Study On Ultrasonic Treatment And Adsorption Properties Of Fly Ash From Hazardous Waste Incineration

In recent years,with the rapid development of China’s national economy and the gradual deepening of the process of industrialization,hazardous waste production and its comprehensive utilization have increased sharply.Incineration of hazardous waste has become one of the widely used hazardous waste disposal technologies in China due to its advantages of reduction,harmless and resource recovery.The fly ash from hazardous waste incineration contains heavy metals,dioxins and other toxic and harmful ingredients,which are also hazardous wastes and need to be treated innocuously.Current fly ash disposal technologies mainly include physical,chemical,solidification/stabilization,etc.In order to explore the possibility of reuse of fly ash from hazardous waste incineration,ultrasonic wave was used to study the leaching characteristics of heavy metals in fly ash from hazardous waste incineration.Ultrasonic wave was used to treat fly ash from hazardous waste incineration and analyze the morphological changes of heavy metals in fly ash before and after ultrasonic treatment.The adsorption characteristics of fly ash treated by ultrasonic wave as adsorbent were studied to provide experimental basis for resource utilization of fly ash from hazardous waste incineration.In this paper,the experimental use of fly ash material selected from a hazardous waste disposal center in liaoning rotary kiln incineration fly ash,gathering outside bag filter for curing landfill of fly ash,and using XRD,SEM,BET and EDS etc.The physical and chemical properties of fly ash samples for testing,including the particle size distribution,element composition,microstructure,heavy metal content and leaching toxicity of heavy metals.By controlling variable method ultrasonic on leaching toxicity of heavy metals in waste incineration fly ash influence study,explore the dosage of additive species,additive,ultrasonic power,ultrasonic treatment time of ultrasonic processing variables such as waste incineration fly ash in Cd,Cr,Cu,Pb and Zn five main characteristics of heavy metal leaching are studied.The results showed that Cd and Pb in the original fly ash exceeded the landfill standard by 3.04times and 2.4 times,and the leaching toxicity of other heavy metals all met the landfill standard.KOH as additive,additive dosage is 0.5,ultrasonic treatment power is 90W,ultrasonic treatment time is 20min,after ultrasonic treatment,the leaching concentration of heavy metals in fly ash decreased significantly,Cd leaching concentration decreased by 86.79%,Pb leaching concentration decreased by 99.48%,both reaching the landfill standard.Through the improved BCR multistage continuous extraction experiment,the morphology of heavy metals in fly ash before and after ultrasonic treatment and the mechanism of ultrasonic leaching of heavy metals were studied.The results showed that:Ultrasonic wave has a certain effect on the stabilization of heavy metals in fly ash from hazardous waste incineration.By changing the occurrence form of heavy metals in fly ash,the leaching concentration of heavy metals can be reduced,so as to achieve the purpose of harmless,rather than simply transferring heavy metals from solid phase fly ash to liquid phase separation solution,so as to reduce the leaching concentration of heavy metals in fly ash.The adsorption characteristics of Cd²⁺,Cr³⁺,Cu²⁺,Pb²⁺and Zn²⁺on fly ash after ultrasonic treatment were studied,and the adsorption mechanism was analyzed by XRD,SEM,BET and EDS.The experimental results show that under the condition of KOH additive dosage 0.5 and ultrasonic power 180W,the fly ash of hazardous waste incineration after ultrasonic treatment for 40min has the best adsorption effect on Cd²⁺,Cr³⁺,Cu²⁺,Pb²⁺and Zn²⁺.The maximum adsorption capacity was 48.99,30.31,51.32,63.79 and 43.22mg/g,respectively.The adsorption process is more consistent with Langmuir isothermal adsorption model,indicating that monolayer adsorption is dominant.The results of kinetic fitting are more consistent with the quasi-second-order kinetic model,indicating that the adsorption process is mainly chemical adsorption.