Science and Technology Degree Programme (SCT)

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Arsenic (V) Removal from Water By Modified Montmorillonite (MMT) from Naturally Occurring Clay Deposits in Sri Lanka
(Uva Wellassa University of Sri Lanka, 2017) Rajamanthri, R.R.M.M.
Montmorillonite (MMT) nano-clay is widely used in many applications. MMT clay has been deposited and enriched in dry zone of Sri Lanka. Identifying the possibilities and methods for use of MMT clay for heavy metal removal was the objective of this research. Mainly naturally occurring clay deposits in Murukkan area were considered. Research focused on arsenic (As) removal by raw MMT clay and modified MMT clay because of the human health problems associated with excessive and long-term exposure to As. The can be either acute and chronic health issues. Purpose of the study was developing suitable and low cost adsorbent materials for arsenic removal. Only the clay particles were used to prepare the samples. Selected MMT samples were characterized using Fourier Transform Infrared Spectroscopy (FTIR) technique. Apart from the identification the samples were modified by FeC13 and modified clay was used to make small pellets for filter media. The pellets were fired at 500°C 600°C temperature range in a furnace. FTIR technique was used to identify composition and functional groups present in resulted product as well as raw MMT. Modified filter media and raw sample§ were treated with As(V) solutions with different contact times and different pH ranges. 'Then filtrate of all samples were analyzed using Atomic Absorption Spectroscopy (AAS) to determine arsenic concentration and iron concentration of each samples. Results of the test prove that the MMT clay is capable of removing arsenic efficiently.
Automatic Accident Detection System Using CCTV Camera
(Uva Wellassa University of Sri Lanka, 2017) Hindurangala, L.S.
This paper deals with development of an automatic accident detection system using CCTV camera videos. These systems are designed to identify and indicate safety levels of the roads and vehicles. Most of systems are used highly accuracy sensors, equipment with higher cost to determine the above requirements. This paper describes a cost effective accident detection system based on the speed of the vehicle. Videos taken from camera were analyzed using algorithm based on the image processing and video processing methods. Set points and the roads were identified by using Specified colour filters to determine the speed of the vehicle. By analyzing each and every frame on the video files speed calculation were done according to the algorithm and average speed was taken to the final result. Threshold value for speed was defined by the system and calculated speed was compared with threshold value. By analyzing above result system was able to give a statement about the safety level of the vehicle depend on the speed of the vehicle.
Automatic Farm Monitroing and Maintaining Through Mobile Apps
(Uva Wellassa University of Sri Lanka, 2017) Srichandrapos, K.
According to our country farming is important. Because most of the people again more income from farm in our country. They are doing in their own level. The maintaining is the very important thing in farming. Good maintaining will give good output. There is more money and man power is spend for maintaining. To decrease these problems I eager to do the automatic farm monitoring and maintaining through mobile apps as my final year research project. By using a webpage the monitoring part can do. The online updates of the farm can observe through the web page. The data will be transfer from Arduino to ethernet. There is a local area network or any other network is needed in the farm area and monitoring area to make maintaining continuously. If there is no internet there may be an error. To do the controlling part of the farm there is no need of internet or Bluetooth in the farm area and controlling area. It's a good advantage in this project. Because if there is no internet then also can control the farm. Only one man can make the maintaining and controlling of a farm. To do the controlling part there is a mobile apps was designed. The controlling person want to install the apps in his mobile and then he can make control through that apps. If there was a problem in the farm an alert message will come to that particular person's mobile. After he got the message he wants to open the apps in mobile. Through the apps he can solve the problem where he is. In here it may be an error when the person could not read the message. By using this system the maintaining and monitoring of a farm is easy. But if there was no internet connection the monitoring cannot make properly. To omit this problem the project wants to modify by using the CCTV camera or any other devices. Controlling can make where we are and without internet or bluetooth. There are so many things can be control but in here I did for few things only. Humidity, temperature, water level and soil moisture are going to control. It can modify by using more sensors and other devices. After modifying it can use not only in farm but also in plants, factories, companies, home gardens, schools, universities and fields. It's a useful project with low expensive. By using this can decrease the man power and save the time. Anyone can use this because handling is easy. In future some modifications want to do.
Autonomous Transport Vehicle for Factory with Auto Charging Dock Using PID
(Uva Wellassa University of Sri Lanka, 2017) Rathnayaka, R.M.D.L.
Autonomous transport vehicle for factory with auto charging dock-using PID, falls under the autonomous guided vehicle (AGV). The intention of this research is to develop the electronic circuit system to measure the battery charge value, and to computer program the intelligent steering drive method using Proportional, Integral and Derivative (PID) functions. Nowadays there are many types of autonomous vehicles, most of them are using wired communication methods, and they have to change their battery manually. This project deals with the development of a transport vehicle based on a line follower with either black, white or different color and the vehicle battery is charged automatically in specific charging dock (charging area). PID control of transport vehicle is a method consisting of Proportional, Integral and Derivative functions to improve the movement of the robot. The vehicle uses special sensors to identify the line thus assisting the robot to stay on the track. The robot is driven by DC gear Motors to control the movement of the wheels. The Arduino Mega Microcontroller will be used to perform and implement PID algorithms to control the speed of the motors which are steering the robot to travel along the line smoothly. This project aims to implement the PID algorithm, control the movement of the robot by proper tuning of the control parameters, and thus achieve better performance.
Changers of Selected Macro/Micro Nutrients in Minimally Processed Banana Blossom Under the Low Temperature (8o C) Storage
(Uva Wellassa University of Sri Lanka, 2012) Dissanayake, D.M.A.B.
Minimally Processed or fresh-cut fruits and vegetables are a rapidly developing segment of the fresh produce industry. These products are manufactured by washing, sorting, peeling, slicing and packaging with plastic film or in plastic trays wrapped with films. Minimally Processed (MP) fruits are new forms of product marketing intended to meet the consumer's desires for convenience and fresh-like quality. Fresh cut products are living cells and they have highly nutritional content than other foods items. Because of that the preparation method, storage condition, storage temperature, packaging material mainly affect to the nutritional quality degradation of the fresh cut products. Effect of chemical treatment and the storage condition to nutrient depletion within their shelf life period was analyzed. Banana l?lossom grow on the end of the stem holding a cluster of bananas it considered an Asian or tropical vegetable.29 cultivars can found in Sri Lanka. Banana processing involved washing in cool (8 °C) distilled water, Chlorine water (100ppm) and cleaned water. Then subjected to CaC12 solution (5g/L).Packaging was done by using LDPE bags and stored under refrigerator condition. Samples of banana flower were analyzed for proximate composition ( protein, total dietary fiber, vitamin C and Anti-Oxidant) following the standard methods published by Association of Official Analytical Chemists (AOAC, 1995). Protein was determined by Kjeldahl method (Kjeldahl, 1883), and thereafter a conversion factor of 6.25 was used to calculate the total nitrogen to crude protein. Total dietary fiber (TDF) was determined according to the Ceramic Fiber Filter Method AOAC Official Method 962.09 (1982).Vitamin C content was determined by the redox titration method using iodine solution. The antioxidant activity was determined by the DPPH (2-2'- diphenylpicrylhydrazyl) assay. Embul kesel blossom have High protein content (19.11 +0.50 g/100g) and Vitamin C content (7.96+0.04 mg/ 100g). Koikuttu kesel have high dietary fiber content than other cultivars. DPPH Radical Scavenging capacities of banana blossoms are high in Embul kesel (21.02 + 0.31 ppm).The most of the Nutrient is slightly reducing during Processing and Storage time period. Therefore, needs develop well processing methods and storing condition to preserve nutrient of minimally processed Banana blossom.
Conversion of Eppawala Apatite into Superphosphate Using Hydrochloric Acid
(Uva Wellassa University of Sri Lanka, 2012) Priyadarshana, W.P.N.
Reaction of Eppawela apatite with HC1 has been investigated in an attempt to convert rock phosphate to phosphorus enriched manure using a simple & low cost method. Although direct reaction of apatite with HC1 lead to a highly hygroscopic product, physical condition of this material could be improved by the treatment with ammonia. Apatite reaction with 12% HC1 followed by PH adjustment using an alkali, leads to the precipitation of dicalcium phosphate (CaHPO4), which could readily be used as a P-fertilizer. Use of ammonia & ammonium salts has an added extra advantage in that the product contains nitrogen in addition to phosphorus. And also the addition of KCl to the mixture ensured availability of K in required proportions. Since the cost of this product depends mainly on the cost of HC1, partial combination with Hydrochloric acid recognized as a potentially useful and economical method.
Crumb-Rubber and Silica Nano-Particle Derived Rubber Composites: A Partial Solution for Waste Management
(Uva Wellassa University of Sri Lanka, 2017) Tharmakulenthiran, V.
Currently, crumb rubber derived flooring is a small, but growing sector in the world floor coverings market. However it is not widely spread in Sri Lanka. Such flooring includes mats, rolls, sheets, and indoor and outdoor tiles. Among the materials for flooring, natural rubber blended with artificial rubber is one of the lower-priced and commonly used ingredients. However, the pristine rubber blends show retarded mechanical properties. Thus, reinforcement with additives and vulcanization is commonly practiced technique. In this research the blend of natural and artificial rubber is reinforced with crumb rubber and silica Nano particles. Both of these additives were prepared from the waste materials. Thus, this research is focused to introduce a partial solution for waste management. The idea is analogues to making large particle reinforced composites such as concretes in which two different sizes of particles (coarse gravel and sand) are densely packed with an adhesive (cement). The rubber crumbs are in micro-to-millimeter length scale while silica is in nanometer length scale. Rubber crumbs act as a good additive while silica particles act as space filler. In this study, crumb rubber with different sizes was prepared by mechanically crushing the waste tyres. The silica was extracted from rice husk by a facile heat treatment process and converted into Nano particles by a precipitation method. The properties of silica Nano particles were further characterized. The composite materials were prepared with different ratios of rubber: silica Nano particles: crumb rubber. The samples with same compositions but different rubber crumb sizes were also prepared. All the composites were further reinforced by vulcanization. Microstructure was evaluated using Scanning Electron Microscope images and the optimum composition was determined by evaluating their mechanical properties. We found that the tensile strength and tear strength increased and compression percentage decreased with increasing until 125 ppr (parts per rubber) crumb rubber added RSS and silica Nano particle composites.
Development of a Colorimeter for the Field Estimation of Fluoride in Drinking Water
(Uva Wellassa University of Sri Lanka, 2012) Kumari, W.G.N.D.
The name "colorimeter" is given to any instrument used for the determination or specification of colors. One type of colorimeter is an instrument used to find the concentration of a substance in solution, based on the intensity of color of the solution. If the solution to be tested is colorless, a reagent is added that reacts with the substance, producing a color. This type of colorimeter has a wide range of applications, including laboratory research, environmental analysis of water quality, analysis of soil components, monitoring of hemoglobin content in the blood and analysis of chemicals used in various industrial settings. Presence of excess fluoride in drinking water causes various diseases that are collectively referred to as fluorosis. Fluorosis is endemic at least in 25 countries. The total number of people affected due to fluoride estimated is tens of millions. The major source of fluoride is lithogenic. Fluoride enters to the human body mainly through water. A minimum amount of fluoride is required in drinking water to prevent tooth decay. According to the WHO guidelines, the permissible limit of fluoride in drinking water is 1.5 mg/L. However, a regular in take of water containing excess F— causes many chronic diseases. In this project a novel colorimeter is designed to determine fluoride concentration in water. The unit has alarming signals to alert people when the levels far exceed WHO recommendations. The colorimeter works according to Beer-Lambert Law of absorption. . It is used in conjunction with the SPADNS method, which shows a color change in the visible region on addition of water containing fluoride to a reagent solution. That color region was identified by web cam and read the color intensity.
Development of Bio Active Herbal Jelly from Cyclea peltata (Kahipittan) Leaves
(Uva Wellassa University of Sri Lanka, 2012) Erangee, K.W.M.
Cyclea peltata is a native herbal plant which belongs to the family Menispermaceae. The C.peltata leave extraction obtained with the aid of water, transforms into semi solid structure as in jelly. This plant is also known to have possessed high medicinal value. Therefore, the gelling ability & medicinal value found in the Kahipittan leaves can be used to produce therapeutic food. To screen the bio activity in terms of anti microbial activity against Staphylococcus aureus, Escherichia coli and fungi Candida albicans were evaluated for three concentrations (0.1g/m1,0.5g/m1,1g/m1) of leaf extractions. For the sensory evaluation four workable solutions were prepared by changing the leave extraction & sugar content. Constant amount of Sodium Meta BiSulfide, permitted amount of colorings and flavors in powder form, 2% of pectin by final volume were added to each sample separately. Sensory attributes such as taste, aroma, flavor, color, appearance, and overall acceptability were evaluated using five point hedonic scale with thirty untrained panelist. Collected data were statistically analyzed using Friedman test with the confidence level of 95% using MINITAB statistical software. Microbiological analysis & shelf life analysis were performed for the selected best sample from the sensory evaluation under the refrigerated condition & room temperature condition separately. Parameters such as pH level and Total Soluble Solids were measured for the selected best sample throughout the storage under both refrigerated and normal room temperature conditions. The leaves soaked in water under the normal room temperature conditions produced the best extraction with a high gelling property. Any inhibition zone was not observed for all the microbial strains. Therefore, antimicrobial activities of C.peltata leaf extracts against all tested microbes were shown negative. According to the results obtained from the sensory evaluation, Sample "B" has scored the highest values for all sensory parameters Therefore, sample B can be recommended as the best formulation which could be improved as a commercial therapeutic jelly especially for gastritis patients. pH of the final product 3.9 and TSS 18° .Product shelf life under refrigerated storage with temperature at 4 0± 1 °C was 7 days . Microbial quality was within the acceptable limit.
Development of Cereal Incorporated Yoghurt
(Uva Wellassa University of Sri Lanka, 2012) Ramawickrama, P.
Yoghurt is a fermented milk products obtained from coagulation of milk by the agency of organisms of types Streptococcus thermophillus and Lactobacillus bulgaricus. Lactobacillus acidophillus may be present. It is known as highly nutritional food item having more health benefits. Cereals are the edible seeds (grains) of the plants of the grass family (Grameneae). Cereals are considered as healthier, and provide staple food for most Asians. Incorporating both nutritional sources, this study was aimed to develop a ready — to — serve cereal incorporated yoghurt as a new yoghurt product, while adding value to local cereal varieties such as Rice (Oryza sativa) and Finger millet (Eleusine coracana). The study was carried out in four major phases, Background Study, Preliminary trials, Experimental trials and the Final analysis where shelf life determination, proximate analysis and cost analysis were done. The best formulae for cereal incorporated yoghurt were, 4% of rice flour incorporated yoghurt (R4) and 8% of flour combination incorporated yoghurt (RF2). Both yoghurt types had higher SNF content and lower fat content than plain milk yoghurt. Basic raw material cost for the production of one R4 yoghurt cup is LKR. 6.14 and that for RF2 yoghurt is LKR. 6.84. The shelf life of R4 yoghurt was 9 days and for RF2 yoghurt it was 11 days. Both were obtained without the addition of preservatives.
The Development of Internal Sensory Panel to Assess the Sensory Qualities of Processed Meat Products
(Uva Wellassa University of Sri Lanka, 2012) Rathnayake, R.M.L.K.H.
In the food industry sensory evaluation has become a standard tool used in the development of new products and the checking the quality of the existing products. Unless the food products meet the desired standards of taste, flavor, texture, etc., the consumer will not accept the product's. Before the product goes in to the market from the industry, product's sensory quality must be checked with the help of sensory evaluators. Establishment, training and performance evaluation of sensory panel is the main objective of the study. The testing instrument for sensory analysis is the panel of human judges who have been recruited and trained to carry out specific tasks of sensory evaluation. Recruiting panelists, training them, monitoring their performance, providing leadership and motivation are the basic steps of establishing sensory panel. Recruitment of the panel was done in 3 steps. First pre screening was done by distributing a. questionnaire among all possible members in the industry. Date was evaluated using maximum score method. Second screening was done in three steps, Meat type identification test; Minced Chicken, Beef, Mutton, Pork, and fish were mixed with minimum amounts of salt. I Og balls were steam cooked and stored at -22°C for 42 hours. Five samples were served in five plates for the potential panelists. Taste type identification test; Chicken samples were made with 0.5% salt, 3% vinegar, 0.2% spice. Potential panelists were asked to identify the taste type. Different threshold level test; Chicken meat samples with each taste (salt, spice, sour) with different intensities were given to potential members. Three samples from each taste will be given to potential panelists and ask them to rank according to low, medium, high levels. 15 panelists were selected by sorting the success ratio. Training and performance evaluation was done for the selected panelists by giving two sets of three samples including one reference sample (company standard sample) with changes in salt level and spice level. Data were analyzed using Kruskal-wallis test test. A triangle test was done with meatball samples having one with 1.5% vinegar. Results of the statistical analysis proved that there is no significant different between panelists and their judgment can make significant different in the test statistics.
Development of Li1/3 Ni1/3 Mn1/3 Co1/3-x Mx O2 Cathodes for Li-ion Battery
(Uva Wellassa University of Sri Lanka, 2012) Perera, M.D.N.
Li-ion batteries are widely used in portable electronic industry, and have been considered for large scale applications such as electric or hybrid electric vehicles. Today the rapid development in electronics industry needs better batteries with higher energy storage, lower capacity decay, lighter weight and low cost. The high cost of the LIB is mainly due to the high cost of cathode materials. This study is mainly focused on the electrochemical performance of a Li1/3 Nil/3 Mni/3 Col/3-x Mx 02 type cathode material. Ni1/3 Mnu3 Co1/3-x Mx 02 powder was successfully synthesized by employing the wet chemical powder preparation method: Glycine-nitrate process. The powder was calcinated at 650°C for two hours in air and using that powder pellets were prepared by uniaxial cold pressing technique. Then the green pellets were sintered in a furnace at 1000°C for two hours in static air. Before measure the electrical conductivity the pellets were gold pasted and heat treated at 730°C for one hour to make the better contact with Pt electrodes. The electrical conductivity of sintered pellets was measured by DC four-probe technique. Flexible electrodes were fabricated for selected materials via tape casting. Tape casting was performed employing the doctor-blade technique. In this process, oxide powder was mixed with polyvinylidene fluoride (PVDF) binder and synthetic graphite in proportions 1: 0.25: 0.10 by weight. Those proportions were mix and blend with propylene carbonate (PC) corresponding to 40% of active material weight and dissolved with acetone. Slurry was stirred in magnetic stirrer and poured in to manual tape caster. The electrical conductivity of the prepared electrodes was measured by van der Pauw technique. Then the electrical conductivity of selected best materials was enhanced by introducing synthetic graphite and Sri Lankan natural graphite as a conductivity enhancer. This study shows that the possibility of using Li1/3 N11/3 Mn1/3 C01/3-x Mx 02 type materials for LIB cathode. According to the observed data Lit/3 Ni1/3 Mn1/3 C01/3-x Mg0 22 02 and Lim Nil/3 Mn1/3 Col/3-x Zn0.11 02 materials got the most sufficient conductivity values that suitable for cathode. As a conductivity enhancer for cathode fabrication Sri Lankan natural graphite also can be used instead of synthetic graphite.
Development of Microbial Biofilms for Better Growth of Eucalyptus grandis Plants
(Uva Wellassa University of Sri Lanka, 2012) Perera, K.P.V.K.
Eucalyptus is the highest grown forest plantation species worldwide (Rhoades and Binkley, 1996) and in Sri Lanka, 20 percent is represented by Eucalyptus grandis (Bandarathilake, 1996). At present sites available for reforestation in Sri Lanka are generally poor in nutrient status and fertilizer application is required for better growth of seedlings (Bandarathilake, 1996). It has being reported that by increasing the soil organic carbon stock, in other words increasing soil carbon sequestration, crop yields could be increased. Microorganisms play a major role in sequestration of soil carbon. If we can use such carbon sequestering microorganisms in biofilm biofertilizers to improve soil organic carbon content, that will be an advantage as these may have a greater potential to boost the level of soil organic carbon and to enhance the growth of crops in an environmental friendly manner. This study focused on the fabrication of a biofilm biofertilizer for the better growth of Eucalyptus grandis plants in a nursery, which could be cost effective and environmental friendly. According to the final outcomes of the study, it is clear that Medawelagama and Pelgahatenna Eucalyptus grandis plantation sites contain the highest organic carbon content among the four sites. When comparing the organic carbon content of two soil layers ("0-15cm" and "15-30cm"), it was statistically proved that "0-15cm" soil layer contains significantly higher organic carbon content than "15-30cm" soil layer. Seven bacteria and three fungi types were isolated during this study. Although all the seven isolated bacterial types were combined and cultured with the three isolated fungal types separately to facilitate biofilm formation, only two combinations were succeeded in formation of biofilms with high intensity. There is a positive effect from the fabricated biofilms ("biofilm 3" and "biofilm 5") for the growth of Eucalyptus grandis nursery plants. But further studies are required to understand the continuous effects of the fabricated biofilms on the growth and productivity of Eucalyptus plantations including their soil organic carbon content.
Development of Modified Fenton’s Reactor Using Iron Pyrite
(Uva Wellassa University of Sri Lanka, 2012) Samaranayaka, P.N.
Disinfectants such as chlorine are used in drinking water treatment to protect the public health from pathogenic microorganisms. However, disinfectants also react with non harmful, naturaly occuring organic substances in the water and form by-products, such as trihalomethanes. Total trihalomethanes (TTHMs) include four compounds: chloroform, bromodichloromethane, dibromochloromethane and bromoform. TTHMs are carcinogenic and have been found to cause adverse pregnancy outcomes. Therefore, objective of the research is to find a feasible and effective method to treat the THM in the treated water and thereby to make it possible for developing countries to use already installed water treatment plants in the future too, without going for the costly methods. The research has shown that THM concentrations can be minimized by using higher paricle sizes and mass of Iron Pyrite which was obtained from the Bogala. The study designed that model for a Fenton Reactor which is low cost and accessible to even poor people.
Development of Spiced Butter Using Pepper(Piper nigrum), Cinnamon (Cinnamomum verum), Ginger(Zingiber officinale) and Garlic(Allium sativum) and Determination of Shelf Life
(Uva Wellassa University of Sri Lanka, 2012) Sheriff, M.A.M.
The use of spices in butter as a flavor enhancer has immense potential in value addition health wise as well as commercially. Butter is essentially the fat of the milk made by agitation or "churning", where the fat content should be not less than 80% and the moisture content should not exceed 16%. It is usually made from sweet cream and is salted. However, it also can be made from acidulated or bacteriologyically soured cream. Butter becomes rancid due to atmospheric oxygen, light, heat, water, metals, enzymes and microorganisms. Rancidity is the development of any off or disagreeable flavors in fat. Butter was produced by churning and working fresh pasteurized cream without the use of preservatives. Spiced butters were made by mixing pepper powder, garlic paste, ginger paste and cinnamon powder in salted butter. Sensory evaluations are carried out to identify the best dosages of spices in butter, to identify the best type of spice preferred in butter and to compare a month old product for significant differences with a fresh product. Shelf life evaluation for a month was carried out by observing the microbiological characteristics where all the butters showed counts under the maximum allowable counts throughout the month and Free Fatty Acid content behavior of the butter while keeping under refrigerated condition. 2.00% pepper treated butter is the most preferred spice butter. The free fatty acid values for the pepper, garlic and cinnamon butter did not exceed the threshold level whereas the ginger butter exceeded it at the latter part of the month.
An Enhancement of Effeciency of Solid-State Dye-Sensitized Solar Cell by Coupling Two Metal Centered Dyes.
(Uva Wellassa University of Sri Lanka, 2012) Rubasinghe, S.H.
After nearly decade of extensively investigate on dye — sensitized photo electro chemical solar cells based on the nano structured semiconductor films, the dye-sensitized solar cells have begun to receive considerable attention as the promising system for conversion energy. However, solid-state solar cells aroused much attention due to capability of usage in electronic devices than dye sensitized solar cells with liquid electrolyte. Several types of organic dyes, natural pigments, various types of hole-conductors have been used by aiming uplift of performance of the n-semiconductor dyelp-semiconductor (NDP) cells. The main objective of this work was to enhance the photo performance of the solid state Dye sensitized solar cells by coupling two metal centered dyes.In there used the ruthenium( I]) polypyridyl complexes.those are cis-bis(isothiocyanato)-bis(2,2'- bipyridy1-4,4'-dicarboxylato)ruthenium(II) (N719) and triscarboxy-ruthenium terpyridine [Ru(4,4',4"-(COOH)3-terpy)(NCS)3] (Black dye) as the metal centered dyes. Experiments were carried out by changing the cell configuration according to the dye immersing sequence.TiO2 semiconductor was used as the anode of the cell and the CuI was used as the hole collector or the p type semiconductor. In there mainly got the results for the cell configurations that having CuIIN719ITiO2, CuljBlack dyeITiO2, CuIIBlack!N7191TiO2 and CuI1N7191BlackiTi02. I-V characteristics data of Open Circuit Voltage Voc, Short-circuit current Ise and the Fill Factor FF, were determined and UV-VIS-NIR spectrometer data were obtained for the each cell configuration and dyes,dye mixtures that used. In this work, maximum power conversion efficiency of 4.98 % was obtained for solar cell with the configuration of CuI1N7191BlackiTiO2 by coupling of two metal centered dyes on TiO2 electrodes. The enhancement of photo-performances of the cell was explained by acceleration of an extra electron flow toward the TiO2 electrode. But it was observed that the configuration that having CuIlBlackIN719ITiO2 shows the low photo-performance than the cell configuration of CuIIN7191B1ackiTiO1
Enhancement of Efficiency of Dye Sensitized Solar Cellsby Coupling of Two Dyes
(Uva Wellassa University of Sri Lanka, 2012) Udayangani, G.N.
D-358 (Indoline) dye, black dye (triscarboxy-rutheniumterpyridine) [Ru4,4',4"- (COOH)3-terpy)(NCS)3] and their cocktails on ZnO films were studied by means of utilization as light harvesting electrodes in ZnO based photo-electrochemical cells. The conversion efficiency of organic dye based dye sensitized solar cells (DSSC) was improved by co-sensitization with dye. Because of the conversion efficiency of the DSSC depends entirely on the sensitizing ability of dyes; extensive efforts have been made to develop highly efficient dyes for panchromatic sensitization. On the other hand one of the other approaches to achieve panchromatic sensitization is by co-sensitization using multiple dyes which have complementary absorption features. TiO2 is well used semiconductor which was obtained highest conversion efficiency with many of organic dyes up to now. In the present work, we have chosen ZnO as a substrate since ZnO has higher electron mobility than TiO2 expecting similar or higher performance of the cell compare to that of titania based DSSCs. Metal free organic dye D -358 (Indoline) and black dye are utilized to sensitized ZnO electrode. The maximum photocurrent of 14.1 mAcm-2 with the overall efficiency of 3.5% was observed for ZnO/D-358/13-4- electrolyte solar cell. An enhancement of absorption of the electrode was observed by coupling of D-358 with triscarboxy¬rutheniumterpyridine "[Ru(4,4',4"-(COOH)3-terpy)(NCS)3] (Black dye). The maximum efficiency of 3.7% and 17.1 mAcm-2 of photo current were observed for ZnO/D-358/Black dye/electrolyte solar cell. The enhancement of photo-performances of the cell was explained by acceleration of an extra electron flow toward the ZnO electrode by malty channel charge transfer process. ZnO/D-358/electrolyte and ZnO/Black/electrolyte cells exhibited maximum photocurrent of 14.1 and 10.0 mAcm2 respectively. ZnO/D-358/black/electrolyte cell exhibited the highest photocurrent values much higher than that of other configuration such as ZnO/Black/D-358/electrolyte considered in this study. According to our results a clear enhancement of overall efficiency and photo current were observed due to enhancement of absorption properties of multi-dye electrodes.
Establishment of Maximum Storage Time for Uht Standardized Milk in Intermediate Storage Tank by Considering Influenced Factors
(Uva Wellassa University of Sri Lanka, 2012) Perera, P.S.P.
The aim of this study was to establish maximum storage time for an intermediate storage tank by considering influenced factors which is used to store UHT standardized milk in case of breakdown. The study was carried out in 2 parts. In the first part, the quality of raw materials, line cleanliness and temperature of standardized milk in intermediate storage were investigated for 15 batch samplesas influenced factors for storage timeusing Total Plate Count (TPC), bacterial spores, yeast and molds. The obtained results were compared with standard norms (Nestle Local Norms). Temperature of standardized milk was considered as constant. In second part, to establish maximum storage time, 15 batchsamples of standardized milk were investigated using pH, conductivity and TPC initially, after 12 hours, after 24 hours, 36 hours, 48 hours and 72 hours. According to the comparison with standard norms it showed that the raw materials were microbiologically accepted for all 15 batch samples. The results from water analysis after Clean in Place (CIP) showed that there were no microbial contaminations after CIP in interior surfaces of the lines. The average pH changedeviated from recommended pH range (6.85 — 7.20) after 24 hours according to the 95% confidence interval level. For 36 hours, 95% CI level was (6.84, 6.93). Similarly, the average TPCdeviated from recommended value (105 CFU/g) after 24 hours. According to the results of 1 sample t test the average TPC in intermediate storage tankat 36 hours was greater than or equal to 105 CFU/g. The average conductivity of standardized milk at 24 hours was 1.0 — 1.5 µS/cm suggesting a recommended conductivity range for standardized milk stored in intermediate storage tank. Statistical analysis of data illustrated that maximum storage time for intermediate storage was 24 hours if the temperature maintained at 8°C with quality raw materials, and line cleanliness.
Fumigant and Contact Toxicity of Selected Underutilized Plants Against Grain Storage Pest Tribolium castaneum(Herbst)
(Uva Wellassa University of Sri Lanka, 2012) Premarathna, V.
Since Sri Lanka is a developing and agriculture based country, it is crucial to minimize the post-harvest losses. The insect infestation of stored grains and their products is a serious problem. Nowadays controlling insects is mainly practiced by using synthetic insecticides and fumigants. But their widespread use has led to some serious problems. This study was carried out to screen the contact and fumigant toxicity of underutilized and highly abundant herbaceous plants on storage pest Tibolium castaneum. For this study methanol crude extract of dried leaves and fresh flowers of Bidens sulphurea, Helliunthus annuus, Tagetes erecta and Tithonia diversifolia were obtained and experiments were conducted with Randomized Complete Block Design and two factor factorial designs. Contact toxicity and fumigant toxicity were tested for T castaneum with five different doses and three different doses respectively. Highest mortality values were found even at the low doses in T. erecta dry leaves, H. annuus dry leaves and T. erecta flowers for contact toxicity. T erecta dry leaves and T diversifolia fresh flowers show high fumigant toxicity. T. erecta dry leaves show\qne highest both toxicity effects on T castaneum. Any mortality was not observed in control, even without food and air supplement. According to the ANOVA, there was no significant interaction effect between dose and crude type to the mean mortality % (p > 0.05). The best selected plants were re¬examined under randomly selected dose series to calculate the median lethal doses (LD50 value) using probit analysis. LD 50 values of T erecta dry leaves, H. annuus dry leaves and B. sulphurea fresh flowers are 13.129 pg/cm2, 38.925 1.tg/cm2 are 51.716 p,g/cm2 respectively for contact toxicity. LD50 values of T erecta dry leaves and T. diversifolia fresh flower were 109.044 i.tg/cm2 and 196.368 gg/cm2 respectively for fumigant toxicity. Hence those two types of extracts can be used in developing a fumigant to eradicate the infestation of Tribolium castaneum.
Identification of Impurities and Optimization of Acid Leaching of Rare Earth Elements in Eppawala Apatite
(Uva Wellassa University of Sri Lanka, 2017) Kiridena, K.M.H.S.
Apatite ore at Eppawala has vast areas of advantages other than production of phosphorus fertilizer. Major impurities contain in apatite are Ca (17.29%) and Fe (0.68%). Apart from those it includes rare earth elements (REE), in smaller quantities (0.1%-0.6%) such as Y, La, Pr, Nd, Ce, Pm, Tb, Dy, Ho, Er, Yb and Lu, which are rich with technological advantages, hence their extraction is very useful. There are two ways to extract REEs from the ore. One way is crushing the ore and physically separating the rare earth oxides from the ore. Other process is leaching. In the case of apatite REEs usually occur as ionic substitutions for Ca within the crystal lattice and not as discrete mineral form. Therefore, leaching is the suitable process. This is a study on effective extraction of REEs from apatite to investigate the influences of acid type, it's concentration, temperature and time on the REE leaching level, was experimented under basic leaching tests with sulfuric, hydrochloric and nitric acids. Hydrochloric acid was the most effective leaching agent according to the results because it was able to remove a significant amount of REEs within fewer hours using low concentrations. In the case of sulfuric acid, most of the REEs in the solutions were lost due to precipitation as insoluble gypsum (CaSO4.2H20). Apart from the above, two methods were investigated for the selective recovery of lanthanides from the leach solution; specifically, REEs were leached from the sample with nitric solution. One method was to precipitate lanthanides by ammonia and the precipitant was dissolved by nitric acid and was precipitated again by oxalic acid. Though lanthanides were recovered, Ca has been also co-precipitated, making this method unsuccessful. The other method was to shake nitrophosphate leach with amyl alcohol.

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