Preparation Of Controllable Wettability Bulk Nanofiber Polymer/Carbon And Their Application

3D porous materials have large specific surface area,low density and rich pore structure,which are suitable for catalyst,emulsion separation,sewage treatment and solar steam generation.However,there is still a lack of effective methods to prepare multifunctional 3D porous materials.In our experiments,we prepare the bulk phenolic resin-based material using phenol and formaldehyde as the precursor,via a simple hydrothermal method.It is easy to control the wettability of polymer.When the hydrothermal temperature is lower than 210℃,the polymer demonstrates superhydrophilic property.When the hydrothermal temperature is higher than 220℃,the polymer demonstrates superhydrophobic property.The wettability of carbon is similar to polymer.The separate emulsion property of polymer/carbon nanofibers were studied.The superhydrophobic polymer/carbon nanofiber can effectively separate the oil-in-water emulsion,and the superhydrophilic polymer/carbon nanofibers can achieve the separation of oil-in-water emulsion.Moreover,the solar steam generation of carbon nanofibers were studied.It has excellent photothermal conversion performance due to the good light absorbance and 3D pore structure.The research contents and conclusion include the following aspects1.Preparation of phenolic resin-based polymer sponge composed of intertwined nanofibers with tunable wettability for high-efficiency separation of oil-water emulsionsThe phenolic resin-based sponge is composed of nanofiber with high aspect ratio via a simple hydrothermal method.It is easy to control the wettability of polymer.When the hydrothermal temperature is lower than 210℃,the polymer demonstrates superhydrophilic and under-water superoleophobic property However,when the hydrothermal temperature is higher than 220℃,the polymer demonstrates superhydrophobic property and the mass of the adsorbed oil can reach 12-28 times relative to its own weight.The as-prepare polymer material is tailored into the slices to separate the emulsion driven by an external pressure of 40 kPa and the filtration flux is 6147 L m-2 h-1.In addition,the results of dynamic analysis based on the Hagen-Poiseuille equation are consistent with the experimental results.The robustness of polymer in the separation of water-oil emulsion can be addressed in light of thermodynamic viewpoint.The result demonstrates that the principle in devising robust porous material for the separation of oil-water emulsions lies in reducing the diameter of polymer nanofibers.2.Bulk carbon based materials with intertwined nanofiber for high-efficiency separation of oil-water emulsionCarbon nanofibers can be obtained by calcining polymers in nitrogen atmosphere.The wettability of carbon is similar to polymer.The polymer with hydrothermal temperature of 180 ℃ has superhydrophilic properties after pyrolysis.On the contrary,the polymer with hydrothermal temperature of 230℃ still has superhydrophobic properties after pyrolysis.The carbon nanofibers inherit the wettability before pyrolysis.The superhydrophobic carbon material,which has good mechanical properties and stable hydrophobic properties,can absorb 9-21 times of its own weight of oil.After 50 times combustion test,the oil absorption capacity can be maintained 70%of initial capacity.Furthermore,the separation performance of carbon nanofibers is investigated.Experimental results illustrate that samples afford efficient separation of oil-water emulsions with surfactant and filtration flux is 105.7 L m-2 h-1.3.Floatable,superhydrophilic bulk carbon nanofiber for the solar evaporation enhancementThe photothermal conversion performance of superhydrophilic carbon was studied.The rich porous structure of the carbon not only provides high absorbance,but also ensures the fluid transport under the action of capillary force.The evaporation rate is 1.30 kg m-2 h-1 under 1 kW m-2 illumination and the photothermal conversion efficiency is 84.3%.When the carbon is 3 cm higher than the water surface,the evaporation rate increases to 1.83 kg m-2 h-1,and the net conversion efficiency increased to 91.8%.Meanwhile,the carbon can purify the emulsion effectively.The carbon can purify the emulsion effectively and the evaporation rate is 1.75 kg m-2 h-1.Meanwhile,the phenomenon that the liquid film appeared on the carbon surface during the evaporation of ethanol solution was studied...