Two-dimensional nanoporous carbon-based membrane has proved to be a promising reverse osmosis (RO) membrane for contaminated ions separation from water. In this study, molecular dynamics simulations are conducted to assess the performance of C2N and g-C3N4 nanosheets for the separation of nitrate and nitrite pollutants from aqueous solution. The nitrate and nitrite rejection were obtained 100 % for both membranes at high pressures, with water fluxes of 25.38 L/cm2DayMPa and 9.13 L/cm2DayMPa through C2N and g-C3N4 membranes, respectively. We observed that the water self-diffusivity increased 3 times in the presence of the C2N and g-C3N4 nonporous membrane, due to the hydrophilic structure of these membranes. The results of potential of the mean force (PMF) for nitrate and nitrite ions confirm the high ions rejection capability of these membranes at high pressure, where hydrogen bonding dynamics enhances water flux.