Molecular dynamics simulations of removal of nonylphenol pollutants by graphene oxide: Experimental study and modelling

Graphene oxide (GO) performs excellent adsorption property in removing organic pollutant out of the aqueous solution. GO adopted in this research was synthesized by using an improved Hummers approach. With the adoption of X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS), the samples were characterized. The mechanism of removing nonylphenol ethoxylates (NPEO10) in the wastewater by GO was investigated through XPS and molecular simulations. The GO model was constructed on the basis of XPS outcomes and typical molecular formula of GO (C10O1(OH)(1)(COOH)(0.5)). The XPS results indicate that the GO surface is significantly within the coverage of NPEO10. From MD simulations, it was shown that NPEO10 molecules adsorbed at GO surface through oxygen-containing functional group, and the polar interactions between the ethoxylate group and oxygen-containing functional group on the GO surface were the primary factors during the process of adsorption. The negative interaction energy existing between NPEO10 and GO model suggests that the GO-water-NPEO10 system becomes more stable after adsorption.