Topic / Scientific concept
Showing 1–5 of 5
- Topic / Scientific conceptTOP-000005
Concentration polarization
The build-up of rejected solutes in a boundary layer at the membrane surface. It raises the osmotic pressure the pump must overcome, increases salt passage and promotes scaling; feed-channel spacers and crossflow velocity limit it.
EstablishedLevel 2 · Dynamic phenomenaOpen record - Topic / Scientific conceptTOP-000004
Mass transfer
The movement of components within and between phases by diffusion and convection. In membrane modules it sets how quickly rejected salts are carried away from the membrane surface.
EstablishedLevel 2 · Dynamic phenomenaOpen record - Topic / Scientific conceptTOP-000003
Diffusion
Transport of a substance from higher to lower concentration by random molecular motion. In dense RO membranes, both water and salt cross the separating layer by solution–diffusion.
EstablishedLevel 2 · Dynamic phenomenaOpen record - Topic / Scientific conceptTOP-000002
Osmotic pressure
The pressure that would have to be applied to a solution to stop water flowing into it by osmosis. For seawater, with about 35 g/L of dissolved salts, it is roughly 25–28 bar.
EstablishedLevel 1 · Intrinsic propertiesOpen record - Topic / Scientific conceptTOP-000001
Osmosis
The net movement of water through a semi-permeable membrane from a dilute solution toward a more concentrated one, driven by the difference in the chemical potential of water.
EstablishedLevel 1 · Intrinsic propertiesOpen record