Modification And Adsorption Mechanism Of Coal Fly Ash

China is the largest coal consumption and production country in the World, More and more coal has been combusted every year due to the rapid economic growth. Therefore, the environmental effect caused by coal combustion is one of the most serious global pollution problems for the pollutants can remove and transform to nearby country and create great harm to human health.Having consulted a large amount of relevant literature, coal fly ash and hazardous solid waste (HSW) incineration fly ash were chosen as the example to study the chemical and physical properties of fly ash particle, with focus on the distribution of trace elements and polycyclic aromatic hydrocarbons (PAHs) in fly ash particle. Based on this work, mechano-chemistry modification method was conducted. A series of macroscopic and microscopic changes has been investigated during the process with the help of various modern characterization methods. Furthermore, application of the modified fly ash has been used on the adsorption of methylene blue and mercury. This thesis is composed of six chapters and one appendix, here is the main context of this thesis:(1) The diameter and particle distribution of fly ash shows close relationship with the combustion conditions, and most major elements and trace elements enrich on smaller particle, which indicating the stronger activity and harmfulness. With the decrease of the particle diameter, the content and occurrence of PAHs shows variously. The toxicity equivalent evaluation shows coal fly ash has more potential toxicity than HSW fly ash, and two ashes are not suitable for soil improved application.(2) Series physical and chemical changes of fly ash particles have taken place in the modify process. Particle size and crystal diameter are sharply reduced, indicating lower crystallinity and enhanced chemical activity of fly ash. Pore size distribution of fly ash has also been changed. Certain changes have taken place in functional group, according to the results of TGA and FTIR.(3) Comparing with the original fly ash, mechano-chemistry modified fly ash obtain better result on methylene blue adsorption, and the equilibrium adsorption capacity was7.97mg/g. Adsorption kinetics equation concluded that the adsorption process was fit with the pseudo-second-order kinetics. Single molecular surface adsorption is the main adsorption form, and the equilibrium adsorption is accordance with from the experimental results. According to the data on mercury adsorption, the mechano-chemistry modified fly ash shows not significant improvement. So solution impregnation modification method has been selected, NaOH modified fly ash increased physical adsorption performance of fly ash by improve the pore size distribution, the adsorption equilibrium capacity was3.85μg/g. While as for the HBr modified fly ash, the mercury adsorption performance has been greatly improved and adsorption equilibrium capacity was37.36μg/g.