Preparation Of Superhydrophilic And Superoleophobic Sponge Based On Polycaffeic Acid And Research On Oil-water Separation Performance

Super-wetting materials have broad application prospects in the field of oil-water separation.High-efficiency oil-water separation materials have been developed through the efforts of researchers,but their application is limited by the complex preparation process,high preparation cost,low separation efficiency,and poor anti-oil adhesion performance.Therefore,the preparation of efficient,economical and environmentally friendly oil-water separation materials needs to be solved urgently.In this study,oxidants and diamines were used to synergistically promote the polymerization of caffeic acid(CA),and a rapid and multifunctional hydrophilic surface coating technology was studied.Combining this technology with the construction roughness of nanomaterials,a superhydrophilic-underwater superoleophobic material was prepared,and its superwetting characteristics,emulsion separation behavior and separation mechanism were studied.On this basis,combined with chemical gas phase reactions,a material with intrinsic superhydrophilic-superoleophobic properties was prepared,and its oil-water separation behavior was studied.The results are as follows:In order to improve the self-cleaning ability of superwetting materials,caffeic acid was selected as the precursor of surface modification,and oxidant and diamine were used to promote the polymerization of caffeic acid(CA),so a rapid and multifunctional hydrophilic surface coating technology was developed.It was found that amino can not only accelerate the polymerization of CA,but also promote the deposition of polymer on sponge surface.Using silica nanoparticles to build roughness,a superhydrophilic sponge(MF/Si O₂&CA)was prepared,and it showed good underwater super-oleophobicity and anti-oil adhesion properties.DFT simulation was employed to explore the potential mechanism of the anti-oil adhesion ability.In addition,combined with the mechanical compression strategy,the modified sponge exhibited a high efficiency of 99.10%with a permeation flux of19080±700 Lm^-2h^-1 in emulsion separation just under the action of gravity.In addition,according to the interaction between surfactant and material surface,the separation mechanism was discussed.In summary,the separation mechanism of oil-in-water emulsions was discussed in terms of pore structure,coalescence effect,and the interaction between surfactants and the surface of the material.In order to obtain the intrinsic superhydrophilic-superoleophobic material,firstly,caffeic acid and acrylic acid were used to co-deposition for surface modification,and the sponge surface of the polarity was adjusted through alkali-neutralized acrylic acid;then,a small amount of perfluorodecyl mercaptan was used to adjust the dispersion composition of the sponge by chemical vapor deposition,and the superhydrophilic-oleophobic sponge(PCA/AA/PFET@MF)was successfully prepared.FTIR,SEM,EDX and XPS were used to verify the successful preparation of the materials.The hydrophilic and oleophobic properties of the modified sponge were tested,and the results showed that water can infiltrate the surface of the modified sponge at a very fast rate of 180ms;the contact angle of paraffin oil in the air can reach 135°.The modified sponge also exhibits superoleophobicity underwater,and the contact angle of oil can reach more than150°.The modified sponge also has excellent mechanical durability and chemical stability.After 100 times of loading and unloading,it only slightly deforms;the modified sponge maintains good performance under 200°C high temperature for two hours.The oil-water separation properties of modified sponges were studied by using four different oil-water mixtures.Under the gravity condition,the modified sponge oil-water separation flux can reach more than 24900 Lm^-2h^-1,and the separation efficiency is above 97%.After five times of oil-water separation,the modified sponge maintains excellent oil-water separation performance.The above results indicate that superhydrophilic-oleophobic sponge has good application prospects in the field of oil-water separation.