Browsing by Author "Swarnamali, V.M.R."

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    Antibacterial Activity of Silver Deposited Vein Graphite Against Waterborne Pathogenic Escherichia coli Synthesized by Chemical Reduction Method
    (Uva Wellassa University of Sri Lanka, 2019) Kumari, T.D.D.; Swarnamali, V.M.R.; Amaraweera, T.H.N.G.; Premathilake, M.M.S.N.; Wijayasinghe, H.W.M.A.C.; Balasooriya, N.W.B.
    Graphite is one of the common materials using for the fabrication of composite materials. Graphite oxide, graphene oxide and many other materials are used as effective antibacterial substances, but most of them are expensive and need highly toxic chemicals for the synthesis. Nowadays, silver is considered as a most effective antibacterial material. Therefore, this study was focused on synthesizing cost effective less hazardous antibacterial material using silver and graphite. Graphite sample was purified by acid leaching, followed by modifying the surface with Conc. HNO3. The silver graphite composite material was synthesized using AgNO3 as precursor and tri-sodium citrate as reducing agent. X-ray diffractometry and Scanning electron microscopy investigations of the synthesized silver graphite composite revealed that the pure crystalline nano silver particles were deposited on the graphite surface. Antibacterial efficacy of the synthesized material was investigated using waterborne pathogenic Escherichia coli. The antibacterial test was carried out against E. coli using prepared composite samples according to the shake flask test. A commercial antibiotic (Ofloxin-200 mg) was used as the positive control. The samples were drawn at times 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 5 and 6 hours by counting the number of surviving bacterial colonies on Eosin Methylene Blue (EMB) Agar, using plate count method according to standard procedures. After 24 hours, the results showed that surviving bacterial colonies contained in counted petri plates of all the synthesized composites with different Ag: Graphite ratios were reduced, with the time in an efficiency of over 98%. Therefore, this study suggests that Ag-vein graphite composite synthesized via chemical reduction method can be effectively used as an antibacterial agent against E. coli.
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    Removal of Cu (Ii) Ions from Industrial Waste Water Using Low Cost Biosorbent Prepared from Jackfruit (Artocarpus Heterophyllus) Leaf Powder
    (Uva Wellassa University of Sri Lanka, 2017) Swarnamali, V.M.R.
    The presence of heavy metals in industrial waste water has become a major concern of environmental pollution. In recent years, various technologies for heavy metal removal from industrial wastewater have been developed. In this regard, adsorption of heavy metals on solid surfaces has gained a growing interest. Activated carbon is widely used to adsorb heavy metal ions, but the high cost of activated carbon restricts its use in developing countries. As a result, the process of heavy metal removal by adsorption has diverted to the use of lower cost adsorbents. The main objective of this study is to investigate the efficiency of Cu (II) ion removal from wastewater by using jackfruit leaf powder (JLP) and chemically modified .JLP. It is much suitable to use JLP as a biosorbent because of its abundant availability without any commercial value and the ability to be disposed after the use without need for expensive regeneration. Batch adsorption technique was utilized for the removal of Cu (II) ions in aqueous solution by JLP under different experimental conditions. The effect of various process parameters including _biosorbent dose, contact time, pH, particle size and various initial copper concentration were investigated and optimized. Maximum sorption for copper was reached at pH 5. The efficiency of adsorbent for copper removal was 98.8% for dilute solutions at 1g/50m1 adsorbent dose. Equilibrium data were successfully fitted to the Langmuir model. The maximum adsorption capacity onto JLP was found to be 48.85mg/g for Cu. JLP was treated using HNO3 acid to chemically modify its surface. The adsorption efficiencies of untreated JLP and HNO3 treated JLP were compared. Treatment using HNO3 has slightly increased the Cu ion removal efficiency of the adsorbent. The results confirm that untreated JLP is a promising biosorbent for the removal of Cu (II) due to its high efficiency, economic feasibility and simplicity of preparation. Keywords: Industrial wastewater, Jackfruit leaf powder, Batch adsorption technique, Adsorption, Biosorbent.