Preparation And Oil-water Separation Performance Of Organic-inorganic Hybrid Super-Infiltrating Coating

Oily water exists widely in petrochemical and catering industry.It not only pollutes the environment but also wastes oil and water resources greatly.Therefore the separation of oil-water mixture is a common concern in related industries.The traditional oil-water separation methods have different limitations in application due to many defects.In recent years,the use of special wettability materials as oil-water separation materials provides a new method for the efficient treatment of oily wastewater.On the basis of previous work,a special wettability coating material was prepared by means of organic and inorganic hybrid,and its oil-water separation performance was studied.304 stainless steel mesh was chosen as the substrate,through three different processes?two-step spraying method,one-step immersion method,mixed two-step spraying method?,A super-hydrophobic and Superoleophilic coating with micro-nano-composite structure was constructed by using FEVE/PU resin and SiO₂ particles on its surface.The oil-water separation characteristics and durability of the coating were investigated.The prepared coating has excellent wettability,the contact angle of water droplets is 159°,the rolling angle is 4°,means the coating has super hydrophobic and superoleophilic properties.The separation efficiency of various oil-water mixtures is more than 99%,and t CCl₄/water mixture can still be up to 99.5%after 55 consecutive separation,which means excellent oil-water separation characteristics.In addition,the coating has good chemical stability and mechanical durability.After immersion in acid-base solution of pH=1-11 for 24 hours and solutions of pH=2 and 12 for 7 days,the contact angle of the coating remains above 150°,showing good acid-alkali resistance.The contact angle of water droplets is above 150°after water impact and sand washing respectively,indicating its outstanding mechanical durability.The Superhydrophilic and Underwater Superoleophobic stainless steel mesh coated by SiO₂nanoparticles was successfully prepared by one-step spraying method,which can separate a variety of oil-water mixtures with high separation efficiency.The contact angle of the coating to water and oil is 0°in air,and the contact angle of underwater oil droplets is more than 150°.In addition,the prepared omentum coating can separate a variety of oil-water mixtures and maintain over 99%separation efficiency after 55 cycles of separation.The coating can still achieve oil-water separation after 200 times of finger grinding,acid solution immersion and 30 days underwater immersion.Through the combination of superhydrophilic film and superhydrophilic membrane,the high-efficiency and continuous oil-water separation is realized in a T-shape oil-water separation unit.This method is simple,effective and durable and it has a wide application in the fields of rapid separation,which lays a foundation for the design of a new type of oil-water separation device.The filter media of walnut shell with special wettability?super hydrophobic oil,super hydrophobic super lipophilic oil,super hydrophilic underwater super hydrophobic oil?were prepared.The filtration efficiency was 57.62%,65.77%,61.26%,84.01%,respectively,and the oil content of the backwashing solution was 487.1 mg/L?172.4 mg/L?505.8 mg/L?786.4 mg/L respectively.The filtration efficiency and the oil content of the backwashing solution are the highest,indicating that the hydrophilic and underwater hydrophobic walnut shell can improve the filtration effect and enhance the backwashing ability,which is suitable for filling filter media.