Research On Micro-nano Carbon Composite Oil Absorption And Separation Functional Materials

Micro/nano carbon,such as graphite powder（GPd）,graphene（GE）,carbon nanotubes（CNT）,etc.,possessed high specific surface area,good mechanical/thermal/electrical properties,excellent chemical stability,as well as hydrophobicity-oleophilicity,they had been widely used in the fields of energy storage,materials,biological,etc.In this paper,based on the polymer surface theory,combined with the hydrophobicity-oleophilicity of micro/nano carbon with appropriate porous substrate,a series of micro/nano carbon composite absorption and separation functional materials were prepared through reasonable material structure design,which could effectively deal with different kinds of oil/water mixture.The separation mechanism and its practical application were also investigated.The hydrophobic-superoleophilic GPd coated polyurethane（PU）composite（PGPd-PU）sponge was prepared by dip-coating method,which coating GPd on PU sponge skeleton,then coating PDMS for enhancing the interfacial bonding between PU sponge and GPd.Then,inspired by special form of hollow fiber membrane,PGPd-PU sponge hollow tube（PGPd-PUHT）was prepared by wrapping PGPd-PU sponge on the porous hollow tube support.The results indicated that the GPd coating could significantly enhance the hydrophobicy of sponge,the water contact angel（WCA）of as-prepared sponge could reach 141.2°,and the absorption capacity could reach upto33 g·g^-1.Furthermore,PGPd-PUHT can effectively separate a series of oil/water mixture under vacuum pressure,and the separation efficiency for toluene/water mixture attained 97.7%with corresponding flux of 15239.38 L·m^-2·h^-1.In addition,the continuous thin oil film collection device based on PGPd-PUHT was designed which can continuous and highly effective collect oil from water surface with the separation efficiency above 92%.The GE coated polyethylene terephthalate（PET）nonwoven（PGNW）was prepared by dip-spray coating method which coating GE on PET fiber then spraying dilute polyvinylidene fluoride（PVDF）solution on the surface of nonwoven.The result indicated that when the GE loading on nonwoven reached 4.73 wt.%,the superhydrophobicity-superolelphilicity was acquired by nonwoven.WCA and water sliding angel of PGNW（WSA）were 154.4°and 8.3°,respectively,and the oil absorption capacity could reached 18-34 times its own weight.Meanwhile,PGNW hollow tube（PGNW-T）can effectively separate a series of oil/water mixture under vacuum pressure with excellent chemical stability,after 10 cycles of oil/water separation test,the separation efficiency remained above 97%.Besides,an automatic-continuous thin oil collection device based on PGNW-T was designed,which had been tried to amplify and combined with the ACTUV,and had demonstrated the ability of efficient recovery of thin oil film in practical application.The superoleophilic-under oil superhydrophobic GE-FEP fabric was prepared by dip-coating and sintering method which coating GE on the surface of FEP fabric then suffering sintering process.The results indicated that the hydrophobicity and oil permeability of as-prepared textile could be simply controlled by adjusting sintering temperature,when the sintering temperature was 210℃,the kerosene flux and water intrusion pressure could reach upto 1794.10 L·m^-2·h^-1 and 2.8 k Pa,respectively.As-prepared GE-FEP fabric can realize gravity-driven separation of immiscible oil/water mixture with separation efficiency of upto 98.6%.Besides,the robust chemical stability was also presented by as-prepared textile.In addition,during sintering process,GE nanosheet between the neighboring fiber acted as the“support”which remain a chanel for oil permeation.Comparing to pristine textile,the oil permeability of GE-FEP fabric significantly improved.The GE-PVDF composite nanofibrous membrane（GPNM）was prepared by one-step electrospinning process with GE nanosheet embedding into nanofibrous network.The results indicated that the average pore size,porosity and hydrophobicy of GPNM can be improved by an appropriate GE addition in electrospinning solution.GPNM possessed good hydrophobicity with WCA of 140.1°,as well as under oil superhydrophobicity.The oil wettability and permeability of GPNM can be significantly enhanced by the embedded GE nanosheet.GPNM can separate a series surfactant-stabilized water-in-oil emulsions driven by gravity with separation efficiency upto 99.8%and flux of 414.01 L·m^-2·h^-1.In addition,the excellent selective absorption ability was also displayed by GPNM with absorption capacity of 10 to 25times its self-weight.The tubular GE-PVDF composite nanofibrous membrane（TPGCM）was prepared by one-step simultaneous electrospinning/electrospraying process with the polyethylene terephthalate（PET）braided tube（Br T）as the support.The result indicated that this simple combined technique allowed the uniform integration of PVDF micro/nanospheres and GE nanosheets into the PVDF nanofibrous network to form a3D hierarchical micro/nano structural composite membrane.The resultant membrane showed under oil superhydrophobicity with corresponding contact angel of 159°.Furthermore,the average poresize,surface roughness and hydrophobicity of TPGCM can be simply controlled by adjusting GE nanosheets content in electrospraying precursor.As-prepared TPGCM can effectively separate a series ofsurfactanc-stabilized water-in-oil emulsions,which showed outstanding separation efficiency of up to 99.8%.In addition,compared to 2D rough surface,as-prepared TPGCM showed hierarchical micro/nano rough structure layer-by-layer,this multilayer rough structure was able to provide a continuous water-solid-oil interface during oil/water separation process,which can retard the water permeation into the network structure,which made it more reliable for practical oily wastewater treatment.