International Research Symposium on Pure and Applied Sciences (IRSPAS)

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    Synthesis and characterization of silica nanoparticles and graphene oxide/nanosilica composite
    (4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Weerasinghe, M. A. S. N.; Liyanage, J. A.; Kumarasinghe, A. R.
    Ordinary sand is commonly used for water purification. Graphene oxide (GO) is capable of absorbing various water pollutants such as heavy metals and organic contaminants. The ability and the efficiency of water treatment process is proposed to be enhanced using silica nanoparticles and GO/nanosilica composites. Silica nanoparticles and GO/nanosilica composite were synthesized and characterized. Silica nanoparticles were synthesized using tetraethyl orthosilicate and following the sol-gel method. Graphene oxide was synthesized using the modified Hummers’ method. Silica nanoparticles, graphene oxide membrane and GO/nanosilica composite were characterized using Fourier Transform Infrared Attenuated Total Reflection Spectroscopy (FT-IR ATR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Absorption Spectroscopy (ED-XAS) and X- ray Diffraction (XRD). The size of silica nanoparticles was found to be in the range of 50-110 nm with SEM data, which confirms the synthesis of nano-sized silica particles. The sheet like structure with aggregated and folded surfaces of graphene oxide was observed in the SEM analysis of graphene oxide. The interphase between silica and graphene oxide was observed in SEM analysis of GO/nanosilica composite. FT-IR ATR data supported for the identification of functional groups of silica nanoparticles, graphene oxide membrane and GO/nanosilica composite. The peak at 1093cm-1- for asymmetric stretching of Si-O-Si bonds and the peak at 800 cm-1 for symmetric stretching of Si-O-Si bonds are characteristics peaks of silica. The peaks at 3441 cm-1 for the stretching vibration of hydroxyl groups, at 1739 cm-1 for the stretching vibration of carbonyl groups and at 1391 cm-1 for the stretching vibrations of epoxy groups are characteristics peaks of graphene oxide. The FT-IR ATR spectrum of GO/nanosilica composites showed peaks for both silica and graphene oxide. ED-XAS data showed the presence of corresponding elements in each samples. Data from ED-XAS of silica nanoparticles supported the presence of silicon and oxygen while the ED-XAS of GO/nanosilica showed that the presence carbon, oxygen, silicon as the main elements of the sample. XRD spectrum of silica nanoparticles showed a strong broad peak at 22.22 (2θ). A broad peak for silica was observed in the XRD spectrum of GO/nanosilica composite similar to the XRD spectrum of silica nanoparticles. The data from SEM, FT-IR ATR, ED-XAS and XRD confirms the successful synthesis of silica nanoparticles and GO/nanosilica composite
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    Characterization of Tween 80® consisting Neem oil-based emulsion
    (Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Abeywardana, Y. N. L.; De Silva, H. H.V. K. N.; Sanjeewani, N. A.; Pathirana, R. N.
    In pharmaceutical industry emulsions provide a liquid drug delivery medium in the form of min globules rather than in bulk form and permits easy drug administration to the human body. Neem oil is used in Ayurveda medicines due to its numerous medicinal properties. It is also used in various cosmetic preparations. A wide variety of different analytical techniques and methodologies have been developed to characterize the properties of emulsions. Since initial properties of an emulsion are changing over the time, characterization should be considered in order to evaluate the quality of an emulsion. The main objective of this study was to formulate and characterize a Tween 80® consisting Neem oil based stable emulsion formulation. Primary emulsions were prepared according to randomly chosen ratios of water: oil: surfactant using magnetic stirrer at 300 rpm for 10-15 min. Secondary emulsions were obtained by secondary homogenization of the prepared primary emulsions using high shear homogenizer at 10,000 rpm for 5 min. Microscopic analysis, pH value, viscosity, creaming index and colour were used as the parameters for the characterization of stable emulsion formulations. Methylene blue was taken as the dye in order to stain the emulsions to observe the type of the emulsions. Samples were subjected to 50% dilution with distilled water to measure the pH using a pH meter. The viscosities of emulsions were measured using a Redwood viscometer. Creaming indices of freshly prepared emulsions were measured after 24 hr. Microscopic analysis revealed that the most stable primary and secondary emulsions were oil in water (O/W) type. Secondary emulsions showed greater viscosity than respective primary emulsions and the most stabilized formula of secondary emulsion had 2750 Redwood seconds of viscosity. Creaming indices were zero for all the emulsions. Secondary emulsions were brighter than the respective primary emulsions. The pH values of stabilized emulsions ranged between 4.35 - 5.20. These values are in the non-skin irritating pH range of 4 - 7. Considering all these characteristics, it can be concluded that this formulation can be developed to use as a topical preparation.