Preparation Of Chitosan-based Composite Materials And Study On Their Oil-/water Separation Performance

The purpose of this paper is to prepare chitosan(CS)-based composites with super wettability and good oil-/water separation performance.Four different CS-based materials were prepared and they are:superhydrophobic CS aerogels were prepared by fluorinated silica(F-SiO₂),coated chitosan superhydrophilic CS aerogels were modified by titanium dioxide(TiO₂),and superhydrophobic CS membranes were modified with graphene fluoride(FG)and polytetrafluoroethylene(PTFE)by electrospinning method respectively.And their composition structure and oil-/water separation performances were characterized and analyzed.The main results in this work are listed as follows:Firstly,CS/polyvinyl alcohol(PVA)was fabricated as the first layer by electrospinning method,and the graphene fluoride/polyvinylidene fluoride(FG/PVDF)was fabricated as the second layer,forming the FG/CS electrospinning membrane with a double-layer structure.The results of FTIR and X-ray diffraction(XRD)showed that FG and PVDF successfully modified FG/CS electrospinning membrane.SEM results showed that CS/PVA layer had a good porous structure,and FG improved the surface roughness of PVDF layer.The tensile test results showed that the tensile strength and elongation at break of the double-layer FG/CS electrospinning membrane increased.Surface wettability and self-cleaning test results showed that the surface of the double-layer FG/CS electrospinning membrane were superhydrophobic and super oleophobic,and self-cleaning of surface pollutants can be cleaned by flowing water.The results of oil-/water separation test showed that FG/CS electrospinning membrane had high separation performance for various heavy oil-water mixtures.Secondly,PTFE was added into CS/PVA to prepare the CS electrospinning membrane,which was modified by FAS to prepare PTFE/CS electrospinning membrane.FTIR results showed that CS/PVA membrane was successfully modified by PTFE and FAS.SEM results showed that PTFE/CS membrane had a good porous structure,and the distribution of PTFE nanoparticles on the nanofibers improved the roughness of the membrane.TG results showed that the thermal stability of PTFE/CS electrospinning membrane increased.The wettability and self-cleaning test results showed that the PTFE/CS electrospinning membrane had superhydrophobic and super oleophilic properties,and had the ability of surface self-cleaning.The results of oil-/water separation test showed that PTFE/CS electrospinning membrane had a good separation effect on a variety of oil-water mixtures.Thirdly,CS aerogel was prepared by cross-linking with glutaraldehyde,and then coated with silica nanoparticles which were modified by triethoxy-1H,1H,2H,2H-trifluoro-octylsilane(FAS)to obtain superhydrophobic chitosan aerogel(F-SiO₂/CS).Infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)results showed that chitosan aerogel was successfully modified with F-SiO₂ nanoparticles.The results of scanning electron microscopy(SEM)showed that F-SiO₂/CS had a good three-dimensional micron network structure,and F-SiO₂nanoparticles were uniformly distributed on the surface of the aerogel,forming a good rough structure.Thermogravimetric(TG)results showed that the thermal stability of F-SiO₂/CS aerogels is higher than that of CS aerogels.Compression test results showed that F-SiO₂/CS aerogel had excellent resilience.The test results of wettability and oil-/water separation performance showed that F-SiO₂/CS had superhydrophobic and super oleophilic properties,which can effectively separate a variety of heavy oil-water mixtures.Finally,superhydrophilic TiO₂/CS aerogel was obtained by coating TiO₂ nanoparticles with polydopamine(PDA).FTIR and XPS test results showed that TiO₂ nanoparticles and PDA successfully modified CS aerogel.SEM results showed that TiO₂/CS aerogel had a good three-dimensional network structure,and TiO₂ nanoparticles were evenly distributed on the surface of aerogel,which improved the surface roughness of aerogel.TG results showed that the thermal stability of TiO₂/CS aerogel increased.Surface wettability and oil-/water separation test results showed that TiO₂/CS aerogel had super hydrophilic and super hydrophilic properties in air,and super oleophobic properties in water.It can separate various light oil-water mixtures effectively.The stability test results showed that TiO₂/CS aerogel was resistant to acid and alkali and ultrasonic damage.