The Preparation Of Cobalt Oxide-based Composite Omentum And Its Oil-water Separation And Catalytic Degradation Performance

As the industry and medical care developed rapidly,the ecosystem is damaged heavily.Accidents such as the oil spill,illegal discharge of wastewater from living and industry and oily sewage have caused the destruction of natural water bodies such as the water on ground and underground.On one hand,it has caused serious economic losses,on the other hand,the oil in water,organic pollutants case serious threats to the living environment of humans and other living things.In order to achieve oil-water separation and synergistic catalytic degradation of organic pollutants,researchers begin to study various related materials.Membrane separation technology has been the direction of researchers to compete for research because of its simple operation,high separation efficiency and low energy consumption.Superwetting materials are used for membrane separation due to their various special wettability（such as superhydrophilic-underwater superoleophobic）.Oil-water separation is achieved in the technology.Superhydrophilic-underwater superoleophobic materials can be obtained by designing the microscopic geometry of the surface of the material and modifying the chemical molecular composition.Inspired by various biological characteristics such as lotus leaf and fish scales,the material exhibits extreme wettability against oil and water through various micro-nano preparation methods,which is especially important influencing factor to the separation of water and oil for such materials.However,the preparation of the material is complicated,and the cycle performance is poor,the cost is high,and it cannot simultaneously and effectively treat the oil pollution and organic pollution in the sewage.In this paper,the stainless steel metal mesh membrane is used as the matrix,and the oxide of metal cobalt ions with graphene and oxide of silicon is supported on the surface of the reticulated membrane by combustion method,and then we make the combination of the method of persulfate oxidation etc.A series of superhydrophilic-underwater superoleophobic inorganic composite mesh membrane materials were prepared.Micro-nano roughness and chemical composition,surface properties and other physical and chemical properties of the composite membrane are studied to study the oil-water separation and catalytic degradation of orgnic pollution.Briefly as follows,the main work of the research is:（1）Using stainless steel mesh as the base and CoCl₂ ethanol solution as the building element,the flame combustion method is used to rapidly oxidize CoCl₂,and the cobalt oxide coating is constructed on the surface of the stainless steel mesh membrane to obtain superhydrophilic-underwater superoleophobic oil mesh with catalytic properties.The effects of parameters such as CoCl₂ concentration and assembly times on the surface morphology and catalytic degradation of organic pollutants and hydrophilic oleophobic properties were investigated.It has been determined through trial and error that the stainless steel mesh has the best performance when the CoCl₂ concentration is 1.0 wt%.The underwater contact angle can reach 157.5±2^o（using dichloroethane oil droplets as the research object）,the oil droplet rolling angle is less than 5.0^o,and the underwater superoleophobic effect is achieved,which can effectively separate the oil-water mixture such as cyclohexane.-water,1,2-dichloroethane-water,and the separation efficiency is above 99.5%.For different oil-water mixtures,the membrane flux is different but all achieve superoleophobic effect.Taking cyclohexane as an example,the separation flux is as high as 52688 L m^-2 h^-1.By catalytically degrading Rhodamine B dye,the time is controlled within 10 minutes,and the simultaneous catalytic PMS for the degradation of organic dyes with the separation oil from water.After the relevant tests,the web has excellent self-cleaning properties,recyclability and excellent mechanical properties.（2）Based on the micro-roughness of the surface of the building material,CoCl₂and TEOS ethanol solution were used as the building blocks,and the flame was burned rapidly to form a Co₃O₄-SiO₂ coating on the surface of the stainless steel mesh.In this chapter,the effects of TEOS concentration,assembly times and other parameters on the surface morphology and catalytic degradation of organic pollutants were investigated.After repeated trials,it was determined that the 300 mesh stainless steel mesh had the best combination performance when the CoCl₂ concentration was1.0 wt%and the TEOS concentration was 3.0 wt%.The underwater contact angle can reach 165^o±1.0^o（using dichloroethane oil droplets as research oil droplets）,and the oil droplets can roll freely on the underwater mesh,the adhesion is extremely low,and the rolling angle is less than 4^o.The rolling angle is smaller than that in the experiment 1,and the contact angle is bigger.It can effectively separate oil-water mixture such as cyclohexane-water,1,2-dichloroethane-water,and the separation efficiency is above 99%.For different oil and water,the membrane flux is big.Taking cyclohexane as an example,the membrane flux can reach up to 59964 L m^-2 h^-1.It can catalyze the degradation of methylene blue solution in 14 min.Compared with the experimental one,the time required to degrade methylene blue is 21 min,which indicates that the catalytic ability is imp roved.At the same time,the mesh has excellent anti-staining ability,recycling property and mechanical properties.（3）In order to improve the mechanical stability and catalytic performance of the metal mesh membrane load,graphene oxide is added to the constituents of the stainless steel mesh membrane.The GO and CoCl₂ solution were used as the building blocks,and the stainless steel mesh structure was constructed by the layer self-assembly method.The effects of parameters such as GO concentration and number of impregnation combustion on hydrophilic oleophobic properties and the effects on catalytic degradation of organic pollutants were studied.The formation regularity of Co₃O₄-rGO was revealed,and the optimum ratio of Co₃O₄-rGO coating was selected.After repeated trials,it was determined that the 300 mesh stainless steel mesh had the best combination performance when the GO mass concentration was 1.0%of the 1.0 wt%CoCl₂ ethanol solution.Its underwater contact angle can reach 164.5^o,achieving the underwater superoleophobic,which can effectively separate oil-water mixture such as cyclohexane-water,1,2-dichloroethane-water,and the separation efficiency is above 99%.In the flux of cyclohexane,the membrane flux reached 61302.2 L m^-2 h^-1.And the catalytic degradation of methylene blue is also controlled within 10 minutes.After relevant tests,the mesh has efficient performance for separation and activation of PMS.