Theses & Dissertations

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https://hdl.handle.net/20.500.14170/194

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  • Publication
    A new development of modified dipping process of the prevulcanized natural rubber latex films: investigation on the tensile and swelling properties.
    ( 2009)
    Noor Marlyna Ismail
    Prevulcanized natural rubber latex films were produced by modified dipping process and their tensile and swelling properties were investigated. Two type of natural rubber latex which is high ammonia (HA) and low ammonia (LA) latex. This research study is divided into three main parts. The first part of this research is mainly to determine the most suitable maturation time for the latex compound. Therefore, each type of latex was matured into three different maturation time, i.e., 1 hour, 3 hour and 24 hour. The latex compounds were further matured in water bath at temperature of 70°C until chloroform number 3 is achieved, in which indicates that coagulum is a non-tacky agglomerates. At this stage, the latex compound is considered moderately vulcanized. Then, the latex compounds were underwent coagulant dipping process and followed by curing/ drying at room temperature, stripping and testing. Results of the tensile test show that tensile strength and tensile modulus (M100 and M300) is increase whereas elongation at break decrease with increasing filler loading, with maturation parameter at 24 hour has shown the highest value for all tensile properties, followed by 3 hour and 1 hour. At similar filler loading, HA latex shows better tensile properties than LA latex. The second part involves the investigation on different curing time and temperature of the latex. The latex compounds were prepared as same method as in the part one with maturation time is 3 hour. The 3 hour maturation was chosen because the process is become more effective in term of time consuming. After that, the dipped compounds were vulcanized in the oven at two different processes. The first oven was set at lower temperature than the second oven, and variables with time. From the tensile test results, this part exhibits that the curing temperature at 70°C and 80°C for Oven A and Oven B, respectively, with curing time of 10 minutes for each oven shows better properties than other curing parameters. For last part, every sample in part one and two were underwent leaching process. The leached latex samples were then tested their tensile properties. At the same time, the vulcanized latex also prepared by modified dipping process in which the dipped compounds were vulcanized in the oven and then proceed with the vulcanization in the water bath. Finally, the cured-leached latex samples were dried at room temperature for 25 hours before testing. The results of modified dipping process latex samples show better tensile properties than samples in part one (vulcanized at room temperature) and part two (vulcanized in oven). Overall, crosslink density increases/ higher with increasing filler loading, maturation time and by using HA latex. The crosslink density is also higher for samples that vulcanized by modified dipping process than vulcanized at room temperature and in the oven.
      2  3
  • Publication
    A study on physical separation processes for recovery metals from waste printed circuit boards (PCBs)
    ( 2011)
    Aimi Noorliyana Hashim
    In view of increasing the waste PCBs, a physical separation process has been carried out to recover metals from waste PCBs. This research is aimed to implement an effective and environmental friendly recovery particularly cooper (Cu) of waste PCBs. The physical separation process begins with comminution to produce controlled particle size. Then, the separation process was divided into two parts according optimum efficiencies at specific size range. The size fraction -600+300µm and -1180+600µm were separated by gravity separation using Mozley laboratory separator. Afterwards, an enrichment step of concentrate fraction was done by magnetic separation using rare-earth roll magnetic separator. Meanwhile, the size fraction -150µm, -300+150µm, and -600+300µm were separated to froth flotation using Denver D-12 laboratory flotation cell. Characterisations of waste PCBs were performed by micrographic analysis and elemental analysis. A qualitative micrographic analysis was conducted using stereo- zoom microscope, optical microscope, and scanning electron microscopy. An elemental analysis was conducted using atomic absorption spectroscopy (AAS) analysis and energy dispersive spectrometer (EDS). Regarding on the particle size analysis, maximising recovery of physical separation is done by targeting recovery in a controlled four size range fraction; -150µm, -150+300µm, - 300+600µm and -600+1180µm. A qualitative liberation assessment of the waste PCBs particle was establish unliberated particles still remain in the waste PCBs fines (-75µm). As the highest metal element in waste PCBs, copper (Cu) recovery (R) and enrichment ratio (ER) was discussed with more emphasis in this project. By Mozley laboratory separator, Cu recovery increase from 80.85% (ER 2.07) at -600+300µm size fraction to 89.65% (1.93) at -1180+600µm size. Thus, the efficiency of gravity separation increases with increasing particle size. A significant of the low recovery at finer size fraction implies valuable metal loss at this size range, thereby be evidence that it is not very effective for finer particles (- 300µm) was recovered by Mozley laboratory separator. For enrichment step using Rareearth roll magnetic separator showed the enrichment ratio (ER) was highly improved. At - 600+300µm non-magnetic fraction, Cu enrichment ratio is 2.51 and 2.15 at -1180+600µm size fraction. Through the reverse froth flotation, higher Cu recovery (R) and lower Cu enrichment ratio (ER) are noticeably with increasing particle size fraction for both flotation conditions (with and without frother). Thus, the efficiency of froth flotation is higher at finer size fraction. At -75µm size fraction, Cu recovery is 84.66% (ER 3.03) under natural hydrophobic responds (without frother). Meanwhile with frother addition, Cu recovery is 82.16% (ER 3.37). In view of frother addition, there is improved in enrichment ratio but poor recovery percentage. Overall, the approach physical separation has high efficiency, easy to run and at same could recover metals and non-metals. It is expected that physical separation process will be developed for the upgrading of metals recovery in waste PCBs.
      2  6
  • Publication
    A study on the potential of polystyrene lightweight aggregate in concrete
    ( 2009)
    Fetra Venny Riza
    Economic reason caused the used of expandable polystyrene increasing every year. The consequence is that the polystyrene wastes also mounted day by day. On the other hand, the source of natural aggregate is non-renewable. Public awareness to save the environment is always be campaigned through all kind media to reuse, reduce or recycle. This research comprised the effort to produce lightweight aggregate concrete from waste expandable polystyrene or also known as polystyrene foam that can be found easily around our neighborhoods as electronic packaging. The polystyrene lightweight aggregate was produce on reducing the size into several mm and prior to heat treatment at temperature ranging from 130°C to 180°C. Characterization of this polystyrene lightweight aggregate were done by several experiments that includes shrinkage measurements, bulk density, water absorption level, compressive strength, also utilized the observation of light microscope, scanning electron microscope, even just visual observation by human eye. In this work, the polystyrene lightweight aggregate product was incorporated in concrete. Concrete characterization was conducted similar to those for aggregate with additional the slump test, compression test and flexural test. The results showed that the best temperature to produce aggregate with highest compressive strength 69.2 MPa was 170°C where the water absorption levels only 2.4% and its bulk density 154.6 kg/m3. This result of bulk density satisfied the classification of lightweight aggregate concrete according to ASTM C330. Unfortunately, this lightweight aggregate concrete compressive strength only 9.8 MPa was not reached the requirements strength for structural concrete which is 17 MPa for 28-day compressive strength. Thus, the used of this polystyrene lightweight aggregate concrete limited for non structural purpose only.
      3  2
  • Publication
    Adsorption of basic red 46 dye using Sea mango (cerbera odollam) activated carbon
    ( 2016)
    Nur Azira Iqlima Azmi
    The limited source of raw materials for production of activated carbon has increased the price of commercial activated carbon price. Due to the presence of lignin and cellulose in sea mango make it as new potential for activated carbon. Sea mango activated carbon was prepared by chemical activation using potassium hydroxide (KOH) at different carbonization temperatures, which are 500ºC (AC500) and 600ºC (AC600) under nitrogen (N2) gas flow. The activated carbon prepared together with sea mango precursor (SMP) was characterized using Scanning Electron Microscope (SEM) and Brunaer Emmet Teller (BET) for surface morphology and specific surface area, respectively. The result showed that the surface of AC500 and AC600 has undergone some alteration where some new pores were developed. The specific surface area measured for SMP, AC500 and AC600 were 0.03 m2/g, 108.79 m2/g and 451.87m2/g, respectively. Fourier Transform Infrared Spectroscopy (FTIR) use to analyse functional group showed band transition between the three samples which indicated that chemical transformation had occurred during activation process. Analysis of Total Ash Content (TAS) has shown that the ash content increased in both AC500 (38.97%) and AC600 (41.82%) compared to SMP (2.53%) whereas AC500 has better yield compared to AC600. In order to study the performance of sea mango activated carbon, AC600 was further used in adsorption of Basic Red 46 dye in batch process. The effects of operating parameters, initial pH solution, adsorbent dosage, initial dye concentration and adsorption temperature were varied where the result obtained indicated that all parameters have played important roles in the adsorption process. High initial dye concentration has resulted in low adsorption of Basic Red 46 dye with the best initial pH solution was 11. It was found that the removal of Basic Red 46 dye increased with the increasing amount of adsorbent dosage and adsorption temperature. Interaction between parameters was studied using Response Surface Methodology (RSM). The optimum parameters were recorded at 150 mg/L initial dye concentration, initial pH solution of 11.00 and 1.00 g/L adsorbent dosage with R2 of 0.9943. Moreover, from the isotherm and kinetic analysis conducted, the results showed a monolayer adsorption as the data fitted well on Langmuir isotherm model and pseudo-second-order kinetic model with R2 values closed to 1.
      2  12
  • Publication
    Analyses of cement composites with the addition of quarry dust as partial sand replacement materials
    ( 2016)
    Madzura Mohamad
    The development of cement composites has been proposed for many decades to fulfil the requirements in the construction sector and became one of the major producers of waste and source depletion, especially river sand. Quarry dust became an alternative material in cement composites to reduce the consumption of river sand and ecology rehabilitation in order to promote sustainable development of the construction industry. Therefore, this research was conducted to study the effects of quarry dust as partial sand replacement material on physical, mechanical and durability properties of the cement composites. In relation to this, the cement composites were categorised into two main sections. First section is the proportioning study that investigates the effect of quarry dust on the physical and mechanical properties, crack profile, fracture and surface morphology of cement composites under pressure load. In this study, the fabrication of cement composites was carried out by substituting quarry dust with a portion of river sand according to the various percentages at constant water cement ratio (0.45). The cement composites were produced from a mixture of ordinary Portland cement (OPC), river sand, quarry dust and water. Five different ratios of 1: 1.00: 0.00, 1: 0.90: 0.10, 1: 0.875: 0.125, 1: 0.850: 0.150 and 1: 0.825: 0.175 (cement: river sand: quarry dust) were prepared according to the related standards. The cement composites were cured in water for 7 and 28 days, and tested to determine the mechanical properties such as compressive strength and modulus of rupture, physical properties such as density, water absorption and moisture content. The other section is the durability study, which was conducted to observe the length change of cement composites when subjected to sulphate attack with the addition of 12.5 wt.% and 17.5 wt.% of the quarry dust.
  • Publication
    Antimicrobial and antioxidant activities from leaves and roots of (Elephantopus Scaber L.) extracted using different solvents
    ( 2017)
    Mohammed Riyadh Mohammed
    Medicinal plants are used traditionally in treatment of various kinds of diseases since time immemorial. The present study was carried out to evaluate the antimicrobial and antioxidant activities of roots and leaves of Elephantopus scaber by using different solvent (ethyl alcohol ,acetone and water). The ethyl alcohol, acetone and water extracts of the roots and leaves were subjected to phytochemical analyses, which revealed the presence of alkaloids, phenols, flavonoids, saponins, steroids, tannins, coumarins, quinones and glycosides in most of the selected of roots and leaves useing different solvents. Ethyl alcohol, acetone and water extracts of roots and leaves were investigated for in.vitro.antimicrobial activity against Escherichia coli, Salmonella typhis, Klebsiella pneumonia, Streptococcus pyogenes, Staphylococcus aureus, and Candida Albican by well diffusion method using different concentrations (20, 40, 60, 80, 100)mg/ml. Bioassay data obtained from the active extracts and oils were subjected to statistical analysis of variance (ANOVA). Treatment means showing significant difference (p ≤ 0.05) were separated using Student-Newman-Keuls test (SNK). Ethyl alcohol and acetone extract of roots showed promising antimicrobial activity against all test organisms. Ethyl alcohol extract of root gave a significant effect activity against all test organisms compared with the other sample. Ethyl alcohol extract of leaves was also higher compared with the acetone extract of roots for a concentrations of 100 and 20mg/ml. The water extract of leaves has a weak activity against all test organisms and did not inhibit the growth of Klebsiella pneumonia for a concentrations of 100mg/ml but at a concentrations of 20mg/ml did not inhibit the growth of all test organisms. The Minimum inhibitory concentration (MIC) of the roots and leaves extracts by using different solvent were also determined against different test organisms. The MIC value of roots and leaves extract ranged from 100 mg/ml to 500 mg/ml. The ethyl alcohol, acetone and water extract of roots and leaves were selected for possible antimicrobial activity. The antimicrobial activity was studied against six microorganisms namely Escherichia coli, Salmonella typhis, Klebsiella pneumonia, Streptococcus pyogenes, Staphylococcus aureus, and Candida Albican. It was found that ethyl alcohol extract of roots showed height influence against Escherichia coli, Salmonella typhis, Streptococcus pyogenes, Staphylococcus aureus, and Candida Albican but less effective against Klebsiella pneumonia. The water extract showed a weak effect against all tests organisms and did not has any effect against Klebsiella pneumonia. The roots and leaves extract from Elephantopus scaber using different solvents to extract were evaluated for antioxidant activity by using DPPH method using a different concentrations (1, 10, 20, 30, 40, 60, 80, 100) μg/ml. The results from the analysis were compared with ascorbic acid as standard.
  • Publication
    Antioxidative properties of Diplazium Esculentum extract by using pressurized hot water extractor: optimization study
    ( 2010)
    Nur Azirah Jamial
    Pressurized hot water extraction (PHWE) was implemented in attempt to reduce the use of toxic organic solvent in extracting bioactive compounds from Diplazium esculentum. Comparison extraction methods were done and the results shows that the PHWE had higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity (70%) and total phenolic contents (118.83f.lg catechin equivalentlmg dry samples) c,.ompared to autoclaving, boiling, soaking, sonicating and Soxhlet extraction. Soaking extraction had the highest total flavonoids contents (28.03f.lg rutin equivalentlmg dry extract). By applying Box-Behnken design of response surface methodology, the optimized condition for the best antioxidant activity of PH WE was at 17SoC, 21 minutes extraction time and SOmL water volume added to 2g of dried ground D. esculentum. The DPPH antiradical efficiency was analyzed where the D. esculentum extracts had ECso value of 1241.14f.lg/mL and time to reach steady state (TEC50) was 79.83 minutes. Thus, the extract was categorized as slow in scavenging the DPPH free radicals. Through HPLC, the identified flavonoids in the crude extracts were quercetin and myricetin.
      2  13
  • Publication
    Applicability of protease and urea as a molluscicide for Pomacea canaliculata (Siput Gondang Emas)
    ( 2015)
    Noor Hasyierah Mohd Salleh
    Pomacea canaliculata is regarded as one of the most destructive molluscs as it causes severe damage to paddy fields. This mollusc is commonly combated by using chemical molluscicide like metaldehyde, which is known as toxic chemicals, therefore causes negative impact to the farmers and the environment. Hence, there is a great demand for a user and environmental-friendly molluscicide to reduce P. canaliculata population. The present study investigates the applicability of protease and urea as an alternative molluscicide for combating both flesh and eggs of P. canaliculata. Studies on the effect of each agent on snail eggs cover chemical and physical analyses; namely unhatchability, cuticle protein profile, water loss, conductivity, gas exchange and morphological changes. For snail flesh, it covers biological, chemical and physical studies, namely, mortality, respiration, food intake, responsiveness, movement, protein, ammonia and peroxidase level of the flesh. The studies were extended by producing cell free extract protease (CFE protease) using locally available raw material like cassava, and subsequently applied as a biomolluscicide. Likewise, studies regarding urea were also extended by using coated urea with rice husk ash and starch before subsequently applied to the paddy demonstration plot. For the flesh of P. canaliculata studies, it was found that the mortality were 31% and 90% after exposure to 3.9U/mL CFE protease and 0.02M urea respectively for 20hrs. It was also observed that the respiration rate increased proportionally with the increase of urea concentration. Additionally, the exposure to CFE protease and urea also reduced the snail appetite, responsiveness and movement as compared to the control snail. Extension of the work using coated urea for paddy plot studies saved 93% of paddy from snail attack. As for the P. canaliculata eggs studies, 71%, 52% and 35% hatchability have been suppressed after treating to 0.75U/mL commercial protease, 0.19U/mL CFE protease and 0.02M urea respectively. Besides that, the rate of conductivity, water loss and respiration increased proportionally with the increase of either commercial protease activity or urea concentration. The findings from these studies show the applicability of protease and urea as a molluscicide for both the flesh and eggs of P. canaliculata.
      1  8
  • Publication
    Application of chitosan biopolymer as a sensing material
    ( 2009)
    Roshida Mustaffa
    The chitosan solution has been succesfully deposited on the silicon wafer using sol-gel method to fabricate the chitosan thin film sensors. The effect of different annealing temperature and annealing time to their electrical characteristics were studied without and under light illumination. The current-voltage (I-V) characteristics showed that sensitivity of chitosan thin film sensors depend on the annealing temperature and annealing time. For the annealing temperature effect, it was found that the film annealed at 190oC has the highest photocurrent compared to the others. While for the annealing time effect, it was shown that the higher annealing time, the higher photocurrent. The changes of photocurrent are related to the different microstructure of chitosan thin film sensors. Although, the photocurrent values of the films illuminated with light exhibit the fluctuation to the photocurrent values without light illumination. Overall the chitosan thin films are sensitive to the visible and UV light. Therefore, they have a good potential as thin film light sensors.
      2  5
  • Publication
    Biosensor for measuring the anti-diabetic potential of medicinal plants
    ( 2014)
    Md. Mohiuddin
    Three alternative electro-enzyme techniques were developed for measuring antidiabetic potential of medicinal plants. All three techniques are based on the inhibition of α- glucosidase (AG) enzyme in the conversion of para-nitrophenyl-α-D-glucopyranoside (PNPG) into para-nitrophenol (p-NP) which is catalyzed by AG enzyme. The first technique, multi-walled carbon nanotubes (MWCNTs) paste electrode comprised of a uniform mixture of MWCNTs powder and mineral oil at the ratio of 60: 40 and used with free enzyme and PNPG solution. The second technique, screen printed carbon nanotubes (SP-CNTs) electrode was based on commercial screen printed electrode (SPE) and used with free enzyme and PNPG solution. The third technique, disposable biosensor, was based on the extension of the first and second electrodes where AG enzyme was covalently immobilized onto amine functionalized multi-walled carbon nanotubes (MWCNTs-NH2) followed by entrapment of PNPG as a substrate using freezing–thawing treated poly(vinyl alcohol) on the SP-CNTs. The PNPG was entrapped at low pH to prevent the premature reaction between PNPG and immobilized enzyme. The immobilized AG enzyme and PNPG on MWCNTs-NH2 was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The applicability of each technique for measuring antidiabetic was tested using three types medicinal plants namely Tebengau (Ehretia laevis), Cemumar (Micromelum pubescens), Kedondong (Spondias dulcis) and a commercial antidiabetic drug Acarbose via spectrophotometric, cyclic voltammetry (CV) and amperometric methods. The results showed that the inhibition obtained in the presence of Tebengau plant extracts is higher than that obtained with Acarbose, Cemumar and Kedondong. The kinetic of immobilized and non-immobilized enzyme was measured using Lineweaver-Burk equation. The CV response for inhibition of AG enzyme activity within the biosensor by Tebengau plant extracts showed a linear relationship in the range from 0.5 – 3.5 mg/mL and an inhibition detection limit was 0.5 mg/mL. The biosensor exhibited good sensitivity (1.037 μA/mg Tebengau plant extracts) and rapid response within 22 seconds. The biosensor retains about 79.16 % its initial activity even after 30 days when stored at 40C. The repeatability and reproducibility of the technique and disposable biosensor was satisfactory. Therefore, the techniques and disposable biosensor could be used for measuring the anti-diabetic potential of medicinal plants as well as to monitor the activity of commercial antidiabetic drugs.
  • Publication
    Bottom ash effect in portland cement composite performance
    ( 2018)
    Ng Hooi Jun
    The main goal of this study was to investigate the effectiveness of bottom ash in Portland cement in improving the cement properties. The insufficient of published literature regarding to replacement of bottom ash into Portland cement create meticulous investigations in order to use widely through technically viable for highly performance of cement in construction industry. Three types of particle sizes (63, 75, 150 μm) and effect of using various weight percentage of bottom ash were investigated. The bottom ash cement composite were prepared with the same water to cement ratio (0.5) where the replacement of cement to bottom ash was 10, 20, 30, and 40 wt%. The compressive strength result of bottom ash cement composite was encouraging after 1, 7, 14, 28, 60, 90, and 360 days of curing (20.44 to 36.79 MPa). The mechanical analysis result shows that samples containing bottom ash may achieve the compressive strength that are very close to the performance presented by Portland cement. Furthermore, it was observed that the greatest combination of bottom ash was 10 % replacement. The replacement of bottom ash does not affect the strength properties as the strength still remains within the ASTM C270 limit. The optimum pozzolanic activity index result (63 μm with 10 % BA replacement) shows excellent performance that close to 0.94 on the 28th day and reaching 0.96 at 90th day which indicated that bottom ash is a pozzolanic material with high pozzolanic activity. Material properties such as morphology, mineralogical, chemical compound, and ternary phase diagram are explored which provide strong evidence and fundamental explanation to this research findings. The optimum replacement ratio of bottom ash (63 μm with 10 % BA replacement) was used to determine its application in acid and fire resistance. The major factors that causing chemical and physical attack are mechanism of chemical transport and temperature. Evaluation of acid and fire resistance of bottom ash cement composite was as important as mechanical testing where external hydrochloric acid and thermal fire properties were examined by performing the laboratory test. The results of acid resistance indicated that bottom ash cement composite have better resistance towards hydrochloric acid as compared to Portland cement. The performance of fire resistance of bottom ash cement composite under 600 °C have almost identical result as control Portland cement whereas result of 1200 °C shows reduction in compressive strength. The productive use of bottom ash is the best way to solve the problems associated with its disposal by solving landfill problem.
  • Publication
    Bovine Adipose tissue derived stem cells bioengineering: isolation, characterization and differentiation studies
    ( 2013)
    Fhataheya Buang
    There is a significant potential for stem cells to be exploited for regenerative medicine. Stem cells act as a repair system for the body by differentiating into specialised cells and replenishing cells in regenerative organs such as skin or intestinal tissues. Conventionally in the current cell therapy, the renewed, differentiated cells were mostly sourced form bone marrow mesenchymal stem cell (MSCs) yielding low number of cells and involved a painful procedure under general anaesthesia. In tissue engineering, bioprocessing stem cells are crucial thus, stem cells from adipose tissue were revealed as a new promising source of MSCs. Abundant source of stromal vascular fraction (SVF) needs a good bioprocessing tools for an optimize culture. Isolation of bovine adipose tissue derived stem cells (ASCs) are found to better perform in 0.075% collagenase Type 1 and agitated for 2 hours from the experiment carried out. The static cultures were best inoculated at 1.0 x 104 cells/ml in 6 well plate. The suspension cultures were cultured best in 200rpm, 5ml DMEM: F12 / MesenPRO RS™ at 1.0 x 104 cells/ml in 50ml tube. Suspension (3D) culture of sphere aggregates yield cells density of 1.07 x 106 ASCs upon culture compared to static (2D) culture of 5 x 105 ASCs on average. However the viability of static culture are found to be more superior to suspension culture at high volume, agitation and inoculation sizes suggesting that the parameter are an unfavourable environment to culture in 50ml tubes. Successful differentiation of osteoblast cells were evaluated via Fourier Transform Infra-Red (FTIR) and conventional Van Kossa staining. Simulation of suspension (3D) culture via Computational Fluid Dynamic (CFD) using Volume of Fluid (VOF) model assist in developing an optimised ASCs culture protocol vis-à-vis conventional static (2D) culturing in flask.
      3  10
  • Publication
    Carbon Dioxide absorption from Biogas using Piperazine-Promoted 2-Amino-2-Methyl-1-Propanol blended solution in packed column
    ( 2021)
    Viga Rajiman
    Biogas is a renewable energy source that is mainly composed of methane (CH4) (40%–75%) and carbon dioxide (CO₂) (20%–60%). Monoethanolamine (MEA) is an established absorbent in CO₂ absorption, yet its removal performances are challenged by its limitations. In order to overcome the limitations of individual amine absorbents, a potential blended amine solution; piperazine-promoted 2-amino-2-methyl-1-propanol (PZ/AMP) has a remarkable performance in capturing CO₂ at low CO₂ partial pressure conditions (< 20 kPa), and suited for the conditions in flue gas treatment. However, for biogas upgrading applications, higher CO₂ partial pressure (> 20 kPa) should be considered due to the presence of high CO₂ concentration in the feed gas. Since the mass transfer behaviour at higher CO₂ compositions in the feed gas can affect the process performance in a packed column, it is crucial to explore the effectiveness of the potential absorbent in removing CO₂ at higher than 20 kPa of CO₂ partial pressure. Therefore, in this research, CO₂ absorption from simulated biogas was investigated using different blends of PZ/AMP solution in an absorption system at 200 kPa. CO₂ absorption performance was evaluated at different ratios of PZ to AMP solution (0/30, 3/27, 5/25, 7/23, and 9/21 wt.%/wt.%) and was benchmarked with 30 wt.% of MEA solution. The effects of process parameters CO₂ absorption into PZ/AMP blended solution were also examined and thoroughly discussed, in terms of process performance, including CO₂ partial pressure (20–110 kPa), gas flow rate (22.10–35.36 kmol/m2∙h), liquid flow rate (3.25–5.42 m3/m2∙h), chemical concentration (10–40 wt.%), and inlet liquid temperature (30 ± 2 to 45 ± 2 °C). The data were presented as CO₂ removal profiles along the column and evaluated in terms of CO₂ removal efficiency (%) and average overall volumetric mass transfer coefficient in the gas phase (KGav !!!!!!). Increased PZ concentration in AMP solution was found to have significantly increased CO₂ absorption and mass transfer performance, while the 7 wt.% of PZ/23 wt.% of AMP blend has a similar removal performance as 30 wt.% of MEA solution. Increased CO₂ partial pressure and gas flow rate in the process have been shown to decrease CO₂ removal performance from 100% to 58% and 72%, respectively. Meanwhile, the KGav !!!!!! values were decreased from 0.63 to 0.039 kmol/m3∙h∙kPa (CO₂ partial pressure) and 0.317 to 0.092 kmol/m3∙h∙kPa (gas flow rate). In contrast, increased liquid flow rate and chemical concentration exhibited positive impacts on CO₂ removal performance. The results showed that increasing liquid flow rate and chemical concentration have increased the CO₂ removal efficiency from 70% and 33%, respectively, to a complete removal. Similarly, the KGav !!!!!! values were increased from 0.066 to 0.389 kmol/m3∙h∙kPa (liquid flow rate) and 0.024 to 0.276 kmol/m3∙h∙kPa (chemical concentration). Meanwhile, the optimum inlet liquid temperature was observed at 35 ± 2 °C in this study, with a 100% CO₂ removal efficiency and 0.36 kmol/m3∙h∙kPa of KGav !!!!!! value. Overall, the PZ/AMP blended solution showed great potential to be commercialised in industrial biogas production.
  • Publication
    Characterisation and properties of aluminium/zinc oxide composites as catalytic gases from depolymerisation of low density polyethylene to liquid oil
    ( 2012)
    Nurul Razliana Abdul Razak
    The effects of addition zinc oxide (ZnO) or magnesium trisilicate (MTS) in aluminum (Al) matrix composites on physical and mechanical properties at different sintering temperature were studied. The Al/ZnO and Al/MTS composites prepared by powder metallurgy (PM) method. The composites were mixed using a milling machine at a speed of 131 rpm with ball to powder weight ratio is 10:1, then compressed at 200 MPa for 2 minutes. The results show that the additions of ZnO or MTS in Al composites have increased the density and hardness but decrease the compressive strength of the composites. The Al/ZnO or Al/MTS composites sintered at 750 °C have higher density, hardness and compressive strength than composites sintered at 650 °C. The effect of different sintering temperature gives effect to intensity of the composites. The microstructure of Al/ZnO or Al/MTS sintered at 750 °C show better interaction between filler and Al matrix. The effect of stearic acid or zinc stearate in Al/ZnO composites has increased the hardness and compressive strength of composites but density reduced at sintered 750 °C. The XRD patterns of Al/ZnO composites with stearic acid or zinc stearate show the changed in intensity peak of composites. The presence of stearic acid and zinc stearate as binder improved the adhesion and interaction between ZnO and Al matrix composites. The Al/ZnO composites with zinc stearate have higher physical and mechanical properties compared to other composites. The applied of Al/ZnO composites with zinc stearate as catalyst in the depolymerisation of low density polyethylene (LDPE) has produced yield 76.22 % of liquid oil. The liquid oil product consists of light hydrocarbons such as gasoline was proven by using gas chromatography - mass spectrometer (GC-MS).
  • Publication
    Characterisation and properties of biocomposites fabricated from Cyperus odoratus and linear low density polyetheylene
    ( 2018)
    Nik Ahmad Faris Nik Abdullah
    The potential of Cyperus Odoratus (CY) as a filler was studied. In powder form, CY was mixed with linear low density polyethylene (LLDPE), prior to being fed into a twin screw extruder and subsequently into an injection moulding machine to produce LLDPY/CY biocomposite dumbbell specimens. LLDPE/CY biocomposites with composition ratios of 5% to 20 wt% were studied. The results obtained showed that the increased of CY loading and size resulted in an increment of the Young’s modulus, but slightly reduction in tensile strength and elongation at break (Eb). In addition, as determined through the SEM, the morphology characterisation of tensile fracture surface of these composites showed poor interfacial adhesion between the CY filler and thermoplastic LLDPE matrix. A 5% NaOH treatment on CY improved the tensile strength and Young’s modulus of the LLDPE/CY biocomposites significantly, although it caused a decrement in Eb. The NaOH treatment enhanced both the tensile and thermal properties of the composites. In terms of crystallinity and thermal stability, the treated composites were superior compared with those of the untreated composites. Meanwhile, electron beam irradiation (EBI) was applied on the composites for crosslinking purposes, using a 1.5 MeV electron beam accelerator within the dosage range of 0–150 kGy. Based on the results of the tensile strength, the radiation at 100 kGy caused the optimum absorption by the LLDPE/CY biocomposites. Trimethylolpropane triacrylate (TMPTA) and tripropylene glycol diacrylate (TPGDA) were used as the crosslink promoters and the results indicated that the composites added with TMPTA showed higher tensile properties, thermal stability, gel content, and crystallinity, compared with those of the composites added with TPGDA. Also, the addition of TMPTA and EBI at 100 kGy improved all the physical properties, which provided suitable material based on natural polymer for biocomposites. The presence of TMPTA enhanced the crosslinking of LLDPE/CY during irradiation, which in turn enhanced the thermal stability of the composites. The natural soil burial and weathering of LLDPE/CY biocomposites were carried out for 1 year and the samples were collected and measured after 3, 6, and 12 months for degradability tests, by means of tensile tests, morphological study, and weight loss measurements. Within the 1-year exposure to soil burial and weathering test, the tensile strength and Eb of the composites decreased, while their Young’s modulus increased. The deterioration in weight properties of the composites was investigated, where the presence of CY filler in the composites significantly accelerated the degradation of the LLDPE/CY biocomposites. The effects of cobalt stearate (CS) in natural soil burial and weathering on the properties of LLDPE/CY biocomposites were also examined, and the results indicate that the tensile strength and Eb of the composites decreased, while the Young’s modulus increased with the increment in CY and CS contents. The morphology characterisation through SEM proved that the addition of CS to the composites accelerated their degradation.
      1  25
  • Publication
    Characteristics and properties of activated carbon from bamboo filled Styrene Butadiene Rubber (SBR) vulcanizates
    ( 2016)
    Nor Munirah Rohaizad
    Carbonized bamboo and bamboo activated carbon (AC) were prepared via carbonization process and chemical activation process using potassium hydroxide (KOH) as activating agent. Carbonization process was conducted at different carbonization temperature (250, 450 and 650 ºC) with heating rate of 5 and 15 ºC/min. As carbonization temperature increased, the percentage of char yield decreased, however the carbon content increased. The BET surface area of carbonized bamboo increased with increasing carbonization temperature and more pores were created as shown in SEM micrographs. Carbonized bamboo produced at 650 ºC with heating rate 15 ºC/min showed the highest potential to produce bamboo AC, subsequently used as filler in SBR compounds owing to its higher carbon content with higher BET surface area. Next, carbonized bamboo and bamboo activated carbon filled SBR (SBR-CGS and SBR-AC) compounds with varying filler loading from 10 to 50 part per hundred rubber (phr) were prepared. The effects of filler loading on the cure characteristics, physical and tensile properties were determined. Results showed that the improvement in cure characteristics for both SBR-CGS and SBR-AC vulcanizates. The physical properties of both filled SBR vulcanizates improved in terms of increment in hardness and decrement in resilience as the filler loading increased. Besides, the tensile properties for both SBR-CGS and SBRAC vulcanizates also enhanced which the tensile strength and tensile modulus as well as elongation at break (EB) increased. The morphology studies showed that both filler dispersed homogeneously in SBR compounds, resulted in good filler-rubber interaction and consequently improved the tensile properties. Comparing both filled SBR vulcanizates, it showed that SBR-AC vulcanizates have better properties than SBR-CGS vulcanizates due to the porosity of bamboo AC filler. SBR-AC vulcanizate with 50 phr of bamboo AC exhibited optimum properties and was selected to be added with transpolyoctylene (TOR) as compatibilizer. Incorporation of TOR into SBR-AC vulcanizates showed slightly increment in tensile strength and reduction in hardness and tensile modulus as the compatibilizer loading increased from 2 to 8 phr.
  • Publication
    Characterization and In-vitro activity of powder metallurgy Magnesium-zinc/bioglass composite for biomedical applications
    ( 2015)
    Mohd Amin Farhan Zaludin
    In this study, bio-glass 45S5 powder was added into the mixture of Mg-Zn powders to produce biocomposite using powder metallurgy method for biomedical applications. The bio-glass composition was varied from 0, 5, 10, 15, 20, 25, to 30 wt. %. The objective of this works is to study the effect of bio-glass addition into Mg-Zn based biomaterials in terms of physical, mechanical, corrosion resistance and bioactivity properties. Optical microscope, Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM-EDS) and X-Ray Diffraction (XRD) were used to characterize the microstructure and phases present in the composites. Microstructure result shows that bio-glass was distributed in the matrix Mg-Zn. EDS results show that Zn has not completely diffuse into the Mg matrix due to the effect of processing parameter. There is no evidence of bio-glass diffusion into the matrix. XRD diffraction patterns of as sintered samples show expected peak of Mg in all samples. Properties such as density and compressive strength were determined using the pycnometer and Instron machine respectively. Density of the composite was compared with the theoretical value and the result trends indicated that the density has increased as the amount of bio-glass increased. The trends are valid for the true, theoretical, and bulk densities. Increment of densities value could be subjected to the filling of interparticles spacing by bio-glass. However, the total porosity also increased as the bio-glass amount increased. It could be attributed to the segregation of bio-glass particles. As the amount of bio-glass increase, more bio-glass segregate and leads to bigger size of bio-glass inclusion size inside the composite. Since no reaction between magnesium and bio-glass, the bigger the size of bio-glass inclusions, the larger the voids form at the interface, which will eventually give raise to total porosity results. The compressive strength shows that as the amount of bio-glass increased, the compressive strength of the composites decreased. This also could be attributed to the voids left at the interface of bio-glass and matrix which acts as crack initiators. In vitro test was conducted, in which samples were immersed in Simulated Body Fluid (SBF) to determine the corrosion rate and bioactivity of the composites. The results showed that corrosion rate of the samples decreases with increasing content of bio-glass. The accumulation of corrosion products, alongside with the formation of apatite layer retarded the corrosion process. The apatite layer that used to indicate the bioactivity was also traced on the surface of composites. The apatite layer formed has a lower value of Ca/P ratio compared to the ideal crystalline hydroxyapatite, however it is still compliant with biomaterials requirement
  • Publication
    Characterization and mechanical properties of coconut shell filled acrylonitrile butadiene styrene / ethylene propylene diene monomer composites
    ( 2009)
    Siti Noorkhartina Ishak
    Coconut shell filled ABS/EPDM composites were prepared using a Z-blade mixer at processing temperature 2000C and rotor speed 50rpm.Effect of chemical treatment,different composition of blend ratio , different filler loading and effect of thermal aging on mechanical, thermal, and morphological properties of coconut shell filled ABS/EPDM composites was investigated.Maleic acid (MA) were used to treat the fiber surface.The increasing composition of EPDM will decrease the tensile strength and Young’s modulus but increasing in elongation at break.The increasing in filler loading and the presence of maleic acid increase the tensile strength and Young’s modulus but decrease the elongation at break is decreased.Result after thermal aging shows the same trend but lower than before aging.Morphological investigation using SEM revealed that the improvement in tensile strength and Young’s modulus was due to enhancement of the interfacial adhesion between coconut shell and ABS/EPDM. The thermal stability of coconut shell filled ABS/EPDM blends improved with the presence of MA.
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  • Publication
    Characterization and mechanical properties of geopolymer materials using kaolin and white clay for coating application
    ( 2016)
    Noor Fifinatasha Shahedan
    Geopolymer exhibit a wide variety of properties in various applications including coating. Geopolymer as inorganic coating has good bonding structure of amorphous inorganic polymer which has excellent bonding agent properties and form at low temperature compare to organic coating. The use of new source materials such as kaolin and white clay has potential as geopolymer coating plus can reduce the use of existing cement as main material in existing cementitious coating. The performance of kaolin and white clay geopolymer coating has been tested on glass reinforced epoxy (GRE) pipe sample which provided from Saudi Arabia. The parameter to find the best mix design for kaolin and white clay is by fixing the solid/liquid ratio at 1.0 while the ratio of Na2SiO3/NaOH ratio is verified and has been cured at room temperature, 80°C, 200°C and 400°C to get the stable coating surface based on coating properties appearance before proceed to the strength testing. The microstructure of kaolin and white clay geopolymer coating were testing under chemical composition analysis, phase analysis and morphology analysis for raw materials (kaolin and white clay) and geopolymer coating products (kaolin and white clay). After sample of Na2SiO3/NaOH ratio from 0.40 – 0.60 can stand cured at room temperature, 80°C, 200°C and 400°C, sample then is proceed to mechanical strength testing by flexural strength, adhesive strength, water absorption, and hardness to get the best formulation. The morphology of the interfacial layer contact between substrate (glass reinforced epoxy sample) and geopolymer coating (kaolin and white clay) layer is studied using optical microscope. The best mix design for kaolin geopolymer coating was at 0.45 ratio Na2SiO3/NaOH with maximum flexural strength at 33.88 MPa. The adhesive strength at this mix design was among the highest strength which is 5.5 MPa as well as the water absorption achieved the lowest percentage at this mix design which is 1.91 %. During hardness test, the highest strength (229.8 MPa) was identified in the best mix design kaolin geopolymer coating.
      1  3
  • Publication
    Characterization and properties of calcium carbonate filled polypropylene (PP) / ethylene propylene diene terpolymer (EPDM) composites
    ( 2009)
    Siti Rohana Ahmad
    Composites of thermoplastic elastomer blend of polypropylene (PP) and ethylene propylene diene terpolymer (EPDM) reinforced calcium carbonate (CaCO3) was investigated. All the composites were prepared by using Z-blade mixer at 180oC and rotor speed 50 rpm. The effect of filler loading of calcium carbonate filled PP/EPDM composites on mechanical properties, water absorption, morphology and thermal properties were studied. In general, increased of calcium carbonate loading have increased the value of modulus of elasticity, water absorption, thermal stability, whereas tensile strength, elongation at break and crystallinity of composites reduced. A compatibilizer, (MAPP) or coupling agent, (3-APE) was used to improve the mechanical properties of composites. The presence of MAPP or 3-APE improved the tensile strength, modulus of elasticity, thermal stability and crystallinity composites, whereas elongation at break and water absorption reduced. Results from scanning electron microscope (SEM) show that fillermatrix interaction was improved with incorporation of MAPP or 3-APE. The effect chemical modification of calcium carbonate with acrylic acid (AA) in PP/EPDM composites increased the tensile strength, elongation at break, modulus of elasticity, thermal stability and crystallinity composite but water absorption reduced. The micrograph SEM showed the treated composites with acrylic acid has better dispersion in PP/EPDM matrix. Effects of dynamic vulcanization on the properties of PP/EPDM/CaCO3 composites exhibit higher tensile strength, elongation at break and modulus of elasticity but lower water absorption. The SEM study of tensile fracture surface of dynamic vulcanized composites show interfacial interaction between calcium carbonate and PP/EPDM matrix has been improved. The dynamic vulcanized composites also exhibit better thermal stability and higher crystallinity.
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