Palm and Eucalyptus waste-derived biochars for removing imidacloprid and myclobutanil from pesticide- contaminated water.

Two biochars, palm petiole biochar (PPB) and eucalyptus leaf biochar (ELB), were prepared from palm (Phoenix dactylifera) petioles and eucalyptus (Eucalyptus sp.) leaves and evaluated as low-cost sorbents for the removal of imidacloprid and myclobutanil from aqueous solutions. Batch adsorption experiments were conducted to examine the effects of adsorbent dose, pH, temperature, contact time, and initial pesticide concentration. The highest removal was achieved at pH 7, 25 ± 1 °C, 24 h contact time, a biochar dose of 5 g L⁻¹, and an initial concentration of 50 mg L⁻¹ for each pesticide. Thermodynamic analysis indicated that the adsorption process was spontaneous and exothermic. Adsorption kinetics were evaluated using pseudo-first order and pseudo-second-order models, whereas equilibrium data were analyzed using the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models. Among the tested equilibrium models, Langmuir and Freundlich provided the best fit to the adsorption data. PPB showed stronger practical removal performance than ELB. Under rapid-treatment conditions using 100 mg of biochar, PPB removed 87.4% of imidacloprid and 92.1% of myclobutanil, whereas ELB removed 66.6% and 80.0%, respectively. These findings demonstrate that PPB and ELB, particularly PPB, are promising eco-friendly sorbents for the treatment of pesticide-contaminated water and concentrated agricultural point-source wastewaters.