusing on coagulant dosage, pH, and temperature as independent variables, and turbidity removal as the response variable. Quadratic models showed strong fits (R2 = 0.9191 for leaf, 0.8720 for shell, and 0.8962 for kernel). Dosage was the most influential factor, with optimized coagulation efficiencies of 95.02 % for leaf, 92.66 % for shell, and 91.44 % for kernel extracts at specific conditions: 1 % v/v (leaf) at pH 8.3 and 45 °C; 0.5 % v/v (shell) at pH 3 and 15 °C; and 4 % v/v (kernel) at pH 8.3 and 45 °C. However, validation and comparison with alum were performed under neutral pH and room temperature to reflect practical application and allow a fair comparison with alum performance. In this setting, alum (4 % dose) achieved 98.76 % removal, while the leaf extract reached 88.83 %, followed by the shell at 78.05 % and the kernel at 77.05 %, all using optimized doses. Cost analysis revealed that the shell extract was the most economical at 0.05 USD/m3, while the leaf extract (2.0 USD/m3) had a favourable efficiency-to-cost ratio. The kernel extract was least cost-effective at 24.0 USD/m3. Compared to alum (20 USD/m3), both Jatropha leaf and shell extracts show promise as sustainable, low-cost coagulants.