Preparation And Catalytic Degradation Of C_f/SiC_nws/Ni Composites

Microwave-assisted catalytic oxidation(MACO)is a new technology for wastewater treatment.It can improve the treatment efficiency of refractory organic wastewater and accelerate the treatment speed of wastewater.Single carbon material or SiC has a limited ability to absorb electromagnetic waves,and it was inefficient to use it as a microwave-assisted catalyst for organic degradation.In order to improve the absorption and microwave-assisted degradation of organic compounds,Cf/SiCnws/Ni composites were prepared by compounding carbon fiber,SiC and nickel particles.The temperature of carbothermal reduction reaction,the amount of nickel source loading,the way of nickel source loading and the effect of substrate materials on the morphology,structure and catalytic degradation of Cf/SiCnws/Ni composites were studied.The specific conclusions are as follows:(1)NiO was deposited on the surface of carbon fibers by hydrothermal deposition and Cf/Ni porous preform was obtained after heat treatment.With Ni as catalyst,SiC nanowires were grown by VLS mechanism.The reaction temperature had a significant effect on the structure of SiC nanowires.The reaction temperature has a significant effect on the structure of SiC nanowires.With the increase of the reaction temperature,the number and length of SiC nanowires have increased significantly.The diameter of SiC nanowires in the Cf/SiCnws/Ni composites prepared at 1400? was 150?200 nm.The diameter of nickel particles was 200?250 nm.The composite material exhibits excellent microwave degradation ability,and the degradation rate of microwave irradiation in 7 minutes can reach 85.4%.The composite material exhibits excellent microwave degradation ability,and the degradation rate of microwave irradiation in 7 minutes can reach 85.4%.This brush-like composite structure was more conducive to the tip discharge of Ni nanoparticles,forming a "hot spot" effect,reacting O2 and H2O in water to form active substances such as hydroxyl radicals,superoxide radicals and h+and promoting the degradation of methylene blue.(2)Studies on the structure and microwave degradation behavior of Cf/SiCnws/Ni composites by loading Ni content on the surface of carbon fibers show that when the Ni loading was 0,the growth of SiC nanowires was a VS mechanism and the diameter of SiC nanowires was 200?600 nm,the length of the SiC nano wires was more than 10 ?m.The growth mechanism of SiC nanowires in the presence of a nickel source in the sample was VLS mechanism.SiC nanowires have a diameter of 100?300 nm and a length of 10?20 ?m.When the Ni loading was 0.5 g,it was beneficial to the formation of SiC nanowires,the increase of Ni loading tends to form SiC coatings or SiC microspheres.Studies on the microwave degradation behavior of Cf/SiCnws/Ni composites with different structures show that the coupling effect of nano Ni particles and SiC nanowires has the best microwave degradation ability.The degradation rate of the methylene blue solution of the CSN2 sample under microwave radiation at 7 minutes can reach 85.4%.(3)The nickel source was added in different ways.At high temperatures,the nickel source uses the VLS mechanism to grow one-dimensional SiC.Ni(g)had very good catalytic performance among three different sources of nickel catalysts:Ni(HT),Ni(g)and Ni(F).The diameter of SiC nanowires grown at 1400? Ni(g)was?120 nm,the length of the SiC nanowires was suitable,the diameter of the top nickel nanoparticles was?150 nm.The degradation efficiency of the prepared Cf/SiC/Ni(HT),Cf/SiC/Ni(g)and Cf/SiC/Ni(F)composites under microwave radiation at 7 minutes reached 85.4%,97.2%and 66.8%,respectively.Cyclic test experiments show that Cf/SiC/Ni(HT)and Cf/SiC/Ni(+)composites have good stability.Cf/SiC/Ni(F)composites had slight damage after ten cycles.(4)Cnfs/SiC/Ni composites were prepared by electrospinning technology,the effects of the amount of nickel acetate and the type of nickel source on the Cnfs/SiC/Ni composites were investigated.When the amount of nickel acetate was 0,a Cnfs/SiC composite with a diameter of about 300 nm was prepared.When the amount of nickel acetate was 1 mmol and 2 mmol,one-dimensional SiC in the prepared Cnfs/SiC/Ni composite were prepared.The amount of one-dimensional SiC was small and a large number of nickel microspheres appear.Due to the high activity of nano-carbon fibers,SiO reacts directly with carbon to form SiC nanowires with nano-carbon fibers as templates and as the Ni content increases,the number of nickel microspheres precipitated increases.