Synthesis and characterization of manganese dioxide nanoparticles via direct heating method
Loading...
Date
2018-06
Authors
Wong, Chee Leong
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Coloured effluent discharged from textile industry has become critical
environmental concern since it is difficult to be degraded. Advanced oxidation
process (AOPs) using photocatalyst is one of the emerging techniques for effluent
treatment, but most of the wide-bandgap photocatalyst is Ultraviolet (UV)-
activated which is not practical in the real environment. Also, problem arises when
there is a need to remove these photocatalyst in particle form from the treated
effluent after application. In this project, narrow-bandgap MnO2 nanoparticles
were synthesized using co-precipitation and sol gel methods. MnO2 nanoparticles
were also grown on the Khantal wire coil via direct heating synthesis. The resulting
products were characterised using various analytical tools (e.g. X-Ray Diffraction
(XRD), X-Ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy
(SEM), Transmission Electron Microscope (TEM)) and were employed for dye
removal study under UV, visible light irradiation and dark condition with addition
of hydrochloric acid (HCl) or sulphuric acid (H2SO4). MnO2 nanoparticles alone
was not efficient in removing dye. With addition of H2SO4, removal efficiency
reached 96.63% and 57.93% after 12min for nanoparticles synthesized by co precipitation and sol gel methods respectively. Washing of nanoparticles with
deionised water and ethanol inluenced the dye removal efficiency. It was found
that the removal mechanism of MnO2 nanoparticles was oxidative degradation
process. To minimise lost of nanoparticles, MnO2 nanoparticles with hierarchical
structures were grown on the wire coil with various heating power and growth time.
Secondary nucleation was prominent with increasing heating power whereas Ostwald
ripening was obvious with increasing growth time. Besides, MnO2 nanoparticles grown
on wire coil could be used for dye removal process. MnO2 nanoparticles grown with
heating power of 30W with 10min growth time and growth duration of 30min at 24W
exhibited highest efficiency which were 98.25% and 85.69%, respectively.