Browsing by Author "Perera, A. D. L. C."

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Comparative desorption efficiency of Cd(II) and Pb(II) from used plasma-functionalized coconut coir biochar
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) De Alwis, B.; Rathnayake, I.; Munaweera, I.; Perera, A. D. L. C.; Jayasinghe, S.
This study investigates the desorption of Cadmium (Cd(II)) and Lead (Pb(II)) ions from used plasmafunctionalized coconut coir biochar (PBC), a process crucial for wastewater treatment. The improper disposal of used adsorbents laden with Cd(II) and Pb(II) contributes to environmental pollution, making this research significant. Coconut coir biochar (BC) was prepared using coconut coir dust via pyrolysis at 500 °C for 3 h under controlled N2 environment. The BC was subjected to atmospheric air plasma treatment (AAPT) for 30 min to produce PBC. Both BC and PBC were characterized using Fourier Transform Infrared Spectroscopy (FTIR), point of zero charge (pHPZC), methylene blue (MB) and iodine number, moisture and ash content. The quantitative analysis was performed using a flame atomic absorption spectrometer (FAAS). At pH 7, PBC adsorbs 130.00 mg g-1 of Cd(II) from a 250 ppm solution, and at pH 5, it adsorbs 80.97 mg g-1 of Pb(II) from a 500 ppm solution within 1 minute. In comparison, BC shows lower adsorption capacities of 96.00 mg g-1for Cd(II) and 50.01 mg g-1for Pb(II) under the same conditions. Desorption experiments were conducted using 25.0 mg of Cd(II) and Pb(II) adsorbed BC and PBC, which were shaken with HNO3 as the desorbing agent at 30 °C. The pH and contact time were optimized to evaluate the maximum desorption capacity of both BC and PBC. The maximum desorption capacity of Pb(II) for PBC was 73.80 mg g-1 within a contact time of 15-minute and for Cd(II), it was 8.91 mg g-1 under the optimum conditions of pH 1 and 1-minute contact time. For BC maximum desorption capacity of Pb(II) was 47.63 mg g-1 with a 30-minute contact time and for Cd(II), it was 8.54 mg g-1 under the pH 1 and 1-minute contact time. The desorption percentage from the adsorbed amount was 91.14% for Pb(II) and 6.85% for Cd(II) for PBC. For BC, it was 95.24% for Pb(II) and 8.83% for Cd(II). These results highlight the potential of PBC as an efficient adsorbent for the remediation of Pb(II) and Cd(II) in wastewater, demonstrating high efficiency in Pb(II) desorption but limited efficiency in Cd(II) desorption.
Developing a natural fungicide from O/W Emulsion using essential oils and MgO nanoparticles
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Wewalage, I. U.; Perera, A. D. L. C.; Jayasinghe, S.
For the farmers and cultivators to boost their crop yield in cultivation, preventing fungal attacks is an indispensable measure. In Sri Lanka as well as worldwide, vegetable and fruit cultivation and also ornamental plant cultivation are being extensively attacked by diseases like powdery mildew, downy mildew, grey mold, black spot disease, early blight disease, late blight diseases, etc., which are caused by fungal pathogens. Here in, a Pickering emulsion (PE) was formulated using trace amounts of magnesium oxide (MgO) nanoparticles (NPs) and cinnamon leaf (CL) oil as a natural fungicide. MgO NPs were synthesised by the sol-gel method using magnesium chloride (MgCl2) and sodium hydroxide (NaOH). The experimental yield of MgO NPs was achieved as 73.8%. The PE was formulated by mixing CL oil, deionised water and MgO NPs to get a homogeneous mixture. A polysorbate 80 emulsifier was used to enhance the stability of the emulsion. The most suitable emulsion system was comprised of 20% CL oil and 80% deionised water by mass percentage, and it was doped with 50 mg of MgO NPs to achieve a total mass of 50 g. To check the efficacy of the formulated PE, an antifungal susceptibility test was conducted against the fungus Aspergillus niger, a widely used model organism. Based on the inhibition zones, it was determined that the 1:10 dilution of the formulated PE exhibits the Minimum Inhibitory Concentration (MIC) required to inhibit the growth of the fungus Aspergillus niger, relative to the known positive standard, Fluconazole, at a concentration of 15,000 ppm. In the field, the diluted emulsion should be sprayed on the crops once every five days to get the best results. This method provides a natural and effective solution for managing fungal infections in cultivation, potentially leading to increased crop yields and healthier plants. A unique application for sustainable agriculture is offered by the combination of MgO NPs and CL oil in PE, which act as natural antifungal agents to lessen the need for synthetic fungicides. Future directions could investigate the feasibility of commercialising emulsion, particularly aimed at identified plant fungal pathogens, by integrating economically viable essential oils
Enhancing the water solubility of curcumin by encapsulating in Carrageenan using excipients
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Weerasinghe, N. N.; Jayathilake, N. S.; Perera, A. D. L. C.; Jayasinghe, S.
Curcumin is a polyphenolic compound known to alleviate several ailments and can be used as a drug. However, its practical application as a nutraceutical/drug is limited due to problems such as high hydrophobicity, high photosensitivity, and low bioavailability. Therefore, encapsulation of curcumin into nanoparticle (NP) carriers has been developed to increase the aqueous (physiological) solubility of curcumin. Carrageenan, a natural polysaccharide, is widely used in the formulation of nanoparticles as a controlled-release drug delivery system. In this study, a water-soluble product was developed by encapsulating curcumin in a carrageenan matrix using surfactant excipients (Tween 20 & Tween 80). Encapsulation provides protection to drugs against physiological degradation and ensures effective release at targeted sites. The role of the surfactant excipients is to help increase the water solubility and the stability of the particles. Curcumin-encapsulated carrageenan nanoparticles were prepared via the ionic gelation method, varying the mass of the curcumin, the mass of the carrageenan, and the type of excipient used. A water solubility test for NPs was conducted to evaluate the solubility of NPs in water. The average particle sizes of the NPs were obtained as 470.4 nm. The highest encapsulation efficiency of curcumin-encapsulated carrageenan NPs was calculated as 90% for NPs prepared using both excipients. In-vitro release studies were performed on the drug-loaded NPs and the results showed that the release was pH dependant and had a high release (50%-60%) of curcumin in intestinal fluid compared to free curcumin. Confirmation of successful encapsulation and characterisation of the curcumin-encapsulated carrageenan NPs was carried out using fourier transform infrared spectroscopy (FTIR) analysis. The stability of the NPs against photodegradation and thermal degradation was checked using the accelerated shelf life method. Scanning electron microscope (SEM) images of both nanoparticles prepared using both excipients displayed a nearly spherical shape. These empirical data proved that newly formulated NPs could preserve the activities of curcumin and hence could be used in functional food production to increase the nutritional value without changing texture and colour. Also, this study successfully demonstrated that even though the hydrophilic–lipophilic balance (HLB) values of tween 20 (16.7) and tween 80 (15.0) are different, both are equally effective in enhancing the solubility, encapsulation efficiency, and stability of curcumin-loaded carrageenan NPs. Future studies could investigate the scalability of the nanoparticle formulation process for industrial applications and explore the potential of combining these NPs with other bioactive compounds to develop multifunctional delivery systems.