Browsing by Author "Priyadarshana, W.M.G.I."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Nanosilica from Sri Lankan Vein Quartz: Synthesis, Surface Modification and Characterization
    (Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Premaratne, W.A.P.J.; Priyadarshana, W.M.G.I.
    Vein quartz is one of the most abundant minerals in Sri Lanka and it is mainly mined for porcelain and materials industries. Vein quartz is an economically viable earth resource for the production of nanosilica through chemical methods as a value added product. Nanosilica is one of the widely used nanomaterials in adhesives, sealants, paints & coatings, cement-based building materials and rubber composites as a reinforcing, thickening and flattening agent. In this research work, pure nanosilica was synthesized by a chemical precipitation method from Sri Lankan vein quartz. Finley ground quartz was refluxed with 3 M NaOH and then 0.5 M H2SO4 was added drop wise to adjust the pH of the solution to be around 8.0 to precipitate nanosilica. X-ray diffraction (XRD) data indicated that the natural Sri Lankan vein quartz is highly crystalline and pure. Energy dispersive X-ray spectroscopy (EDX) data confirmed that vein quartz comprises pure silicon oxide with less impurities. Scanning electron micrographs (SEM) data showed that synthesized nanosilica particles from vein quartz were in the agglomerate form with average particle size of 50 nm. XRD data showed a strong broad peak around 22.14o (2) indicating synthesized nanosilica was in amorphous form. Fourier transform infrared spectroscopy (FTIR) data indicated the structural change from crystalline silica (in vein quartz) to amorphous silica by the absence of a sharp peak at 695 cm-1 in the FTIR spectrum of nanosilica synthesized. Silica nanoparticles were subjected to surface modification by oleic acid (C18H34O2). Thermo gravimetric analysis (TGA) graph indicated the thermal decomposition of oleic acid in functionalized nanosilica with a significant weight loss between 350 ºC to 400 ºC. FTIR data showed that modified nanosilica with oleic acid indicated a carbonyl stretching peak of an ester bond at 1711 cm-1, which confirmed the ester bonding between silinol group and the carboxylic group of the oleic acid.
  • Thumbnail Image
    Item
    Synthesis of Nanosilica from Paddy Husk Ash and Their Surface Functionalization
    (University of Kelaniya, 2013) Premaratne, W.A.P.J.; Priyadarshana, W.M.G.I.; Gunawardena, S.H.P.; de Alwis, A.A.P.
    Nanosilica was synthesized by a chemical precipitation process from paddy husk ash (PHA) efficiently and effectively. Surface functionalization of the silica nanoparticles was carried out with oleic acid (C18H34O2). Scanning electron micrographs (SEM) data showed that the nanosilica particle size was in the range of 50-70 nm and they were in the agglomerate form. X-ray diffraction (XRD) analysis data revealed that synthesized nanosilica was in amorphous form showing a strong broad peak at 22.14o (2). Fourier transform infrared spectroscopy (FT-IR) data supported the presence of hydrogen bonded silanol group and siloxane groups in nanosilica. Surface functionalized nanosilica with oleic acid was characterized using thermogravimetric analysis (TGA) and FT-IR methods. FT-IR experimental data showed that the modified nanosilica formed the ester bonding between silanol group in nanosilica and the carboxylic group of oleic acid with a successful functionalization.