Fabrication Of Cellulose-based Composite Materials With Switchable Wettability For Oil-water Separation

Along with growing industrial development,oil spill and emissions of the large amount of industrial wastewater have influenced our living environment and the aquatic environment and have threaten the survival of humans,animals and plants.Therefore,it is urgent to prepare new materials with high efficient capacity of oil/water separation in recent years.At present,the separation and cycle performance of bionic interfacial materials for oil-water separation were relatively poor.So responsive interfacial biomimetic materials with switchable wettability have attracted public attention for oil-water separation.Furthermore,cellulose,as the most abundant biomass resource on the earth is no secondary pollution,biodegradable and owns a large number of hydroxyl,which can occur a serious of reactions such as esterification,oxidation,etherification and bromination.Thus,the paper mainly selects the cellulose as basal materials,designing bionic interfacial materials with controllable wettability to realize the efficient oil/water separation and dye removal.The main contents of the paper are as follows:?1?The cellulose foam,selecting degreasing cotton as raw material,NaOH/Urea/H₂O solution as a cellulose solvent,was prepared by sol-gel and freeze-drying methods.Then cellulose foam was modified by the method of atom transfer radical polymerization?ATRP?to graft pH responsive and light responsive monomers.The morphology and structure of modified foam were characterized by using SEM,ATR-FTIR,XPS,TGA and contact angle.The result proved that pH responsive and light responsive monomer was grafted successfully to modified foams.In addition,the modified foams was hydrophobic and adsorbed oil in pH=7.0 and under the condition of visible light.However,it can turn into hydrophilic and desorb oil in the acidic solution?pH=3.0?and exposed UV light?UV=365 nm?,realizing the selective separation of oil-water mixtures and quickly recovery of oil spill.?2?The novel cotton fabric?CF?with pH controlled wettability transition was designed by a simple,environmentally friendly dip coating copolymer/SiO₂ nanoparticles,poly?heptadecafluorodecylmethacrylate-co-3-trimethoxysilylpropylmethacrylate-co-2-vinilpiridine??PHDFDMA-co-PTMSPMA-co-P2VP?.Furthermore,the structure and morphology of coated CF was confirmed by ¹HNMR,Fourier transform infrared spectroscopy?FT-IR?,thermo-gravimetric analysis?TGA?,X-ray photoelectron spectroscopy?XPS?and scanning electron microscopy?SEM?.The results showed CF was modified successfully coated CF and displayed switchable wettability between superhydrophobicity and superhydrophilicity via adjusting pH value.Therefore,the coated CF could be applied to separate different oil/water mixtures and surfactant stabilized emulsions?oil-in-water,water-in-oil?and oil/water/oil three phase mixtures continuously and exhibits the superior separation capacity for oil-water mixtures.?3?The glass powder/cellulose composite foams?CFs?,selecting cotton as raw material,NaOH/Urea/H₂O solution as a cellulose solvent,were prepared by sol-gel and freeze-drying methods.Then,we prepared a novel pH-responsive 3D cellulose/glass powder composite foam?CF?with copolymer coating through an ordinary dip coating non-fluorinated copolymer,poly?2-vinilpiridine-co-3-trimethoxysilylpropylmethacrylate-co-styrene??P2VP-co-PTMSPMA-co-PS?on the three-dimensional foams.The structure and morphology of coated CF was confirmed was demonstrated by SEM,¹HNMR,FTIR,XPS and contact angle.When the resulting CFs is placed in the neutral aqueous?pH=7.0?,it is superhydrophobic and superoleophilic in the air.It allows oil fluids to go through but rejects water.However,in acidic aqueous environment?p H=3.0?,it turns superhydrophilic and underwater superoleophobic,which allows water to penetrate through but blocking oil.And then,the coated CFs also shows outstanding performance for removal of cationic dye?methylene blue?quickly from water during the oil/water separation process.