Study On Preparation Of Superhydrophilic Titanium Dioxide Film For Oil-Water Separation

With the development of industry,oil leakage accidents and the discharge of oily wastewater have posed serious threats to the environment and human beings.In order to solve this problem,the filtration method using superhydrophilic/underwater superoleophobic materials has attracted wide attention due to its high efficiency,low energy consumption and low cost.However,the preparation method of filter membrane is often complicated,which seriously limits its practical application.In this study,TiO₂coating was prepared on the commercial stainless steel mesh by using atomic layer deposition（ALD）.The coating has a rough fish-scale-like biomimetic nanostructure,which can achieve high efficiency,high flux oil and water separation,and has good wear resistance and self-cleaning performance under UV irradiation.Firstly,TiO₂ superhydrophilic film was prepared by ALD technology on silicon substrate,and the influence of deposition temperature,source bottle temperature and deposition period on film properties was studied.The element composition,surface morphology,growth rate and wettability of the films were analyzed by means of XPS,AFM,ellipsometer and contact angle tester.Thus,the optimal process conditions are as follows:deposition temperature is 200℃,source bottle temperature is 75℃,and the deposition period ranges from 400 to 600 to obtain the fastest growth rate and the minimum water contact angle.It was also verified that TiO₂ films prepared by this process could obtain good superhydrophilic on different substrates.Secondly,TiO₂ coating with fish-scale nanostructure was prepared on stainless steel mesh by optimal process.The effects of coating thickness,mesh number and different liquid phase media on wettability of TiO₂ coated mesh and oil-water separation performance were studied.The surface morphology and wettability of coated mesh were analyzed by means of SEM and contact angle tester,and the oil-water separation performance was measured.The experimental results show that the best oil-water separation effect can be obtained by depositing 12 nm thick film on 400 mesh substrate:the separation efficiency is more than 99.0%,the flux is 107856 L·m^-2·h^-1,the immersion pressure was 4208 Pa.The fish scale nanostructure helps to stabilize the construction of water film,and the mixture of oil and water can be separated under the action of water film obstruction,upward capillary-driven pressure and capillary wall adhesion resistance.Finally,the self-cleaning and wear resistance of TiO₂ coated mesh were investigated.Organic pollutants on the surface of titanium dioxide omentum are oxidized to inorganic substances such as CO₂ and H₂ under the action of hydroxyl radicals and superoxide radicals produced by UV excitation.Through the analysis of infrared spectrum,SEM,contact angle tester and other characterization means,it is proved that the coated mesh has good self-cleaning ability under UV irradiation,excellent mechanical stability and substrate adhesion,stable impact resistance,bending resistance and circulation separation ability.In this paper,the one-step method of bionic TiO₂ coated mesh is realized by ALD technology.In the process of high efficiency,high flux oil and water separation,it has excellent self-cleaning and wear resistance.It provides a new idea for the preparation of oil-water separation membrane materials.