Modeling of fenuron pesticide adsorption on CNTs for mechanistic insight and removal in water

Inexpensive multi-walled carbon nanotubes (MCNTs) were prepared with 10-40 nm particle sizes and 9.0 m²g^-1 surface area. Fenuron pesticide was removed in water using these CNTs with 100.0 µgL^-1 concentration, 60 min contact time, 2.0 g L^-1 dose, 7.0 pH, and 25 °C. 90% removal of fenuron pesticide was achieved. Adsorption data obeyed Tempkin, Freundlich, Langmuir and Dubinin-Radushkevich models. The standard free energies values of fenuron pesticide adsorption were -11.89, -11.59, -11.55 kJ mol^-1. The values of enthalpy and entropy were -9.12 kJmol^-1 and -26.61 × 10^-3 kJ mol^-1 K. The negative values of free energy showed speedy adsorption of fenuron pesticide on CNTs. The supramolecular mechanism of fenuron adsorption onto CNTs was fixed by simulation studies and the binding energy and binding affinity of fenuron with CNTs were - 6.5 kcal mol^-1 and 5.85 × 10⁴ M^-1, respectively. There were one π-σ, seven π-π stacked, one π-π T-shaped, and three π-alkyl type of hydrophobic interactions between fenuron and carbon nanotube. These results clearly indicated the physical nature of the adsorption. The method is speedy, cost-effective, efficient and repeatable. Therefore, the established adsorption method is appropriate for adsorption of fenuron pesticide in waters.

Fenuron pesticide; Mechanism of uptake; Modeling and adsorption; Multi-walled carbon nanotubes; Thermodynamics and kinetics; Water.