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Adsorption of a Polyaromatic Compound on Silica Surfaces from Organic Solvents Studied by Molecular Dynamics Simulation and AFM Imaging

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journal contribution
posted on 2017-02-06, 00:00 authored by Yong Xiong, Tiantian Cao, Qian Chen, Zhen Li, Yue Yang, Shengming Xu, Shiling Yuan, Johan Sjöblom, Zhenghe Xu
Molecular dynamics simulation was used to investigate the adsorption of a polyaromatic compound (C5Pe) on silica surfaces from organic solvents. Heptane and toluene were used as oil phase to probe the effect of solvent properties on C5Pe adsorption. The results showed that C5Pe molecules tend to adsorb rapidly on silica surface in heptane and assemble to form long strip shaped aggregates, while in toluene C5Pe prefers to form aggregates which remain mostly in bulk oil phase. The van der Waals interactions were found to provide the largest contribution for driving the adsorption of C5Pe from heptane solutions due to the protonated state of C5Pe molecules. The calculated lower system free energy of C5Pe adsorption from heptane than from toluene corresponded well with the observed stronger adsorption of C5Pe from heptane than from toluene. AFM imaging confirmed the observed trend of C5Pe adsorption on silica from heptane and toluene.