A photocatalytic TiO2/graphene bilayer membrane design for water desalination: a molecular dynamic simulation

Abstract

The research about finding the effective membrane material is in progress; however, there are pros and cons for each material. Graphene membrane is a single layer of atoms in a two-dimensional hexagonal lattice which achieved high performance in water purification field. Addition of TiO2 to the graphene membrane has been studied for the membrane modifications due to its high stability and photocatalytic performance. In this study, graphene/TiO2 bilayer nanocomposite membrane has been simulated to enhance the mechanical and electronic properties of graphene membrane. Anatase TiO2 (A-TiO2), rutile TiO2 (R-TiO2), and their composite with graphene (G) have been simulated to evaluate the stability of the nanocomposite bilayers in water desalination for higher salt rejection percentage and water permeation. The membrane structure has been created and optimized using the geometry optimization task. The simulation of electronic and mechanical properties has been done by using Material Studio 2019. TiO2 consisting rutile and anatase phases showed a band gap of 2.248eV, which was reduced to 1.175eV in combination with graphene. The bilayer composite of TiO2 and graphene achieved higher membrane stability, and the salt rejection was 98% under applied pressure of 100MPa. The graphene/TiO2 bilayer nanocomposite membranes have been evaluated by simulation for water desalination process using molecular dynamics by ReaxFF software. In comparison with a graphene membrane, the results showed an increment in salt rejection and water permeability under different applied pressure.