IPRC - 2019
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/20881
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Item Synthesis of Surface-Modified Graphene-Based Sand for Fluoride Removal from the Drinking Water(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Perera, W.P.R.T.; Fernando, W.S.K.; Premasinghe, N.; Liyanage, J.A.; Kumarasinghe, A.R.Graphene and graphene-based material such as graphene oxide (GO) are materials of great interest for potential applications in nanoelectronics, nanoelectromechanical systems, sensors, polymer composites, catalysis. As graphene does not possess its native oxide, GO is routinely obtained via the chemical treatment of either graphene or widely available regular graphite. Chemically exfoliated graphene with various oxygenated functional groups bound to sp2 basal plane and edges of graphene sheet is called graphene oxide (GO). The surface sites on commercial sand used in water treatment are dominantly negative (pH = 2.7), and chemically inert. Therefore, they show a low affinity for most of the contaminants present in drinking water. However, conventional sand filters are used in water turbidity removal. Graphene oxide (GO) was synthesized using the modified Hammer’s method and purified sand was coated with GO dispersion to make super sand which can be used for many purposes including water purification. Single GO coated super sand (GO1) and multiple coated super sand (GO2, GO3, GO4, GO5) were prepared. Optimization studies were done for the fluoride removal process by super sand. Multiple coated super sand and fluoride adsorbed super sand were characterized using Scanning Electron Microscopy (SEM), energy dispersive X-ray absorption (EDXA) spectra, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD). When increasing the coating times, the Enhancement of the GO coatings on the sand surface was clearly depicted by the SEM images and later by later coatings of the GO were observed on the sand surface. Respective EDXA spectra were also taken from both samples which show higher carbon content for sand/GO5 sample than sand/GO1. EDXA spectra of the Fluoride adsorbed five times coated sand show a small percentage of F in addition to the C, O and Si in the spectrum. The FT-IR spectrum for graphite oxide shows major peaks at wavenumbers of 3427, 1744, 1630, 1186, and 875 and 576 cm -1 due to the functional groups such as –OH, C=O, C-O. More or less similar peak patterns were observed on GO coated sand and peak intensities have been decreased when increasing the coatings. A noticeable decrease of the intensity of the peak at 1070 cm -1, which is assigned to be originating from sand, is a clear indication of the formation of layers of GO covering the sand. A noticeable peak of the FT-IR spectrum of Fluoride adsorbed 3 times coated sand observed around 3500 cm-1. It may be due to the Fluoride bond with Hydrogen in the GO. The highest performance of fluoride removal is shown at pH 3.22 and 7.21 for Sand-GO-1 and Sand-GO-5, respectively. In both instances, the fluoride removal efficiency is around 70 % when 3 ppm initial fluoride was used. So finally it can be concluded that five times coated Sand-GO is most suitable for fluoride removal from the contaminated drinking water.Item The Role of Fluoride, Cadmium and Water Hardness in Drinking Water: A Critical Study of Potential Factors of Chronic Kidney Disease of Unknown Etiology (CKDu) in the Prevalence Area, Sri Lanka(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Botheju, W.S.M.; Liyanage, J.A.Chronic Kidney Disease of unknown etiology (CKDu) is a major public health problem in North Central Region in Sri Lanka, and it is receiving global attention due to the absence of clear evidence to determine the causative factors. Although indisputable epidemiological data are lacking, high concentrations of water hardness, fluoride, cadmium, and other heavy metals in drinking water could be major causes for the prevalence of CKDu. Therefore, the present investigation was carried out to assess the role of fluoride (F), cadmium (Cd) and water hardness in drinking water sources as potential risk factors for CKDu in a prevailing area of Sri Lanka. Drinking water samples were randomly collected from 30 dug wells in Girandurukotte Grama Niladhari Division (GND), Badulla District and Buddhangala GND in Ampara District (as reference sampling site) in the dry season (June 2019), Sri Lanka. Cd and F contents of the collected drinking water samples were analyzed using Inductive Coupled Plasma Mass Spectrometry and Fluoride meter respectively according to the standard procedures. Total water hardness values were calculated based on calcium and magnesium contents which were analyzed using Atomic Absorption Spectrometry. Each analysis was performed in triplicates. Results were statistically analyzed using MINITAB 17 software. Inverse distance weight (IDW) and spatial autocorrelation (Moran’s Index - MI) tools in ArcMap 10.2.2 software were used to interpolate the spatial distribution patterns of F, Cd and total hardness in collected water samples. According to the results, mean F, Cd, and total hardness values of analyzed water samples in Girandurukotte GND were 1.64±0.04 mg/L, 0.124±0.074 μg/L and 83.60±4.02 mg/L respectively. Mean F content of the analyzed water samples in the CKDu prevalence area exceeded the maximum permissible levels of SLS standards (SLS 614: 2013, F - 1.0 mg/L) whereas the total water hardness values indicated the ‘moderately hard water’ (60 to 120 mg/L). As per the results, mean Cd concentration in Girandurukotte GND consented with SLS standard limits (Cd - 3.00 μg/L). Furthermore, mean F, Cd and total hardness values in reference sampling site were 0.504778±0.076 mg/L, 0.018±0.006 μg/L and 30.76±8.06 mg/L respectively and those results complied with SLS standard limits. Mean water hardness values in the reference sampling site indicated the ‘soft water’ (0 to 60 mg/L). According to the statistical analysis, F, Cd and total hardness values in Girandurukotte GND were significantly higher compared to the reference site (P<0.05). Moran’s indices of F, Cd and total hardness in Girandurukotte GND were -0.013, -0.006, and -0.011 respectively as per the Moran’s Index Tool. Based on the results, it can be concluded that high concentrations of fluoride, water hardness and long term exposure to heavy metals such as cadmium can lead to the occurrence of CKDu prevalence. Therefore, utilization of treated water can be recommended as a preventive measure of CKDu in the study area and these findings can be used as a benchmark in the water supply design processes in CKDu affected areas.