Selective Permeable Properties Of Macro-membrane And Its Application Based On Non-covalent Interaction

Hydrogen bond and the cation-? interaction,as two kinds of the most important non-covalent weak interactions,possess their strengths which are less than one-tenth of the traditional covalent bond;therefore,many other molecules even under normal states are strong enough to damage these non-covalents.As a result,it's quite easy to make these non-covalent weak interactions damaged as well as reformed.The research works in this paper are exactly based on these two kinds of non-covalent interactions.Meanwhile,because of the special structures of many nano-materials whose surfaces can easily form the weak non-covalent interactions,for example oxide nanowires and oxide nanobelts.Here,on the one hand,we used super-long ?-MnO2 nanowires/V₂O₅ nanobelts as building blocks to fabricate a kind of macro-membrane by means of vacuum filtration method.Because of the oxygen atoms exposed on the surfaces of the building blocks,serving as hydrogen bond acceptors,it‘s quite easy for these building blocks to form hydrogen bond on their surfaces with the hydroxy as hydrogen bond donors.When the membrane was treated by H2 O,the hydroxyl in water molecules could be bonded by the oxygen atoms existing on the surfaces of the building blocks,leading to the exposing of hydrogen atoms from water molecules;and at this time,non-polar organic solvents cannot pass the membrane.However,when the membrane was treated by ethanol,alkyl groups could be exposed because of the same way;and at this time,non-polar organic solvents can pass the membrane freely.Therefore,when treated by water and ethanol alternatively,the chemical environment of the membrane surface could be changed alternatively.If we consider this phenomenon as a kind of “switch effect”,then the degree of this switch could be well controlled by mix of H2O-EtOH.Based on the results above,this membrane was successfully used in the separation of water/oil,and even emulsion separation.On the other hand,another kind of a nanostructure was also used as building blocks,graphene oxide.As we know,there are sp2 ?-electron system and sp3 matrix in the GO structure,when cations were added in GO solution,these cations will immediately combine with the sp2 ?-electron and the oxygen containing groups on the GO nanosheets by cation-? interactions and coordination effects.Comparing with pure GO membrane,this cation-decorated-GO membrane shows apparently different permeation behaviors towards a series of organic solvents;it endows every different organic solvent with their own special flow rate.To be specific,we classified the solvents we used into four types: H2 O can pass though this membrane,alcohol cannot pass through it,aromatic solvents can pass through it with different flow rates,and the last type are those with lone pair electrons,which can also pass though this membrane quickly.Based on these results,we design a kind of membrane reactor which actually was composed by a reaction chamber and a product collecting chamber,additionally with the cation-decorated GO membrane fixed between the two chamber.By this membrane reactor,a series of esterification reactions were successfully performed and the generated product?esters?were simultaneously separated and collected,which can make the reaction continuously.