This study investigates the use of pine cones as a natural and abundant bio-coagulant for treating industrial wastewater and removing crystal violet (CV) dye. Pine cones, rich in active molecules, were processed into powder and extracts using distilled water and sodium chloride. The coagulants (proteins, polyphenols, and carbohydrates) were effective in reducing turbidity, chemical oxygen demand (COD), and zeta potential. The bio-adsorbent, formed from the residue of the extraction process, was used to remove CV. Coagulation-flocculation experiments were conducted using a jar test, and the Box–Behnken design was employed to optimize the adsorption process. The results showed that pine cone powder and extracts with NaCl achieved 96%, 94%, and 98% turbidity reductions, respectively. The bio-adsorbent, PCER, effectively removed 99.9% of CV under optimal conditions. The model developed for the adsorption process had a high R² value (0.965) and an adjusted R² value (0.926), indicating its significance. The study highlights the potential of pine cones as a sustainable and cost-effective solution for wastewater treatment and dye removal.This study investigates the use of pine cones as a natural and abundant bio-coagulant for treating industrial wastewater and removing crystal violet (CV) dye. Pine cones, rich in active molecules, were processed into powder and extracts using distilled water and sodium chloride. The coagulants (proteins, polyphenols, and carbohydrates) were effective in reducing turbidity, chemical oxygen demand (COD), and zeta potential. The bio-adsorbent, formed from the residue of the extraction process, was used to remove CV. Coagulation-flocculation experiments were conducted using a jar test, and the Box–Behnken design was employed to optimize the adsorption process. The results showed that pine cone powder and extracts with NaCl achieved 96%, 94%, and 98% turbidity reductions, respectively. The bio-adsorbent, PCER, effectively removed 99.9% of CV under optimal conditions. The model developed for the adsorption process had a high R² value (0.965) and an adjusted R² value (0.926), indicating its significance. The study highlights the potential of pine cones as a sustainable and cost-effective solution for wastewater treatment and dye removal.