Research Papers - School of Natural Sciences

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Subject: search.filters.subject.Nanoparticles

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    One pot synthesis of α-Fe2O3/turbostratic carbon composites and their photocatalytic activity under sunlight
    (Elsevier, 2021-10-01) Thambiliyagodage, C. J; Nakandala, S; Siriwardana, B; Lansakara, B
    Sucrose naturally obtained from sugar cane was catalytically graphitized by incorporation of varying amounts of iron (1, 5, 7.5 and 10%) as a one-pot synthesis. The weight of iron was varied relative to the weight of sucrose. Synthesized sucrose-Fe2O3 nanocomposites (FeGC) were characterized by X-ray diffractometry (XRD), Raman spectroscopy, and UV-Visible spectroscopy. It is observed that turbostratic carbon is produced upon the incorporation of iron and the percentage of graphitization increase with increasing loading of iron as revealed by XRD analysis. Quantitative analysis of Raman spectra confirm that the ordering of carbon increase with increasing loading of iron. The equilibrium adsorption capacity of carbon with the highest iron loading (10FeGC), 0.50 mg/g is higher than that with carbon without any metal, AC (0.2 mg/g), and the highest adsorption capacity (0.58 mg/g) resulted in carbon with 5% iron (5FeGC). Methylene blue adsorption to AC and carbon with 1% iron (1FeGC) followed pseudo-first-order kinetics and carbon materials with 5, 7.5 and 10% iron followed pseudo-second-order kinetics. The initial rate constant for the photodegradation of methylene blue in the presence of AC was 0.001 min−1 and that of 1FeGC (0.005 min−1) increased with increasing loading of iron where the highest initial rate constant (0.158 min−1) was obtained with 10FeGC. Ordered carbon enhances photocatalytic activity by being photoactive and increasing the separation of charges generated at α-Fe2O3.
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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, 2021-10) Usgodaarachchi, L; Thambiliyagodage, C. J
    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 Fe 3O4.