Fast Water Thermo-pumping Flow Across Nanotube Membranes for Desalination.

Development of high-efficiency and low-cost seawater desalination technologies is critical to meet global water crisis. Here we report a fast water pumping method in which the water molecules in seawater are continuously pumped across nanotube membranes driven by a small temperature difference, opening the possibility of high-throughput small-scale desalination devices driven by low-grade thermal energy. Using molecular dynamics simulations, we show that an equivalent driving pressure of 5.3 MPa is achieved with a temperature difference of only 15 K. The remarkable water pumping ability is attributed to the asymmetric thermal fluctuation of water molecules. With this method, a 10 cm(2) nanotube membrane with 1.5 × 10(13) pores per cm(2) will produce freshwater with a flow rate of 7.77 L/h under a small temperature difference of 15 K.