| With the rapid development of science and technology and accelerated industrialization,mankind has produced a large amount of municipal waste while continuously enriching the wealth of society.The current traditional methods of waste incineration fly ash disposal are solidification and landfill,but such methods are encountering more and more challenges due to the decreasing available landfill space and possible leaching of hazardous substances.It becomes very important and urgent to develop new methods for treating and utilizing incineration fly ash.This paper investigates the physical and chemical properties of waste fly ash with organic stabilizer and waste incineration fly ash without any stabilizer.The study examines the effects of alkali roasting pretreatment,hydrothermal treatment,microwave treatment,microwave-hydrothermal treatment,and hydrothermal-microwave treatment on the adsorption of methylene blue.Additionally,XRD,SEM,and BET analysis were conducted on each material.The main research findings and conclusions are presented below:1)The optimal roasting conditions for the raw ash were 500°C,3.0 h roasting time and 0.4 g addition of sodium hydroxide under nitrogen atmosphere,and the decolorization rate of methylene blue reached 28.82%and the adsorption amount reached 17.02mg·g-1.The optimal hydrothermal conditions for the raw ash were 150℃,12 h hydrothermal time,0.3 silica conditioner addition ratio,and 12 p H of the hydrothermal solution,and the decolorization rate of methylene blue reached 99.98%and the adsorption amount was 82.59 mg·g-1.The microwave reaction time was 1.5 optimum,and the decolorization of methylene blue was 100%with the adsorption amount of 83.53mg·g-1.The best adsorption of methylene blue was achieved by the combined raw ash roasting-microwave-hydrothermal process,reaching 100%at 50 min with an adsorption capacity of 84.35 mg·g-1.The gradual increase in decolorization rate is due to the synthesis of molecular sieve-like materials treated by hydrothermal,microwave and combined processes,with a gradual increase in specific surface area.2)The optimal roasting conditions for organic ash were roasting temperature of 550℃,roasting time of 4.0 h and addition of 0.5 g of sodium hydroxide under argon atmosphere,and the decolorization rate of methylene blue was 41.35%and the adsorption amount was 24.15 mg·g-1.The optimal hydrothermal conditions for organic ash were 150℃,9 h hydrothermal time,0.3 silica conditioner addition ratio,and 12 p H of hydrothermal solution,and the decolorization rate of methylene blue was 91.26%and the adsorption amount was 77.37mg·g-1.The microwave reaction time was optimal for 2.0 h.The decolorization rate of methylene blue was 93.62%and the adsorption amount was 77.65mg·g-1.The combined organic ash roasting-microwave-hydrothermal process showed the best adsorption of methylene blue with 99.11%decolorization and 82.98 mg·g-1adsorption capacity.3)The adsorption effect of the raw ash hydrothermal,microwave and combined process materials on methylene blue was better than that of the organic ash,which was due to the high crystallinity and large specific surface area of the molecular sieves synthesized in the raw ash treatment processes.At the same time,both the raw ash and organic ash treatment materials conformed to the secondary adsorption kinetics.4)The adsorption rates of raw ash roasted-microwave-hydrothermal materials and organic ash roasted-microwave-hydrothermal materials were 84.68%and 80.99%for lead ions and 15.79%and 30.47%for chromium ions.And the leached heavy metals of these two materials met the limit values. |
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