氧化石墨烯吸附水体中酚类有机污染物的分子动力学模拟

Adsorption of Phenolic Organic Pollutants on Graphene Oxide:Molecular Dynamics Study

研究采用分子动力学模拟(Molecular dynamics simulation,MD)的方法,以苯酚、α-萘酚和4-辛基酚为代表,研究了酚类有机污染物(Phenolic Organic Pollutants,POPs)在氧化石墨烯(Graphene Oxide,GO)上单独和竞争吸附过程。通过自由能计算得到三种POPs在GO表面的吸附能分别为:4-辛基酚(41.34 kJ/mol)>α-萘酚(33.23 kJ/mol)>苯酚(19.31 kJ/mol)。吸附过程中的主要作用力为POPs的疏水作用,而分子团簇、范德华相互作用、静电相互作用以及氢键等在一定程度上增加了GO对POPs的吸附能力。在混合体系中,POPs之间存在明显的竞争吸附现象,吸附过程包含了直接吸附和形成分子团簇的间接性吸附两个过程。本研究结果为含POPs水体的治理以及GO材料的设计和筛选提供了一定的理论依据。

In this work,molecular dynamics(MD)simulations were applied to address the major concerns about the independent and competitive adsorption processes of phenolic organic pollutants(POPs)on the graphene oxide(GO)in aqueous solution.Phenol,α-naphthol and 4-octyl-phenol were adopted as representatives of POPs and their adsorption energies were calculated,which followed an order of 4-octyl-phenol(41.34 kJ/mol)>α-naphthol(33.23 kJ/mol)>phenol(19.31 kJ/mol).The simulation results showed that hydrophobic properties of POPs were recognized as the driving force for their adsorption behaviors.Moreover,van der Waals interaction,electrostatic interaction,as well as hydrogen bonds,may also improve the adsorption capacity of GO towards POPs.The competitive adsorption process revealed that in addition to the direct adsorption onto the GO surface,the molecular aggregation may be another indirect adsorption way existed in the mixed system.Understanding the interaction between GO and POPs in aqueous solution is critical to the design and application of graphene-based materials and our findings are believed to contribute further theoretical basis to the engineering treatment of POPs-containing waste water.