Preparation Of Superhydrophobic/superoleophilic Functional Paper And Its Application In Oil-water Separation

With the rapid development of the oil industry and chemical industry,the discharge of oil spill,chemical industry organic oily wastewater and life sewage,caused serious water pollution,human health and ecological balance were threatened.Traditional oil/water separation methods including gravity,centrifugation,biodegradable,and combustion,ineluctably have several disadvantages of complex operation,high energy consumption,low efficiency,and secondary pollution.Therefore,it is necessary to develop a simple,low-cost,environment-friendly and high efficiency oil/water separation method.Oil-water separation materials with special wettability have been widely concerned in recent years.The metal mesh superhydrophobic material is widely used in oil-water separation,but the metal mesh cost is high,and it is difficult to recycle and easily cause resource waste.In this paper,a superhydrophobic coating was constructed on the surface of renewable cellulose filter paper by three different modification methods.The modified paper was characterized,and the possibility of application of modified paper in oil-water separation was evaluated.（1）The superhydrophobic paper with a water contact Angle（WCA）of 152.1°was prepared by a simple solution-immersion method involving deposition of a magnesium hydroxide（Mg（OH）₂）nanostructure,then modified with polydimethylsiloxane（PDMS）.The surface chemical composition,granular phase structure,morphology,and wettability of the modified paper were investigated by X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）,scanning electron microscope（SEM）,atomic force microscope（AFM）and water contact Angle（WCA）.The as-prepared superhydrophobic paper effectively separated both oil-water mixtures and water-in-oil emulsions while exhibiting good reusability.The mechanical stability of the superhydrophobic paper was not good by sandpaper abrasion and bending folding.The thermogravimetric analysis（TG）and vertical combustion test showed that the superhydrophobic paper has certain flame retardant property.（2）Zn O nanoparticles and carrageenan（CR）were deposited alternately on the surface of paper via electrostatic layer self-assembly（LBL）to construct Zn O/CR multilayers,then polydimethylsiloxane（PDMS）hydrophobic treatment.The surface chemical composition,surface potetial,surface morphology,and wettability of the modified paper were investigated by XPS,Zeta potential,SEM,AFM and wettability test.The PDMS/（Zn O/CR）₇ multilayer-modified paper showed a WCA of 154.0°and2.6%higher tensile strength compared with original paper.The PDMS/（Zn O/CR）₇multilayer-modified superhydrophobic paper had self-cleaning,anti-fouling and water-repellency properties,showed outstanding separation performances for oil-water mixture and water-in-oil emulsion as well as excellent recyclability.In addition,the superhydrophobic paper has good ability of adsorption and photocatalytic degradation of methylene blue dye wastewater Stability results presented that the superhydrophobic paper has excellent mechanical stability and environmental stability.（3）Poly-dopamine and Ag particles were deposited on the surface of paper by inspired-Mussel technology,subsequently dodecyl mercaptan（DM）treatment.The single factor experiment was used to optimize the preparation conditions of the superhydrophobic paper.It was found that the maximum WCA of the modified paper could reach 159.7°when the concentration of dopamine was 8 mg/m L,the concentration of silver nitrate was 1 mg/m L and the volume ratio of dodecyl mercaptan to anhydrous ethanol was 1:500 m L/m L.The modified superhydrophobic paper was named PDA@Ag@DM paper.The surface chemical composition,chrmical structures,and morphology of the modified paper were investigated by XPS,fourier transform infrared spectroscopy（FTIR）,SEM and AFM.The tensile strength of PDA@Ag@DM paper is increased by 54.3%compaired with original paper.The PDA@Ag@DM paper had self-cleaning,anti-fouling,water-repellency properties,and anti-bacterial adhesion ability,showed good separation performances for oil-water mixture and water-in-oil emulsion.Moreover,the as-prepared superhydrophobic paper has excellent ability of adsorption and photocatalytic degradation of methylene blue dye wastewater Stability test results showed that the PDA@Ag@DM paper has good mechanical stability and environmental stability.