Biological, chemical and mathematical sciences

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    Carbon cryogel production from lignin, ionic liquid and liquefield oil palm frond as catalyst for esterification of levulinic acid
    (Universiti Teknologi Malaysia, 2017) Mohammad Zainol, Muzakkir
    Carbon cryogel synthesized from lignin, ionic liquid (IL) and mixtures of liquefied oil palm frond-ionic liquid (LOPF-IL), was used as an acid catalyst for esterification of levulinic acid in ethanol. Commercial lignin was reacted with furfural via sol-gel poly-condensation reaction at 90 °C for 30 min and the gel was freeze-dried and finally carbonized or calcined to produce carbon cryogel. Parametric study for the gel preparation was conducted to evaluate the carbon cryogel surface area and acidity. Similar parametric study was also performed on gel synthesis from IL and furfural. The selected gel condition of IL and furfural was applied for gel preparation from LOPF-IL and furfural. Nitrogen physisorption and temperature programmed desorption of ammonia measurements revealed the selected carbon cryogels obtained a large total surface area (>200 m2/g) and high acidity (>10 mmol/g). The selected carbon cryogels from lignin-furfural (CCLF), IL-furfural (CCIL) and liquefied OPF-IL-furfural (CCOPF) were further characterized using thermogravimetric analyzer, Fourier transform infrared spectroscopy, x-ray diffraction and field emission scanning electron microscopy with energy dispersive x-ray spectrometry. The phase structure of the synthesized spherical carbon cryogel was amorphous, has micro structures (microspheres) and thermally stable. The synthesized CCLF, CCIL and CCOPF were tested as catalyst in the esterification of levulinic acid. Carbon cryogels showed high potential as an acid catalyst for levulinic acid esterification with above 70.0 mol.% yield of ethyl levulinate. The kinetic studies using CCLF and CCIL revealed the esterification of levulinic acid followed pseudo-first order kinetics and have low activation energy. Meanwhile, the thermodynamic parameters conferred the reaction was endergonic and more ordered.
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    Amine-functionalized kenaf as carbon dioxide adsorbent in pressure swing adsorption system
    (Universiti Teknologi Malaysia, 2016) Zaini, Nabilah
    Kenaf (Hibiscus Cannabinus L.) that belongs to the family of Malvaceae is abundantly grown in Malaysia since 2006 to replace tobacco plantation as it is inexpensive, easy to grow, and biodegradable. The use of kenaf as adsorbent is seen as an attractive and innovative method, and it has been used for various adsorptions. Adsorption is a promising technology that has the ability to capture carbon dioxide (CO2), the predominant contributor of global climate change. Inspired by the established and well–known amine–based absorption process of carbon capture and storage technology, the development towards new adsorbent by introducing amine functional group has been studied. Therefore, this study explores the potential of modified kenaf as adsorbent by incorporating amine functional group on the surface and investigates the CO2 adsorptive characteristics of amine–modified kenaf adsorbent using pressure swing adsorption system (PSA). The preparation of amine–modified kenaf was conducted via the incipient wetness impregnation technique. The physical and structural characteristics of amine–modified kenaf were determined via micromeritics 3 flex, field emission scanning electrons microscopy, energy dispersive x–ray, Fourier transform infrared spectroscopy, and thermogravimetric analyzer. The results show that the types of amine, amine loading concentration, and impregnation time affect the physical and structural properties of kenaf and thus affecting the capability for capturing CO2. Screening of various types of amines via PSA revealed that tetraethylenepentamine (TEPA) has recorded the highest CO2 adsorption (0.914 mmol/g). Further examination on amine loading divulged that kenaf to TEPA ratio of 1:2 presents the highest CO2 adsorption (2.086 mmol/g) with 5 hour impregnation time. To examine the utilization of amine–modified kenaf adsorbent in PSA system, pressure bed, adsorption time, and feed flowing rate were evaluated. The result revealed that these parameters affect the gas adsorption of amine–modified kenaf adsorbent. The regeneration study had shown that kenaf adsorbent could sustain the repeated adsorption/desorption cyclic operations. This study also found that physical and chemical adsorption occurred during the adsorption of CO2 on raw kenaf and amine–modified kenaf. Thus, amine–modified kenaf adsorbent has high potential to be used as low–cost CO2 agro–based adsorbent hence inducing towards innovative material in the field of gas adsorption
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    Biopulping of pineapple leaf fiber using ceriporiopsis subvermispora fungus and its characterization
    (Universiti Teknologi Malaysia, 2014) Mat Nayan, Nadirul Hasraf
    Environmental awareness and depletion of wood resources are among vital factors that motivate researchers to explore the potential of agro-based crops as an alternative source of fiber material in paper industries. Fibers from agro-based crops are available in abundance, low cost, and most importantly its biodegradability features, which referred as "ecofriendly" materials. However, conventional pulping process which employed numerous chemical substances has resulted in a number of adverse effects on the environment. Hence, the aims of this study were to biopulp the pineapple leaf fiber (PALF) via means of Ceriporiopsis subvermispora fungus and determining its effect towards the properties of PALF fiber and paper forms. The individual fibers were characterized having good tensile properties at 0.3% of fungus treatment and favourable structural properties as characterized by Fourier transform infra-red (FTIR) spectroscopy and X-ray diffraction (XRD). It was also shown that the biopulped PALF paper achieved desirable tear index value, remarkable burst resistance and uniform morphological observations compared to the conventional chemical pulping method. On the contrary, for water absorption characteristic, the biopulped PALF paper exhibited a slight increment compared to paper produced from conventional chemical pulping. The paper making process was then optimized using design of experiment (DOE). The effects of temperature, pulping time and fungus concentration on the tear index of the PALF paper were successfully studied using response surface methodology (RSM). The DOE revealed that the pulping time had the most significant influence on the response. Optimum process conditions were obtained at pulping time of 3.15 weeks, temperature of 45°C and fungus concentration of 0.25 M which resulted in tear index of 2.485 Nm2/kg. In addition, the incorporation of corn steep liquor into the biopulping process was proven to stimulate the Ceriporiopsis subvermispora growth, thus reducing the biopulping time. However, there were no increment to the mechanical and physical properties of the PALF paper
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    The application of lattice gas automata for simulating polymer injection porous media
    (Universiti Teknologi Malaysia, 2006) Fathaddin, Muhammad Taufiq
    The simulation of polymer displacement in a reservoir is one of the important techniques in petroleum engineering that is used to predict the performance of oil production. Modeling of polymer flow through a porous medium is often derived by a macroscopic scale approach. In order to gain better insight of the polymer flow, a pore scale (mesoscale) model is applied in this thesis to determine the macroscopic properties. The objectives of this research are to develop the Frisch-Hasslacher-Pomeau (FHP) III models of lattice gas automata to simulate microscopic polymer and oil flow for the study of macroscopic properties of adsorption, gelation and polymer displacement phenomena. In the single-phase flow simulation, collision rules of interactions between polymer and solid material for adsorption and gelation processes were proposed. Correlations between various macroscopic properties such as polymer concentration, porosity, surface length, pore width were obtained. In general, the lattice gas automata simulations were in good agreement with previous studies, where the differences between them were between 2.0% to 17.4%. In the two-phase flow simulation, the displacement mechanism for various mobility ratio and adsorption rate was estimated. The change of saturation in dead-end pores during the displacement was analyzed. The results of the two-phase flow simulations were in good agreement with those of laboratory experiments, where differences of all parameters were between 3.1% to 18.4%. The computation time is a crucial factor influencing the feasibility of a mesoscale model application in simulating large porous media. Due to the nature of lattice gas automata, the simulation can run using parallel computers effectively. The use of parallel computers is able to reduce the computation time problem. In this thesis, a parallel computation technique has been proposed to run the lattice gas automata simulation. A cluster system and standalone computers were used to simulate communicating and non-communicating flow in porous media, respectively. The results of the parallel simulations were in good agreement with those of single simulations, where maximum difference of all parameters was 3.93%. The computation time was reduced by a factor that ranged from 1.9083 to 14.3411.
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    Empirical and kinetic modelling on supercritical fluid extraction profile of areca catechu nuts
    (Universiti Teknologi Malaysia, 2016) Ruslan, Muhammad Syafiq Hazwan
    Supercritical fluid extraction (SFE) using carbon dioxide is an advanced extraction technique commonly used for extraction of organic and bio-active compounds from herbs and plants, sterilization, waste treatment, cleaning, and polymer material plasticizer. In the extraction of Areca catechu nut, the active compound is catechin which possesses a dye pigment in it. The aims were to determine the best operating conditions for extraction of catehin from Areca catechu nut using SFE method and conduct solubility and kinetic studies on the extraction process. Operating conditions used for optimization were pressure (20 to 30 MPa), temperature (50 to 70 °C) and flow rate (2 to 4 mL/min). Extraction conducted using SFE with 5% methanol as co-solvent to enhance the polarity of solvent while detection and quantification of catechin were done using a high performance liquid chromatogram (HPLC). Solubility studies were also conducted to get the best correlation with the lowest value of absolute average relative deviation (AARD) using the modified Chrastil equation, modified Del Valle-Aguilera (DVA) model, Mendez Santiago-Teja (MST) model, Thakur-Gupta (T-G) model and Gordillo model. While kinetic study was conducted using the Broken and Intact Cell (BIC) model coupled with the simplified Sovová model. Preliminary studies show that the best particle size used for extraction using supercritical fluid is 177.5 µm with 5% methanol as co-solvent. The highest extract was obtained at the highest extraction condition of 4 mL/min, 70 °C and 30 MPa with 0.3400 g/ 10 g sample. Concurrently, the highest concentration of catechin was also obtained at the same conditions with 9.9772 µg catechin / mg extracts. The MST model shows the best correlation with overall AARD value of 0.3734% followed by the T-G model, modified Chrastil equation, Gordillo model and modified DVA model. The mass transfer coefficient of fluid phase varies from 0.35 to 3.96 min-1 and solid phase from 0.00015 to 0.00353 min-1 with overall AARD value of 7.37%. The study has proposed a new solubility model to comply with the usage of modifier in the process