Optimization of metals degradation and vitrification from fly ash using Taguchi design combined with plasma pyrolysis and recycling in cement construction

Abstract

Fly ash has been widely recognized as the hazardous waste due to its toxicity to environment. It should be treated properly for preventing the high contamination to the environment and generate volatile organic compounds (VOCs) from the pyrolysis treatment. The aim of this study is to investigate the most influenced parameters in elimination of elements, vitrification and destruction of volatile organic compounds (VOCs) from the fly ash via a plasma pyrolysis with the combination of Taguchi method and recycling it into the cement construction, which potentially applied in the real application. The combination of fly ash treatment with CaCO3, SiO2, Al2O3 and glass gives the high removal efficiency of VOCs at 4.653 ppm under the nitrogen plasma. Furthermore, the gas flow rate has the most significant impact on the destruction of elements based on the Taguchi analysis. The best removals of element are known as follows: Hg>Cd>Se>As>Cr>Pb>Cu. Lastly, compressive test of the cement at age 28 days with the substitution of 10% fly ash confirmed greater result on cement quality. The most influenced parameter, namely gas flow rates with the combination of flux agents are thus suggested for degrading harmful elements and VOCs. Fly ash from plasma post-treatment has the potential for replacing the cement material when used in the construction material to implemented the recycling concept.