osmosis involves the movement of

反透析膜（reverse osmosis membrane）去除离子的原理是什么?是孔径截留还是亲/疏水性?
1、RO膜孔径最小可达0.1nm,水分子大小为0.4nm,钠离子大小是0.102nm,不可能透过大的透不过小的；
2、电荷数越大越难透过RO膜,这个性质貌似跟亲/疏水性有关,但我没有在网上搜到任何权威材料明确说明这点.
请牛人指教.

在生物学中“osmosis”可解释为哪种细胞的运输方式?
最好是把三种运输方式都列出来（最好是中英）,有图更好,

英语翻译
Water gets into a fish's body through osmosis.For example,if there is more water outside of a cell than inside,water will try to flow into the cell until there is the same concentration of water on either side of the cell's membrane.The body of a fish acts the same way,either absorbing or losing water depending on its surroundings.
Whether a fish absorbs or loses water is based on the fact that all fish must maintain a certain amount of salt in their bodies to stay healthy.Fish that live in fresh water have a higher concentration of salt in their bodies than the surrounding water.
Ocean fish have the opposite problem.Surrounded by salt water,their bodies contain a relatively lower concentration of salt than the ocean water.In this case osmosis causes the fish to constantly lose water in order to equalize salt concentration inside and outside the fish.to partially compensate for the water loss,ocean fish actually drink water through their mouths.And to get rid of the excess salt they take in by drinking seawater,they excrete some salt through cells in their gills.