Study On Advanced Fabrication And Functionalization Of Porous Fly Ash Ceramics Based On “Superwettability Plus”principle

Fly ash is one of the largest industrial waste in the world,which causes serious pollution and impact on the ecological environment and human health.Although currently there are many ways of fly ash reutilization,there is a common problem in most fly ash reuse technologies,i.e.,the secondary products upon fly ash reuse have low added value and limited economic profit,hindering the development of related industries.Based on the principle of"superwettabiliy plus",this study creatively puts forward a new technique for reutilization of fly ash solid waste,which uses fly ash as the main feedstock material to prepare porous ceramics,and then endows porous fly ash ceramics with advanced super-hydrophobic,self-cleaning,and underwater super-hydrophobic properties,as well as photocatalysis and other functions via special surface treatment by superwettabiliy technology.This study significantly improves the application potential of fly ash in the fields of energy and environmental protection and offers strong theoretical and engineering support for high value-added reutilization of low end industrial wastes.The main research of this study includes:（1）Upon fly ash powder decoration at the molecular level and powder modification,a porous ceramic emulsion was prepared by mixing fly ash powder with oil,water and slurry.The further forming,debinding and sintering process of the porous ceramic emulsion were explored to fabricate the porous fly ash ceramics,and the effect of the mass ratio of fly ash and alumina powder on the microstructure and mechanical properties of porous ceramics was investigated.The results show that the pore structure and mechanical properties of the porous ceramics can be effectively controlled by tailoring the mass ratio of alumina to fly ash.With the increase of alumina content in the alumina-fly ash powder mixture,the pore structure gradually changes from random pores to ordered porous honeycomb structure.When alumina content is 50 wt%,the open porosity of porous fly ash ceramic upon sintering can be as high as 73%,and the density is only 0.85 g/cm~3.At the same time,the porous fly ash ceramic has high compressive strength of 80.93 MPa,showing the excellent light weight and high strength properties.Through the above research,light-weight high-strength fly ash porous ceramics were successfully prepared based on emulsion-assisted template self-assembly method.（2）Based on the scientific principle of superwettabiliy,the self-cleaning porous ceramics with superhydrophobic properties were prepared via the decoration of polydimethylsiloxane（PDMS）with low surface energy on the surface of honeycomb micro-nano rough porous ceramics by chemical vapor precipitation method.The contact angle,durability,self-cleaning performance,and other properties were characterized.The results show that the contact angles between the porous fly ash ceramic surface and water,beer,soy sauce,milk,coffee and other liquids are all more than 150°,demonstrating super anti-fouling and self-cleaning properties.Under high temperature（500℃）and acid-base environment,the above contact angles are basically unchanged,and the porous fly ash ceramic shows good chemical stability and engineering tolerance.Although the surface hydrophobic coating can be damaged and the superhydrophobicity and self-cleaning ability can be diminished to a certain degree upon sand blasting test,the rough micro/nano structure of the porous fly ash ceramic surface will not be destroyed,and the super hydrophobicity and self-cleaning ability can be restored after re-decoration of PDMS,showing good repeat utilizaiton performance.（3）Fly ash porous ceramics with underwater super-hydrophobic and photocatalytic properties were prepared by applying photocatalysis and super-infiltration technology to porous fly ash ceramics.Ti O₂ sol was prepared by sol-gel method,and Ti O₂ Photocatalytic and underwater superhydrophobic performance of porous fly ash ceramics were investigated via the experiment of photocatalytic degradation of methyl orange solution and the evaluation of underwater contact angle to evaluate.The results shows that the degradation rate of methyl orange solution of 4 mg/l reached 99.51%after 7 hours of ultraviolet light,and the porous fly ash ceramics show good reuse performance.The surface of the porous fly ash ceramics shows the characteristics of super hydrophilicity and high lipophilicity in the air,and shows excellent Superoleophobic under water.The contact angle to corn oil,soybean oil,isooctane and other oils under water is nearly 160°.what is moer,The super hydrophobic property of the material under water can be enhanced by ultraviolet light irradiation.In this study,the preparation and functionalization of porous ceramics based on the material characteristics of fly ash,a common industrial waste,has successfully expanded the material scope of high-end reutilization of low-end industrial wastes and significantly enhanced the application potential of fly ash,an extremely common industrial waste,in the fields of energy and environmental protection.added value of fly ash products.This study has a broad application prospect in the fields of construction,home decoration,environmental protection,and self-cleaning materials etc.