Browsing by Author "Walpalage, S"

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item: Article-Abstract
Applicability of pressure retarded osmosis power generation technology in Sri Lanka
(2015-08-18) Karunarathne, HDSS; Walpalage, S
In this study the applicability of pressure retarded osmosis power generation was investigated in order to fulfil current electricity demand in Sir Lanka. Pressure retarded osmosis (PRO) process is a renewable and green technology with zero carbon emission to the environment. Salinity gradient through a membrane is the key parameter in osmotic pressure development. Theoretically it is a pressure increment of 26 bar which is equivalent to 270 m high water column for fixed volume of salt water compartment. This hydrostatic pressure can be used to generate electricity by sending pressurized water through a turbine. According to the literature, 1 MW electricity generation requires 1m3/s flow of fresh water. Sri Lanka has a great potential to develop this technology as it is surrounded by sea. Subsequently the country is having 103 number of water rich river basins over the country. Currently the electricity demand of the entire country is about 2100MW and it is already being supplied by both hydro and thermal power plant. The country spends an immense amount of money for the thermal power generation in every year. This can be reduced by introducing PRO power generation. Calculations over the PRO power generation reveal that it is possible to generate 7.84% of country energy requirement via some selected river basins through this technology.
item:
Applicability of pressure retarded osmosis power generation technology in Sri Lanka
(2014-06-27) Karunarathne, HDSS; Walpalage, S
In this study the applicability of pressure retarded osmosis power generation was investigated in order to fulfil current electricity demand in Sir Lanka. Pressure retarded osmosis (PRO) process is a renewable and green technology with zero carbon emission to the environment. Salinity gradient through a membrane is the key parameter in osmotic pressure development. Theoretically it is a pressure increment of 26 bar which is equivalent to 270 m high water column for fixed volume of salt water compartment. This hydrostatic pressure can be used to generate electricity by sending pressurized water through a turbine. According to the literature 1 MW electricity generation requires 1m3/s flow of fresh water. Sri Lanka has a great potential to develop this technology as it is surrounded by sea. Subsequently the country is having 103 number of water rich river basins over the country. Currently the electricity demand of the entire country is about 2100MW and it is already being supplied by both hydro and thermal power plant. The country spends an immense amount of money for the thermal power generation in every year. This can be reduced by introducing PRO power generation. Calculations over the PRO power generation reveal that it is possible to generate 7.84% of country energy requirement via some selected river basins through this technology.
item: Thesis-Full-text
Application of nanoclay on polyester fabrics as a bio-inspired approach to improve moisture management
(2018) Abeywardena, SBY; Walpalage, S; Perera, WPSK; Somararatne, MCW
Bio-inspired and biomimetic surface modifications are identified as one of the fascinating areas of research. In this study, nature’s way of cooling elephants’ body temperature using mud bathing was mimicked to create moisture management in polyester fabric. For that, bentonite nanoclay (BNC) was covalently grafted on polyester fabric using (3-aminopropyl) triethoxysilane (APTES) as a coupling agent. The novel modification method was proved qualitatively and quantitatively using characterization techniques such as X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Xray fluorescence (XRF) and Thermo gravimetric analysis (TGA). Moisture management tests, and physical and mechanical properties of modified polyester fabric were used to analyse the accomplishment of the modification. Hydroxyl groups on edges of BNC played a vital role in grafting with APTES. Primary amine group in APTES reacted with ester groups in polyester fibres, while silanols reacted with BNC. XRD analysis confirmed grafting of APTES on the surface of BNC without intercalation. XPS and FTIR spectroscopies confirmed the new secondary amide bond formation, while surface morphology was observed from SEM images. The significant enhancement in wettability, absorptive capacity, drying rate and wicking length proved moisture management property of polyester fabric. This fabric coating strongly withstood more than 10 cycles of laundry and against 5000 abrasion cycles. Physical and mechanical properties of modified fabrics remained unchanged, while tensile strength and elongation showed a slight improvement due to fibre preserving aminolysis reaction between APTES and ester groups in polyester fabrics. It is expected that this bio-inspired BNC modified polyester fabric may break the barrier of using polyester in various hydrophilic textile applications.
item: Conference-Full-text
Biodegradable introducing polyethylene polymeric composites starch oleates into prepared by low-density
(2005) Dias, GMGD; Premachandra, BAJK; Walpalage, S
As a solution to the environmental damage caused by the synthetic polymers in wasted materials, the use of biodegradable polymers has gained much attention during the last couple of years. The current research involved the preparation and characterization of novel biodegradable polymeric composites. In these composites, Low-Density Polyethylene was used as the continuous phase. Tapioca starch, a naturally occurring biodegradable polymer available in Sri Lanka was used as the other component in the composites. Compatibility of starch with (LDPE) was increased by replacing hydrophilic OH groups in starch molecules to different extents by oleate fatty-ester moieties. Mechanical properties, morphology, water absorptivity and biodegradability of the resulting composites were investigated.
item: Conference-Abstract
Biodiesel production using rendered oil from waste chicken skin
(Department of Chemical & Process Engineering University of Moratuwa., 2023-08-17) Wickramathilaka, A; Gunarathne, S; Rathnayake, M; Walpalage, S; Gunawardena, S; Narayana, M; Gunasekera, M
Biodiesel is a prominent biofuel that can be locally produced from various feedstock options to replace/blend with diesel. This study explores the feasibility of biodiesel production from waste chicken skin in the laboratory-scale. The average yield of rendered oil obtained from waste chicken skin is 280 mL/kg. The rendered chicken skin oil displayed minimal impurities and exhibited a yellow color, demonstrating the presence of natural pigments. To determine the suitability of the rendered oil for biodiesel production, experimental tests were conducted to measure the Free Fatty Acid (FFA) content and Acid Value (AV). The FFA content was found to be less than 3%, indicating the possibility of direct conversion of rendered chicken skin oil into biodiesel via transesterification. The biodiesel yield obtained from the rendered chicken skin oil samples ranged with an average yield of 43%. The results demonstrate the potential of waste chicken skin as a viable feedstock for local biodiesel production. While density and net calorific value are nearly the same, biodiesel samples display significantly lower kinematic viscosity, suggesting improved flow characteristics while reporting a higher flash point than that of diesel, indicating the requirement of a higher ignition temperature. Further, an economic analysis was also performed to evaluate the overall production cost of a scaled-up biodiesel production plant from waste chicken skin. This study demonstrates the potential of waste chicken skin as a viable feedstock for biodiesel production and supports important findings for future developments of commercial scale biodiesel production from locally available bio-waste/food-waste sources.
item: Conference-Abstract
ChemECon 2023 Solutions worth spreading (Pre Text)
(Department of Chemical & Process Engineering University of Moratuwa., 2023-08-17) Walpalage, S; Gunawardena, S; Narayana, M; Gunasekera, M
Proceedings of ChemECon 2023 Solutions worth spreading
item: Conference-Extended-Abstract
Comparative performance of bio filter packing materials for waste gas treatment
(2009) Wijayawardhana, AJ; Wijeyekoon, SLJ; Walpalage, S; Amarasinghe, ADUS
A study was conducted to evaluate the removal efficiency of NH3 and H2S emitted from an industrial waste gas source by biofiltration. Four types of packing material were used and NH3 and H2S in the contaminated air stream, ranged between 43-90 ppm and 70-100 ppm respectively. The experiments were carried out over an effective period of 45 .days. Results indicate that 100% removal efficiencies of NH3 and H2S can be achieved for coconut fiber/tobacco compost and peat/wood chips mediums.
item: Conference-Full-text
comparative study on cure, mechanical and dynamic-mechanical properties of natural rubber compounds formulated with dixp, tbztd, zbec and tbbs accelerators
(IEEE, 2021-07) Samarasinghe, H; Walpalage, S; Edirisinghe, D; Egodage, S; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Today, it is obligatory to replace nitrosamine releasing traditional accelerators owing to the various health, safety and environment regulations and surviving with safe alternative is a one of the key challenges in the rubber industry. In this work four groups of commercially available nitrosamine free/safe accelerators were selected, i,e., diisopropyl xanthogen polysulfide (DIXP), tetrabenzyl thiuramdisulfide (TBzTD), zinc dibenzyl dithiocarbamate (ZBeC) and N-tert-butyl-2-benzothiazole sulfenamide (TBBS). The effect of accelerator type on cure, crosslink density, physico-mechanical and dynamic-mechanical properties of efficient sulfur vulcanized natural rubber (NR) compounds was investigated. Results reveal that accelerator type does not only affect the cure characteristics, but also has a great impact on physical and mechanical properties, DIXP possess the least modulus and strength properties while providing satisfactory optimum cure time for the vulcanization compared to the TBBS accelerator. Improvement in mechanical properties is observed in the order ZBeC, TBzTD, TBBS and corroborates well with the crosslink density. ZBeC and TBzTD show relatively higher hardness, storage modulus and lower hysteresis in the rubbery region indicating different microstructure arrangement compared to commonly use of non-regulated nitrosamine safe TBBS accelerated vulcanizates.
item: Article-Abstract
Contribution of hydrogen and/or covalent bonds on reinforcement of natural rubber latex films with surface modified silica
(2015-09-01) Somaratne, MCW; Liyanage, MVK; Walpalage, S
A macromolecular coupling agent containing hydrophilic and hydrophobic groups is made to react with precipitated silica. Interfacial interactions between [BOND]OH groups of silica and [BOND]COOH groups of macromolecule are found to be created through either hydrogen bonds alone or through hydrogen bonds and covalent bonds. Aqueous dispersions of unmodified and modified silica are prepared and the colloidal stability and particle size distribution of the dispersions are observed. The dispersions at neutral pH are incorporated into vulcanized/unvulcanized natural rubber latex. The formation of hydrogen bonds and/or covalent bonds is studied via FTIR spectroscopy and their contribution in encouraging filler-rubber interactions is emphasized through mechanical and swelling properties. Uniform distribution and dispersion of modified filler particles throughout the rubber matrix is confirmed by the microstructures of the latex films cast from filler added natural rubber latex.
item: Article-Abstract
Design and performance of an industrial scale biofilter for odorous gas treatment
(2016-05-24) Wijayawardhana, AJ; Wijeyekoon, SLJ; Walpalage, S; Amarasinghe, ADUS
Odorous gas treatment is a challenging task due to the difficulties in identifying odor specific gases and their varied characteristics. A bio filter was designed for the treatment of waste gas stream from a tobacco leaf processing factory that discharged a high temperature gas stream from drying chambers with characteristics of tobacco odor. Major constituents of the foul smelling gas (gas flow rate of 1160 - 2100 rn'lr1) were identified and quantified using thin film micro sensors and was found to constitute mainly ammonia (60 - 80 ppm (v/v)) and hydrogen sulfide (80 -100 ppm (v/v)) after pre-treatment. A bio filter unit (11.65 m3 in volume) with a mixture of coconut fiber and compost as filter media was used to treat the odorous gases which eliminated the hydrogen sulfide completely while removing more than 80% of ammonia at the EBRT of 36 (s), producing a non odorous gas stream. The pH (6.5-7.5) and moisture (60 -65%) were kept at optimum levels to facilitate microbial growth and minimal pressure drops within the system. This paper details design, construction, operation, performance monitoring aspects involved in bio filtration in an industrial scale application and recommend many practical engineering solutions in its application.
item: Article-Abstract
Designing a small scale industrial type vacuum distillation column that based on laboratory and pilot plant studies
Wickramasinghe, PMYG; Walpalage, S; Amarasinghe, ADUS
Rolling oil is used in packaging industry Abstract: for cooling and lubricating rolling sheets during production process. However, the properties of the rolling oil changes with time and that becomes unsuitable for the. use. This study was conducted to find out the applicability of vacuum distillation process for purifying the rolling oil and to design a small scale industrial type vacuum distillation column. At laboratory scale, the oil properties were significantly improved when the used oil was distilled under vacuum. However, it was difficult to investigate the packing material parameters and number of theoretical plates in the laboratory scale vacuum distillation unit. Therefore, a pilot scale vacuum distillation unit was fabricated and tested to identify the number of theoretical plates required to reach the final quality of rolling oil. The optimum purity was reached with a column height of 2800 mm and 25 mm ceramic raschig rings as a packing material. Further increase in the height of the column gave no significant improvement and the number of theoretical plate corresponding to the column height of 2800mm was 5. Data obtained in the pilot study was subsequently used to design a industrial scale plant.
item: Article-Abstract
Designing a small scale industrial type vacuum distillation column that based on laboratory and pilot plant studies
(2016-05-24) Wickramasinghe, PMYG; Amarasinghe, ADUS; Walpalage, S
Rolling oil is used in packaging industry for cooling and lubricating rolling sheets during production process. However, the properties of the rolling oil changes with time and that becomes unsuitable for the use. This study was conducted to find out the applicability of vacuum distillation process for purifying the rolling oil and to design a small scale industrial type vacuum distillation column. At laboratory scale, the oil properties were significantly improved when the used oil was distilled under vacuum. However, it was difficult to investigate the packing material parameters and number of theoretical plates in the laboratory scale vacuum distillation unit. Therefore, a pilot scale vacuum distillation unit was fabricated and tested to identify the number of theoretical plates required to reach the final quality of rolling oil. The optimum purity was reached with a column height of 2800 mm and 25 mm ceramic raschig rings as a packing material. Further increase in the height of the column gave no significant improvement and the number of theoretical plate corresponding to the column height of 2800mm was 5. Data obtained in the pilot study was subsequently used to design a industrial scale plant.
item: Conference-Full-text
Development of a competitive thermoplastic vulcanizate roofing sheet from natural rubber and high-density polyethylene
(IEEE, 2021-07) Wickramaarachchi, WH; Walpalage, S; Egodage, SM; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Clay, asbestos, plastic and metal are commonly used as roofing materials in Sri Lanka and every material has its inherent drawbacks. Asbestos sheets are going to be banned due to health hazards. Thermoplastic Vulcanizate (TPV), a kind of polymer blends, gives combined properties of their individual polymers. Therefore, this study was aimed to develop a health hazard-free and economically viable roofing material from TPV to be competitive with the existing roofing materials. TPV pellets of 20/80 Natural rubber (NR)/High-Density Polyethylene (HDPE) in two different formulas were prepared using a twin-screw extruder. Roofing sheets having size of 40 cm × 40 cm × 0.6 cm were moulded using TPV pellets. Properties were tested according to the ASTM standards for Poly-Vinyl Chloride (PVC) roofing sheet and the certificates for properties of the PVC roofing sheets available in Sri Lanka. Properties of the two TPV sheets prepared were compared with those of the PVC sheets. TPV sheet having 1 phr of dicumyl peroxide and 50 phr of barium sulphate showed the optimum properties and were comparable with impact strength, elongation at break, density and thermal conductivity of PVC roofing. The developed TPV sheet is cost competitive and suitable for the high-class customer segment.
item: Article-Abstract
Development of Correlation Between Potassium Hydroxide Number and Conductivity of Concentrated Natural Rubber Latex
Walpalage, S; Ganga, I; Silva, KMD
Increase in the ion concentration in the medium was found to increase conductivity and potassium hydroxide number (KOH No) in natural rubber latex (NRL). Addition of long chain fatty acids can increase the ion concentration in themedium and stability of NRL. A series of concentrated natural rubber latex samples from three different areas with different soils and climatic conditions were tested for the parameters such as KOH No and conductivity. They have been measured over a period of 62 days, upon addition of soap to natural rubber latex concentrate. The result showed that there was a strong positive linear correlation between conductivity and KOH No. The regression equation to express the relationship between the variables has also been found.
item: Conference-Abstract
The development of rubber-thermoplastic blends from ground tyre rubber and waste polypropylene
(2006) Egodage, SM; Harper, JF; Walpalage, S
Rubber-thermoplastic blends are regarded as economical alternatives to the synthesis of new polymers with moderate characteristics and the market for such materials has grown dramatically because of the ability to recycle and process them in conventional thermoplastic machinery. Polymer blending entails the combination of the attractive features of several materials to improve the deficient characteristics of anyone of them, with a reduction in the price of the end product. Blending of polymer waste further reduces the price whilst helping to solve the waste disposal problem that industry currently faces. Rubber rich blends produce a soft thermoplastic elastomer while plastic rich blends produce a rubber toughened thermoplastic. However, literature reveals that the additions of rubber to a thermoplastic matrix result in a significant overall deterioration in mechanical properties.
item: Conference-Abstract
Dye sensitized solar cells using natural dyes derived from chaetomorpha, microcladia borealis, elisolandia elongate and sea lettuce
(Department of Chemical & Process Engineering University of Moratuwa., 2023-08-17) Illlankoon, HMUB; Sumudushantha, WANT; De Alwis, A; Perera, U; Walpalage, S; Gunawardena, S; Narayana, M; Gunasekera, M
Natural dye-sensitized solar cells (DSSCs) are a promising area in renewable energy. These innovative devices employ natural dyes extracted from plants to absorb sunlight and convert it into electricity. The dyes (anthocyanins in berries or chlorophyll in green plants), act as sensitizers, absorbing sunlight and generating excited electrons. One of the significant advantages of natural DSSCs is their eco-friendly nature, as they utilize renewable resources and have a low environmental impact compared to traditional solar cells. Moreover, their production is cost-effective and can be easily scaled up for industrial applications. With ongoing R&D efforts, natural DSSCs have the potential to contribute significantly to a cleaner and sustainable energy future. Reinforcing above, this study investigated the efficiencies of DSSCs produced using dyes of novel seaweed varieties (Microcladia borealis, Ellisolendia elongata, sea lettuce and Chaetomorpha) from shallow seas in Sri Lanka. Dye extracts from sea weeds have been studied sparsely with DSSCs. This research dives into the extensive color resources contained in the Sri Lankan seaweeds. The absorption of the dye and the electron emitting efficiency of the dye showed a clear relationship which can be further used in research for better dyes without following the full procedure of producing the cell. Additionally, the research opens a path for further research whether nano TiO is a mandatory factor in producing a DSSC. The highest efficiency was shown by dye extracted from Microcladia borealis which was 1.7x10 %.
item: Article-Abstract
Effect of activated carbon on the properties of natural rubber latex foams
Rajakaruna, ARM; Walpalage, S; Perera, DGPM
Activated carbon used as an adsorber in many industries. In this research work activated carbon (AC) has been incorporated as a filler with natural rubber latex compounds to enhance the odour adsorption property of latex foam products. Incorporation of AC into natural rubber latex (NRL) has not been reported in the literature. A methodology was developed to prepare stable colloidal dispersion of AC and incorporate it into NRL compound without affecting the stability of the NRL compound, fine cell structure of the final foam and physical properties of final foam product. It was found that stable AC dispersion with 36% maximum Total Solid Content (TSQ can be prepared by ball milling for 18 h in the absence of dispersion stabilizer. It has been revealed that up to 2% (on dry weight) dosage of AC dispersion can be incorporated into latex compound without disturbing the fine and continuous cell structure of final foam. The incorporation of AC dispersion into latex rubber foam leads to sorption enhancement of ammonia (NH3). The average sorption percentage of AC filled foam is found to be 9.70% and it was 5.04% for foam sample without incorporating AC.
item: Article-Abstract
Effect of different aeration levels on natural rubber latex upon maturation
Roshanie, LKS; Walpalage, S
Mechanical Stability (MS) of Natural Rubber Latex (NRL) is practically important to the latex producer and consumer whenever latex is handled. MS of fresh NRL is very low and fresh NRL cannot be directly used for manufacturing processes. Thus, freshly tapped NRL is kept for maturation and MS naturally develops and achieve steady level around 21 days. Water soluble fatty acid soap is used as an accelerator for the MS development and excess soap is added by NRL manufacturers to cut-down the maturation time. Appearing tiny pin holes on dipped latex films is one the major drawback due to excess soap in NRL. The main aim of this research was to find the alternative method to accelerate the MS development process without adding excess soap. Aeration of NRL was selected as an alternative technique and NRL samples were matured with different levels of air quantity and minimum soap content which is needed only to centrifuge. It was found that Mechanical Stability Time (MST), Volatile Fatty Acid (VFA) Number, Alkalinity, Conductivity and Viscosity changed with the air quantity. At minimum soap level, time duration to obtain standard MST was changed with air quantity. VFA number was slowly increased as air quantity increase, but it was not very significant.
item: Article-Abstract
Effect of maleimide curing on mechanical properties of ground tyre rubber/waste polypropylene blends
Egodage, SM; Harper, JF; Walpalage, S
Blends of ground tyre rubber and waste polypropylene with a maleimide curing system (50: 50blends of ground tyre rubber/waste polypropylene) were prepared in a Haake Rheocord Polylab System, at 180°C and 90 rev min-1 for 5 min. The curing agent and the activator used were N,N'- meta-phenylene dimaleimide (HVA-2) and di(tert-butylperoxyisopropyl) benzene (DTBPIB) respectively. The HVA-2 level varied from a to 5 parts per hundred parts (pphp), while the DTBPIB level varied from a to 1 pphp. Melt viscosity, tensile strength and elongation at break showed an increase with HVA-2 content, while the impact energy showed an optimum at 3 pphp level. The addition of the DTBPIB increased melt viscosity further and produced a homogeneous phase morphology of the blends. Impact energy improved with the DTBPIB level, while elongation at break and tensile strength showed an optimum at 0·6 pphp. Swelling behaviour and gel/sol from the boiled xylene extractions were studied, and the results obtained were correlated with the impact and tensile properties.
item: Conference-Abstract
Effect of the filler materials in urea formaldehyde adhesives used in wood composite manufacturing industry
(Department of Chemical & Process Engineering University of Moratuwa., 2023-08-17) Chandrarathna, AHMHG; Weerakoon, SJ; Sethunga, DSMDP; Walpalage, S; Gunawardena, S; Narayana, S; Gunasekera, M
This research examines the effect of filler materials on urea formaldehyde (UF) adhesives used in the wood composite manufacturing industry. The study compares the performance of wheat flour, a commonlyused but expensivefiller, with coal fly ash and wood fly ash, waste productswith adverse environmental impacts. The objectives include evaluating the impact of coal fly ash and wood fly ash fillers on adhesive viscosity and the mechanical properties (bending strength and modulus of elasticity) of wood composites and comparing the results with wheat flour. Viscosity measurements conducted with a Brookfield viscosity meter indicate a significant increase in UF adhesive viscosity over time with the addition of wheat flour. Wood fly ash shows minimal impact on viscosity, while coal fly ash contributes moderately compared to wheat flour and wood fly ash. Bending tests (ASTM D790) and empirical equations, following EN-325 sampling standards, are employed to assess the effect of filler materials and concentration on bending strength and modulusof elasticity in the final wood composites. Plywood bonded with coal fly ash demonstrates the highest bending strength and modulus of elasticity, with wheat flour as the reference filler. Both wheat flour and coal fly ash exhibit improved bending strength with increasing filler concentration, whilewood fly ash exhibits the opposite effect. In conclusion, coal fly ash proves to be a suitable substitute for wheat flour as a filler in urea formaldehyde adhesives, providing satisfactory adhesive properties and enhancing the performance of wood composites.