| With the rapid development of the global industry,the oil-containing wastewater discharged from offshore oil spills and petrochemical industries not only causes serious waste of resources,but also brings serious pollution to the ecological environment.Therefore,how to recover oil spills in sea and efficiently separate oil-water mixtures has become a worldwide problem.Inspired by natural hydrophobic surfaces like lotus leaves,superhydrophobic materials have attracted attention and are considered to be important materials for solving oil-water separation problems.Compared with traditional oil-water separation methods（such as sedimentation,booms,skimmers,bioremediation,etc.）,superhydrophobic materials have received a lot of attention from researchers and made great progress because of their advantages of easy operation,low cost and high efficiency.At present,the common superhydrophobic modified substrates include sponge,stencil and special substrates,all of these have the disadvantages of large cost and environmental unfriendliness.Sugarcane bagasse（SCB）and sawdust（SD）are wastes from the production process.A large amount of SCB and SD are used for incineration every year,which not only causes waste of resources,but also brings serious pollution to the environment.SCB and SD are an environmentally friendly and economical bio-based material with a wide range of source,low cost and biodegradability.By modifying SCB and SD with superhydrophobicity and using them for oil-water separation,the integrated reuse of resources can be achieved.Since the superhydrophobicity of materials are mainly influenced by the surface roughness and the used low surface energy modifiers,therefore,bio-based materials such as SCB and SD are used as substrates and modified with low surface energy benzoxazine and cheap hydrophobic SiO2 particles for superhydrophobicity in this work.The prepared superhydrophobic bio-based materials were applied to oil-water separation,and the specific contents are as follows:（1）Using environmentally friendly and economical SCB as the substrate,superhydrophobic modified sugarcane bagasse（PC-O/SiO2/SCB）was successfully prepared by loading hydrophobic SiO2 nanoparticles and benzoxazine based on cardanol and octadecylamine（C-O）onto the surface of SCB with a simple dip-coating and curing method.C-O was characterized by FTIR and 1H NMR,and the surface morphology and surface chemical compositions of PC-O/SiO2/SCB were analyzed by using scanning electron microscope（SEM）and energy dispersive Spectroscopy（EDS）.In addition,the infiltration performance,oil adsorption performance,oil/water mixture separation performance,emulsion separation performance,reusability performance and chemical stability of superhydrophobic SCB were investigated.The results show that the water contact angle（WCA）of the modified SCB was up to 152°,and the OCA was 0°,which is superhydrophobic and superlipophilic.PC-O/SiO2/SCB not only exhibits good absorption capacity（11.84-20.46 g/g）for a wide range of oils and organic solvents but also display an excellent oil/water mixture and emulsion separation performance with a separation efficiency of over 99.0%for various oil/water mixtures and emulsions.The performance of superhydrophobic SCB does not decrease significantly even after 30 repeated uses,proving its excellent reusability.After immersion in harsh water environments such as hydrochloric acid（p H=1）,sodium hydroxide solution（p H=13）and3.5 wt%Na Cl solution for 48 hours,the superhydrophobic SCB could remain a WCA of above145°,suggesting its excellent chemical stability.（2）Using SD as a substrate,superhydrophobic sawdust（PPG-D/SiO2/SD）was successfully prepared by loading hydrophobic SiO2 nanoparticles and low surface energy benzoxazine based on pyrogallol and dodecylamine（PG-D）onto the surface of SD with dip-coating and curing method.PG-D was characterized by FTIR and 1H NMR,and the surface morphology and surface elemental compositions of superhydrophobic SD were analyzed by SEM and EDS.In addition,the infiltration performance,oil adsorption performance,oil/water mixture separation performance,emulsion separation performance,reuse performance and stability of superhydrophobic SD were investigated.The results show that the WCA of the superhydrophobic SD was up to 154°,while the OCA was 0°,indicating the superhydrophobic and superoleophilic properties of the obtained SD.PPG-D/SiO2/SD exhibits good absorption capacity（6.62-11.83 g/g）for a wide range of oils and organic solvents.It exhibits excellent oil/water mixture and emulsion separation performance with over 99.1%separation efficiency for various oil/water mixtures and emulsions.In addition,PPG-D/SiO2/SD also has excellent recycling performance,and it could still maintains superhydrophobicity and excellent oil-water separation ability after repeated used for 30 times.After immersion in harsh water environments such as hydrochloric acid（p H=1）,sodium hydroxide solution（p H=13）and 3.5 wt%Na Cl solution for 48 hours,the superhydrophobic SD could still remain a WCA of above 150°,suggesting its excellent chemical stability.（3）Using SCB and SD as substrates.β-FeOOH nanoparticles were grown on SCB and SD surfaces by in-situ reduction method.Then,hydrophobic SiO2 nanoparticles and low surface energy benzoxazine based on cardanol and dodecylamine（C-D）were loaded onto the surfaces ofβ-FeOOH/SCB andβ-FeOOH/SD with a simple dipping and curing method.Finally,superhydrophobic SCB（PC-D/β-FeOOH@SiO2/SCB）and superhydrophobic SD（PC-D/β-FeOOH@SiO2/SD）with photocatalytic properties were successfully prepared.C-D was characterized by FTIR and 1H NMR,and the surface morphology and surface elemental compositions of PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD were analyzed by SEM,EDS and XRD.The photocatalytic properties of PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD were investigated by Ultraviolet-visible Spectrophotometer（UV-Vis）.In addition,the infiltration performance,oil adsorption performance,oil/water mixture separation performance,emulsion separation performance,reuse performance and stability of PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD were investigated.The results show that the WCA of the PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD were up to 154°,while the OCA were 0°.Their adsorption ranges for various oils are 11.8-22.6 g/g and 4.76-9.76 g/g,respectively.The separation efficiency of the two superhydrophobic materials for various oil/water mixtures and emulsions all above 99.1%.Even after 30 reuses,PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD could still maintain extremely high oil adsorption performance,oil/water separation efficiency and emulsion separation efficiency.PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD can efficiently degrade the methylene blue under natural light irradiation.After immersion in harsh water environments such as hydrochloric acid（p H=1）,sodium hydroxide solution（p H=13）and 3.5 wt%Na Cl solution for 48 hours,PC-D/β-FeOOH@SiO2/SCB and PC-D/β-FeOOH@SiO2/SD could still remain a WCA of above 150°,suggesting its excellent chemical stability. |
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