Study On Preparation And Properties Of Two-Dimensional Mesh Membrane In Oil-Water Separation

In recent years,oily wastewater from industrial discharges such as metallurgy,textiles and mechanical processing,as well as frequent oil spills during oil extraction and transportation,has become an urgent challenge around the world.Therefore,oil-water separation materials and technologies have important scientific significance and application prospects in terms of environmental governance and energy recycling.Traditional techniques for oil-water separation,such as gravity sedimentation,centrifugation,adsorption,flotation,and demulsification,face disadvantages such as high operating costs,low separation efficiency,and secondary pollution.Membrane separation,with its advantages of simple operation,low energy consumption and high separation efficiency,is a very promising new technology to solve energy and environmental challenges,which has developed rapidly in the past few decades.Two-dimensional materials have recently been studied for the preparation of 2D separation membrane materials due to their unique atomic thickness and micron lateral dimensions,showing excellent properties in gas separation,desalination,etc.But so far,2D oil-water separation membrane materials have rarely been reported.It is well known that the wettability of solid surfaces is mainly affected by surface chemical composition and microscopic geometry.The contact angle of Young's equation is commonly used to assess the wettability of solid surfaces.Young's equation is applicable to both liquid droplets on solid surfaces in the air and liquid droplets on solid surfaces under second liquid.Until now,there are mainly two types of oil-water separation membranes,one is the"oil-removing"separation membrane with both superhydrophobic and superoleophilic surface wettability.Generally,for the realization of superhydrophobic surfaces,almost all materials require post-treatment of low surface energy coatings such as polytetrafluoroethylene?PTFE?,polydimethylsiloxane?PDMS?,1-dodecanethiol,and the like.However,low surface energy compounds such as fluorochemicals used to modify surfaces are expensive and harmful,and these disadvantages not only cause environmental pollution,but also severely limit their large-scale production.So it is important to seek a stable,fluorine-free hydrophobic material.Due to the hydrophobicity and flake-like structure of the two-dimensional metal-organic framework?MOF?,the 2D MOF?MAMS-1?nanosheets were first deposited on a stainless steel mesh by a simple hot drop method to fabricate a novel superhydrophobic mesh membrane with a corrugated micro-and nanostructure surface in this paper.At the same time,the structural characterization and performance test of the oil-water separation membrane were carried out.The roughness and wettability of the membrane surface were discussed.The oil-water separation performance,stability and cyclability of the membrane were studied in detail.The experimental results show that the MAMS-1 oil-water separation membrane can achieve gravity-driven high-efficiency oil-water separation under fluorine-free conditions,with stable hydrophobicity and excellent recyclability.Simultaneously,the mesh membrane can be prepared in a large area.Another oil-water separation membrane is"water-removing"membrane with superoleophobic surfaces.Due to the hydrophilicity and flake-like structure of the two-dimensional?2D?MXene?Ti₃C₂T_x?,a novel hydrophilic and underwater superoleophobic mesh membrane with a corrugated micro-and nanostructure surface was prepared for the first time on the stainless steel mesh by vacuum filtration in this text.In addition,through structural characterization such as PXRD,SEM,TEM characterization and FTIR spectroscopy and a series of performance tests,we can see:for a series of oil-water mixtures,the MXene-caoted mesh membrane can achieve gravity-driven high-efficiency oil-water separation with excellent separation efficiency of over 99.99%,residual oil content of less than 4 ppm in collected water,and water flux up to 57.52 L·m^-2·s^-1.In addition,MXene-coated mesh membranes display outstanding stability and cycleability.