Study On Preparation And Performance Of Underwater Superoleophobic Inorganic Membrane

With the rapid development of the oil industry and other industries,a large amount of oily wastewater is inevitably produced in industry and life,which has a certain impact on the ecological environment and human health.Therefore,it is of great practical significance to explore the treatment technology of oily wastewater.Traditional degreasing methods mainly include gravity separation,adsorption,centrifugation and biodegradation,but these methods are expensively,inefficient,and difficult to separate emulsified oil-water mixtures（d<20μm）,sometimes even causing secondary pollution.Compared with conventional degreasing technology,membrane separation is one of the most promising technologies for the treatment of oily wastewater due to its high efficiency,low energy consumption and simple operation.So far,researchers have researched and prepared different membrane separation materials,but at present,the emulsions separated by these membrane materials are single,especially for high viscosity crude oil.In addition,according to the current practical application status,it is urgent to prepare membrane materials with robust mechanical properties and corrosion resistance.Based on the literature research,this research has prepared all kinds of membrane materials with special wetting properties,and synthetically analyzed their separation performance.The main research contents are as follows:1.A 2300 mesh stainless steel mesh was used as the substrate,and the waterborne polyurethane was mixed with Al₂O₃ and SiO₂ uniformly.The Al₂O₃/SiO₂ mixed mesh membrane with underwater superoleophobicity was prepared by simple spray method.Combining the underwater superoleophobicity and sieving effect,the membrane can successfully separate different surfactant-stabilized oil-in-water emulsions.More importantly,the mixed mesh membrane can maintain underwater superoleophobicity after friction test and ultrasonic,and can still efficiently separate oil-in-water emulsions.2.Based on high molecular polymer membrane（PVDF）,the waste egg shells were deposited on the surface of the PVDF membrane.The membranes showed excellent superhydrophilic/underwater superoleophobic properties,and had relatively low rolling angle and adhesion,which can efficiently separate crude oil-in-water emulsions.In addition,the separation efficiency remained above 99.5%after several separations cycle tests.3.Utilizing the special layered structure and hydrophilicity of Ti₃C₂T_x,we prepared a two-dimensional MXene membrane with superhydrophilic/underwater superoleophobic properties by suction filtration deposition.The membrane can efficiently separate a series of oil-in-water emulsions with small particle sizes,the separation efficiency can be maintained above 99.4%,and the permeate flux reached 887 L m^-22 h^-1 bar^-1.More importantly,this MXene membrane can maintain underwater superoleophobic properties even when soaked in 3 M HCl,3 M NaOH and 3.5 wt%NaCl.In addition,the separation efficiency of MXene membrane for corrosive emulsions was as high as99.4%,and it’s permeate flux can reach 1000 L m^-22 h^-1 bar^-1.