Preparation And Application Of Metallic Liquid Gating Composite Membranes

Metallic porous membranes are often used as structural support for complex composite materials due to their stable mechanical properties,high-temperature resistance,high-pressure resistance,high permeability,and excellent processability.However,due to the poor corrosion resistance and pollution resistance of the metallic porous membranes,the membrane structures are easy to be polluted and damaged,which leads to a reduction in long-term operation and an increase in cost.Liquid-based gating membrane(LGM)utilizes a molecular-level smooth gated liquid layer to transfer the solid-gas or solid-liquid interface of traditional solid membranes to the liquid-gas or liquid-liquid interface.Although the previous LGM based on polymer substrates has antifouling property,energy-saving and controllable multiphase selectivity,its wide application is limited by the mechanical stability of the solid membrane substrates.Based on this,this thesis proposes a simple electrochemical method for manufacturing multifunctional metallic liquid gating membranes(MLGMs).It mainly focuses on the preparation of metallic porous membranes and the characterization of membrane surface wettability,the construction of stable metallic liquid gating membranes and the gas/liquid transport and two-phase separation through metallic liquid gating membranes.The main research works are shown as follows.1.By different electrodeposition and hydrophobization methods,we prepared and characterized metallic porous membranes(MPM s).The experimental results show that the surface roughness of the MPMs changed by surface modification of tungsten oxide(WO3)and cobalt hydroxide(Co(OH)2)electrochemical deposition,resulting in nano and micro-nano composite structures on the surface,respectively.Since the MPMs had the better hydrophobicity after being hydrophobized by the low-surface-energy phosphate ester bearing fluorinated alkyl chains of mixed lengths(FS-100),the hydrophobic MPMs being modified by FS-100 was selected to construct the MLGMs.2.The hydrophobic MPMs and the gating liquid are combined to construct the MLGMs.The affinity of various gating liquids and the membranes was characterized by testing surface wettability and work of adhesion.Then the stability of the MLGMs was theoretically studied by the calculation of interface energy.The results show that the MLGMs with K103 as the gating liquid had excellent stability experimentally and theoretically.Besides,the MLGMs also exhibited excellent antifouling and anticorrosion properties.3.The self-built pressure test system was used to test the transmembrane critical pressures of air and water passing through the MPMs and the MLGMs.Then based on the difference in the transmembrane critical pressures of air and water passing through the MLGMs,a controlled gas/water two-phase separation experiment was performed on the mixture of air and water.The experimental results show that the MLGMs had an excellent energy-saving when transporting liquids.Moreover,the gas/water two-phase separation can be achieved by adjusting the applied pressure,the separation efficiency could reach 97.3%.