Molecular Dynamics Simulation Study Of Pollutants Adsorbed On The Interface/surface Of Clay Minerals

The siloxane surface of clay minerals are good adsorption sites to environmentpollutants with nano lamellar structure and huge specific surface area. Theinterface/surface interactions between pollutants and clay minerals can significantlyinfluence the transport and fate of pollutants in the environment,but the relatedresearch was rarely reported. In this article, we will systematically investigate theinfluence of various factors on the interface/surface interaction characteristicsbetween clay minerals and pollutants throw exploring the adsorption sites andadsorption state, which can reasonably describe pollutants and clay minerals adoptingmolecular dynamics simulation,it can provide information of microstructure,thermodynamics, dynamics for research object. The expected research results canprovide some basic data for understanding the influence of environment behaviour bythe interface/surface interactions and for developing clay mineral materials onpollution controlling. The main conclusions of this work are as follows:(1) The adsorption properties of fullereneon on pyrophyllite outer surface areproposed. Simulation results show that：fullereneon can active adsorption on thepyrophyllites siloxane outer surface, multiple fullerene molecules tend to be tiled onpyrophyllite outer surface, close to each other. With the increase of number offullerene molecules adsorbed on pyrophyllite outer surface, the adsorption free energyof system for single fullereneon decrease, the absolute value of free energy increase,Adsorption interaction are enhanced.(2) The available interlayer space plays the dominant role for their adsorptioncapacity towards HOCs. When the organo-montmorillonite is synthesized with smallorganic cations,the adsorption capacity of the organo-montmorillonite alwaysdecreases as the volume of the organic cation increases, and it is generally believedthat the reduced surface area should be responsible for the decrease of sorptioncapacity. Simulation results show that：Comparing with TMA-Mt, TPA-Mt has largeradsorption energy toward TCDD but smaller amount of interlayer space foraccommodating TCDD, it severely limits the adsorption quantity of TPA-Mt toTCDD.(3) The interlayer of CTMAB and CV composite modified organic bentonite areformed by compact organic phase, it can occur synergistic adsorption. Simulation results show that：the2-naphthol has big diffusion coefficient in composite modifiedorganic bentonite rather than single modified bentonite. The interlayer of compositemodified organic bentonite has bigger and more compact organic phase,it can adsorb2-naphthol by partial function,and shows synergistic adsorption.