Browsing by Author "De Silva, R.C.L."

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Activation of wood biochar and red brick using natural coconut vinegar
(Faculty of Science, University of Kelaniya, Sri Lanka, 2020) Malka, U.K.M.; De Silva, R.C.L.; De Silva, D.S.M.; Chandrajith, R.
Number of studies have been carried out to determine the efficiency of strong oxidizers in activating natural raw materials used in low cost water purification processes. However, rural communities find it difficult to acquire most of such chemicals. Therefore, this study was aimed to determine the ability of natural coconut vinegar, which is a common domestic acidic solution, in activating abundantly available potential water purifying materials to reduce calcium (Ca2+) ions from water, further reducing the water hardness. In this study mature barks of Glyricidia (Glyricidia sepium), Gadumba (Trema orientalis) and Ipil Ipil (Leucaena leucocephala) were collected and air dried. These were carbonized (400-450 °C) in a closed vessel (2 hours) to produce biochar. Both biochar and brick particles in the range of 2.0-5.6 mm were selected for the analysis. For the activation these samples were soaked in natural coconut vinegar (biochar/brick: vinegar, 1:2 V/V) for 24 hours and completely dried in an oven (120 °C) for 3 hours. Laboratory scale glass columns (2 cm in diameter) were used to calculate Ca2+ adsorption and retaining capacities. Filtrates were analyzed for Ca2+ using flame photometer. Ca2+ adsorption and retaining capacities of each material were calculated per unit bulk volume of the material. Each test was duplicated, and the average was recorded. Untreated red brick and biochar of Glyricidia, Gadumba, Ipil Ipil showed Ca2+ adsorption capacities of 0.44, 0.30, 0.31, 0.27 mg cm3 and retaining capacities of 0.19, 0.01, 0.02, 0.02 mg cm-3 respectively. Activated red brick and biochar of Glyricidia, Gadumba and Ipil Ipil showed Ca2+ adsorption capacities of 0.76, 0.58, 0.68 and 0.63 mg cm-3 and retaining capacities of 0.25, 0.20, 0.23 and 0.15 mg cm-3 respectively. Increase in Ca2+ adsorption and retaining capacities were observed in all the materials tested after activation with vinegar. Further studies are continued to use the vinegar activated natural materials in a low-cost domestic drinking water purification process.
Calcium ion Adsorption Capacities of Potential Water Purifying Materials- Red Brick and Biochar of Glyricidia (Glyricidia sepium), Gadumba (Trema orientalis), Ipil Ipil (Leucaena leucocephala)
(International Postgraduate Research Conference 2019, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2019) Malka, U.K.M.; Suriyaarachchi, S.A.A.K.; S.A.A.K., D.S.M.; De Silva, R.C.L.
This is a preliminary study on several locally available potential water purifying materials for their Ca2+ adsorption capacity. According to literature, researchers have found a number of locally available clay and biochar materials with high metal adsorption. However, these studies do not provide satisfactory information about the life span and the adsorption and retaining capacities of the filter beds as it gets gradually saturated. The main objective of this study is to further examine and modify already explored materials for the development of a cheap, simple, effective and renewable domestic water filter for the dry zone of Sri Lanka. In this study red brick and biochar of Glyricidia (Glyricidia sepium), Gadumba (Trema orientalis), Ipil Ipil (Leucaena leucocephala) were considered which are commonly found in the dry zone. Plant materials were burned (~400 ºC) to produce biochar in a closed vessel on fire for 2 hours. Particles in the range of 2-5.6 mm were selected for analysis. A laboratory scale filter unit was prepared with a glass column (diameter 1.8 cm) and the sample materials were packed individually and examined for Ca2+ adsorption by leaching a Ca2+ solution (400 ppm) through the column until saturation. After saturation Ca2+ was desorbed from the column with de-ionized water. Effluents were analyzed for Ca2+ by using flame photometer. Calcium ion adsorption capacity of each material was calculated per unit bulk volume of the material. Red brick showed the highest Ca2+ adsorption capacity of 0.44 mg cm-3. Biochar of Glyricidia, Gadumba and Ipil Ipil showed Ca2+ adsorption capacities of 0.26, 0.26 and 0.18 mg cm-3, respectively. Retaining capacity of Ca2+ was also calculated as the difference of adsorbed and desorbed Ca2+ amount per unit volume. Red brick showed the highest Ca2+ retaining capacity of 0.26 mg cm-3. Biochar of Gadumba showed a Ca2+ retaining capacity of 0.04 mg cm-3 while Glyricidia and Ipil Ipil have not shown any significant retaining of Ca2+. Optimization of the filter bed conditions and using them in a practical set up are intended to be carried out.
Mapping of Water and Soil Quality Parameters in the Gampaha-Ihalagama East and Eldeniya East Grama Niladhari Divisions, Sri Lanka
(University of Ruhuna, Sri Lanka, 2024) Deraniyagala, P.E.P.S.; Heenkenda, H.M.D.S.D.; De Silva, R.C.L.
Water and soil are important natural resources, and the study of their distribution is of great interest. The Grama Niladhari Divisions, Ihalagama-East and Eldeniya-East, located in the Gampaha district, are selected as the study areas, and this is done as a pilot study. Different water and soil quality parameters are investigated followed by the construction of contour maps. As water quality parameters, pH, conductivity, phosphate content, nitrate content, and Ca2+ hardness were determined, and as soil quality parameters, pH, nitrate, organic matter, water-soluble Na+ and K+, extractable Na+ and K+, and water-soluble Ca2+ ion contents were determined. The pH of water samples lies within the range of 4.41 − 7.11 and 3.79 – 7.18 in the Ihalagama-East and Eldeniya East divisions, respectively. Almost all the samples have acidic pH values, with some falling below the lower limit of the WHO guidelines for safe drinking water (6.5 − 8.5). Conductivity values vary from 52.0 − 277.0 μS/cm and between 54.0 – 403.0 μS/cm, respectively, which is below the WHO permissible level of 1500 μS/cm. The phosphate content varies from 1.374 − 3.986 mg/L in Ihalagama-East and water-soluble phosphate was not detected in Eldeniya−East, indicating a very low range and suggesting that the water samples are less contaminated with phosphate-containing substances. Considerably high values in the range of 1.24 − 279.00 mg/L for Ihalagama-east and 59.5 mg/L − 168.0 mg/L for Eldeniya−East, are obtained for the nitrate content where most of them are beyond the safe level of drinking water, 50 mg/L. The soil pH in all the samples falls within the acidic range, varying from 2.99 − 6.73 in Ihalagama-East and 3.07 – 6.68 in Eldeniya-East. Most of the soil samples contain high nitrate contents, indicating significant contamination. The percentage soil organic matter content varies between 0.60% and 13.27% in both areas. Many fertile agricultural soils typically have an organic matter content ranging from 3% − 6% revealing that most of the samples are beyond the standard levels. The distribution of water-soluble and extractable cations does not exhibit a wide range. According to the findings, though two Grama Niladhari Divisions are selected, they also display a huge variation. This reveals the importance of mapping to address contaminations, effects of natural disasters which lead to changes in the studied water and soil quality parameters.
Phyto-extraction of Chromium from Polluted Terrestrial Environments by Talinum triangulare (Ceylon Spinach) and the effect of External Chelators on the Chromium Extraction Potential
(Research Journal of Chemistry and Environment, 2020) Jayalath, K.G.; De Silva, R.C.L.; Deeyamulla, M.P.
The study was carried out to investigate the potential of Talinum triangulare (Ceylon Spinach) to remediate Cr contaminated soil under greenhouse conditions. In primary studies, T. triangulare showed significant resistance to Cr toxicity, however the amount of metal extracted was not sufficient enough to consider it as a potential phyto-extractor. Further pot experiments were conducted to find out the effect on Cr accumulation using EDTA as chelant under 2.0, 4.0, 6.0, 8.0 and 10.0 mmol kg-1 chelator concentrations. EDTA had virtually a significant effect on uptake of the metals by the plant and elevated Cr concentrations in plant organs as compared with the control. Optimum phytoextraction was observed when 2.0 mmol kg−1 EDTA was added with relatively high biomass production of plant species. EDTA modifies the uptake and the translocation of Cr by plants but the results concerning the uptake and the accumulation depend on the available Cr concentration in soil.
Phytoremediation potential of Talinum triangulare (Ceylon spinach) towards Cr in different soils
(Faculty of Graduate Studies, University of Kelaniya, 2015) Jayalath, K.G.; De Silva, R.C.L.; Deeyamulla, M.P.
Phytoremediation has emerged as a plant-based and cost-effective alternative to remediate heavy metal contaminated soils. Although this technique is widely known, a significant study has not been reported yet to find out a potentially capable plant to clean Cr contaminated soils. In studies carried out by our group, six plant species (Vernonia cinerea, Tridax procumbens, Sphagnaticola trilobata, Talinum triangulare, Clitoria ternatea and Vernonia zeylanica) have been tested under Cr contaminated conditions and identified T. triangulare (Ceylon spinach) with comparatively higher tolerance to Cr with relatively higher biomass than other plants under contaminated conditions. The aim of this study was to compare the phytoremediation potential of T. triangulare towards Cr for various soil types under Cr contamination conditions. Pot experiments were carried out using four different types of soils (sand, loamy sand, clay and laterite) under Cr contamination conditions (treatments with 200 and 300 mg of Cr/ kg dry soil). Plants were harvested at 60 days of growth and Cr uptake by plant shoot and root were separately analysed by atomic absorption spectrometry. The Cr uptake by T. triangulare under different soil types with maximum contaminated conditions of Cr (300 mg/kg) were analysed (ANOVA, p < 0.05) and showed no significant difference between loamy sand and sandy soil with the mean value of 109.30 (±18.45) mg kg- 1 and 136.00 (±34.70) mg kg-1 respectively and also no significant difference between Laterite and Clay with the mean value of 36.26 (±6.12) mg kg-1 and 43.44 (±4.29) mg kg-1 respectively. The results of this study indicated that, Cr uptake capacity and the tolerability of T. triangulare significantly change with soil types. Even though T. triangulare shows to be capable of habituation in different soils, its Cr uptake capacities varies significantly. T. triangulare shows potential of being introduced to different terrestrial environments to remediate Cr. However, future study of the plant in different soil environments is suggested.
Use of natural curcumin extracted from turmeric in determination of boron in steel.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Walpita, W. K. D. L. K.; De Silva, R.C.L.
Boron containing alloy steels are used in constructional, automotive and many other applications. The presence of even trace amounts of boron affects greatly on the properties of steel such as hardness and machinability. As the traces of boron affect the properties of steel, it is important to determine it accurately and precisely in the manufacture of these alloys. Due to the drawbacks of common advanced techniques such as Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma-Atomic emission Spectroscopy (ICP-AES), the universally accepted method for determination of boron in steel is the spectrophotometric method using curcumin as an auxiliary agent. Although curcumin is the most sensitive spectrophotometric reagent for the above analysis, synthetic curcumin is relatively expensive and it tends to degrade rapidly once it is exposed to air. Furthermore, this method is time consuming. One of the main objectives of this study was to investigate the possibility of using natural curcumin extracted from turmeric in the analysis instead of using synthetic curcumin. Curcuminoids were extracted from turmeric (Curcuma longa) using soxhlet extraction and they were separated using column chromatography. Extracted crude, separated curcumin fraction and synthetic curcumin were analyzed using FTIR. FTIR spectra of synthetic curcumin and natural curcumin were similar to each other and the spectrum of extracted crude indicate the presence of more carbohydrate impurities. Finally the possibility of using natural curcumin in the analysis of boron in steel was determined using the method given by American Society for Testing and Materials (ASTM). A boron-steel alloy sample found to be containing 0.26±0.01 percent of boron with synthetic curcumin gave 0.25±0.00 percent of boron with natural curcumin, indicating no significant difference in the determination. Cost analysis showed that it is more cost effective to use natural curcumin over synthetic curcumin. Findings of this study implies that natural curcumin extracted from turmeric can be used as efficiently and accurately as synthetic curcumin in the analysis and it is more cost effective in large scale industrial determination of boron in steel.