Browsing by Author "Thambiliyagodage, C."

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    Photocatalytic activity of Cobalt-doped Fe2TiO5 nanoparticles from natural Ilmenite using acid leaching steps under visible light
    (Faculty of Science, University of Kelaniya Sri Lanka, 2023) Thambiliyagodage, C.; Liyanage, M. R.
    This research project was primarily carried out to observe the photocatalytic decolourisations of Cobalt-doped Fe2TiO5 nanoparticles in wastewater contaminated with dyes. The possibility of using commonly accessible Ilmenite as a raw material in a low-cost, non-toxic, stable, and highly reactive process of synthesising the aforementioned Fe2TiO5 is also explored in this research. Acid-leaching techniques were used, to remove impurities. Then Ammonia solution was used for precipitation, followed by filtration, drying, and calcination at 7000 C to produce Fe2TiO5 nanoparticles. Cobalt salt was added to the acid leachate, and the same precipitating and calcination procedure was followed to produce CoO/Co2O3/Co3O4/Fe2TiO5, which were then characterised utilising PXRD, Raman spectroscopy, XRF, XPS and SEM. PXRD patterns collected to identify the crystal structure of the synthesised nanoparticles show the presence of pseudobrookite, Fe2TiO5 and α-Fe2O3. Moreover, finding peaks in PXRD analysis for CoO/Co2O3/Co3O4 is challenging due to the low concentration of Co utilised. Raman analysis part depicts the existence of α-Fe2O3 and the anatase phase of TiO2 in the Cobalt-doped sample. XRF analysis was performed on a Cobalt-doped sample to identify the elemental distribution of Ti, Fe, Co and other elements. XPS analysis reveals the presence of Ti, Fe, O, C, and Co in the Cobaltdoped sample, confirming the CoO/Co2O3/Co3O4/Fe2TiO5 composition. The aforementioned analysis techniques confirm the Fe2TiO5/TiO2 in the initially synthesised undoped sample. SEM image of synthesised Fe2TiO5 shows the distribution of an irregular nanostructure of small and large nanoparticles. However, the Cobalt-doped sample shows how the irregularity is disturbed. The catalytic activity of Fe2TiO5/TiO2 and Cobalt-doped catalysts was observed in the presence and absence of persulfate under sunlight using UV visible spectroscopy. The CoO/Co2O3/Co3O4/Fe2TiO5 nanoparticles showed 37.31% dye removal for Methylene Blue after 2 hours, which was an insignificant result under sunlight. However, the addition of persulfate also did not show any significant improvement in the dye removal percentage, with only 32.54% decolouration of Methylene Blue observed after 2 hours. These results show a negligible photocatalytic effect in Cobalt-doped Fe2TiO5 nanoparticles using low concentrations of Cobalt.
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    Photocatalytic activity of Go/Fe3O4 fabricated by Sri Lankan graphite under visible light irradiation
    (Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Usgodaarachchi, L.; Thambiliyagodage, C.
    Graphene oxide (GO) was synthesized using Sri Lankan naturally available graphite by modified Hummer’s method. Fe3O4 nanoparticles were synthesized successfully by co-precipitation of Fe3+ and Fe2+ in a 2:1 molar ratio via the addition of NH4OH. Magnetically separable GO/Fe3O4 nanocomposite was fabricated by synthesizing Fe3O4 nanoparticles in the presence of GO. The synthesized nanocomposites were characterized by X-ray diffractometry (XRD), Scanning electron microscopy (SEM), and FT-IR spectroscopy. The formation of GO was confirmed by the C(002) peak at 9.39° in the XRD pattern. XRD pattern of the nanoparticles confirms the formation of crystalline Fe3O4 nanoparticles, and the diffraction peak corresponds to graphene oxide disappear in the GO/ Fe3O4 due to the absence of the folded structure of graphene oxide. SEM image of GO shows the crumpled and wrinkled lamellae structure of graphene oxide, and the images of GO/ Fe3O4 show the distribution of Fe3O4 nanoparticles with an average size of 107 nm on GO where the folded structure of GO was not present while restacking of the nanosheets, was observed. FT-IR spectrum of GO shows the presence of polar oxygenated functional groups such as carboxylic acid (-COOH), hydroxyl (-OH), and epoxy (-COC-). The photocatalytic performance of the photocatalysts was evaluated on photodegradation of methylene blue under visible light irradiation. The GO/ Fe3O4 shows better adsorption behaviour and excellent photocatalytic activity where it could be successfully used for three cycles without significant activity loss. The rate constant for the degradation of MB (0.0187 min-1) at the first cycle decreased to 0.0101 min-1 at the third cycle. The conversion of MB decreased from 98.31% at the first cycle to 92.15% at the third cycle. The drop in the conversion is only 6.16% going from cycle 1 to 3, which could be due to the accumulation of the MB molecules at the pore structure. The obtained high photocatalytic activity could be due to the enhanced charge separation resulted due to the presence of GO sheets and better interactions between GO and Fe3O4.