Preparation Of Superhydrophilic Underwater Superoleophobic Quartz Sand Filter And Its Oil/water Separation

The rapid development of industry and agriculture has produced a large amount of wastewater.Oil leakage at sea and the arbitrary discharge of catering waste water and industrial waste water not only cause waste of resources,but also cause serious pollution to the ecological environment,threatening the development of human beings.Therefore,it is of great significance to study the feasible oil/water separation technology.In order to overcome the shortcomings of traditional oil/water separation technology such as long time and complicated operation,it is of potential value to carry out research on special wettability materials.The superhydrophobic and superoleophilic materials are suitable for treating the mixture of heavy oil and water,but the surface is easy to be blocked by accumulated oil stains after long-term use,which affects the use effect.The superhydrophilic and underwater superoleophobic material is suitable for separating the mixture of light oil and water.The oil droplets cannot wet the solid surface under water,so it is not easy to be blocked and adhered by oil.The superhydrophilic and superoleophobic material is suitable for water removal,but the preparation method is more complicated.A single superwettability material has the disadvantages of a single processing object,limited pressure resistance,and non-continuous separation.Therefore,this paper prepares a superhydrophilic and underwater superoleophobic quartz sand,which has superoleophilicity and underoil high hydrophobicity,combined to form a new type of oil/water separation device.The separation properties of oil/water mixture and the adsorption properties of water-soluble dyes are investigated.The specific contents are as follows:(1)The preparation of superhydrophilic and underwater superoleophobic quartz sand.Coconut shell powder is activated by alkali and grafted onto quartz sand by soaking.The coconut shell powder is cellulose.The-CH₂OH group on the activated cellulose reacts with the-OH group on quartz sand.The hydrophilic group is grafted to the surface of quartz sand by chemical binding to form a micron rough structure.Waterborne polyurethane is used to make cellulose stick to quartz sand more firmly.The contact angle of underwater oil of coconut shell modified quartz sand is more than 150°,which reaches the level of underwater superoleophobic.And the contact angle of underoil water is more than 130°,which reaches the state of underoil high hydrophobic.(2)Characterization of modified quartz sand.The result obtained by SEM analysis is that the original quartz sand presents irregular sections and corners,the surface porosity is not developed,and it is relatively smooth.The surface of the quartz sand modified by coconut shell powder is covered with a white coating,randomly attached with flake and long fine fiber particles,which are coconut shell powder particles,forming a micron-level rough structure on the surface of the CSQS.The results of FTIR analysis show that the modified quartz sand has newly added C=C groups and C=O groups,and the stretching vibration peak of the-OH group is enhanced.Coconut shell powder successfully adhered to the quartz sand in the form of physical and chemical combination.XPS analysis shows that the surface of quartz sand is mainly composed of two elements,Si and O,and there is a small amount of C on the surface.The modified quartz sand has an increased content of C element and a new addition of N element,which is derived from the components of coconut shell and water-based polyurethane.(3)Design a new type of oil/water separation device.The quartz sand modified by coconut shell powder is filled in equal amounts on both sides of the oil/water separation device.The combined new device can realize continuous filtration of the oil/water mixture with good effect.(4)Experimental research on oil/water separation.The continuous oil/water separation device can separate a variety of oil/water mixtures(whether heavy oil or light oil)into water and oil at the same time,with a separation efficiency of more than 99.92%.The device can continuously filter 12.3 L of oil/water mixture.When the lyophobic liquid penetrates the filter layer,the filter layer can be restored by reverse extrusion,so that the separation efficiency of the filter layer is still above 99.99%.Finally,the mechanism of oil/water separation is discussed.(5)Research on the separation of actual oily wastewater.The separation efficiency of the oil/water separation device for filtering restaurant wastewater and petrochemical wastewater is96.51%and 96.14%,respectively,effectively treating oily wastewater in daily life.(6)Experimental research on adsorption of dyes.Coconut shell powder modified quartz sand can not only be used for the separation of insoluble oil-water mixtures,but also can effectively adsorb the water-soluble dye methylene blue in a short time,with a removal rate of98.94%and an equilibrium adsorption capacity of 0.2862 mg/g.The adsorption of MB by CSQS is mainly affected by chemical reaction.(7)Stability studies.A series of stability test results show that the coconut shell powder modified quartz sand exhibits good mechanical wear resistance,acid and alkali soaking resistance,surfactant washing resistance and air exposure resistance.In summary,the above experiments show that CSQS has excellent oil/water separation performance.The designed oil/water separation device has a good effect on the continuous separation of multi-liter oil/water mixture.It has a certain practical value in the actual oily wastewater treatment application.CSQS has good adsorption of dyes and excellent stability in different environments.