Sorption of chlorpyrifos onto zinc oxide nanoparticles impregnated Pea peels (Pisum sativum L): Equilibrium, kinetic and thermodynamic studies

This study was focused on the sorption of chlorpyrifos from aqueous media utilizing synthesized zinc oxide nanoparticles impregnated Pea peels (ZnONPs-IPPs) in batch mode under the impact of pH of solution, dosage of sorbent, time of contact, temperature and initial pesticide concentration. The prepared composite was characterized by SEM, EDX, Surface area pore size analyzer and FTIR before and after sorption of chlorpyrifos. It was observed that the sorption of chlorpyrifos depends upon pH and maximal sorption (56%) was occurred at pH 2. The data of sorption process were fitted into Freundlich, Langmuir, Temkin and Dubinin–Radushkevich (D–R) isotherm models and the results indicate that Temkin isotherm is a suitable choice to describe the data owing to higher R² value (0.99). Monolayer sorption capacity of ZnONPs-IPPs for chlorpyrifos of the Langmuir isotherm was found to be 47.846 mg g⁻¹. Kinetics of sorption were described by fitting data into pseudo-1st-order, pseudo-2nd-order, Elovich, intraparticle and liquid film diffusion models and the results showed that pseudo-2nd order interprets the data well owing to the higher R² (0.99) well as the close agreement between the calculated and experimental sorption capacity. Thermodynamic parameters (ΔG^∘ is negative and ΔH^∘ is positive) imply that sorption process of chlorpyrifos utilizing ZnONPs-IPPs is spontaneous and endothermic in nature. The prepared composite is an economical and eco-friendly biomass and may be efficiently used for the removal of other pollutants.