Comprehensive Utilization Of Carbon-high Fly Ash

Fly ash is an industrial waste and usually uses in building as a substitute because of the pozzolanic activity.However,the reutilization restricted by its carbon,so a lot of fly ash in the landfill or open dumping contaminated the air and the underground water,even injured to health.Although massive carbon-high fly ash was produced in industry every year,researchers cared for how to separate carbon rather used more effectively.The separation of carbon from fly ash needs a lot of energy,and produced secondary pollution easily,so the development of utilization method for carbon-high fly ash has a great significance.This paper carried out a systematic study on the utilization of carbonhigh fly ash.In order to utilize effectively,the technological mineralogy of carbon-high fly ash was initially studied by using optical microscope,SEM,EDS,XPS,XRD,FT-IR and LOI analysis.The results characterized the microstructure,and determined kinds of mine,element,and carbon content.The composition of carbon-high fly ash is similar to that of ordinary fly ash,but the carbon content reaches 34%.Moreover,it is difficult to separate carbon by traditional methods because of fitting with inorganic oxides mutually.Therefore,the key of improving utilization efficiency is direct utilization of carbon-high fly ash.Surface modification is a good way to solve poor compatibility of carbon-high fly ash as a filler.Hydrophobic fillers are widely used in water treatment,oil-water separation and energy transmission.It is feasible to modify carbon-high fly ash to obtain compatibility and superhydrophobicity.Firstly,the ball milling was used to prepare small size particles including microscale and nanoscale.Next,Zn O nanosheets were grown as a honeycomb-like nanostructure on the surface of carbon-high fly ash by hydrothermal synthesis.Finally,surface modification was carried out by using a low surface energy material stearic acid.The static water contact angle showed that the modified fly ash is superhydrophobic.The key of modification is that esterification reacted between stearic acid and surface hydroxyl successfully.The reaction time,reaction temperature and aging time had a great influence on the superhydrophobic fly ash.This superhydrophobic material is a good filler.Next,the carbon-high fly ash was used as a filler in the epoxy coating after ballmilling.In order to contrast with the carbon-high fly ash,the decarbonized fly ash was also filled into the epoxy coating.Carbon-high fly ash reduced the hardness,adhesion,impact strength and friction resistance of the coating.On the contrary,the hardness and wear resistance of the coating with a certain amount of decarbonized fly ash were improved.The dispersion of fly ash in the coating affected the anticorrosion performance.The dispersion of carbon-high fly ash was better than that of decarbonized fly ash.The anticorrosion performance and salt spray resistance of the film with carbon was better than without carbon.Electrochemical analysis showed that carbon played a barrier and buffer role in the film before and middle stage of corrosion,but carbon adsorption saturated in the later stage accelerated the corrosion of the substrate.Therefore,carbon-high fly ash is suitable for functional coatings,such as antifouling coatings,decorative coatings,etc.Finally,carbon-high fly ash was used to modify polyurethane sponge.As a threedimensional porous material,polyurethane sponge can adsorb both water and oil,but the unmodified polyurethane sponge cannot adsorb oil well.The carbon-high fly ash was loaded onto the surface of the polyurethane sponge by silane coupling agent,and then the sponge was modified by stearic acid.The super hydrophobic and oil-absorbing polyurethane sponge was obtained,and the water contact angle could reach 162.04°.The loaded fly ash increased the roughness of polyurethane sponge,and the protruded fly ash particles also prevent the spill of oil and organic solvents,thus improving the adsorption performance of polyurethane sponge.The modified sponge had a good adsorption capacity for crude oil,soybean oil,toluene and other oils and organic solvents with high density,and also had a certain adsorption capacity for low density oils and organic solvents.Through a variety of experiments,we knew that high carbon fly ash was a kind of material that could be used in many fields.