Preparation Of Three-dimensional Porous Foam By Vacuum-assisted Solution Casting And Its Oil-water Separation Performance

In recent years,with the rapid development of the petroleum and chemical industries,the leakage of petroleum and the discharge of large amounts of industrial organic pollutants have posed a huge threat to the ecological environment.Comparing with traditional separation materials,three-dimensional(3-D)porous separation materials have a higher specific surface area and porosity,making it easier to absorb,store,transport and continuously remove oil,and this has attracted more and more attention.The low cost,easy processing,and molding properties,good mechanical properties,and corrosion resistance of 3-D porous polymer materials are considered some of the most promising oily absorbent materials.This article focuses on the preparation,surface modification and oil-water separation properties of 3-D porous polyurethane(TPU)composite foam.The main tasks include:1.The TPU porous foam was prepared by vacuum-assisted solution pouring/particle leaching and thermally induced phase separation technology,and studying the influence of molding process parameters,such as the concentration of pouring solution and deionized water content on the morphology,porosity,oil absorption,and wetting properties of TPU porous foam.The experimental finding show that when the TPU concentration is 8%and the deionized water content is 8.5ml,the prepared TPU three-dimensional porous material has good connectivity and better pore structure.The pore shape,structure,porosity,oil absorption and surface wettability of the three-dimensional porous material can be controlled by adjusting the molding process parameters.2.The combination of vacuum-assisted solution casting/particle leaching and thermally induced phase separation technology is used to prepare TPU/PVDF composite porous foam with polyvinylidene fluoride(PVDF)and TPU as raw materials.The effects of different material formulations and different particle diameters of salt particles on the morphology,porosity,oil absorption and wetting properties of TPU/PVDF composite porous foam were studied.The experimental finding show that:TPU/PVDF composite porous foam shows super lipophilicity and hydrophobic properties.With the aid of a peristaltic pump,the TPU/PVDF composite porous foam can continuously separate oil/water pollutants,and after multiple cycles,it still maintains a separation efficiency of 98.5%.Similarly,the composite porous foam also has the ability of emulsion separation.Therefore,composite porous foam has huge potential applications in sewage treatment and offshore oil spills.3.To further enhance the versatility of the porous foam,the TPU/TiO₂/PDA composite porous foam is prepared using a combination of ultrasonic assist and coating technology,using TPU,titanium dioxide(TiO₂)and polydopamine(PDA)as raw materials.The morphology,structure,thermal stability,mechanical properties,surface wettability,oil-water separation performance,and photocatalytic performance of the composite porous foam were studied.The experimental finding show that:TPU/TiO₂/PDA composite porous foam has hydrophilic and super lipophilic properties in the air,superoleophobic underwater,and superhydrophobic under oil.Only under the action of gravity,the composite porous foam material can not only effectively separate oil and water but also separate emulsions.Besides,under visible light irradiation,the composite foam catalyzed rhodamine B(RhB)for 1 hour,and its removal rate was 96.05%.This is due to the synergistic effect of TiO₂ and PDA so that the composite porous foam has versatility.