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Author: search.filters.author.Thambiliyagodage, C. JSubject: search.filters.subject.Methylene blue

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Now showing 1 - 4 of 4
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    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.
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    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.
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    PublicationOpen Access
    Effect of surfactants on morphology and textural parameters of silica nanoparticles derived from paddy husk and their efficient removal of methylene blue
    (International Conference on Innovations in Energy Engineering & Cleaner Production (IEE CP’21), 2021) Gunathilaka, H; Thambiliyagodage, C. J; Usgodaarchchi, L; Angappan, S
    Effective removal of textile dyes is important in environmental remediation especially for decontamination of wastewater. Herein, we report the synthesis of mesoporous silica nanoparticles (MSNs) from paddy husk with varying concentrations of surfactants, Cetyltrimethylammonium bromide (CTAB), and Polyethyleneglycol (PEG) by sol-gel synthesis method. Ratios of the surfactants CTAB: PEG were varied as 2:0 (MSN1),1:1 (MSN2), 0:2 (MSN3). MSNs were characterized by scanning electron microscope (SEM), Brunauer-Emmett-Teller surface area analyzer (BET), Thermogravimetric analyzer (TGA), and X-ray diffractometer. According to the SEM images, MSNs of all the combinations were aggregated with spherical and irregular shaped nanoparticles. MSNs synthesized with a 1:1 surfactant ratio showed more spherical nanoparticles. BET surface areas of MSN1, MSN2, and MSN3 are 468.35, 95.94, 177.46 m2/g, respectively. TGA curve indicated that desorption of the physisorbed water was completed at 125 °C. The effect of dye removal by the MSNs was studied on the adsorption of methylene blue (MB). Effect of dye concentration (5-30 mg/l), adsorbent dosage (5-20 mg), pH of the medium (2-10), ionic strength of the medium (0-6g/l NaCl), presence of a heavy metal (Pb2+- 0-500 mg/l) and temperature (25-55 °C) on MB adsorption was studied. At all the varied parameters, the adsorption efficiency of MB varied as MSN1> MSN3> MSN2, being similar to the trend of the surface area. The percentage of MB adsorption decreased with increasing MB concentration while it increased with increasing adsorbent dosage. The highest efficiency of MB adsorption was obtained at pH 10 and it decreased with increasing ionic strength and increasing concentration of heavy metal ions. The maximum percentage of MB adsorption resulted at 55 °C. Therefore, it can be concluded that the MSNs synthesized using only CTAB as the surfactant is an effective adsorbent in removing textile dyes from wastewater.
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    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.