Richard M. Lueptow's Research Group

Molecular dynamics simulations show hydrogen bond formation during contaminant transport in reverse osmosis membranes at the atomic level. This video shows hydrogen bonds (in red) during reverse osmosis filtration of urea contaminant molecules (blue) in water. The polymer structure (green) is a polyamide membrane that is about 4 nm thick (about 50 times thinner than actual reverse osmosis membranes). Water molecules, which are not shown, buffet the urea molecules and the membrane (Brownian motion). As urea molecules enter the membrane they are slowed by the hydrogen bonds that form between them and the membrane.  Eventually, some urea molecules slip through the membrane to the right side. This simulation was done by Dr. Meng Shen under the direction of Professors Sinan Keten and Richard M. Lueptow at Northwestern University, 2015.