چكيده به لاتين
Before the appearance of graphene, it was believed that two-dimensional materials could not exist outside the field of theory due to thermodynamic instability. But contrary to the expectations, scientists have succeeded in producing such materials in the last few years. Discovering graphene with its marvelous properties has led to focusing further research on this substance in order to find its possible potentials in a variety of fields. One of the applications of this substance is water purification and desalination, which has recently been studied theoretically and experimentally. Multi-layer type of this material has attracted even more attention due to its simpler synthesis and mass production capability. However, multi-layer graphene membranes are faced with some structural weakness due to poor Van der Waals, or physical bonds between the layers. For this reason, many efforts have been made to solve this problem by creating covalent bonds between the layers by various chemical agents and composite structures. In this study, by mean of molecular dynamics simulation technique, the ion beam irradiation process was introduced as a method for creating nanopores and, at the same time, strengthening stacks of graphene layers. This process is a technique previously used to weld nanotubes and graphene planes. By using this method, individual graphene sheets create covalent bonds together. According to the mechanical tests, the ultimate tensile strength of the bonded sheets in the vertical direction is about 4 to 6 GPa. This process can also weld the adjacent graphene stacks with a strength of 2.5 to 15 GPa. This special structure of the graphene stacks is capable of water purification, both through inside the pore and through the interlayer spacing. The performance of these two configurations was further investigated in the discussion of desalting water. By changing the configurations and parameters such as pore diameter, pressure, thickness, ion concentration, and pore geometry, the water transfer rate has been observed from 100 L/m2h2bar to 1000 L/m2h2bar. The results of this study can be useful for making the superior membranes to facing the water crisis.
