Interaction and dragging of 2,4-D molecules in SPC/E water by (6,5) carbon nanotubes at ambient pressure

Abstract

Abstract We present a computer simulation study of the herbicide 2,4-dichlorophenoxyacetic acid, interacting with a single-walled (6,5) carbon nanotube in water. Our study was conducted at 1 bar of pressure, and the temperature varied from 280 to 370 K. Pair correlation functions, coordination number, water hydrogen bonding, density, static dielectric constant, and interaction energy between the nanotube and acid molecules, were determined. Mean square displacement and self-diffusion were also obtained. Our results showed that the herbicide molecules and the nanotube form a complex. Pair correlation functions revealed that acid molecules are most likely found at a distance of 7.4 Å from the nanotube and are located within 20 Å of it. Water hydrogen bonding and dielectric behavior of the mixture were similar to those of pure water. The mean square displacement revealed an incipient plateau located between two regions of linear behavior, which might be related to the frequent coming and going of 2,4-D molecules around the nanotube. The diffusion coefficient of 2,4-D was higher than that of the nanotube. Our results show a trend similar to that revealed in experiments on the capture of 2,4-D herbicide by (6,5) carbon nanotubes, indicating that the interaction parameters here used, produce a reasonable description of the calculated properties. As a general conclusion, our data support the idea that using carbon nanotubes in domestic devices for the dragging and removal of 2,4-D herbicide from water might be feasible.