Browsing by Author "Priyantha, N."

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Acidification and neutralization potentials of rainwater at University of Peradeniya
(Faculty of Graduate Studies, University of Kelaniya, 2015) Kumari, D.M.R.A.; Liyandeniya, A.B.; Priyantha, N.
Constituents present in rainwater affects compositional changes leading to acidification or neutralization, and hence the quantification of constituents in rain water. In this respect, the purpose of the present study was to establish a relationship between acidification and neutralization potential of rainwater particulates via bulk precipitation and ambient air quality via dry deposition. Analysis of 30 samples of bulk deposition and 11 samples of dry deposition collected during the four month period from May to September, 2013 at the University of Peradeniya premises for main ions responsible for acidification and neutralization reveals that Na+, Mg2+, Ca2+, K+, NH4 +, NO3  and SO4 2- were major ions present in the samples, and further, Ca2+ and NH4 + dominated constituents for neutralization of rainwater acidity, while NO3  and SO4 2- led to high level of acidity. The regression analysis between the summation of the concentrations of NO3  and SO4 2− vs. the summation of the concentrations of Ca2+ and NH4 + reveals that there is a significant correlation with r = 0.66 for bulk precipitation although the correlation is not good for dry deposition with r = 0.38. This difference can be attributed to the different deposition rates of particulates present in ambient air. . Regression analysis applied on each variable demonstrates that, Ca2+ can be present as CaSO4 and Ca(NO3)2 and NH4 + can be present as (NH4)2SO4 and NH4NO3. Further analysis of the results of compositional variables indicates that 53.3% of SO4 2 can be explained by Ca2+ and NH4 +in bulk precipitation, among which 47.5% appears as CaSO4 and only 5.8% as (NH4)2SO4. Further, only 19% of the NO3  is explained by both Ca2+ and NH4 + out of which 6% appears as Ca(NO3)2 and 13% as NH4NO3. In dry deposition, 33.5% of SO4 2 and 95.4% NO3  were explained by the above two cationic independent parameters, and 33% of SO4 2 appears as CaSO4 and only about 0.5% as (NH4)2SO4. Among 95.4% of explained NO3 , 39.2% appears as Ca(NO3)2 and 56.2% NH4NO3. The linear regression analysis suggests that, Ca2+ is involved in a higher percentage (62.5%) for the neutralization process, whereas the involvement of NH4 + is at lower level of 37.5%.
Adsorption of Methylene blue on leaves of Guinea Grass (Panicum maximum)
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Weerathunga, M. A. O. Y.; Dinusha, M. D. N.; Karunathilaka, R. M. M. K.; Priyantha, N.
Massive amounts of industrial pollutants released to the environment because of industrial expansion, which is needed to fulfil the demands of the ever-increasing population, have become a global threat. Consequently, the use of effective treatment methodologies is a necessity, and such methodologies should not only be economical, but also be environmentally friendly. In this respect, biosorption has become a sound alternative for removing toxic industrial dyes. Although many biosorbents have been researched, attempts on their practicability have not been much attended to. This study focuses on the use of Guinea grass (Panicum maximum) leaves, a biosorbent that has not been extensively investigated, for the removal of methylene blue (MB), a common dye used in textiles and other industries. The fibrous nature of this biosorbent would make it suitable for surface modification as needed. Biosorbent for this investigation was prepared by mature leaves of guinea grass, collected randomly from Kandy district, cut into 1.0 – 2.0 cm lengths followed by thorough washing with tap water and deionised water, and then crushing followed by thorough washing again with deionised water until the supernatant became colourless. Samples were then dried at 120 °C for 2.0 h. Parameter optimisation was conducted using 50.0 mL of 10 ppm MB solutions, with one parameter varied at a time while keeping the others unchanged. This process led to optimal values of 0.25 g of adsorbent dosage, 20 minutes of shaking time, 20 minutes of settling time, and a pH of 5.66, based on absorption measurements recorded at 664 nm, achieving an excellent removal rate of 97.5% is obtained. Moreover, this biosorption system reaches equilibrium in a very short time owing to the fibrous nature which is advantageous for extension of bench work toward large-scale removal of MB from contaminated industrial effluents. It is further determined that the transfer of MB from solution to the biosorbent surface follows the pseudo secondorder kinetics model with a high correlation coefficient (R2) of 0.9889.
Characterization of trace metal concentration (Al, Fe, Mn, Cu, Zn, Pb) of bulk precipitation in Kandy district, Sri Lanka
(Faculty of Graduate Studies, University of Kelaniya, 2015) Liyandeniya, A.B.; Priyantha, N.; Deeyamulla, M.P.; Wickramasinghe, W.G.R.C.
The atmospheric precipitation is an important phenomenon in which pollutants are scavenged from the atmosphere. Wet deposition accounts for rain, fog and snow, while dry deposition is the accumulation and fallout of aerosol particles and gases without dissolution of water. It is very important to have baseline data on the chemical composition of the atmosphere to take regulatory measures to control atmospheric pollution in Sri Lanka. The main objective of this study was thus to determine selected trace metals (Al, Fe, Mn, Cu, Zn, Pb) in bulk precipitation samples collected weekly in three sampling locations, namely the University of Peradeniya premises, Polgolla and Kandy for a period of one year from August 2013 to July 2014. Trace metals were determined in filtered and preserved rainwater (bulk) samples using Graphite Furnace Atomic Absorption Spectrometer, and volume weighted mean values of selected trace metals were subsequently calculated. Kandy municipality showed the highest contamination and followed the sequence of Al > Zn > Fe > Mn > Cu > Pb and volume weighted mean concentrations of above sequence are 53.6 μg L-1, 38.0 μg L-1, 5.8 μg L-1, 5.4 μg L-1, 4.2 μg L-1, <2.0 μg L-1. Polgolla dam site also recorded some trace metal contamination following the sequence, Al > Zn > Fe > Cu > Mn > Pb and volume weighted mean concentrations of above sequence are 51.5 μg L-1, 40.5 μg L-1, 4.8 μg L-1, 2.4 μg L-1, 1.5 μg L-1, <2.0 μg L-1. Despite less industrialization and less traffic congestion, Peradeniya University premises also showed some extent of atmospheric trace metal contamination following sequence of Al > Zn > Cu > Fe > Mn > Pb and volume weighted mean concentrations of above sequence are 46.1 μg L-1, 44.3 μg L-1, 2.6 μg L-1, 1.9 μg L-1, 1.7 μg L-1, <2.0 μg L-1. Principal component analysis (PCA), used to predict possible sources for the above trace metal contaminants, indicates that Mn, Cu and Zn are originated mainly from anthropogenic activities, such as fossil fuel combustion and burning municipal waste. Al and Fe are mainly originated from natural sources as those metals are the major components of alumino-silicate based earth crust.
Chemical composition of rainwater at three sites in Kandy/Peradeniya, Sri Lanka, and its effect on air pollution
(2023) Madhushani, L.S.; Dharmapriya, T.N.; Dharaka, B.D.P.; Deeyamulla, M.P.; Priyantha, N.
The composition of atmospheric precipitation, an important criterion considered to account for air pollution, is usually determined with respect to wet precipitation and dry precipitation, or as bulk deposition in combined form. Although rainwater quality should be continuously monitored in order to understand the extent of air pollution, such investigation lacks attention in Sri Lanka. This study was thus aimed to determine the composition of bulk deposition collected weekly for a period of eleven months from February to December 2019, in three sampling locations; namely the University of Peradeniya (UOP), Kandy City Central (KCC) and Polgolla. Parameters quantitatively determined, rainfall, pH, conductivity, salinity, total dissolved solids (TDS), hardness, anions: Cl−, NO3−, SO42−, F−, PO43− and trace metals: Zn, Fe, Al, Mn, Cu, Pb, Cr, using standard analytical methods indicated that the KCC site showed the overall highest degree of air pollution followed by UOP and Polgolla sites. Nevertheless, no acid rain occurrences were observed during the sampling period in any of the three sites according to pH measurements. Anions of bulk deposition showed the sequence Cl−> SO42− > NO3−in all three sites with Cl−and SO42- being dominant anions. Furthermore, trace metals of bulk deposition showed the sequence, Zn > Fe > Al > Mn > Cu > Pb, in all three sites. Bulk precipitation data analyzed using Pearson correlation showed high positive significant correlations between conductivity and salinity, conductivity and TDS, and salinity and TDS, among all water quality parameters. Among trace metals, the highest positive significant correlation was found to be between Fe and Mn at the UOP Site. The highest positive significant correlation was between Al and Zn at the KCC site. No correlation between trace metals was found at the Polgolla Site.
Comparative study on the sustainable utilization of banana flowers mediated nanomaterials for pigment dye degradation via photo catalysis
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Gamage, V.; Thiripuranathar, G.; Nishshanka, U.; Priyantha, N.; Goonatilleke, M. D.; Guiton, B. S.; Jayanetti, S.
Dyeing is prevalent in the textile industry; however, they are often harm to the environment. Photodegradation plays a crucial role in dye removal by utilizing nanoparticles (NPs) as catalysts. These NPs effectively break down harmful dyes, thereby significantly reducing their environmental impact. Employing biogenic NPs not only reduces environmental burden associated with waste disposal but also enhances resource efficiency and conservation efforts. This study focuses on synthesizing silver NPs (Ag NPs), zinc oxide NPs (ZnO NPs), and silver-zinc oxide nanocomposite (Ag-ZnO NCs) derived from Banana Flower (BF), with a specific focus on evaluating their photocatalytic efficacy against IC orange pigment dye (PD), a commonly employed textile dye. The optimal conditions for synthesizing Ag NPs, ZnO NPs, and Ag-ZnO NCs with higher yields were identified by varying the conditions, such as ion precursor concentration, ratio of plant extract to ion solution, irradiation methods, pH, and incubation time. UV-Vis spectroscopy, FT-IR, SEM, TEM, EDS, and XRD analyses were utilized to characterize the NPs and NCs. The synthesized NMs were confirmed by surface plasmon resonance peaks: 400-430 nm for AgNPs, 350-360 nm for ZnO NPs, and 350–450 nm for Ag-ZnO NCs. FT-IR analysis identified bioactive compounds in the phytoextracts acting as reducing, capping, and stabilizing agents. Also, the stretching mode of the Zn-O bond in the range of 500–700 cm-1 confirms the synthesis of ZnO NPs. SEM analysis confirmed successful formation of Ag NPs, ZnO NPs, and Ag-ZnO NCs, with a spherical shape, flake, and nanoflower-shaped NMs, respectively. TEM images showed the coexistence of Ag on ZnO for NCs, with an average particle size of 97.1 nm. Further, the BF-mediated Ag NPs and ZnO NPs showed the particle size of 64.6 nm and 84.3 nm, respectively. XRD analysis indicated a hexagonal wurtzite structure for ZnO NPs and a face-centered structure for Ag NPs and both structures were present in Ag-ZnO NCs. The EDS analysis confirmed the chemical elements as Ag for Ag NPs and Zn and O for ZnO NPs while all three elements for NCs. Under the optimum operational conditions (pH, catalytic load, and dye concentration), the BF-mediated NMs were studied for the degradation of PD. The ZnO NPs synthesized using BF demonstrated exceptional photodegradation efficiency of 93.8 % at 7 hours while for Ag NPs and the NCs it was 10.6%, and 87.9 % respectively. This exceptional performance of BF-mediated ZnO NPs are due to the wide-bandgap semiconductor capabilities of the ZnO NPs, aligning with the absorption of solar light. In contrast, Ag NPs have lower photodegradation efficiency because of their less effective charge separation and lower generation of reactive oxygen species. Thus, the findings of this study unveil the promising potential of NMs synthesized with BF as a sustainable solution for advancing textile and wastewater remediation.
Comparison of adsorption characteristics of Ni(II) on fibres of Agave americana and areca nut husk
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Wickramasinghe, W. R. M. N. R.; Vithana, P. V. A. S.; Karunathilaka, R. M. M. K.; Priyantha, N.
Heavy metal contamination is of major concern at present due to its adverse impacts on humans and the environment. Among many heavy metal remediation methods, biosorption has become attractive in the recent past due to its low-cost and environmentally sustainable nature. Nevertheless, fibrous biosorbents have not been much explored, especially for the removal of Ni(II) species. Though Ni is a micronutrient that contributes to certain cellular functions in the human body and plants, higher concentrations of it could impose adverse health effects as well as ecological damage. Hence, Ni remediation should be carried out before releasing industrial effluent to the environment. This work is thus based on a comparative study to investigate the adsorption potential of Agave americana fibre and Areca nut husk fibre for the removal of Ni(II) ions from aqueous solutions. This study aims to optimize experimental parameters varying one parameter at a time throughout a broad range keeping others constant for the two biosorbents separately. Both Agave americana fibre and Areca nut husk fibre exhibit significant adsorption capacities toward the adsorption of Ni(II) ions with average removal of 90.39% and 93.27%, respectively, in batch experiments, conducted using 10 mg L-1 Ni(II) solution under optimized conditions of 60 min shaking time, 20 min settling time, ambient pH, ambient temperature and 150 rpm agitation speed for an optimum dosage of 20.00 g L-1 of the biosorbents. Adsorption isotherm studies, conducted using Ni(II) solutions of initial concentrations in the range from 10 mg L-1 to 350 mg L-1, show that the Langmuir model is a better fit for the two types of fibre with higher regression coefficients of 0.9836 and 0.9937 than those of the Freundlich model for Agave americana and Areca nut husk fibre, with the maximum adsorption capacities of 1.03 mg g-1 and 1.68 mg g-1 respectively. These studies could be extended for the design of treatment plants for large-scale removal of Ni(II) ions from contaminated water.
Monitoring of Rainwater Quality in Kandy and Peradeniya, Sri Lanka
(2023) Wijewantha, H.L.S.S.; Dharaka, B.D.P.; Priyantha, N.; Deeyamulla, M.P.
The composition of atmospheric deposition is a measure of air quality, an important aspect of the health of the ecosystem. Consequently, continuous monitoring of atmospheric deposition is crucial to obtain remedial measures to avoid undesirable aspects that would affect living things. In this context, the objective of this study was to determine the rainwater quality at selected locations in Kandy and Peradeniya area of Sri Lanka, namely, Kandy city, Polgolla and University of Peradeniya (UOP), and to identify possible correlations between quality parameters through statistical means. Forty (40) rainwater samples from the UOP site and seven (07) samples each from the Kandy city and Polgolla sites were collected from the 18th May 2020 to 28th April 2021. The volume weighted average (VWA) pH values of UOP, Kandy and Polgolla sites were determined to be 7.44, 7.19 and 7.19, respectively, and moreover, acid rain (pH < 5.6) occurrences were not detected during the sampling period. The VWA values of rainfall, conductivity, salinity, TDS and hardness at the UOP site were 40.12 mm, 51.93 µS cm− 1, 0.0300 ppt, 26.59 mg L− 1 and 13.55 mg L− 1, respectively. The corresponding values of the Kandy city site were 16.52 mm, 64.04 µS cm− 1, 0.0361 ppt, 30.80 mg L− 1 and 19.49 mg L− 1, respectively; and those of the Polgolla site were 33.10 mm, 53.90 µS cm− 1, 0.0310 ppt, 25.76 mg L− 1 and 19.31 mg L− 1, respectively. The VWA values of conductivity, salinity, TDS were the highest at the Kandy city site. Further, the VWA values of hardness at Kandy and Polgolla were approximately equal, probably due to spring of Ca2+ and Mg2+ particulates from the dolomite quarry located in Digana area. The most prominent anion was identified as Cl− in bulk deposition at all three sites, while NO3− showed the lowest concentration of all sites. Moreover, very strong significant positive correlations were identified between conductivity-TDS, conductivity-salinity, conductivity-hardness, TDS-hardness, TDS-salinity, salinity-hardness, SO42− - Cl−, and NO3− - Cl− according to relevant Pearson correlation coefficients. It is thus concluded that the pollutants come from the same sources, either natural or anthropogenic.