Molecular Dynamic Simulation of Nitrate Adsorption from Drinking water using graphene and Comparison with Experimental Data

Environmental pollutions due to human activities is a serious risk for drinking water resources. Many of water resources are infected by nitrate at the moment. Too many different adsorbents have been studied extensively for removal of nitrate from drinking water. Molecular dynamic simulation could be used as a strong instrument in forecasting of adsorption of pollutants from drinking water and in addition to the time and cost saving, it provides better understanding of the adsorption process. In this article, adsorption of nitrate from drinking water by graphene is first investigated by molecular dynamic simulation and then the results are compared with experimental data that shows a good consistency. We first applied an NVT ensemble to fix the temperature around 300oK. Then for getting to stable conditions of pressure, we used 3 sequential runs on an NPT ensemble. The final NVE run investigated for adsorption analysis parameters such as mean square displacement of nitrate ions, density distribution before and after adsorption and g(r) function. The results showed decrease in MD amount after adsorption indication decrease in movement on nitrate ion and its adsorption. Density distribution of nitrate ions and g(r) function shows distribution of nitrate ions on both sides of graphene sheet. A fortran code was used to count the number of nitrate ions at the distance of 5Ao of the sheet (these nitrate ions considered as adsorbed ions). The experimental data of adsorption of nitrate on graphene performed at 300oK. the amount of adsorbed nitrate (about 60 percent) was in Consistency with the results of MD simulation.

Keywords:

Drinking Water , Adsorption , Nitrate , graphene , Molecular Dynamic Simulation