Katerina Emilova Lazarova

Title : Coal fly ashes zeolites as a foundation towards functional nanocomposites

Abstract:

In the context of the circular economy for environmentally friendly waste management and saving of raw materials, the production of zeolites from fly ash (FA) from combustion of coal, which is generated as a byproduct in the energy production from coal-fired thermal power plants (TPPs), is intensively studied.  Mostly used method for recycling of waste of coal is the synthesis of zeolites from this waste material as the zeolites thus obtained can be used for a variety of purposes. In this study lignite coal fly ash collected from the electrostatic precipitators of one of the biggest TPPs in Bulgaria was used in order to synthesize Na-X type zeolites by ultrasonic-assisted double stage fusion-hydrothermal alkaline conversion. In order to reduce the size of the thus obtained zeolites they were wet-milled for 60, 120, and 540 s prior to the incorporation in the sol–gel Nb2O5 matrix.

Surface morphology and structure of the zeolites in form of powder was studied by scanning electron microscopy and X-ray diffraction, their porosity and particle size prior to and after wet-milling - by N2-physisorption and Dynamic Light Scattering, respectively.

Spin-coating method was used to deposit niobium pentoxide (Nb₂O₅)/zeolites composite films in two different volume concentrations (1% and 5%) and a complete optical characterization was made. Sensing properties toward acetone vapors were studied via evaluation of the change in the reflection coefficient ?R of the films after exposure to the selected analyte.

Acknowledgments: Research equipment of Distributed Research Infrastructure INFRAMAT, part of Bulgarian National Roadmap for Research Infrastructures, supported by Bulgarian Ministry of Education and Science was used in this investigation.

Audience take-away:

• How conversion of waste raw fly ash (FA) to a single Na-X phase zeolite is achieved by ultrasonic-assisted double-stage fusion-hydrothermal alkaline conversion.
• What is the effect of zeolites’ size on optical and sensing properties of the nanocomposite Nb₂O₅ thin films and achieved different levels of porosity, after wet-milling of the zeolites prior to the incorporation in the sol–gel matrix.
• Is utilization of Nb₂O₅/Na- X zeolites thin films as sensitive element for optical detection of acetone possible?

Biography:

Dr. Katerina Lazarova has been a scientist at the Bulgarian Academy of Sciences for the last 9 years. In 2013 she began her doctorate in the field of photonic crystals and optical sensors based on zeolites and porous materials. In 2016 she became a chief assistant at the IOMT, and from 2019 to 2021 is a postdoctoral fellow with a scholarship in the same field.  Author of 40 articles, with awards for presentations in scientific forums and participation in numerous scientific projects in collaboration with other scientific organizations.