Research Papers - School of Natural Sciences

Permanent URI for this collectionhttps://rda.sliit.lk/handle/123456789/1352

Browse

Filters

20213

Advanced Search

Filter by

Settings

Author: search.filters.author.Usgodaarachchi, LSubject: search.filters.subject.Methylene blue

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    PublicationOpen Access
    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.
  • Thumbnail Image
    PublicationEmbargo
    Efficient removal of methylene blue by turbostratic carbon/Fe3C/Fe composite synthesized by catalytic graphitization of sucrose
    (Elsevier, 2021-12-07) Thambiliyagodage, C. J; Usgodaarachchi, L
    Turbostratic carbon/Fe3C/Fe composite was prepared by catalytic graphitization of sucrose by α-Fe2O3. The synthesized composites were characterized by X-ray diffractometry (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). XRD patterns revealed the formation of turbostratic carbon with a d spacing of 0.3412 nm and the presence of Fe3C and Fe nanoparticles. Raman spectrum exhibited the D, G and G' peaks. XPS analysis shows the presence of graphitic carbon and +3 oxidation state of iron. Synthesized composite can remove methylene blue with an adsorption capacity of 17.8 mg/g at pH 7. Adsorption follows pseudo second order kinetics and the Langmuir isotherm model. As the synthesized composite is magnetic it could be easily separated from the mixture and could be reused effectively without significant activity loss for five cycles.
  • Thumbnail Image
    PublicationOpen Access
    Synthesis of mesoporous silica nanoparticles derived from rice husk and surface-controlled amine functionalization for efficient adsorption of methylene blue from aqueous solution
    (Elsevier, 2021-01-01) Usgodaarachchi, L; Thambiliyagodage, C. J; Wijesekera, R; Bakker, M. G
    Mesoporous silica nanoparticles (MSN) were synthesized using rice husk (RH) as the raw material via sol-gel pathway using cetyltrimethylammonium bromide (CTAB) as the structure directing agent. Silica nanoparticles were successfully functionalized with 3-aminopropyl triethoxysilane (APTES) via in-situ and post functionalization methods. Synthesized nanoparticles were characterized by X-Ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area analysis. The amorphous silica nanoparticles were of 50–60 ​nm in diameter with a surface area of 150 ​m2/g, pore volume of 0.237 ​cm3/g and average pore size of 3.62 ​nm. Morphology and textural parameters were changed upon functionalization. The equilibrium adsorption capacity of MSN-A (4.94 ​mg/g) to adsorb 10 ​mg/L methylene blue (MB), was higher than in amine functionalized silica nanoparticles. The influence of experimental factors such as pH, adsorbent dosage, and initial MB concentration on adsorption of MB to MSN-A were studied. The equilibrium data for MB adsorption on mesoporous silica nanoparticles well fitted to Langmuir equation, with a maximum monolayer capacity of 19.26 ​mg/g. The adsorption of MB could be best described by the pseudo-second order model. The results indicate that MSN-A is a potential mesoporous material fabricated by cheap natural resources to remove MB from aqueous solutions.