Fabrication And Application Of Superhydrophilic Polyester Fabric And Polyvinylidene Fluoride Porous Membrane

Wastewater with oil from petroleum,iron and steel,coking,food processing and other industries seriously threatens natural environment,ecosystems and human health worldwide.Superhydrophilic porous materials based on fabrics,metal meshes and polymer membranes are able to conveniently and efficiently separate oil from water.However,the reported superhydrophilic porous materials have some disadvantages such as complicated preparation process,poor recyclability,and inability to adsorb heavy metal ions,thus limiting its application in practical production and life.The aim of this work is to produce superhydrophilic porous materials by a simple method to achieve efficient oil-water separation.The main contents and results are listed as follows:?1?The plasma-treated polyester fabric was immersed in an aqueous dispersion of aminated multi-walled carbon nanotubes?MWCNTs-NH₂?to obtain a fabric attached with MWCNT-NH₂.Subsequently,the fabric was immersed in a silver ammonia solution.Silver nanoparticles were generated in situ by dropwise addition of glucose solution and immobilized on the surface of the fabric by the amino group on MWCNT-NH₂.Finally,the Ag-S bonds formed between silver and thiol were used to immobilize L-cysteine on the silver nanoparticles to obtain a MWCNTs-NH₂@Ag NPs@L-cys superhydrophilic fabric.Scanning electron microscopy?SEM?,total reflection infrared spectroscopy?ATR-FTIR?,X-ray photoelectron spectroscopy?XPS?,and contact angle?CA?measuring instruments were used to investigate the effects of the concentration of the dispersion and the mass percentage of Ag NO₃ in the silver ammonia solution on the fabric surface morphology and hydrophilicity.The results showed that when the the concentration of the MWCNTs-NH₂ dispersion,mass percentage of Ag NO₃ in the silver ammonia solution and the concentration of L-cys solution were 3 mg/m L,1 wt%and 30mg/L,the water contact angle?WCA?of the fabric could reach 0^o within 18 ms,and the underwater oil contact angle was 155^o.In addition,the fabric had high separation efficiency and good Cu²⁺adsorption performance.?2?Nano-silica particles?Si O₂-SH?with reactive mercapto groups on the surface were firstly prepared by using?3-mercaptopropyl?-trimethoxysilane?KH590?to modify the surface of nano-silica particles?Si O₂?.Subsequently,the cleaned polyester fabric was immersed in ethanol solution containing Si O₂-SH,poly?ethylene glycol?dimethacrylate?PEGDMA?,[2-?methacryloyloxy?ethyl]trimethylammonium chloride solution?DMC?and 2-hydroxy-2-methylpropiophenone?Darocur 1173?.Then,the polyester fabric was taken out and irradiated under ultraviolet light to initiate mercapto-ene click reaction,and superhydrohilic polyester fabric was obtained.The effect of addition amount of Si O₂-SH,ratio of M?PEGDMA?/M?DMC?and ultraviolet light irradiation time on the surface morphology and wettability of the fabric were studied with SEM,ATR-FTIR and WCA.The results indicated that when the ratio of M?PEGDMA?/M?DMC?,ultraviolet irradiation time and Si O₂-SH amount were 1:3,180 s and10 wt%,the double bonds on PEGDMA and DMC reacted completely.The WCA reached 0^owithin 18 ms,and the underwater oil contact angle was 143^o.In addition,the fabric had good abrasion resistance and tape-peeling resistance,and it was successfully applied for oil-water separation.?3?Polyvinylidene fluoride?PVDF?powders were used as raw material,and the N-methyl-2-pyrrolidone?NMP?and polyvinylpyrrolidone?PVP?were used as solvent and pore-forming agent,respectively,and PVDF porous membranes with micro-nano pores were prepared by solution phase inversion method.Then,a layer of polydopamine?PDA?was formed on the surface of the PVDF porous membrane through the polymerization of dopamine?DA?to obtain a PDA@PVDF porous membrane.After that,the amino group on L-cysteine?L-cys?was used to get Schiff base reaction with amino group on L-cysteine and catechol structure of PDA to introduce mercapto and carboxyl groups.Finally,SBMA-?L-cys?-PDA@PVDF superhydrophilic membrane was obtained with the mercapto-ene click reaction between the mercapto groups of L-cys and the double bonds of[2-?methacryloyloxy?ethyl]dimethyl-?3-sulfopropyl??SBMA?.SEM,ATR-FTIR,XPS and CA were used to study the micromorphologies of PVDF film prepared with different amounts of PVP and polymerization times of dopamine.The morphology and surface wettability,chemical structure and wettability of the PVDF films prepared after different steps were characterized and compared.The results indicated that when the mass percentage of PVP,concentration of sodium periodate,time of self-polymerization,concentration of L-cys solution were 5.0 wt%,22 mmol/L,2 h and 1.21 g/L,the WCA of SBMA-?L-cys?-PDA@PVDF porous membrane reached 0^o within 1.5 s,and the contact angles to various oils in water environment were greater than 150^o.Additionally,the superhydrophilic PVDF porous membrane was successfully applied for emulsion separation,showing high separation efficiency,large filtration flux and resuability.