Paulus Wilfred

XRD and EDXRF Analysis of Anatase Nano-TiO2 Synthesized from Mineral Precursors

This work details the characterization of anatase nanoTiO2 particles synthesized from Malaysian mineral precursors using the XRD and EDXRF. The properties that were analyzed were its crystallite sizes, relative crystallinity, phases, and chemical composition. It was determined that the crystallite size was quite small (15.6 nm), although the crystallinity of the sample is relatively low. The anatase phase seems to be dominant (100%), although in some cases when the processing parameters were changed or heat treatment were conducted, the existence of rutile is detected. The chemical composition showed that TiO2 is the majority compound in the sample (~96%), although some metallic and non-metallic impurities are present (Zr, Nb, and S). It is concluded that Malaysian mineral precursors are capable of producing relatively high quality nanoTiO2.

Photocatalytic Active Nanorutile TiO2: Synthesis Characterization and Photocatalysis Tests

We are able to produce nanoscale rutile TiO2 product from titanium mineral via a modified hydrothermal synthesis method, with the inclusion of an alkaline fusion stage. The mineral was totally dissolved in an acidic solution, and is followed by the nucleation reaction, producing anatase having a crystallite size of 15.4nm. Annealing of the nanoanatase resulted in a phase transformation process, and the rutile phase was detected when annealed at 800°C. Single rutile phase was achieved when the anatase sample was annealed at 1,000°C. As the starting mineral contains a significant amount of Nb and Zr impurities, these elements are naturally doped into the nanosized rutile. A paint formulation was then produced by adding 2g of this nanoanatase/nanorutile into the paint. Using this nanotitania added paint under visible light source, a photocatalytic study on the degradation of methylene blue was conducted. A comparative study was also carried out with commercial grade pure nanorutile under similar condition. The result showed that our nanorutile managed to degrade the methylene blue to almost a similar 85% degradation compared to the commercial pure nanoanatase. A pure nanorutile product resulted in a much lower photodegradation rate, standing at 77%. Tests on the photodegradation of nitrous oxide gas also reveals that the nanorutile paint was able to degrade the VOC in much shorter times compared to the other nanotitania added paints.

Characterization of Titania Nanoparticles Synthesized by the Hydrothermal Method with Low Grade Mineral Precursors

The objective of this work is to utilize a low-grade synthetic rutile to produce high-grade titania nanoparticles. Due to the nature of the precursor, the hydrothermal method needs modification in order to accommodate the precursors and chemical reagents. The product will be characterized with the XRD (crystallite size and crystallinity), EDXRF (chemical composition), SEM (Morphology), N2 adsorption-desorption (Surface Area) and UV-Vis-NIR. Results revealed a crystallite size of less than 20 nm, a surface area of 186.8 m2/g, a morphology that is a combination of agglomeration and particles, and an optical band gap of 3.23 eV. It is concluded that synthetic rutile is a viable precursor to produce high quality titania nanoparticles.

High Velocity Nano Alumina Wet Milling in Zirconia and Corundum Mills

The paper presents a study on the effect of high energy milling to the crystallite size and lattice strain of α-alumina in zirconia and corundum mills. A Fritsch Pervesette 7 which has a maximum milling speed of 1100 rpm was used for this comparison. Milled samples were analyzed using the X-Ray Diffraction (XRD) technique to calculate for the crystallite size using the Scherrer method while lattice strain was determined by the Tangent method. Scanning electron microscope (SEM) was also used to determine changes in the morphology of the alumina powder sample after the milling process. Zirconia was found to be the better abrasive material and the optimum conditions used to obtain the smallest crystallite size of 51.2 nm are milling speed and time of 1100 rpm and 180 minutes respectively.

Effect of Fractional Precipitation on Quality of Nanostructured Alumina Produced from Black Aluminium Dross Waste

Black aluminium dross produced from a local aluminium smelting plant was used in this study. Solvothermal method was used to produce nanostructured alumina from this waste. Initial product obtained is of low quality with 86.9% Al2O3 content and mixed crystalline phases of 71% α-alumina and 29% calcium dodeca aluminate (CaO(Al2O3)6). The introduction of the fractional precipitation stage into the process helps in improving the purity of the alumina product to 96.5% and also produces 100% α-alumina crystalline phase. The study also shows that the crystallite size of the α-alumina products produced from this process is less than 100nm.

Study on Use of Nanosized Alpha Alumina from Schedule Waste as Formulation in Thermal Insulation Paint

Schedule waste used in this study is white aluminium dross produce from an aluminium smelting plant. It has a gibbsite crystal form, and was calcined at high temperature and transformed into α-alumina. nanosized powder with 76 nm primary particle size was produced by top-down method via high velocity wet milling. Comparative thermal insulation study was then performed in paints made from 15 wt% of these nanosize and micron-size alumina. The results from this study shows that the nanosize α-alumina is the best insulator, with a temperature reduction of 57 and 41% less, compared to micron-size α-alumina respectively for ceramic and steel plate.

Role of Alkaline Fusion in the Growth of Sodium Titanite Nanostructures from Rutile Mineral

The paper presents a study on the use of alkaline fusion to produce nanostructured sodium titanate from rutile mineral. The spherical structure of the micron-sized starting material changed and transformed to a two-dimensional nanostructure after the alkaline fusion process. After 7 hours dissolution with 30% NaOH, the growth of sodium titanate nanorod is observed, and after undergoing prolonged dissolution, nanowires, with an average diameter of 20-40 nm and a length of 1-4 µm are formed. The study also showed that using 0.1M HCl to wash the titanate complex results in a sodium titanate that is free from NaOH residue, although at higher molarities, the nanostructure will collapse, and spherical grains formed. The important role of alkaline fusion in this hydrothermal process is that it will reduce dissolution time, while NaOH concentration is required for the growth of nanostructured sodium titanate.

Quantitative Energy Dispersive X-Ray Flourescence Analysis of Low Alloy Steel by Regression and Modified Fundamental Parameter Techniques

EDXRF analysis provides several important advantages such as simultaneous determination of the elements present, analyses of wide concentration ranges, and fast analysis with no sample preparation. The paper relates a comparative quantitative analysis using regression and modified Fundamental Parameter Technique FPT methods in the determination of minor elements present in low alloy steel. Regression was developed by plotting calibration graphs using low alloy reference standards while the modified FPT method involves incorporation of pure metal spectrum to the existing equation to improve on the accuracy of the analysis. Discrepancy tests carried out for the two methods showed that the error ranges were 0.3-6.5% and 1.2-7.9% for regression and modified FPT analyses, respectively. This makes the FPT method more acceptable for quantitative analysis of elements present in low alloy steel.

Comparison in Phase Transformation of Calcium Phosphate and Zirconium Doped Calcium Phosphate Biomaterials by In Situ XRD

Pure calcium phosphate and ZrO2 doped calcium phosphate biomaterials were synthesized using an organic based phosphoric acid (DEHPA) as its starting material. The precipitated products obtained from the sol-gel reaction were then used to compare the phase transformation using in-situ XRD. The study shows that amongst the notable difference between these two samples is that the ZrO2 doped calcium phosphate tends to form the β-Ca(PO3)2, β-TCP and HA phases at lower heating temperatures compared to the pure calcium phosphate. Another major different seen in the phase transformation of the ZrO2 doped calcium phosphate is the transformation of β-TCP into HA before it leads to the formation of α-TCP at higher temperatures.

Effect of Milling Time and Dispersant on Microstructures of Alpha Alumina Nanopowder Synthesized from Aluminium Dross Waste

The paper presents a study on the effect of milling time and addition of SLS dispersant on the crystallite and particle size reduction of α-alumina produced from aluminium dross waste. Wet milling was performed in high velocity planetary mill at speed of 1100 rpm and milled for 2 to 5 hours. XRD analysis shows both peak broadening and shifting occurred especially at longer milling time. The peak broadening effect was then used to calculate both the crystallite size and lattice strain. Samples milled with dispersant gave smaller crystallite size and the smallest crystallite value was 39.4nm obtained using 5 hours milling time. Similarly the mean particle size obtained for samples milled with dispersant gave smaller value and the smaller mean particle size obtained was 0.771 μm after 5 hours of milling.