Faculty of Engineering, Chemical & Process Engineering
http://dl.lib.uom.lk/handle/123/26
Theses / Dissertations submitted to Department of Chemical & Process Engineering2024-03-28T07:45:02ZApplication of polyethylene terephthalate scraps for the manufacturing long oil alkyd resin
http://dl.lib.uom.lk/handle/123/21739
Application of polyethylene terephthalate scraps for the manufacturing long oil alkyd resin
Darshana, LAP
A new aspect of work that covers Polyethylene terephthalate (PET) waste recycling and application in coating industry is presented through this report. It was shown that chemical recycled PET can be used in the manufacturing long oil alkyd resin. In Sri Lanka alone, about 6.5 million polyethylene terephthalate bottles (water bottles, food and other liquid containers, etc) are used monthly. Then large amount of Polyethylene terephthalate scraps are discharged in to the environment. The development of effective recycling technology was based on chemical de-polymerization of post-consumer PET bottles in order to use manufacturing alkyd resin based paint. The depolymerization of PET can be carried out in many ways such as glycolysis, hydrolysis, aminolysis, methanolysis and simultaneous hydrolysis and glycolysis. The useful material terephthalic salt can be synthesis through the hydrolysis process of PET. That could be used to derive terephthalic acid. This terephtalic acid can be used for alkyd resin process. Alkyd resins were any of a large group of thermoplastic resins that were essentially polyester made by heating polyhydric alcohol with polybasic acids or their anhydride and used chiefly in making protective coatings. Originally, alkyd resins were merely the reaction products of phthalic anhydride and glycerine. But these products were too brittle to make satisfactory coatings. The use of oils or unsaturated fatty acids in combination with the brittle alkyds resulted in the air-drying coatings which revolutionized the chemical coating industry. The properties of Terephthalic acid have far same to the phthalic acid. Phthalic anhydride was used as a main material in esterification reaction of alkyd resin process. Then pththalic anhydride could be replaced by Terephthalic acid. This process has been done in two stages. At the first stage, reaction between PET waste and sodium hydroxide were used to produce terepththalic acid. At the second stage, application of terepththalic acid was done in the manufacturing process of long oil alkyd resin. That could be used in industrially. Terephthalic salt could be produced successfully by hydrolysis process using Ethylglycol and sodium hydroxide at the higher temperature (180°C). The reacting mixture was neutralized using strong Acid to take Terephthalic acid. Then terephthalic acid could be applied in alkyd resin process without filtering. This new application of the recycled PET in synthesis of alkyd resin had provided same properties of normal alkyd resins. This method was cost saving method by reducing Rs. 3.00 per one kilogram of resin. As well as this can be used as environmental friendly method to give a better solution for the environment pollution due to plastic waste.
2012-12-01T00:00:00ZDevelopment of a computational fluid dynamics model for pollutant dispersion in complex terrain
http://dl.lib.uom.lk/handle/123/21690
Development of a computational fluid dynamics model for pollutant dispersion in complex terrain
Sivakunalan I
This research investigated the issues of vehicular-emitted pollution in Kandy City, a
valley-like environment experiencing severe air pollution problems due to a higher
traffic volume, topographical aspect, and prevailing weather conditions. The COPERT
emission model was used to calculate the total emission rates of 𝑁𝑂
, 𝐶𝑂, and 𝑃𝑀 in
major road segments of the city. An OpenFOAM-based CFD model was developed to
predict dispersion characteristics over the complex terrain, considering physical phenomena
such as surface roughness, wind shear, Coriolis’s effect, surface heat flux,
buoyancy effect, and turbulence. The developed model was validated against experimental
results to investigate its sensitivity and efficiency, and it was found to show
good agreement.
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The developed CFD model was then applied to simulate the dispersion of vehiculargenerated
air pollutants in Kandy City, considering the region’s two main wind patterns
NE and SW, topography, and emission rates of major road segments. The model’s
concentration and dispersion pattern of pollutants were found to vary with urban topography
and wind pattern, with higher concentrations of pollutants observed in areas
with high traffic volume and severe traffic congestion, such as the central business district
and areas close to bus stands. The model was also used to investigate pollution
dispersion patterns in 27 locations at the pedestrian level, with good agreement found
between the model’s predicted concentrations of 𝑁𝑂
and experimental results.
Overall, this study highlights the significance of considering topography and me-
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teorological conditions when evaluating pollution dispersion mechanisms in urban environments.
The developed CFD model can be used as a promising tool for predicting
pollutant transport and wind flow in the built environment, aiding in proper urban
planning to reduce pollution accumulation in significant locations. This research
can contribute towards effective policies and interventions to mitigate the impacts of
vehicular-generated air pollution in valley cities.
2023-01-01T00:00:00ZLife cycle assessment of bioethanol production from water hyacinth using process simulation
http://dl.lib.uom.lk/handle/123/22212
Life cycle assessment of bioethanol production from water hyacinth using process simulation
Abeysuriya DI
Water Hyacinth (WH) is an undesirable plant in the aquatic vegetation with a proven record
of the possibility as a raw material to produce bioethanol. One of the advantages of using
water hyacinth as a bioethanol feedstock is that it does not require land use or significant
resource consumption for cultivation. The aim of this study was to evaluate the performance
of water hyacinth as a bioethanol feedstock by modelling bioethanol production plant for
future industrial purposes beyond labs-scale for different bioethanol production methods
using the Aspen Plus software. By alternating two feedstock pretreatment methods (alkaline
and dilute acid) and two bioethanol dehydration techniques (extractive and azeotropic
distillation), four process scenarios were created (WH1, WH2, WH3, and WH4) for mass
and energy flow comparison. Results showed that the alkaline pretreatment provided a 254
L/tonne-WH yield which is higher compared with the obtained by yield dilute acid
pretreatment method (210 L/tonne-WH). Additionally, the process pathway that used NaOH
for pretreatment and extractive distillation for the dehydration (WH1) resulted the least
energy usage for the plant (45,310 MJ/FU). Based on these results, a comprehensive LCA
was performed for bioethanol production from WH. The total energy consumption for the
cradle-to-gate life cycle to produce bioethanol from WH is 56,202 MJ/FU. The study also
evaluated energy sustainability indicators resulting 0.54 net ratio and a 1.87 renewability
factor. Further, the study conducted a sensitivity analysis to interpret the effects of the key
process parameters at two stages within the research project; first, for the bioethanol
production process; second, for the life cycle. The prominent finding is that the parameter
with the highest impact on the production plant and the life cycle is the solid loading ratio.
Moreover, the energy hotspot was identified as the pretreatment stage. Finally, the study
discussed feasible methods water hyacinth can be used for commercial production of fuelgrade
bioethanol.
2023-01-01T00:00:00ZOptimization of influencing parameters for dry anaerobic co-digestion of lignocellulosic biomass
http://dl.lib.uom.lk/handle/123/21405
Optimization of influencing parameters for dry anaerobic co-digestion of lignocellulosic biomass
Lakshitha WAA
Anaerobic digestion offers an attractive solution for recovering energy from rice straw (RS)
which is a lignocellulosic agricultural residue produced in huge quantities in Asia and
Africa. Given the high solids content of this feedstock, high solids anaerobic co-digestion in
batch mode is a process that can be applied. In this study, optimal operating conditions for
the co-digestion of RS with cow dung (CD) in pure batch reactors and batch reactors with
leachate recirculation are assessed. The preliminary experiments carried out in pure batch
conditions showed that the initial concentration of RS in the mixture of substrates, i.e., S
0
, (g
VS rice straw /kg of mixture) is an important parameter. Only the batch reactors with the
lowest S
0
values (29g VS
RS
/kg) produced biogas after a long lag phase of 14 days. The use of
digestate from a previous batch as an inoculum was investigated with S
0
values of 29 and 55
g VS
RS
/kg. Re-use of the digestate as an inoculum source drastically improved both the
initial degradation kinetics and the methane yield measured after 60 days for the S
0
of 29 g
VS
RS
/kg, as lag phase time period almost reached to zero and final methane yield of this
reactor was 222 ml/g VS. This indicates a 104 % increase of specific methane yield increase
compared to the reactor that only has the same S
0
concentration but the substrate mixture
comprises only RS and CD. However, for 55 g VS
RS
/kg, the degradation kinetics were
affected: after two months, 32% of the biodegradable organic matter was not eliminated.
Leachate recirculation experiments were conducted in leach-bed reactors (LBRs)
with S
0
between 30 and 65 g VS
RS
/kg, the highest methane yield was recorded at the lowest
S
0
value, confirming that in batch mode during high solids anaerobic co-digestion (HSAcoD)
conditions, an initial RS concentration around 30 g VS
RS
/kg is recommended for
industrial applications.
Then mathematical modeling was applied to estimate kinetic parameters related to HS-AcoD
process using the modified Gompertz model. Results obtained from Batch experiment no.3
(i.e., the three consecutive batches) were considered for the mathematical modelling.
Modified Gompertz model very closely predicted the ultimate methane yield (M
max
almost 0.99 in each scenario. Degradation kinetics improved drastically with the strategy of
re-using digestate, as for the Batch-2 the lag phase period (λ) reduced from 14 days to almost
zero. Ultimate methane yield increased by 104% through this approach. Degradation kinetics
were negatively affected with the increase of TS% within the substrate mixture even though
digestate was reused as an inoculum. In Batch-3 ultimate methane yield was 138 ml/g VS
which was a 38% reduction compared to Batch-2, even though digestate was used as the
main inoculum source for the both batches. But it was a 27% increase compared to Batch-1
which CD was used as the only inoculum.
2021-01-01T00:00:00Z