Browsing by Author "Munaweera, I."

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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.
Enzyme-assisted extraction of cinnamon (Cinnamomum zeylanicum) bark oil and its effect on extraction yield and quality
(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Sethunga, S. M. M. C.; Ranaweera, K. K. D. S.; Munaweera, I.; Gunathilake, K. D. P. P.
Cinnamon (Cinnamomumzeylanicum) is a highly significant spice, native to Sri Lanka and its bark oil is used as a fragrance, flavor in many applications and in the pharmaceutical industry. The volatiles are mainly extracted using traditional distillation methods such as hydro-distillation and steam distillation. In this study, the novel extraction method, Enzyme-assisted Distillation (EAD) is studied to extract the volatile compounds from plant matrices. Aqueous Enzyme solution of Viscozyme and α-amylase were prepared in different concentrations of 0.25%, 0.5%, 1% ((w/w) of raw materials). In the method, the crushed plant materials were soaked in a prepared enzyme solution (pH 4-5) and incubated at 45+2 °C for 90 min followed by hydro-distillation for 6 hours. The same procedure was followed for the control sample without enzyme pretreatment. Cinnamon Bark Oil (CBO) yield was determined for all the samples and GC-MS analysis was carried out to analyze Trans-Cinnamaldehyde Content (TCC) in the prepared samples. The CBO yield and the TCC of the pre-treated samples with enzymes were significantly higher (P < 0.05at 95% confidence level) compared to the control (1.4487±0.0033% CBO yield, 57.095±0.593 % TCC). Amidst various treatments, which were done using different types of enzymes and different concentrations, viscozyme treated sample showed significantly higher CBO yields of 1.6369±0.0019% and 1.6362±0.0022% at 0.5% and at 1% concentrations respectively. TCC was significantly higher in same concentrations of viscozyme; 67.577±0.288% at 0.5% and 67.623±0.080 at 1%. The mixture of viscozyme and α-amylase concentrations showed high CBO yields and trans-cinnamaldehyde content than α-amylase in all concentrations. Therefore, the overall study reveals that viscozyme enzyme is performing better compared to α-amylase enzyme as a pretreatment for cinnamon bark oil distillation. This happens due to the disruption of the cell wall structure in cinnamon after treating with vicozyme, which is composed of cellulase and pectinase than the treatment with α-amylase. Further, the study demonstrated that the 0.5% Viscozyme concentration is the optimum concentration for treating cinnamon bark. The application of Enzyme-assisted extraction substantially improved the oil yield compared to traditional methods. The overall results of this study reveal that EAD could be effectively used in the spice industry to enhance the extraction yield as well as the quality of cinnamon bark oil in an economical way.