StuM, I understand that capillary action can create tremendous pressure, and in fact create higher pressure than the osmotic pressure of seawater. The problem is that capillary action only works while water is confined to small tubes and the smaller the tube the more powerful the capillary action. The pores in graphene oxide membranes are perhaps the smallest a water molecule can fit through so the capillary pressure would be at or near it's maximum theoretical value. The problem is that capillary pressure only works while the water molecules are confined inside the tube and water does not accumulate at the open end of the tube. Tall trees like redwoods do this by evaporating the water at their tops and consuming water in the process of photosynthesis in their leaves, both of which remove water from the top of the tree. If water accumulated there even as drops the capillary action would stop. If the capillary tube is short and water accumulates on the "fresh water" side the there is no more capillary action. You could conceivably evaporate the water off of the fresh water side at a high rate to keep the capillary action going, but if your purpose is to use that fresh water, evaporating it away seems to be counter productive, not to mention energetically expensive. As soon as water starts accumulating on the "fresh water" side of the graphene membrane, capillary action stops and osmotic pressure becomes the dominant physical force. At that point the graphene membrane is now no different than any other semipermeable membrane.
Zboss's video from China
demonstrated nano filtration of fresh water, not desalinization of sea water. It stated that it reduced TDS and salinity. Given that the salinity is already very low in "fresh water" i'm not surprised at all that they might have seen a reduced salinity in their product water. It looked to me like their head
pressure was about a half a meter. That would mean that they could reduce their salinity until the osmotic pressure at the bottom was about 1 PSI lower than the water poured into the top. That is a reduction, which is all they claimed, and it should be noted they did not provide before and after numbers.