Molecular Dynamics Simulation of Water Treatment Using Thermal Driving Force and Carbon Nanotube Membrane

Abstract

The temperature difference between the pure and impure water on the two sides of a membrane can lead to water purification. The asymmetry of molecular kinetic energy on both sides of the membrane causes pure water to move from the hot side to the cold one. In this research, a carbon nanotube membrane filtration system based on the temperature difference between water sources has been investigated by the molecular dynamics simulation method. The effect of various factors has been investigated. The simulation results confirm the possibility of using a thermal driving force for water purification with carbon nanotubes. The results show that by increasing the hot source temperature, the water passage and the purification speed increase. Such that increasing the temperature difference between sources from 15 to 60 K increases the water purification rate by 30%. Simultaneously, the possibility of impurities passing through the nanotube also increases. Increasing the impurity concentration slows down the purification process. Increasing the diameter of the nanotube up to 15 Å increases the water purification rate. In nanotubes with a diameter of less than 15 Å, 100% of impurities are removed. Among the examined nanotubes, the best performance was obtained for the armchair carbon nanotube.

Keywords

• carbon nanotube
• molecular dynamic simulation
• temperature difference
• water purification