Biological, chemical and mathematical sciences

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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.
The characterization and removal of foam promoting impurities from blended methyldiethanolamine - piperazine solution using membrane
(Universiti Teknologi Malaysia, 2009) Ratman, Iwan
The removal of acid gases from natural gas stream is an important process in many gas processing plants and for environmental protection. The most widely used acid gas removal technology nowadays is the absorption process using amine-based solvent. Foaming is the major cause that leads operational problems, resulting in excessive solvent losses, failure to meet treated gas specification and a reduction in gas treating capacity. Therefore, the main objectives of this research were to study the foam characteristics and the surface tension phenomenon of alkanolamines solution and to reduce their foaming promoters. The effect of natural gas impurities (foam promoters) in the blended methyldiethanolamine (MDEA)-piperazine solution such as hydrocarbon liquids, iron sulfide (dissolved solid), sodium chloride (salt), acetic acid (organic acid), methanol (hydrate inhibitor) and glycol (dehydrating agent) were investigated. The concentration of MDEA was found to significantly influence the foam activity in the solution. Iron sulfide, hydrocarbon and sodium chloride present in the solution had been identified as the impurities which apparently contributed to the high foaming tendency. At 5000 ppm concentration of impurities, the foam height achieved was 425 ml. Iron sulfide appeared to be the major foam promoter in the range of concentration solutions studied. Response surface methodology and central composite design had been applied to optimize the three factors that affected the foaming phenomenon. These factors were then correlated to the surface tension and foaming tendency. Asymmetric mixed matrix membrane (MMM) was applied to remove foam promoters in the amine solvent in order to reduce its foaming tendency. The MMM characteristics and performance were tested using scanning electron microscope, differential scanning calorimetry, Fourier transform infrared and membrane filtration tests. The contents of iron sulfide, hydrocarbon and sodium chloride as the main foam promoters had been successfully reduced as indicated by reduction of surface tension values by 12 %, 6.3% and 16 % respectively. These results indicated that membrane is a promising and viable technology to enhance the effectiveness of gas treatment system through the reduction of foam formation
Compatibiliser effects on properties of polyamide-6/acrylonitrile-butadiene-styrene and polyamide-6/acrylonitrile-butadiene-styrene/short glass fibre thermoplastic composites
(Universiti Teknologi Malaysia, 2010) Arsad, Agus
Polyamide-6 (PA6), acrylonitrile-butadiene-styrene (ABS)and their blends are an important class of engineering thermoplastics that are widely used in electronic and automotive industries. Many efforts have been taken to improve the properties of both pure components and the blends. It was for this reason that the dynamic mechanical and rheological properties of PA6/ABS blend systems compatibilised by acrylonitrile-butadiene-styrene–maleic anhydride (ABS-g-MAH) was studied. The compatibiliser levels were kept up to 5wt. % in the blends. Short glass fibre (SGF) was used to improve the stiffness of the compatibilised blends and the fibre contents were from 10 to 30 wt. %. Therefore, the reason behind blending the PA6/ABS blends with short glass fibre was to balance the toughness and stiffness. Both the blends and corresponding composites were compounded using a counter-rotating twin screw extruder. Tensile, flexural and impact properties were determined using the injection moulded test samples according to ASTM standards. The mechanical properties of the blends and the composites were investigated in both static and dynamic modes. Rheological properties were investigated using rotational and capillary rheometer. In general, the mechanical strength either dynamic (refer to dynamic mechanical properties) or static conditions improved by incorporation of compatibiliser to the PA6/ABS blends. The incorporation of SGF into the PA6/ABS blends enhanced the mechanical strength but reduced the toughness of the composites. The rheological measurements confirmed the interaction between the blend components with the incorporation of compatibiliser has been improved. However, the compatibiliser has no favourable effect on the mechanical properties of the composites although it has significant effect on the blends of PA6/ABS. The compatibiliser increased the melt viscosity of the blends. The SGF increased the rheological properties especially viscosity and flowability of the composites. The optimum ratio of compatibiliser and SGF concentration were determined using power law, n and consistency index, K analyses. From the analysis, the optimum ratio obtained was 1.5 wt. % for 50/50 and 60/40 PA6/ABS blends and 3 wt. % for 70/30 PA6/ABS blends. The n values drastically decreased, when concentration of the SGF was about 20 wt % indicating more pseudoplastic nature for the composites and suggesting that, 20 wt % is the optimum SGF concentration.
Development of hollow fiber membranes for carbon dioxide absorption in gas-liquid membrane contactors
(Universiti Teknologi Malaysia, 2010) Mansourizadeh, Amir
Porous asymmetric polyvinylidene fluoride (PVDF) and polysulfone (PSF) hollow fiber membranes were structurally developed to improve gas permeability, wetting resistance and carbon dioxide (CO2) absorption flux. The membranes were prepared via a wet phase-inversion process and used in gas-liquid membrane contactors for CO2 absorption. Phase-inversion behavior of the polymer solutions was studied by plotting the ternary phase diagrams of polymer/solventadditive/water. The effect of different non-solvent additives on the structure and performance of the PVDF and PSF membranes was investigated. The membranes structure was examined in terms of gas permeation, critical water entry pressure (CEPw), collapsing pressure, overall porosity, contact angle, mass transfer resistance and field emission scanning electronic microscopy (FESEM). The CO2 absorption performance of the membranes was investigated and compared with the commercial polypropylene (PP) and polytetrafluoroethylene (PTFE) hollow fiber membranes. In addition, the effect of different operating conditions on the physical and chemical CO2 flux of the PVDF membrane was also investigated. The results showed that the PSF membranes have a thicker skin layer with smaller pore sizes and lower surface porosity compared to the PVDF membranes. The PVDF membranes demonstrated low mass transfer resistance and high wetting resistance. Therefore, the hydrophobic PVDF membranes indicated an improved structure, which considerably increased the CO2 flux compared to the PSF membranes and symmetric PP and PTFE commercial membranes. A maximum CO2 flux of 8.20×10-4 mol./m2 .s was achieved at the absorbent flow rate of 310 ml/min, which was approximately 110 % higher than CO2 flux of the PTFE membrane at the same operating conditions. In case of physical absorption with distilled water, a significant increase in the CO2 flux was observed as the pressure increased and the temperature decreased. However, in the case of chemical absorption with 1M sodium hydroxide (NaOH) solution, the CO2 flux was significantly increased by increasing temperature, where the reaction rate was dominant. Moreover, it was found that the operation remains stable at the same gas and liquid pressure without bubble formation in the liquid phase when the liquid contacts the skin layer of the membrane. Results of the long-term study demonstrated that after a certain initial CO2 flux reduction the membrane performance maintained constant over 150 h operation. Therefore, it can be concluded that the porous hydrophobic membrane with developed structure can be a promising alternative for CO2 removal from the gas streams.
Properties of starch-based packaging film incorporated with chitosan and lauric acid as antimicrobial agents
(Universiti Teknologi Malaysia, 2011) Salleh, Eraricar
This study aimed to develop the antimicrobial (AM) packaging based on wheat starch incorporated with chitosan and lauric acid as antimicrobial agents. A series of blends with different ratio of starch, chitosan and lauric acid (S:C:LA) were prepared by casting method. Effects of incorporation of antimicrobial agents into starch-based film were investigated in order to improve the spectrum activity based on measured distributions of inhibitory results. The diffusivity equation approach for describing the antimicrobial effects was also extended to include information on the molecular size of particles in the formed matrices. The Agar Disc Diffusion Assay and Liquid Culture Test measured the distributions of inhibitory effect towards the type of bacterial contamination in terms of Gram-positive, Gram-negative and their combination of wider spectrum activity in the blend films. For the first time, the inhibition size distribution resulting from rationing of base polymers and lauric acid as filler in the starch-base film itself was quantified. Spectrum activity of different Gram-stained bacteria as measured by the bacterial growth inhibition, gave surprisingly consistent pattern on rationing of compositions in the film. This indicates that the spectrum activity produced by the antimicrobial components can be related directly to the ratio on blending during film preparation. This phenomenon is proven by dominating of chitosan (S:C:LA ratio 1:9:0.08 to 3:7:0.24) for 48% increase of effective E. coli inhibition (Gram-negative bacteria). More positively, however, it signifies that the affinity of lauric acid towards starch as reported by previous research indicates relatively unambiguously the ratio required to achieve a constant degree of B. subtilis (Gram-positive) bacterial inhibition from starch/chitosan/lauric acid dominating of S:C:LA ratio at 4:6:0.32 to 7:3:0.56. Furthermore, S:C:LA ratio 8:2:0.64 and 9:1:0.72 showed good synergic inhibition of 54% higher relative to sole chitosan towards both bacteria. This implies that the ratio index is inherently meaningful, and explains why it has been possible in this work to relate the ratio index directly to a change in physical property of the structural-modified polymer matrices. Further studies of antimicrobial effects investigated the mode of release from the base film. The release of lauric acid in fatty acid food stimulant was satisfactorily expressed by Fickian-diffusion mechanism described by zero order kinetics which indicated that lauric acid released from the film matrix remains constant over time. The physical and mechanical properties of the films were improved relative to sole starch film. Increasing starch amount resulted in progressive interaction and stronger bonding between starch and chitosan molecules nevertheless decreasing the mechanical properties as shown by the results from OTR, WVTR and microstructure studies. S:C:LA ratio 5:5:0.40 gave the most smooth surfaces followed by S:C:LA ratio 6:4:0.48 which confirmed the most homogeneous and dense structure achievable. That is an indicative of a homogeneous and good miscibility or blending of starch and chitosan where SEM, XRD and FTIR analysis confirmed these properties. Results showed that S:C:LA ratio 5:5:0.40 is the phase inversion between S:C:LA ratio dominate by chitosan (S:C:LA ratio 1:9:0.08-4:6:0.32) and S:C:LA ratio dominated by starch (S:C:LA ratio 6:4:0.48-9:1:0.72). These were proven by the SEM, XRD, tensile strength, percent elongation, water uptake, diffusion coefficient, OTR and WVTR results analysis.
Fouling studies on natural rubber skim latex concentration using integrated ultrafiltration membrane system
(Universiti Teknologi Malaysia, 2011) Veerasamy, Devaraj
Fouling studies on natural rubber skim latex (NRSL) concentration using an integrated ultrafiltration membrane system has been conducted. This study focuses on parameters which influence fouling, identification of foulants, optimization of latex preservation system and subsequently identification of fouling mechanisms in NRSL concentration process. This investigation is divided into three stages. In the first stage, parameters affecting membrane fouling were studied by adopting an ideal preservation system for concentrating NRSL effectively. The second stage involves studying and identifying the major foulants in the ultrafiltration membrane system during the concentration of NRSL. The optimization of latex preservation system was conducted based on results from previous stages. Fouling mechanisms were identified to quantify all the hydraulic membrane resistances and subsequently the most significant resistances as well as the chemical nature of foulants were determined. The final stage of the study is to minimize the most significant resistance by in-situ ultrasonication in order to optimize the NRSL concentration process. The membrane resistances were quantified through membrane autopsy procedures and by using the resistance-in-series model. The pure water flux test was used to facilitate the design of an effective membrane cleaning procedure. Attenuated total internal reflection fourier transform spectrophotometer (FTIR-ATR), scanning electron microscope (SEM), atomic force microscope (AFM), energy-dispersive X-ray spectroscopy (EDX), atomic absorption spectrophotometer (AAS) and total organic carbon analyzer (TOC) were used in membrane autopsy procedures to characterize the foulants. Results show that the composite preservation system consisting of 0.3% ammonia and 0.2% ammonium laurate is the optimum preservation chemical composition for the concentration of NRSL. The concentration polarization resistance was found to be the highest of the membrane resistances during skim latex concentration process. The foulants identified are amino acids, rubber particles and protein derivatives. Alkaline (0.1M NaOH) and acid (0.1M HNO3) cleaning of the fouled polyvinylidene fluoride (PVDF) tubular membrane at a temperature of 50°C with ultrasonication, achieved the highest flux recovery of 93%. Concentration polarization membrane resistance was found to be the biggest threat to an efficient NRSL concentration process as it can develop at any time, at any trans-membrane pressure, and at any feed concentration. In-situ ultrasonication of 45 kHz frequency was applied to reduce the concentration polarization resistance during NRSL concentration process. The application of in-situ ultrasonication effectively reduced the time required to achieve the targeted concentration and cost savings by almost 30%. The integrated ultrafiltration membrane system developed in this study could effectively optimize the NRSL concentration. This newly developed system would become an economically and environmentally viable process to solve environmental problems associated with the natural rubber (NR) latex industry.
Extracellular secretion of cyclodextrin glucanotransferase in escherichia coli by modification of hemolysin transport system
(Universiti Teknologi Malaysia, 2011) Low, Kheng Oon
Direct transport of recombinant protein from cytoplasm to the extracellular medium offers enormous advantages such as simple purification step and high specific activity. One of the approaches is through the hemolysin (Hly) transport system. The objective of this project is to construct an efficient extracellular protein secretion system using the Hly transport system by mutagenesis and process optimisation. Cyclodextrin glucanotransferase (CGTase) fused to a C-terminal 61 amino acid HlyA (HlyAs61) was shown to be secreted specifically by the Hly system, albeit at a low level (1.96 ± 0.21 U/ml). In order to make the system competitive for industrial application, protein engineering via error-prone PCR was performed on hly genes (hlyAs, hlyB and hlyD). Through screening of about 1 x 104 transformants generated by error-prone PCR, five mutants that showed a 35% to 217% increase in secretion level of CGT-HlyAs61 relative to the wild-type strain were isolated. The mutation sites of each mutant were located at HlyB, primarily along the transmembrane domain. It was shown that mutant HlyB-V162A has the ability to secrete a wide range of recombinant proteins, as demonstrated on CGTase and cutinase. Combination of beneficial mutations further increased protein secretion in a range of 6 – 27% than mutant HlyB-V162A. In order to rationalize the effect of beneficial mutations, molecular models of HlyB were constructed using homology modeling. A putative substrate peptide binding pocket was proposed based on protein-protein docking between HlyB and HlyA signal sequence models. However, the effect of beneficial mutations towards increased-secretion phenotype was not observed. To further increase recombinant CGTase secretion level, a novel secretion system, termed as dual-plasmid system, was constructed in which gene expression for CGTase-HlyAs61 and Hly membrane proteins (hlyB and hlyD) were regulated by T7lac and PBAD promoter, respectively. At least 4-fold higher CGTase secretion level was obtained by the dual-plasmid system over the initial plasmid system. Subsequent optimisation via response surface methodology was carried out to maximise extracellular yield of recombinant CGTase. The optimised culture conditions were found to be 25.76 µM IPTG, 1.0% (w/v) arabinose and 34.7°C postinduction temperature which gave an extracellular CGTase activity of 69.15 ± 0.71 U/ml, resulting in a 3.45-fold increment compared to the initial condition. An optimum expression of transported protein and translocation machineries (HlyBHlyD) is essential for maximum target protein secretion. Single-step purification of the extracellular CGTase-HlyAs61 by starch adsorption resulted in a near homogeneity protein sample. As a conclusion, novel mutants HlyB and plasmid system designs, which lead to increased protein secretion level, were constructed.
Synthesis, characterization and optimization of polyacrylonitrile electrospun nanofiber membranes
(Universiti Teknologi Malaysia, 2012) Mataram, Agung
The control of electrospinning process parameters, such as high electric potential, flow rate, screen distance and concentration becomes increasingly difficult. Electrospinning is capable of producing fibers in nanosize diameter range due to the increase of mechanical forces to drive the fiber formation process. Polyacrylonitrile (PAN) nanofiber membrane produced by electrospinnning was structurally developed to improve the performance of wastewater treatment. The dispersion of silica nanoparticle concentration in dope solution of 1 wt.% has changed the structural and mechanical properties of fibers. The fiber structure was examined in terms of pore size, contact angle, tensile strength, Young’s modulus, fourier transform infrared spectrometer (FTIR), and scanning electronic microscopy (SEM). The results indicated that the increase of polymer concentration and flow rate, the average fiber diameter increases. On the other hand, the increase of screen distance and electric potential decreased average fibers diameter. Young’s modulus and tensile strength increased by the addition of silica content at 1 wt.% and decreased with the increase of the silica content of 2 wt.%. The further addition of silica particles concentration produced more brittle and fragile PAN/silica composite fibers. The effect of silver functionalized membranes to pathogen removal was also studied and the tests were performed in a flow through system. Response Surface Methodology (RSM) was also performed to investigate the influence of the variables on the quality and quantity of permeate to attain the optimized conditions for preparing electrospun PAN fibers. Results from RSM were used to assess the interaction factors, namely, screen distance, polymer concentration and voltage. The quadratic models based on the responses resulted in potential of pore size, contact angle, young modulus and clean water permeation (CWP) to suitable chemical oxygen demand (COD), total suspended solids (TSS), ammonia nitrogen (NH3-N) and e. coli removal efficiencies. The results showed high removal of TSS, COD, NH3-N and e. coli at 96.18%, 91.82%, 68.89%, and no detectable, respectively. Therefore, it can be concluded that electrospun nanofibers membrane can be promising alternative materials in water filtration, especially as membrane for antibacterial and stand-alone microfiltration unit.
Development and characterization of phototrophic aerobic granular sludge
(Universiti Teknologi Malaysia, 2012) Dahalan, Farrah Aini, author; Ujang, Zaini, thesis advisor
Carbon dioxide (CO2) produced in aerobic wastewater treatment has contributed to the greenhouse gases (GHG) emissions in the atmosphere and can cause global warming. Existing biological system of the wastewater treatment needs to be reviewed in order to minimise the emission of GHG especially the CO2. In order to minimise CO2 emission, photosynthetic bacteria can be employed for utilisation of CO2 during the wastewater treatment processes. In this perspective, sequential anaerobic-aerobic process is able to enhance efficient solid-liquid separation through the formation of aerobic granules. The objective of the study looks at the possibility to integrate the three elements: CO2 minimisation, photosynthetic bacteria utilisation and aerobic granulation technology by developing photosynthetic aerobic granular sludge (AGSP) to treat municipal wastewater under phototrophic condition. Synthetic wastewater was used throughout this study to obtain the aerobic granules. Significant physicochemical parameters, i.e. pH, temperature, and light intensity, which enhance phototrophic bacterial growth were determined at the preliminary stage to provide best condition for the growth of photosynthetic bacteria. The optimum physicochemical conditions was applied on a 3-L bioreactor (SBRP) to produce AGSP. After one month of aerobic granules development, mature AGSP gained high settling velocity for efficient settleability of the treated wastewater. The biomass concentration increased from 3 to 14 gL-1. Such growth has resulted a maximum settling velocity of 40 mh-1 with granule average size of ~ 2.0 mm. The high settling velocity was found to be attributed by the smooth, compact, and regular characteristics of the aerobic granules. High magnification microscopic analysis revealed that AGSP was dominated by cocci-shaped bacteria embedded within the extracellular polymeric substances (EPS). Detailed observation on the structure of the AGSP showed the presence of 30 µm of cavity to allow nutrients and gas exchanges within the aerobic granule. Scanning Electron Microscope - Energy-Dispersive X-ray (SEM-EDX) examination showed AGSP composed of different types of inorganic and organic compounds. The presence of high concentration of bacteriochlorophylls (BChl) with 0.86 mg/L in AGSP confirm the presence of photosynthetic pigments in the aerobic granule indicating the occurence of photosynthesis in bacterial cells. AGSP achieved 92% of CO2 reduction and 84% of chemical oxygen demand (COD) removal. The 16s ribonucleic acid (rRNA) sequencing analysis has detected the presence of aerobic, anaerobic and facultative anaerobic bacteria within the granules. The presence of photosynthetic bacteria in the AGSP, i.e Magnetococcus sp, Rhodopseudomonas palustris, Bacteroides thetaiotaomicron, Rhodococcus erythropolis and Desulfovibrio vulgaris showed that CO2 emission in wastewater treatment can be minimised with enhancement of phototrophic conditions.
Simultaneous saccharification and fermentation of microwave - alkali pre-treated oil palm empty fruit bunch fiber for lactic acid production
(Universiti Teknologi Malaysia, 2012) Hamzah, Fazlena, author; Idris, Ani, thesis advisor
The novelty of this study is the production of lactic acid from pre-treated oil palm empty fruit bunch (OPEFB) fibre via microwave–alkali (Mw-A) and simultaneous saccharification and fermentation (SSF) process with Rhizopus oryzae. The present work involved a pre – treatment of OPEFB using two different methods; the conventional heating–alkali and Mw-A techniques. Physical and chemical changes on OPEFB fibre, saccharification and hydrolysis process of treated OPEFB were identified for the evaluation of the accessibility of the treated OPEFB. Suitable conditions for R. oryzae morphology and effective SSF process of the treated OPEFB for lactic acid production were also investigated. Results revealed that the Mw-A technique is more effective pre – treatment for OPEFB compared to the conventional heating–alkali. Application of Mw-A on native OPEFB break the ligninhemicellulose seal, disrupted the crystalline structure of the cellulose and thus, resulted in reduction of the lignin and hemicelluloses composition. Reduction of lignin and hemicellulose through Mw-A was significantly increased an accessibility of the cellulose to the enzymatic attack. In fermentation of Mw-A treated OPEFB using R. oryzae, R. oryzae in pellet form was better than R. oryzae in the form of clump and ellipsoidal due to a higher production of lactic acid. The lactic acid production in SSF process was optimised using Face Centred Central Composite Design (FCCCD). The main effects considered were enzyme concentration (100 – 600 mgL-1), pH (4 – 6) and temperature (37°C – 50°C), and the response variables measured were lactic acid, glucose and protein concentration. From statistical analysis, the optimum lactic acid production was achieved at pH of the medium of 6 and temperature of 37°C. The cellulase concentration required to support production of 900 gL-1 of lactic acid at optimum condition was 600 mgL-1 (98.4 FPU ml-1 cellulase and 770 IU ml-1 ß 1-4 glucosidase). The present study revealed that through Mw-A technique, the cellulose molecule inside OPEFB are wisely utilized by enzyme and R. oryzae in order to produce optimum lactic acid in SSF process
Production of transgenic eggplant (Solanum Melongena L.) resistant to herbicide Bromoxynil
(Universiti Teknologi Malaysia, 2013) Taghipour, Farhad
Eggplant (Solanum melongena L.) is an economically important vegetable crop grown in various tropical and temperate parts of the world. Bromoxynil is a nitrile herbicide which inhibits electron transfer in photosystem II during photosynthesis and consequently led to leaf necrosis in eggplant. Synthetic bxn gene was ligated into pGS21a expression vector and introduced into E.coli strain BL21(DE3)pLySs for in vitro gene expression test and the recombinant protein was evaluated by SDS-PAGE. The synthetic bxn gene fragment was also cloned into pCAMBIA 1301 for plant genetic transformation. The cloning was carried out using standard method and the ligated bxn gene was checked by double digestion and sequencing analysis. The recombinant plasmid was designated as pCAMBIA(bxn+). pCAMBIA(bxn+) was then introduced into Agrobacterium tumefaciens strain LBA4404 and used for genetic transformation of tobacco control plant and target eggplant. The integration of bxn gene in tobacco genomic DNA was proved by PCR and Southern blotting followed by bio-assay test. Therefore, the genomic DNA of transformed tobacco was used as a positive control in molecular analyses of transgenic eggplant production. In vitro tissue culture of eggplant was established as the prerequisite for genetic transformation using cotyledon and leaf explants. Cotyledon explants was selected with efficiency of 86.67±6.67 % and mean of 4.3±0.33 in shoot regeneration than cultured leaf explants for genetic transformation. Shoot regeneration medium number 10 (SRM10) supplied with 0.5 mg/L NAA, 0.1 mg/L BAP and 2 mg/L TDZ in combination with MS medium was selected and used for regeneration of transformed cotyledon explants. The genetic transformation of 100 cotyledon explants of eggplant was carried out with 9% efficiency. The integration of synthetic bxn gene in eggplant genome was checked by PCR and Southern blotting. The bio-assay test showed plant resistance up to 50 mg/200ml ratio of [bromoxynil:water (1:4)]. This phenomenon suggests the eggplant plantlets successfully transformed with synthetic bxn gene
Optimal operating conditions of Eurycoma Longifolia extraction
(Universiti Teknologi Malaysia, 2013) Mohamad, Mardawani
Eurycoma longifolia is known locally as Tongkat Ali and it is sold as a spray dried product. Its extract has shown medicinal benefits and it is considered as a valued product in pharmaceutical industries. The extraction yield depends on the extraction process parameters such as extraction time, agitation speed, solid to solvent ratio, temperature, particle type and type of solvent. Optimum extraction was focussed on eurycomanone, benzoic acid and gallic acid as the product of interests. Batch extraction experiments were conducted to study the effect of operating parameters on the extraction yield. The optimization of experimental results was performed using response surface methodology (RSM). A mathematical model for estimating the extraction yield has been developed and compared to results obtained experimentally. Comparative studies showed that results by mathematical model had shown good agreement with that of experimental results for the effect of extraction time, agitation speed and temperature on the extraction yield. Optimization of the simulated model was performed using genetic algorithm (GA). The optimum operating conditions obtained from eurycomanone were 100 °C, solid to solvent ratio of 1:24.5, 45 minutes and 398 rpm whilst 94.6 °C, 45 minutes and 360 rpm were obtained from GA. Similar tests on benzoic acid have shown 58.2 °C, solid to solvent ratio of 1:20, 44.7 minutes and 390 rpm were obtained from RSM whilst 46.5°C, 41 minutes and 398 rpm were obtained from GA. Finally, the optimum operating conditions for gallic acid using RSM were 85.7 °C, solid to solvent ratio of 1:20, 45 minutes and 390 rpm whilst 78 °C, 45 minutes and 400 rpm were obtained using GA. Relative error studies showed that only slight difference were observed for both RSM and GA.
Electrosynthesis of zirconia, zinc and iron supported HY zeolite-based catalysts for enhanced photodecolorization of dyes
(Universiti Teknologi Malaysia, 2013) Sapawe, Norzahir
A facile one-pot electrosynthesis method of Zr, Zn, and Fe nanoparticles supported on HY zeolite to form single (ZrO2/HY, ZnO/HY, Fe2O3/HY), double (ZrO2 -ZnO/HY, ZrO2 -Fe2 O3 /HY, ZnO-Fe2 O3 /HY), and triple (ZrO2 -ZnO - Fe2O3/HY) catalysts was studied. The catalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), Brunauer- Emmett-Teller (BET), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), 29 Si and 27 Al magic angle spin nuclear magnetic resonance (2 9 Si and 27Al MAS NMR), X-ray photoelectron spectroscopy (XPS), and inductive coupled plasma-mass spectrometry (ICP-MS). A dealumination accompanied by isomorphous substitution of related metal ions was found to have occurred in the framework of aluminosilicate HY during the electrolysis, to form a new active species (Si-O-M), which indeed affects the photocatalytic activity toward methylene blue (MB) decolorization. A 10 mg L-1 MB was completely decolorized when using 0.38 g L-1 (single and triple metal) and 0.60 g L-1 (double metal) of 1 wt% metal/HY catalysts at pH 11 under light irradiation. The modification of catalysts has allowed the use of ultraviolet (UV) to visible light and also shortened the contact time from 6 to 1-2 h. According to biological oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) analyses, nearly complete mineralization of MB was achieved. The catalysts were still stable after five cycles with just a small decrement (<10%) of decolorization percentage without any ions leaching. The degradation followed pseudo first-order kinetic rationalized Langmuir-Hinshelwood model. The dye adsorption is the controlling step of the process for all of the catalysts except for ZrO2 /HY and ZnO/HY, in which the reaction occurred in the bulk solution and at the surface of the catalyst. Response surface methodology (RSM) shows good significance of findings (confidence level, CL = 95%) with very low probability values (<0.0001) and a high coefficient of determination (R ). Good activity towards decolorization of other synthetic dyes such as Congo red (93.4%), methyl orange (85.3%), and simulated dyes (100%) promises the catalysts to be used in textiles industry wastewater treatment and also other applications
Enhanced production of recombinant B-1, 4-endoxylanase by Kluyveromyces lactis GG799
(Universiti Teknologi Malaysia, 2013) Mohamad Fuzi, Siti Fatimah Zaharah
Investigation of recombinant ß-1,4-endoxylanase (Xyn2) expression and production strategies in Kluyveromyces lactis GG799 were carried out in this study. Nutrient composition and culture conditions were observed to affect the secretion, production level and stability of the recombinant host and Xyn2. The experiments were performed in shake-flasks followed by bioreactor propagation in batch and fed batch fermentation. Medium developed in this study consists of nitrogen sources such as ammonium sulfate and free amino acid (casamino acid) as well as compounds like MgSO4·7H2O, Na2SO4, ZnSO4·6H2O, MnSO4·4H2O and KH2PO4 and exhibited good support for the growth and recombinant Xyn2 production by K. lactis GG799. Optimization of batch fermentation was carried out using 2 l bioreactor with 1 l working volume. Optimum dissolved oxygen (DO) level and initial glucose concentration were obtained using Response Surface Methodology (RSM) in order to improve both cell growth and recombinant Xyn2 production in K. lactis GG799. Cell concentration and maximum recombinant Xyn2 activity of 7.54 g/l and 75.53 U/ml, respectively were obtained under optimum condition. The productivity and specific activity of the enzyme were also higher in this system. The optimized conditions produced 12 U/ml/h of recombinant Xyn2 compared to fermentation conditions without oxygen supplied (6 U/ml/h). The study of fed batch fermentation was carried out to enhance the biomass and recombinant Xyn2 production in K. lactis GG799. The addition of 0.5 % (w/v) yeast extract in the feeding medium proves to increase the recombinant Xyn2 and biomass production. Exponential feeding with the specific growth rate controlled at 0.05 /h showed highest increment in recombinant Xyn2 and biomass production by 54 % and 25 %, respectively compared with the batch fermentation. Moreover, high cell density cultures of 74.85 g/l was achieved in this study, and productivity of recombinant Xyn2 at 8.1 U/ml/h was also obtained. In conclusion, the present studies show the importance and influence of medium design, DO level and feeding strategy in increasing the performance of K. lactis GG799 as expression host
Preparation and characterization of biodegradable polyacrylic acid based hydrogel for agricultural application
(Universiti Teknologi Malaysia, 2013) Laftah, Waham Ashaier
In this study, the influences of different plant natural fibres (PNF) on the properties of poly (acrylic acid) (PAA) based hydrogel were investigated. Polymer hydrogel composites (PHGCs) of poly (acrylic acid) grafted microfibre of cotton (CTN) and oil palm empty fruit bunch (OPEFB) were successfully prepared using solution polymerization technique. Surface methodology and central composite design (CCD) were used to optimize the best content of the initiator (APS), cross-linker (MBA), neutralizer (NaOH) and plant natural microfibres (CTN, OPEFB). The functional groups of PHGs were characterized using Fourier Transform Infrared (FTIR). The effects of CTN and OPEFB on swelling rate, re-swelling capability, thermal, mechanical, biodegradation properties were investigated. Morphological study of PHGs was carried out using Scanning Electron Microscopy (SEM). The effect of PHGs on soil holding capacity, urea leaching loss rate (ULLR) and red okra plant growth were evaluated. The average optimum content of APS, MBA, NaOH and natural fibre were 1.3-1.6, 0.15-0.16, 11.9-14.6 and 13.9-15 wt. % respectively. SEM images indicated that the polymer hydrogel grafted CTN fibre has bigger pore size than that of polymer hydrogel grafted OPEFB fibre and plain PHG. PHGs grafted natural fibres showed higher thermal stability, mechanical properties, biodegradation, swelling rate and re-swelling capability compared to plain polymer hydrogel. Polymer hydrogel grafted micro natural fibre of high cellulose content (CTN) has superior properties compared to that of grafted with microfibre of less cellulose content (OPEFB) and plain polymer hydrogel. Polymer hydrogel composites as soil conditioner and slow release system have positive effect on the holding capacity of sandy soil, ULLR and consequently on red okra plant growth.
Decolourisation and degradation of acid orange 7 using an acclimatised BAC-ZS mixed bacterial culture
(Universiti Teknologi Malaysia, 2014) Bay, Hui Han
Formation of dark coloured auto-oxidation compounds had resulted in reduced efficiency of the sequential anaerobic-aerobic treatment system to decolourise sulphonated azo dyes. In view of this, a monosulphonated azo dye, Acid Orange 7 (AO7) was selected as a model dye to study the decolourisation of AO7 and its auto-oxidation compounds by a mixed bacterial culture, BAC-ZS. It consisted of three bacteria namely Brevibacillus panacihumi strain ZB1, Lysinibacillus fusiformis strain ZB2 and Enterococcus faecalis strain ZL. The decolourisation and degradation process was performed using the sequential facultative anaerobicaerobic system. Optimisation of the co-substrate showed that the combination of glucose (5 g/L) and yeast extract (3 g/L) was the best co-substrate for decolourisation; 98% of AO7 colour was removed within 2 h of facultative anaerobic phase. When the decolourised solution was further treated under the aerobic phase, auto-oxidation reaction resulted in heavy browning effect after 24 h of agitation. The browning effect had drastically decreased the decolourisation to 72%. However, continuous agitation up to 48 h successfully decolourised the auto-oxidation compounds as indicated by the increase in decolourisation up to 90%. Consequently, the decolourisation was accompanied by 73% decrease in Chemical Oxygen Demands (COD) and an increase of 94% of bacteria concentration (absorbance at 600 nm). It was also found that the initial pH 6.6 of AO7 solution dropped to pH 4.5 during facultative anaerobic decolourisation and increased to pH 7.7 at the end of aerobic treatment. The degradation of AO7 dye was determined and confirmed using the UV-Vis spectrophotometry and FTIR analysis. In addition, the formation of autooxidation compounds, 1,2-naphtholquinone and 1,4-benzoquinone were detected and monitored using HPLC analysis. Further phytotoxicity tests using Cucumis sativus confirmed detoxification of the final treated solution by BAC-ZS. Quantification of BAC-ZS using real-time polymerase chain reaction (RT-PCR) showed E. faecalis strain ZL was the dominant bacteria in the acclimatised BAC-ZS and throughout the AO7 treatment process. The annotatation of the draft genome of each bacteria revealed presence of genes coding for the azoreductases, dioxygenases and monooxygenases which played important roles in degradation and mineralisation of AO7 dye. In conclusion, the acclimatised BAC-ZS mixed bacterial culture has good potential to be used in the biological treatment of textile effluent
Decolourisation of palm oil mill effluent using curvularia clavata
(Universiti Teknologi Malaysia, 2014) Neoh, Chin Hong
The conventional treatment process of palm oil mill effluent (POME) produces highly coloured effluent. The coloured compounds in POME cause reduction in photosynthetic activities, produce carcinogenic by-products in drinking water, chelate with metal ions, and are toxic to aquatic biota. Thus, failure of the conventional treatment methods to decolourise POME has become an important problem to be addressed. From the 24 fungi that were isolated, 11 of the fungal strains were able to decolourise the POME. Aspergillus fumigatus isolated from POME sludge and Curvularia clavata isolated from pineapple solid wastes showed the highest decolourisation of POME. C. clavata was selected for the forthcoming experiments as its decolourisation was contributed by adsorption and enzymatic degradation and this is potentially useful in degrading and transforming of coloured pollutants. After optimisation using response surface methodology, C. clavata showed removal of colour by 81% at pH 5, 10% v/v inoculum, 0.6% w/v fructose and 0.3% w/v peptone. Ecotoxicity test indicated that the decolourised effluent was safe for discharge. To determine the longevity of the fungus for a prolonged decolourisation period, sequential batch decolourisation studies were carried out. The results showed that lignin peroxidase and laccase were the main ligninolytic enzymes involved in the degradation of colour. Carboxymethylcellulase (CMCase) and xylanase activities were also detected suggesting possible roles of the enzymes in promoting growth of the fungus which consequently contributed to improve decolourisation of POME. This study has shown the potential use of C. clavata for decolourisation and degradation of agricultural wastewater containing polyphenolic compounds
Treatment of toluene and xylene compounds from wastewater using air stripping and non thermal plasma system
(Universiti Teknologi Malaysia, 2014) Evuti, Abdullahi Mohammed
The limitations of the conventional methods in the treatment of volatile organic compounds such as toluene and xylene from wastewater have led to researches into the application of non-thermal plasma technology as an alternative treatment method. The application of this technology as an integrated system comprising air stripping and non-thermal plasma reactor in the treatment of toluene and xylene from wastewater coupled with online Fourier transform infrared spectroscopy (FTIR) as a by-product detection technique were studied. The toluene and xylene rich air stream from the air stripper was directly fed to the non-thermal plasma reactor system. The performance of the integrated system was evaluated at various experimental conditions. The modelling and optimization of applied voltage, discharge gap and gas flow rate on the non-thermal plasma decomposition of toluene and xylene as well as the decomposition by-products determined from the FTIR spectra were also carried out. It was found that toluene and xylene removal efficiencies from air stripping increased non-linearly with temperature and air-water ratio in which at 50 °C and air-water ratios of 100, 93% removal efficiency for both toluene and xylene was obtained. The decomposition of toluene and xylene in nonthermal plasma reactor was found to be significantly influenced by the applied voltage, discharge gap and gas flow rate in which the developed models showed a good fit with coefficient of correlations of 89.38% and 92.76% for the toluene and xylene respectively. The optimum discharge gap, applied voltage and flow rate for the decomposition of toluene and xylene in non-thermal plasma reactor were 22.3 mm, 15 kV, 3.56 L/min; and 20.1 mm, 15 kV, 3.34 L/min for toluene and xylene, respectively. At this optimized conditions, the equivalent predicted toluene and xylene removal efficiencies of 87 and 82% having 1.3 and 2.2% errors were obtained respectively. The by-products determination by online FTIR indicated that water, carbon dioxide, carbon monoxide and nitrous oxide gases were detected. These findings generally confirm the compatibility of the integrated system and its suitability towards the treatment of volatile organic compounds from wastewater.
Dynamic modeling, simulation, and optimization of hydropurification reactor and crude terephthalic acid purification system troubleshooting
(Universiti Teknologi Malaysia, 2014) Hassankiadeh, Abbas Azarpour
Purified terephthalic acid (PTA) is a raw chemical utilized in polyester production plants. In the PTA production process, para-xylene is oxidized to crude terephthalic acid (CTA), which has to be purified. The CTA hydropurification process is carried out in a fixed-bed catalytic reactor consisting of palladium supported on carbon (0.5 wt. % Pd/C) catalyst. The purpose of this study is to dynamically model, simulate, and optimize the hydropurification reactor and troubleshoot the CTA purification system. In the first step, first principle model (FPM) was developed incorporating Pd/C classical catalyst deactivation equation to model the initial reactor system. However, the classical catalyst deactivation equation does not reflect the actual plant catalyst deactivation performance. Hence, in the second step a hybrid model which combines the FPM with artificial neural network capable of predicting a more accurate catalyst deactivation mechanism was established. In the third step, the reactor performance was optimized by manipulating the critical impurity to increase the rate of production. Finally, an expert system to troubleshoot the CTA purification system was established employing fuzzy logic in order to ensure the system could be run at its optimal conditions as suggested by the models. All models were coded into Matlab 2010b environment. The four models were validated by applying the data of an industrial hydropurification reactor and verifying the results with the plant owners. The result of the hybrid model gave 32 percent more accuracy as compared to the FPM. 4- carboxybenzaldehyde (4-CBA) was found to be the major contributor to the catalyst deactivation affecting the reactor performance. Uncontrolled 4-CBA also led to higher benzoic acid and carbon monoxide (CO) being produced as side reaction, where CO might become a poison to the palladium catalyst. Increase of feed flowrate, feed concentration, and production rate was also found to adversely influence the reactor operation.
Preparation and properties of metallocene linear low density polyethylene/natural rubber/epoxidised natural rubber composites
(Universiti Teknologi Malaysia, 2014) Alwaan, Ismaeel Moslam
Polyethylene has been used as insulation materials in wire and cable applications due to its excellent non-conductive electrical properties. The effect of (90/10) natural rubber/epoxidised natural rubber blend ratio, organo-montmorillonite (OMMT), magnesium oxide (MgO), zinc borate (ZB) with the presence of 2 parts per hundred (phr) N,N-m-phenylenebismaleimide (HVA-2) cross linking agent on the mechanical, dielectric, thermal, flammability, morphology and crystallinity properties of metallocene linear low density polyethylene (mLLDPE) blends were investigated. Blends were prepared by melt mixing in a twin screw extruder, remixing in milling machine and compression molding. The results from the field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infra-red spectroscopy (FTIR), limiting oxygen index (LOI), differential scanning calorimetry, thermogravimetry, tensile strength, elongation, modulus, dielectric constant and loss, breakdown and volume resistivity tests were discussed. The 90/10 mLLDPE/(NR/ENR) blend showed the highest tensile strength values. The results also showed that with increasing rubber loading, the dielectric properties of mLLDPE continuously decreased while the volume resistivity continuously increased. The blend was compounded with different OMMT, MgO and ZB loadings for further studies. The results showed that the tensile strength and elongation at break decreased, while tensile modulus increased with increasing MgO, ZB and OMMT loadings. Also the permittivity increased with increasing voltage in the range of voltage 1-5 KV in all blends. FTIR showed that the epoxy and double bond groups were found to be absent in blends. The loading of 15 and 20 phr MgO in the blends improved the dielectric properties. The thermal stability and LOI were improved with increasing MgO, ZB and OMMT loadings. The overall results showed that optimum blend ratio for cable insulation applications were observed to be at 90/10 mLLDPE/ rubbers, 20 phr MgO, 6 phr ZB and 4 phr OMMT which has a good balance in terms of mechanical, dielectric and flame resistance properties.

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