Preparation Of Biomimetic Superhydrophobic Melamine Composite Sponge And Study On The Application Of Oil-Water Separation

In recent years,the incidents including spill-oil at sea and leakage of chemical organic pollutants have occurred frequently,which have caused irreparable damage to the environment and ecosystem.The treatment of oily wastewater has been one of the severe challenges in the world.How to effectively separate oil-water mixture is an urgent problem to be solved.The adsorption method has become one of the common methods for oil-water separation because of the advantages,such as simple operation,low cost,no equipment requirement,no secondary pollution,and so on.The surface of materials,used in the process of adsorbing oils,usually possesses superhydrophobic-oleophilic performance.The research of superhydrophobic interface materials has become a hot topic.The superhydrophobic materials have be frequently used to selectively separate oil-water mixture according to the different wettability of oil and water.Melamine sponge（MS）is a kind of macromolecular material with three dimensional structure,and possesses many advantages such as super light,high porosity,thermal stability,acid-resistance,alkali-resistance,super elasticity,and so on.At the same time,it is cheap and easy to obtain,environment friendly,and can be cut into any size and shape.Owing to the N element on the surface,MS is favorable for in-situ growth and modification,and used as one kind of basic material for oil-water separation.Fluorine-free silanes are applied as surface hydrophobic modification because of the advantages such as high stability,environmental protection,simple method and mild conditions.In summary,a series of high performance biomimetic superhydrophobic melamine sponges（SMS）were prepared by sol-gel method and self-assembly method using MS as basic material,and applied in oil-water separation.Specific research contents are as follows:（1）C₁₆TMS/VSiO₂/MS were prepared through two-step sol-gel method on MS surface modified with C₁₆TMS/VSiO₂ possessing a large number of vinyl and hexadecyl groups,which was generated with vinyltriethoxysilane（VTES）and hexadecyltrimethoxysilane(C₁₆TMS).The optimum conditions were determined by investigating the effects of experimental conditions and parameters on hydrophobic property.C₁₆TMS/VSiO₂/MS was constructed with micro-nanoscale rough structure possessing low energy,and showed good superhydrophobicity.C₁₆TMS/VSiO₂/MS exhibited the static water contact angle（WCA）of 153.2^o and compressive elasticity of33.1 kPa.C₁₆TMS/VSiO₂/MS showed the excellent selectively adsorption properties for oil-spills and bottom oils from water,for example,the maximum adsorption capacities were 130 g/g of dichloromethane and more than 70 g/g of other oils.The influence factors of WCA and separation efficiency of C₁₆TMS/VSiO₂/MS were studied at different pH value and salt concentration.In addition,C₁₆TMS/VSiO₂/MS also exhibited good abilities of continuous separation of oil-water and cyclic utilization.（2）There were numerous ATP-VSiO₂ complex on C₁₆TMS/ATP-VSiO₂/MS surface,obtained through hydrolytic condensation of VTES and C₁₆TMS.In the process of hydrolytic condensation of VTES,natural mineral attapulgite（ATP）was used as catalyzer.The optimum conditions were determined by investigated the effects of experimental conditions and parameters on hydrophobic property.C₁₆TMS/ATP-VSiO₂/MS possessed the rod-sphere composite rough materials with low surface energy.At the same time,C₁₆TMS/ATP-VSiO₂/MS exhibited the outstanding hydrophobicity（154.1^o of WCA）,good compressive elasticity（32.8 kPa）and self-recovery ability.C₁₆TMS/ATP-VSiO₂/MS showed good adsorption capacity（121 g/g of dichloromethane）,excellent reutilization and acid-alkali resistance.In addition,C₁₆TMS/ATP-VSiO₂/MS showed good recycling performance in the process of continuous separation of oil-water mixture.（3）VTES was used as an organic-inorganic cohesive agent,based on the characteristics of VTES containing inorganic silica and vinyl groups.On the surface of MS,P（VTES-DVB）-SiO₂ was obtained through hydrolytic polycondensation and free radical copolymerization of VETS and DVB.P（VTES-DVB）-SiO₂/MS was prepared through one-step solvothermal method and used in oil-water separation.The influence factor of the WCA of SMS were studied,including the ratio of VTES to DVB and reaction temperature.P（VTES-DVB）-SiO₂/MS exhibited superhydrophobic property（WCA of 157.3^o）,and good compressive elasticity（32.7 kPa）and self-recovery ability.The adsorption experiments showed that P（VTES-DVB）-SiO₂/MS appeared 77-136 g/g of adsorption capacity for different oils,and showed good recycling performance.In the environment of different acid,alkali and salt conditions,P（VTES-DVB）-SiO₂/MS could maintain excellent superhydrophobicity and separation efficiency,and realized the outstanding performance in continuous oil-water separation.This experiment provided a new method for design and preparation of bionic superhydrophobic materials.