Browsing by Author "Malka, U.K.M."

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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.