Reverse osmosis

=== Graphene ===
Graphene membranes are meant to take advantage of their thinness to increase efficiency. Graphene is a singular layer of carbon atoms, so it is about 1000 times thinner than existing membranes. Graphene membranes are around 100&nbsp;nm thick while current membranes are about 100&nbsp;µm. Many researchers were concerned with the durability of graphene and if it would be able to handle RO pressures. New research finds that depending on the substrate (a supporting layer that does no filtration and only provides structural support), graphene membranes can withstand 57MPa of pressure which is about 10 times the typical pressures for seawater RO.<ref>{{Cite journal |last1=Cohen-Tanugi |first1=David |last2=Grossman |first2=Jeffrey C. |date=2014-11-12 |title=Mechanical Strength of Nanoporous Graphene as a Desalination Membrane |url=https://pubs.acs.org/doi/10.1021/nl502399y |journal=Nano Letters |language=en |volume=14 |issue=11 |pages=6171–6178 |doi=10.1021/nl502399y |pmid=25357231 |bibcode=2014NanoL..14.6171C |issn=1530-6984}}</ref>

Batch RO may offer increased [[Energy efficiency (physics)|energy efficiency]], more durable equipment and higher salinity limits.

The conventional approach claimed that molecules cross the membrane individually. A research team devised a "solution-friction" theory, claiming that molecules in groups through transient pores. Characterizing that process could guide membrane development. The accepted theory is that individual water molecules diffuse through the membrane, termed the "solution-diffusion" model.<ref>{{Cite magazine |last=Levy |first=Max G. |title=Everyone Was Wrong About Reverse Osmosis—Until Now |language=en-US |magazine=Wired |url=https://www.wired.com/story/everyone-was-wrong-about-reverse-osmosis-until-now/ |access-date=2023-05-20 |issn=1059-1028}}</ref>