Madalina Ivanovici

Title : Manganese dioxide as efficient catalyst for pollution reduction in aqueous medium

Abstract:

In recent decades, much effort has been made to develop nanostructures inorganic having a desired morphology, size, crystallinity and functionality. These nanostructures are widely used in applications such as electronics, materials with optical properties, energy storage and transformation, solar devices, etc. Manganese dioxide (MnO₂) is a semiconductor material that so far, has been synthesized into various polymorphic forms with different morphologies by the solvothermal/hydrothermal method presenting thermo-photo-electric activity for pollution reduction. Numerous studies have been conducted on improving the environmental purification efficiency of manganese oxides materials in order to understand key features of catalytic reaction mechanism. In this study, MnO₂ was obtained by a relatively low cost and easy hydrothermal method. The manganese oxide present nanowire morphology and alpha-phase crystallinity. The aim of this work is to prove MnO₂ application in the environmental purification systems, either as a catalyst or as a photocatalyst for the degradation of pollutants in aqueous medium. The synthesized compound was subjected to an evaluation of its catalytic activity in comparison with photocatalytic activity toward a selective degradation pathway of Rhodamine B (RhB). The experimental investigations were performed using suspensions of catalyst particles distributed in acidic RhB aqueous solution for two hours and the light irradiation for the photocatalytic study was provided by a solar simulator. The selectivity of degradation reaction was appreciated by analysing the evolution of time-dependent visible spectra of RhB and the degradation pathway was emphasized by the shift of the characteristic RhB absorbance peak toward lower wavelength values simultaneously with the formation of corresponding bands of RhB degradation by-products. Therefore, we observed a different evolution of the time-dependent visible spectra of RhB for the catalysis when compared with the photocatalysis. Enhanced results were obtained for the study carried out under solar irradiation, for which improved hypsochromic shift and higher RhB degradation percent were achieved.

Acknowledgement: This work was conducted within the National Program NUCLEU, Project Code PN 19 22 01 01, Contract No. 40N/2019 funded by Romanian Ministry of Education and Research

Audience take-away:

• The MnO₂ act as an efficient catalyst for selective RhB degradation pathway both in dark and under solar irradiation
• The public will learn how to perform an ecological, economical photocatalytic experiment with direct environmental applications
• The difference between photolysis, catalysis and photocatalysis under friendly conditions.
• The audience will learn how to synthetize MnO₂ nanowires via low-cost hydrothermal method.

Biography:

PhD student, Madalina Ivanovici studied at Industrial Chemistry and Environmental Engineering Faculty from Politehnica University of Timisoara and received bachelor and master degree in chemical engineering. Then she joined in 2018 the research group from National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara as a member team in the ,,Smart buildings adaptable to the climate change effects" project. Currently, her research topics are catalysis and renewable energy.