Browsing by Author "Jayawardena, S."

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Corrosion inhibition of mild steel using Momordica dioica extract in acidic medium
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Pradeepani, E. P. M.; Jayawardena, S.
Corrosion is a natural phenomenon where refined metals transform into more stable substances like metal oxides, sulfides, or hydroxides, resulting in the metal's degradation. Metals higher in the reactivity series, like iron and zinc, are more prone to corrosion, indicating that corrosion involves the oxidation of metals. When an electron acceptor or depolarizer is present, corrosion occurs as an electrochemical process, with oxidation and reduction reactions occurring at different sites on the metal surface. For example, iron corrodes to form a visible reddish-brown layer of iron oxide. Oxygen and moisture are key factors that facilitate corrosion. This degradation can compromise the desired properties of the metal, highlighting the importance of preventive measures to preserve these properties. Mild steel, a type of low-carbon steel, is widely used in various industries. However, its main disadvantage is its vulnerability to corrosion. To improve the corrosion resistance of mild steel, several methods can be utilized, with the addition of inhibitors being the most straightforward and effective. Inhibitors are categorized into three types: cathodic, anodic, and adsorption inhibitors, with natural inhibitors or plant extracts falling into the adsorption category. This study employed electrochemical techniques to examine the effect of methanol plant extract from Momordica dioica on the corrosion inhibition of mild steel. The corrosion inhibition properties of the plant extract were assessed using cyclic voltammetry, which measures the current in an electrochemical cell under a constant potential. An acidic corrosive medium was prepared using a 1 M HCl solution, with the concentration of the plant extract inhibitor in this medium varying from 2% to 8% v/v. This range was chosen based on prior studies that indicated optimal inhibition effects within this concentration. To achieve the same current flow through the inhibitor solutions as compared to control solutions, the applied potential difference had to be increased, indicating resistance to current flow in the inhibitor solutions. The components in the inhibitor solution adsorb onto the surface of the mild steel specimens, forming a protective layer between the mild steel and the corrosive medium. The study confirmed that concentrations within this range provided a significant increase in corrosion resistance, as evidenced by the higher required potential values to maintain the same current flow in inhibitor solutions compared to blank solutions. This suggests that Momordica dioica extract effectively inhibits mild steel corrosion in acidic environments.
Fabrication of reduced Graphene oxide - Zinc oxide electrode for supercapacitor applications
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Thilakarathne, W. A. N. D.; Jayawardena, S.
Scientists are concentrating on developing superior hybrid supercapacitors as an alternate form of energy storage in response to the depletion of fossil fuel sources to fulfill the rising demand for energy storage. In this study, supercapacitive properties of reduced graphene oxide (rGO)-Zinc Oxide (ZnO) hybrid composites were analyzed, where ZnO nanoparticles were prepared using the sol-gel method with zinc acetate as the precursor and rGO was obtained via thermal reduction of graphene oxide synthesized using the modified Hummer’s method. Three rGO-ZnO nanocomposites were prepared with varying weight compositions of rGO at 20%, 50%, and 80% content using a cost effective ultrasonic assisted method as an electrode material for supercapacitor application. Thin layers of each hybrid material, ZnO and rGO were coated on FTO glasses using the interfacial method to fabricate the electrodes. The prepared nanocomposites, ZnO, and rGO were characterized using XRD, FESEM, and FTIR. The XRD was used to confirm the formation and the structure of rGO-ZnO nanocomposites as well as the formation of rGO. FESEM images provided compelling evidence illustrating the successful attachment of ZnO nanoparticless onto the surface of rGO sheets. Through FTIR analysis, the presence of specific functional groups in ZnO, rGO and the hybrid composites were determined and thereby confirmed successful hybridization of the materials. Moreover, the open circuit potential and specific capacitance measurements were conducted for each hybrid composite, ZnO and rGO to evaluate the potential superiority of these materials as supercapacitors. Open circuit potential value for 50% rGOZnO hybrid composite has the highest value among the three composites, which is 148 mV. Cyclic voltammetry was done in the potential range of -0.1 V to 1 V under 50 mVs-1 sweep rate using KCl as the electrolyte. The specific capacitance for 20%, 50%, and 80% rGO-ZnO nanocomposites are 122 Fg- 1, 224 Fg-1, and 62.5 Fg-1 respectively. Among the three rGO-ZnO composites, 50% composite has the highest specific capacitance, which is greater than the specific capacitance of 205 Fg-1 for ZnO and 164 Fg-1 for rGO, confirming its superiority as a supercapacitor material. This is due to the positive synergistic effects arising from the integration of pseudocapacitance and double-layer capacitance. These electrochemical methods suggest that hybridizing rGO and ZnO to 50% rGO composition makes an exceptional electrode material for supercapacitor application.
Syncretism of the God Katharagama, at the Shrine in the Jungle
(University of Kelaniya, 2015) Jayawardena, S.; de Alwis, M.
The divine power of Katharagama Deviyo consists of the syncretism of God of Love, God of War and the God protecting the water tanks in the jungles. He is referred to as Murugan, Skander , Shanmukam , and Minneriya Deviyo etc. The legend as God of Love conveys how Katharagama deviyo at meditation was disturbed by sighting Valli, later his 2nd consort. The annual perahera celebration is escorting the divine on elephant as veneration, to Valli Amma kovil situated right opposite the Maha Devale, and back. The syncretism of God of War at the maha devale reveals the legend of deified Alexander the Great , God Skander of north India and Kande Yaka of the Vedda aborigines. Katharagama deviyo warshiped as a young boy is narrated in the legend of God Murugan of South India and is associated with Devayani Amma, the 1st consort. Another annual celebration is performed for him at the Katharagama shrine on another month of the year. Finally the syncretism of Minneriya deiyo, the god king of Minneriya is revealed in the legend as the one protecting water tanks in the jungles and is preserved at the annual celebrations of the Katharagama shrine at Hurulu weva in the Anuradhapura district. (Uran Keliya) Hunting the wild boar which reveals this legendry story of syncretism is enacted annually as part of the intangible heritage of this shrine.