Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis
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- PublicationMechanism and kinetic reactions of malaysian ilmenite from terengganu in a hydrochloric acid leaching system(2023-07-01)Siti Asmidar Binti IbrahimThe potential of ilmenite sand from Sungai Cheniah, Bukit Kelip, Terengganu, Malaysia to produce synthetic rutile through a reductive leaching method that uses hydrochloric acid as a leaching reagent and iron as a reducing agent is studied. Since inadequate information regards ilmenite deposited at this catchment area, it is critical to investigate the properties of the ilmenite that used in this study which can shed light on the behaviour of ilmenite during the leaching process. Based on the characterization analyses, the ilmenite sand, IS is classified as low grade since the TiO2 content is 41.53% right after the pre-treatment process conducted and were used as the feedstock for the leaching process. It is also having wide span value meaning that its h has a wide size fraction of unidentical size particles. Therefore, the liberation study was executed and (+53-63) µm size fraction was selected to be the input of the leaching study as it consists of the highest liberated particles compare to other size fraction. As to determine the optimum conditions of the reductive leaching process for ilmenite, parameters such as concentration of hydrochloric acid (HCI), acid-to-solid ratio, temperature, and concentration of reducing agent was studied using design of experiment (DOE). The result of the leaching process was assessed using analysis of variance (ANOVA) and optimal criteria were pointed out to be 9M HCl, 90°C, 0.4g/g of iron powder, and 4g/L solid liquid ratio. The maximum recovery is 96.42% Fe and 97.24% Ti. By developing this analysis statistically which is based on the mathematical models, it could be useful for predicting and comprehending the effects of experimental conditions. To elucidate the reaction kinetics and mechanism of ilmenite leaching in HCl solution, only HCl concentration and temperature were considered as the factors for leaching study. Based on Fe-Ti correlation for both factors, it shows that the Fe dissolved two-time folds compared to Ti dissolution. This direct leaching of ilmenite particles obeyed a shrinking core kinetic model, supporting the view that the proton diffusion through a product layer is the rate-controlling step. This can be supported by the activation energy values obtained for both 32.3 kJ/mol Fe and 30.2kJ/mol Ti which is below 40 kJ/mol which indicates the diffusion control rate.
- PublicationNanoporous anodic oxide formation on niobium and niobium-titanium alloys for photoreduction of hexavalent chromium(2023-09-01)Nurhaswani Binti AliasNiobium pentoxide (Nb2O5) nanoparticle, a semiconductor-based compound, has demonstrated significant potential in reducing toxic heavy metal ions such as hexavalent chromium, Cr(VI) to trivalent chromium, Cr(III), comparable to titanium oxide (TiO2). However, the used of this nanoparticle, can create secondary pollutant which is time consuming for the separation step and not economical. The immobilization photocatalyst is one of the best options to address this problem. In this project, the Nb2O5 has been grown on a supported Nb substrate using the anodization procedure and employed right away as a photocatalyst in Cr(VI) solution. The elimination of Cr(VI) from the system is quick and complete when this photocatalyst is used, allowing for repeated uses. The anodization was conducted in fluorinated ethylene glycol (EG) electrolyte at varying anodization parameters included applied voltage, NH4F concentration, anodization time, and electrolyte temperature to optimize the morphology and structural properties of Nb2O5. Anodization of Nb foil at 60 V and 30 min produced weak crystalline orthorhombic Nb2O5 with “pore-in-pore” nanoporous structure. No crystallite Nb2O5 formed when anodization occurred <60 V. Prolonging the anodization time resulted in high dissolution of Nb oxide which are undesirable for the application. The annealing process increased the crystallinity while also influencing the surface and optical properties. When compared to the as-anodized sample, the Nb2O5 annealed sample has a narrow optical band gap, but poor charge separation. As-anodized Nb formed at 60 V and 70 °C electrolyte temperature achieved the highest Cr(VI) reduction (100% reduction within 75 min, surface area: 4 cm2 ) compared to annealed sample (100% reduction within 120 min, surface area: 4 cm2 ), but annealed sample has better cyclability performance (92% of Cr(VI) reduction remained after the fourth cycle). Due to the high recombination rate of photogenerated electron-hole pairs of Nb2O5 and TiO, the TiO2-Nb2O5 mixed oxides were synthesized as well by anodization of TiNb binary alloys in fluorinated EG electrolyte. The TiNb binary alloys was fabricated at different Nb content (wt. %) to evaluate the effect of different composition on morphology and structural properties of mixed oxides TiO2 and Nb2O5 after the anodization. Vertically aligned nanotubular oxide structures were successfully formed on the surface of Ti and TiNb binary alloys pellets as substrate, except on pure Nb, which exhibited the nanopores morphology. The Nb composition in the TiNb binary alloys has an effect on the oxide formation; increasing the Nb content (up to 40 wt.%) resulted in thicker oxide, with sample Ti-40Nb forming the longest nanotubes. Ti-60Nb outperformed all other TiNb binary alloys compositions in photoreduction of Cr(VI) in UV with 100% reduction within 120 minutes (surface area: 1.33 cm2 ). Furthermore, the TiNb mixed oxide exhibits improved photoactivity properties when compared to TiO2 or Nb2O5 alone, owing to excess electrons in TiO2's conduction band that are transferred from Nb2O5 to Cr(VI)
- PublicationPreparation and characterization of self-healing natural rubber latex for fabric coating(2023-05-01)Nuraina Hanim Binti Mohd NizamThe work carried out in this thesis describes a facile technique to develop a novel self-healing coating with the goal of producing autonomous intrinsic self-heal ing fabrics that can recover from damage at room temperature without the use of ex ternal stimuli. The self-healing coating was developed using high ammonia natural rubber latex (HANRL) consisting dynamic reversible metal thiolate ionic network. The work carried out in this thesis started with fabrication and characterization of self healing HANRL films. The effect of zinc thiolate (ZT) (0, 15, 30, 45 phr) contents which is responsible for formation of reversible ionic network within the HANRL was investigated. Formation of reversible ionic network was evidenced by Differential Scanning Calorimetry (DSC), Ultraviolet-visible spectroscopy (UV-vis), Fourier Transform Infrared (FTIR) and zeta potential. The mechanical performance results re vealed that optimum self-healing of the HANRL was achieved at 30 phr of ZT. Sub sequently, impregnation of the selected self-healing HANRL formulation on synthetic polypropylene (PP) during coating was assessed by varying number of coating (single, double, triple, quadruple) layers on fabrics. The morphological showed that HANRL was successfully impregnated into the fabric and filled the gaps between the fiber. In general, the mechanical properties of the fabric improved 130% for single coated fab ric compared to the neat fabric. Moreover, fabric with single coating layer has good breathability and fabric to rubber adhesion. The feasibility of the developed self-heal ing HNRL coating was also investigate on various types of fabrics. The results showed that majority of the fabrics were successfully healed at room temperature
- PublicationThe development of porcine biosensor using self limiting oxidation - atomic force microscope lithography(2023-08-01)Nurain Najihah Binti AliasSilicon nanowires have been studied as biosensor due to excellent in detection of biological molecules. Silicon nanowire biosensor has a huge amount of potential to contribute to the field of biosensor for detecting deoxyribonucleic acid (DNA) molecules due to its distinctive electrical and nanostructure morphological qualities. In this research, silicon nanowires were fabricated using atomic force microscopy – local anodic oxidation (AFM-LAO) via top-down approach. AFM-LAO lithography is a non-destructive technique that provides precise and accurate patterning of nanoscale features without damaging the underlying material. According to prior research, the fabricated silicon sub-micron wires via AFM-LAO produced large range of width. The width of silicon nanowires was scaled down by using self-limiting oxidation (SLO) process to achieve the smallest possible width was studied. Firstly, silicon nanowire device was fabricated on p-type silicon-on-insulator (SOI) wafer via AFM-LAO and important parameters during AFM-LAO process was obtained. The obtained results indicate that the oxide patterns fabricated using Au-coated cantilever tip at 0.3 µm/s of writing speed and 9 V of applied voltage produce good structure of oxide patterns. Therefore, the AFM-LAO optimized parameter was used to fabricated oxide pattern for 5-wires, 10-wires, short-wires and long-wires devices. Then, the oxide patterns undergo silicon wet etching using the mixture of tetramethylammonium hydroxide (TMAH) with and without admixture of Triton X-100 and isopropyl alcohol (IPA) to etch the silicon layer. The surface roughness and wetting behaviour of APTES on etched SOI wafer was considered. The study found that the combination of the ternary solution, TMAH + Triton X-100 + IPA produced the lowest surface roughness which was 2.068 x 10-1 nm. It was also observed that, wetting behaviour of APTES on lowest surface roughness etched SOI wafer produced the most hydrophilic effect on the surface with 19.78 ° of contact angle. The hydrophilic behaviour of the SOI wafer indicates the presence of a high density of OH groups on its surface, facilitating the formation of hydrogen bonds with other molecules. This characteristic indirectly contributes to the more effective detection of porcine DNA in the biosensor. The silicon nanowires were then proceeded with the SLO process to reduce the width of fabricated silicon nanowire. The temperature, soaking time, gas flow rate and number of SLO cycles was investigated. The 1000 °C of temperature with three cycles of SLO removed the most oxide layer after oxide etching. Therefore, 1000 °C of temperature with three cycles of SLO was applied on fabrication of 5-wires, 10-wires, short-wires and long-wires devices. Lastly, silicon nanowire devices were functionalized with 3- aminopropyltriethoxysilane (APTES), glutaraldehyde and amine-terminated DNA to detect porcine DNA. The current-voltage (I-V) characteristics of devices were measured by using semiconductor parameter analysis (SPA) to investigate the device performance based on number of wires and length of wires. For different number of wires, device with 10-wires device obtained the highest sensitivity, 91.93 µAM-1 with 4.12 fM of LOD. While for different length of wires, short-wires device gained the highest sensitivity, 90.80 µAM-1 with 4.44 fM of LOD
- PublicationFabrication and characterization of solid and porous dicalcium phosphate dihydrate-coated β-tricalcium phosphate granular(2023-08-01)Nur Zulaikha Binti Mohamad ZaidiThe aim of this study is to investigate the effect of acidic calcium phosphate solution concentration and soaking time in fabricating DCPD-coated solid and porous β-TCP granular as well as its initial cell responses towards bone-like cell. To understand the effect of acidic calcium phosphate solution concentration and soaking time, the β-TCP granules were immersed into various concentration of an acidic calcium phosphate solution for 10 mins, 30 mins and 60 mins, respectively.. Then, DCPD-coated solid and porous β-TCP granules were characterized through several characterization methods such as X-ray Diffraction (XRD), Fourier Transmission Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Calcium ion release and pH analyses. Based on these analyses showed that that DCPD-coated porous β-TCP granular produced a large formation of DCPD plate-like crystal coating layer that helps in stimulating high concentration of calcium ion released while simultaneously decreasing the pH values of HBSS solution. Meanwhile, to investigate the DCPD-coated solid and porous β-TCP granules responses towards MC3T3-E1 cells, the solid and porous β-TCP granules were immersed with 50 mmol/L MCPM- 25 mmol/L H3PO4 solution for 30 mins. The characterization was similar to the first objective with the addition of qualitative and quantitative cell analyses. The cell study shows that high amount of DCPD plate-like crystals formed in DCPD-coated porous β-TCP granules stimulated MC3T3-E1 cell activities surrounding the DCPD-coated porous β-TCP up to 3 days. Therefore, it was confirmed that the high amount of DCPD crystals formation and usage of porous β-TCP granules as granular inner core were accelerated MC3T3-E1 cell activities surrounding the granular.