Characterization of CFB-Coal Fly Ash Zeolitic Materials and Their Potential Use In Wastewater Treatment

摘要

Two different fly ash(FA)samples were tested for their ability to give synthetic zeoliticproducts.Polish bituminous(PB)and South African(SA)coal fly ash(FA)samples,derived from pilot-scale circulated fluidized bed(CFB)combustion facilities,have beenutilized as raw materials.The two FAs underwent a hydrothermal activation with 1MNaOH solution at 90°C for 24 h.Two different FA/NaOH solution/ratios(50,100 g/L)were applied for each sample and the following zeolitic materials were formed:Na-Al-SiZeolite A(Na),K-Al-Si Zeolite A(K),Erionite,ZSM-18,K-Ca-Al-Si-Hydrate UnnamedZeolite,Erionite and Linde(L).The experimental products were characterized by meansof X-Ray Diffraction(XRD)and Energy Dispersive X-Ray coupled-Scanning ElectronMicroscope(EDX/SEM),while X-Ray Fluorescence(XRF)was applied for thedetermination of their chemical composition.The zeolitic products were also evaluatedin terms of their cation exchange capacity(CEC),specific surface area(SSA),specificgravity(SG),particle size distribution(PSD),pH and the range of their micro-andmacroporosity.The current work focuses on testing the synthesized zeolitic materials for their potentialof retaining heavy metals from industrial wastewater.Therefore,the aforementionedproducts were tested for their ability of adsorbing Cr,Pb,Ni,Cu,Cd and Zn fromcontaminated liquids,by the use of instrumental analytical methodologies.It must benoticed that the main goal is the treatment of liquid waste with such by-products and thecapability of the zeolitic material to inhibit the leaching of the metals.Main parameters,as it is concluded from the experimental results,are the mineralogical composition ofthe initial fly ashes,as well as the type and the amount of the produced zeolite andspecifically the mechanism by which the metals ions are hold on the substrate.