Preparation Of Superhydrophobic/flame-retardant Coating On Cotton Fabric And Its Oil-water Separation Performance

The"lotus leaf effect"provides theoretical guidance for the construction of superhydrophobic surfaces.The superhydrophobic materials have great potential in the fields of self-cleaning,anti-icing,anti-corrosion and especially oil-water separation,in which the oil phase will easily spread and permeate the superhydrophobic materials due to the effect of surface free energy,and then separate from the oil/water mixture.Using materials with special surface-wettability to separate oil spills or industrial oil-bearing wastewater conforms to the development concept of resource conservation and environment friendliness.In addition,the field of flame-retardant is also widely concerned,because fire would cause property damage or even casualties.Therefore,two kinds of superhydrophobic coating and one kind of superhydrophobic/flame-retardant coating were constructed on the surface of cotton fabric,and and their oil-water separation performances were evaluated.The main research contents are as follows:?1?Superhydrophobic Cu/Cu O/Cu₂O@cotton fabric with highly efficient oil/water separation performance was fabricated through in-situ reduction method.Firstly,Cu²⁺was uniformly immobilized on cotton fabric by the interactions between[Cu?NH₃?₄]²⁺complex and cellulose,and then Cu/Cu O/Cu₂O nanoparticles were formed on its surface through in-situ reduction process.Finally,the superhydrophobic Cu/Cu O/Cu₂O@cotton fabric was obtained by the reactions and adsorption between n-octadecathiol?ODT?with low surface energy and the nanoparticles.The Cu/Cu O/Cu₂O@cotton fabric,with water contact angle?WCA?around153.5°,showed hydrophobicity to common household liquids with contact angles?CA?about145°,and exhibited chemical and mechanical stability.In addition,the superhydrophobic Cu/Cu O/Cu₂O@cotton fabric had high oil-water separation efficiency???and reusability.In the 30 times of repeated separation,the?of n-dodecane/water mixture and n-hexane/water mixture maintained 98%and 97%,respectively.When collecting n-dodecane from its mixture,Cu/Cu O/Cu₂O@cotton fabric possessed the highest mass flux rate(₈))at the beginning of separation process which reached 0.34 g cm^-2 s^-1.?2?Superhydrophobic Zr?OH?₄/DTMS@cotton fabric with self-cleaning property was fabricated by sol-gel method.Using the dehydration condensation reactions between-OH groups from cellulose and the hydrolysates of zirconyl?di?chloride?Zr OCl₂.8H₂O?and n-dodecyltrimethoxysilane?DTMS?,the superhydrophobic Zr?OH?₄/DTMS@cotton fabric with self-cleaning property was prepared directly by sol-gel method.According to the results of WCA changes and roughness?RA?,when the adding amount of Zr OCl₂.8H₂O,DTMS and NH₃·H₂O was 0.36 g,0.25 m L and 5 m L,respectively,the coating with suitable roughness was formed on the surface of cotton fabric and exhibited a better superhydrophobicity.The surface functional groups of the coating were characterized by Flourier Transformed Infrared Spectroscopy?FT-IR?and X-Ray Diffraction?XRD?,and the results were consistent with the mechanism of the sol-gel process.Energy Dispersive Spectrometer?EDS?spectra showed the uniform elements distribution on the surface of cotton fabric.In addition,the contact angle?CA?of the superhydrophobic cotton fabric to coke and orange juice was above 152°,to coffee,ink and milk was about 145°,and the obtained fabric also showed excellent self-cleaning performance.?3?Flame-retardant Si O₂/APP/PDMS@cotton fabric with superhydrophobicity and highly efficient oil/water separation property was fabricated.Firstly,the amino functionalized Si O₂nanoparticles?Si O₂-NH₂ NPs?were formed on the surface of cotton fabrics by ultrasonic assisted sol-gel method,and then ammonium phosphate?APP?was successfully adhered on the fabric.The two materials provided roughness for superhydrophobicity.Finally,polydimethysiloxane?PDMS?was introduced to the cotton fabric through dip-coating process,which offered strong adhesion between the nanoparticles and the fabric surface,as well as superhydrophobicity and wear-resistance to cotton fabric.The superhydrophobic Si O₂/APP/PDMS@cotton fabric exhibited a WCA around 154.2°.The results of sandpaper abrasion test,solution immersion test and simulated laundering test indicated the chemical and mechanical stability,as well as good thermal stability of cotton fabric.In addition,the fabric exhibited excellent oil-water separation performance for five kinds of oil/water mixture,and the separation efficiency???of n-dodecane/water mixture and n-hexane/water mixture were maintained at 98.5%and 96%during 10 times of separation,respectively,which implied the good reusability of the as-prepared cotton fabric.Furthermore,when ignited the sample,the polyphosphate produced from the decomposition of APP would dehydrate the cellulose of cotton fabric,forming char residues on the fabric surface,and the synergistic effect of APP and PDMS could provide excellent flame-retardant property to the Si O₂/APP/PDMS@cotton fabric.