Browsing by Author "Jayasuriya, C. K."

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Development and characterization of biodegradable films of cornstarch filled with methylcellulose and gelatin
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Ranasinghe, W. R. A. D. S.; Jayasuriya, C. K.; Premachandra, J. K.
Synthetic plastics play a vital role in many applications such as packaging, electrical, electronics, medical, textiles, furniture, and structural applications due to desirable properties like light- weight, high strength, flexibility, and chemical inertness. However, when the products made from many synthetic plastics are discarded to the natural environment it takes a very long time for degradation. This results in environmental pollution. Therefore, the use of biodegradable plastics in place of non-degradable plastics has gained significant interest as one of the main plastic waste management methods. However, biodegradable plastics such as starch and Polylactic acid do not show desired mechanical properties. In this research, it was expected to synthesize biodegradable films with improved mechanical properties using cornstarch (CS) filled with methylcellulose (MC). Microcrystalline cellulose (MCC) was extracted from cotton fibers through alkali treatment and bleaching, followed by sulphuric acid hydrolysis. Then, MCC was converted to MC using dimethyl sulfate in the presence of acetone as the solvent. This conversion was analyzed by Fourier transform infrared spectroscopy (FTIR). Their FTIR spectra showed significant differences in the regions 2960-3650 cm-1, 2780-2950 cm-1, and 960-1160 cm-1, which indicates that the conversion has occurred. The degree of substitution of the methyl group for H in MCC was determined by an acid-base titration and the resulting value was 1.36 ± 0.02. Then, an aqueous solution of MC (0.5 g/100 mL) was prepared. In the presence of water, CS (4% w/v) was dissolved in different amounts of the prepared MC solution in order to have six solutions with the ratio of MC to CS as 0.00%, 0.625%, 1.25%, 3.125%, 6.125%, 12.125% (w/w). Acetic acid (1% v/v) was added to all these solutions. Afterwards, two series of solutions, series 1 and 2, were prepared by mixing 1% and 2% (v/v) of glycerol, respectively, into the resulting solutions. Similarly, the third series was prepared by mixing glycerol (1% v/v) and gelatin (1% w/v). Three series of films were prepared using these solutions following the casting method. The dried films were characterized on physical, chemical, mechanical, and thermal properties. The film with 0.625% (w/w) MC in series 3, showed the highest tensile strength of 14.06 MPa. Films with MC-1.25% (w/w) in each series showed the lowest water absorptivity, swelling, and solubility properties. All the films produced were transparent. The films tend to twist and swell when treated with chemicals such as NaOH, HCl, NaCl, and ethanol. Also, the transparency of some of the films was reduced after this chemical treatment. FTIR analysis, thermo-gravimetric analysis, and differential scanning calorimetry were performed on the films having optimum properties. These films showed thermal degradation between 323-335 °C, melting temperatures between 267-293 °C, and glass transition temperatures between 84-120 °C. The biodegradability of films was determined by performing a soil burial test. After three months, the films had disappeared. It can be concluded that the biodegradable films developed in this study have the potential to replace polyethylene in some short-term packaging applications.
The effectiveness of electrochemical oxidation in removal of sulforhodamine B textile dye from wastewater
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Aberathna, A. P. A. G.; Jayasuriya, C. K.; Premachandra, J. K.
The rapid expansion of industries has indirectly resulted in a substantial rise in environmental pollution due to the increased discharge of wastewater. Moreover, the lack of suitable and efficient methods for wastewater treatment has aggravated a crucial global issue concerning wastewater. In this context, the textile industry bears the primary responsibility for generating a significant volume of wastewater, primarily due to the processes of dyeing. Out of various wastewater treatment methods, the electrochemical oxidation method has emerged as an effective approach offering advantages of higher selectivity, minimal chemical utilization, energy efficiency, in-situ treatment capability, relatively faster treatment and reduced secondary waste generation. This method harnesses electrically charged electrodes to degrade and eliminate pollutants. In this study, the electrochemical oxidation of synthetic dye sulforhodamine B (Acid red 52), a xanthene dye, was employed to facilitate the removal of dye from wastewater. This dye is extensively used in the textile industry due to its enhanced colourfastness and superior stability across diverse processing conditions. However, its persistent nature poses significant environmental challenges. A series of experiments were conducted using graphite electrodes to optimize the electrochemical oxidation for the removal of dye from wastewater. The research investigated the effects of several parameters on the electrochemical oxidation process. These parameters encompass the applied potential (3 V, 5 V, 9 V), supporting electrolyte concentration (NaCl) (1 g L-1, 2 g L-1, 3 g L-1, 4 g L-1, 5 g L-1), treatment time (0.5 hours, 1 hour, 1.5 hours, 2 hours), and pH level (3, 4, 5, 7, 9) of the sample. The efficacy of sulforhodamine B degradation was assessed by UV-visible spectroscopy and chemical oxygen demand (COD) values. Furthermore, changes in conductivity and pH post-treatment were subjected to analysis. The analysis resulted in the determination of optimal parameters, including an applied voltage of 5 V, treatment time of 1 hour, pH of 7, and NaCl concentration of 3 g L-1. Under optimum conditions it was able to achieve 95.61% colour removal, 99.64% dye degradation, and 66.18% COD reduction. These results confirmed that electrochemical oxidation is an efficient method for removing sulforhodamine B from textile wastewater. To validate the effectiveness of the optimized conditions in practical situations, wastewater samples containing sulforhodamine B collected from a textile industry in Sri Lanka were also analysed under the optimal conditions found. The results obtained impart the use of the electrochemical oxidation method in degrading sulforhodamine B present in textile wastewater in a sustainable and cost-effective manner.
Enhancement of the degradation of vulcanized natural rubber by natural fatty oils.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Ruhunage, C. K.; Jayasuriya, C. K.
The overall use of natural rubber for a large number of applications is constantly on the rise and results in a growing volume of rubber waste. The cross-linked structure of rubber and the presence of stabilizers cause rubber recalcitrance to both chemical and biological degradation. Landfill disposal of rubber materials leads to wastage of valuable rubber causing many environmental problems. Reclaiming and reusing are major approaches to solve this problem worldwide. The current study was focused on studying the degradation of vulcanized natural rubber using natural fatty oils which have the potential to be used as reclaiming agents. The process of degradation strongly suggests that rubbers are susceptible to attack by free radicals from peroxidizable organic compounds under an oxygen atmosphere. Hence the radicals produced from lipid hydroperoxides by lipid autoxidation of unsaturated fatty oils have the ability to promote degradation of rubber. Commercial grade coconut oil, corn oil and sunflower oil were used during the present research to study the degradation of Vulcanized Natural Rubber (VNR). VNR samples (10.6 cm x 10.6 x 0.2 cm) were prepared and immersed in fatty oils (300.0 mL) separately for various time periods such as 3, 6, 9 weeks at room temperature under dark environment and for 6 weeks in the presence of sunlight. At the end of the each time period, testing of mechanical properties was done by BS ISO 37-2010, BS ISO 34-1:2010 and BS ISO 48:2010 methods. Further characterization of the samples was performed using Fourier Transformed Infrared-Attenuated Total Reflectance spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). Results revealed that mechanical properties of VNR decreased when samples were immersed in fatty oils for longer time periods. Also as the degree of unsaturation of fatty oil increases, the mechanical properties decreased dramatically. In addition, the presence of sunlight enhances the loss of mechanical properties. According to the present study, the loss of mechanical properties was higher when vulcanizates immersed in sunflower oil under sunlight. Scanning electron micrographs of surfaces of samples immersed in corn oil and sunflower oil for 6 weeks under sunlight revealed the samples were deteriorated. According to the results of the current study, the degradation of VNR can be enhanced by immersing vulcanized natural rubber in fatty oils such as sunflower oil and corn oil which are rich in polyunsaturated fatty acids. Therefore a new system can be developed for reclaiming and safe disposal of products derived from vulcanized natural rubber with the use of highly unsaturated fatty oils.
Reinforcement of natural rubber using carbon black / mineral hybrid filler.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Wanasinghe, W. M .P. G. S. V.; Jayasuriya, C. K.
Fillers improve the properties of natural rubber. Carbon black is the most abundant reinforcing filler in industry and is derived from the petroleum feed stock. There is a complex and expensive process to obtain Carbon Black from petroleum. It also causes pollution. Optimizing the mechanical properties of natural rubber by replacing part of Carbon black with minerals is therefore, very important. In this research Feldspar, Kaolin, Quartz and Rutile were used as the minerals which were more abundant in earth at low cost. All four minerals were ground separately using TEMA mill and sieved to get particles in the range of 0-180 μm. Three series of samples were prepared by replacing Carbon black with 5 phr (parts per hundred rubber), 10 phr and 15 phr with each type of mineral. All the natural rubber vulcanizates thus prepared were analyzed using Rheometer and times obtained were used to cure the samples. Hardness, tensile strength and tear strength were measured for each series. Samples with Feldspar showed highest tear strength, hardness and minimum torque compared to the samples with other minerals. In most of the cases, properties of the samples with 10% Feldspar showed optimum values. The highest tensile strength was obtained for the sample with quartz (15 phr), which is 11.842 (± 0.544) MPa. Natural rubber vulcanizates with Rutile showed the highest properties in Maximum Torque and cure time 90%. Further characterization was done with Fourier Transformed Infrared-Attenuated Total Reflectance spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). SEM images of tensile fracture surfaces were obtained from Scanning Electron Microscopy to study the morphologies of some samples filled with Quartz and Feldspar. Those microstructural results revealed that quartz (15 phr) showed the uniform dispersion of fillers and lowest agglomerates of the natural rubber vulcanizate, which showed the highest tensile strength. The good interfacial interactions between the minerals and the rubber chains give these vulcanizates excellent tensile strength. FTIR-ATR spectroscopy was used to study the effect of mineral loading on the structure of the filled sample. Extra peaks can be seen in some spectra due to the functional groups of the minerals. However, Peaks could not be assigned accurately due to the complexity of spectra.
Synthesis and characterization of carboxymethyl cellulose-based hydrogels to be used as a slow-release fertilizer
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Abeysinghe, A. M. N. A.; Jayasuriya, C. K.; Permachandra, J. K.
Chemical fertilizers are heavily used in the agricultural sector in Sri Lanka. Since SriLanka does not have high quality raw materials to produce chemical fertilizers, Sri Lanka has to import chemical fertilizers regardless of the rising prices of chemical fertilizers in the global market. On the other hand, the traditional fertilizing methods used in the country result in the overuse of chemical fertilizers and the loss of such fertilizers to the environment through surface runoff and leaching. These hazardous fertilizing methods, pollute soil, and water and contaminate the human food chain leading to critical diseases such as chronic kidney disease (CKD). To overcome this problem, slow-release fertilizers (SRFs) can be used. SRFs are made using materials such as hydrogels, polyolefin resin and other polymeric materials. Such hydrogels can be synthesized in a cost-effective and environmentally friendly processes using natural sources. In this research a series of hydrogel samples were synthesized using carboxymethyl cellulose (CMC) and epichlorohydrin (ECH) as crosslinker, with varying crosslinking densities. The degree of substitution (DS) of the CMC powder was determined by a titrimetric method, whereas crosslinking density (CD) and average molar mass between successive crosslinks (Mc) were determined using the Flory-Rehner theory. The chemical structure of the resulting CMC- hydrogels was analyzed using FTIR-ATR spectroscopy. The swelling ratio of CMC-hydrogels with different CDs in deionized water was also examined. The slow release behaviour of CMC-hydrogel samples was assessed by loading ammonium nitrate (AN) into the samples followed by monitoring the releasing behaviour of AN for two hours at 15 minute intervals using Nessler’s reagent and UV-visible spectrophotometry. Korsmeyer- Peppas model was applied to find the release mechanism of AN from hydrogel samples. Further, the effect of temperature on slow-releasing properties of hydrogel samples was investigated from 10 ºC-50 ºC, and the influence of pH of the medium on the slow- releasing properties of hydrogels was also investigated. As expected, the results indicate that CD and Mc of hydrogels significantly affect the swelling ratio and the release rate of AN. The swelling ratio decreases with the increase of CD and the rate of release of AN at a given time, pH and temperature, decrease as CD is increased. The slow-release mechanism of all the hydrogel samples can be fitted to Fickian diffusion model. Prepared CMC-based SRF hydrogels can be classified as a lower critical solution temperature (LCST) type hydrogel since those showed a decrease in the rate of release of AN with an increase in temperature. Hydrogels showed that the releasing rate of AN increases with increasing pH of the medium. The results of the study proved the suitability of the prepared CMC-based hydrogels in the agriculture sector as SRF.
The use of electrooxidation for treating wastewater generated by automobile service stations
(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Karunagaran, D. V.; Jayasuriya, C. K.; Premachandra, J. K.
Automobile service stations are water intensive and discharge oils, greases, detergents, degreasers and heavy-duty cleaning products during their operations. Hence, treating this effluent before releasing it to the environment is absolutely essential to prevent environmental pollution. Treating the wastewater to a level at which it can be reused for its operations would be economically beneficial to the industry. Also, most importantly, it helps to conserve one of the earth’s most precious resources, water. In this regard, several treatment methods have been proposed and some of those have been employed in Sri Lanka and around the world, including physical, chemical, biological and combined methods. Electrooxidation is an attractive method of treating wastewater, possessing several advantages over conventional treatment methods, such as offering relatively fast treatment, with no use of additional chemicals and no generation of sludge. For industrial applications, the use of graphite electrodes is very beneficial compared to other types of electrodes as they are relatively cheap and inert. The main objective of this study was to investigate the effectiveness of applying electrooxidation using graphite electrodes and sodium chloride as the supporting electrolyte to treat automobile service station wastewater. In addition, it was expected to optimise the applied voltage considering the number of electrodes and the treatment time. Further, it was evaluated whether gravity filtration using a filter of pore size 11 μm as a pre-treatment would improve the process efficiency. Wastewater samples obtained from a service station in Negombo, Sri Lanka, were analyzed for 3-day Biological Oxygen Demand (BOD3), Chemical Oxygen Demand (COD), oils and greases (OG), Total Dissolved Solids (TDS), Total Suspended Solids (TSS) and pH. The levels of COD and OG were detected as 356.70 mg/L and 2650 mg/L, respectively and their variation under different applied voltages (3 V, 5 V, 8 V), numbers of electrodes (2, 3, 4, 5, 6 electrodes) and treatment times (60 minutes, 120 minutes) were used as the basis to assess the efficiency of each treatment condition and select the optimum conditions. It was found that optimum conditions for the treatment process include applying 3 V, the use of 4 electrodes and 120 minute treatment time. The corresponding efficiency removal of the COD and OG were 73.0% and 97.1%, respectively, for the samples that were filtered. The percent removal efficiencies of the COD and OG were 62.2% and 70.4%, respectively by electrooxidation for unfiltered samples. The pH of the water was observed to be close to 7 after the electrooxidation of filtered samples. Further development of this method could be done by optimising other necessary parameters in order to fully improve the water quality up to the requirements for effluent discharge. An industrial scale study could be performed in order to study the applicability of this method to vehicle service stations of different scales, as well as the long-term costs associated with it.