Nur Irfah Mohd Pauzi

Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method

This study was conducted in order to investigate the effect of calcination time on phase and microstructural characteristics of intermetallic matric composite (IMC), NiAl-Al2O3 powder. This powder was synthesized using gel combustion method with octyl alcohol as fuel. Upon completion of the combustion process, the loose powder was calcined at 1050°C for 1, 2 and 4 hours and characterized using XRD, FESEM and TEM. The crystallite size was calculated to be in the range of 29-30 nm. It was found that NiAl-Al2O3 exhibits high crystalline structure after calcination for 4 hours. Furthermore, longer calcination time also cause growth of the particle size. Findings indicate that high crystalline nanostructured NiAl-Al2O3 powder consisting of submicron particles can be successfully produced using gel combustion synthesis with longer calcination time.

Synthesis and Characterizations of SiO2-Ag Core-Shell Nanostructure Using Fatty Alcohols as Surface Modifiers

SiO2-Ag core-shell nanostructure with silica core (SiO2) and silver shell (Ag) nanoparticles with spherical morphology were successfully synthesized using a modified self-assembly sol-gel method. Ag nanoparticles at ca.10-50 nm were successfully attached on monodispersed silica spheres (SiO2) with diameter of ca. 450 nm. Renewable resources of palm oil, derived fatty alcohols (octyl-alcohol (C8), decyl-alcohol (C10) and dodecyl-alcohol (C12)) were employed as nonsurfactant surface modifiers prior to coating with Ag nanoparticles. X-ray diffraction (XRD) patterns of calcined SiO2-Ag core-shell nanostructure prepared with surface modifiers exhibited amorphous structure of SiO2 (core) and face-centered cubic (FCC) structure of metallic Ag nanoparticles (shell). The results obtained in the present work demonstrated the feasibility of employing fatty alcohols as potential nonsurfactant surface modifiers in synthesizing SiO2-Ag core-shell.

Risk assessment predictions of open dumping area after closure using Monte Carlo simulation

Currently, there are many abandoned open dumping areas that were left without any proper mitigation measures. These open dumping areas could pose serious hazard to human and pollute the environment. The objective of this paper is to determine the risk assessment at the open dumping area after they has been closed using Monte Carlo Simulation method. The risk assessment exercise is conducted at the Kuala Lumpur dumping area. The rapid urbanisation of Kuala Lumpur coupled with increase in population lead to increase in waste generation. It leads to more dumping/landfill area in Kuala Lumpur. The first stage of this study involve the assessment of the dumping area and samples collections. It followed by measurement of settlement of dumping area using oedometer. The risk of the settlement is predicted using Monte Carlo simulation method. Monte Carlo simulation calculates the risk and the long-term settlement. The model simulation result shows that risk level of the Kuala Lumpur open dumping area ranges betwee...

Long-term settlement prediction at open dumping area using Hossein and Gabr method for new development

In Malaysia, the most common method of disposal is landfill/open dumping. The soil at the dumping area are mixed with waste and soil. Thus, it was called as waste soil. Due to its heterogeneity properties, waste soil has a different settlement rate because different types of waste tends to settle differently. The Hussein and Gabr model which used empirical model was proposed to compute the long-term settlement. This Hussein and Gabr model is one of the soil settlement model that can be used to predict the long-term settlement at the dumping area. The model relates between the compression index and the time factor. The time factor are t1, t2, t3 and t4. The compression index is Cα1=compression index and Cβ is biodegradation index. The duration for initial compression, the compression, the biological compression and time creep are included in the model. The sample of waste soil is taken from closed dumping area in Lukut, Negeri Sembilan with the height of waste approximately 1 to 3 meters. The sample is tested using consolidation test for determining the geotechnical parameters and compressibility index. Based on the Hossein and Gabr model, the predicted long-term settlement for 20 years (ΔH) for the waste height of 1 to 3 meters are 0.21m, 0.42m and 0.63m respectively and are below the percentages of proposed maximum settlement for waste soil which is acceptable for new development to takes place.. The types of deep or shallow foundation are proposed based on the predicted settlement. The abandoned open dumping area can now be reused for the new development after the long-term settlement are predicted and some of the precaution measures has been taken as a safety measures.

Characterizations of NiAl-Al2O3 Produced Using Gel Combustion Synthesis Method

NiAl is widely used for elevated temperature application because it gives better properties, especially in the gas turbine application. This study was done in order to investigate the effects of calcination temperature on NiAl and α-Al2O3 formation using gel combustion synthesis method. This method used fatty alcohol and fatty acid ester for producing NiAl powders. X-Ray diffraction patterns of calcined samples exhibited NiAl and α-Al2O3 at temperature 1050°C. Therefore, nanostructured NiAl-α- Al2O3 can be successfully produced with the gel combustion method using less expensive and more environmental friendly fatty alcohol and fatty acid ester as fuels.

Settlement Prediction of Soil at Closed Dumping area using Power Creep Function

In Malaysia, total dumping sites are 73 sites, controlled dumping sites are 71 sites and sanitary landfill are 11 sites. These disposal sites will increase over time because population in Malaysia has been increased at a rate of 2.4% per annum or about 600,000 per annum since 1994. The increase in population would increase the amount of waste generated. Thus, it will increase the number of dumping sites. The dumping area which has a full capacity of waste will eventually closed. These closed dumping area which are to be developed for new development are prone to settlement. The settlement at dumping area are to be predicted and simulated using Power Creep Function. The heterogeneous content of waste soil from dumping area are complicated to characterize and classified. The content of waste dumped at the dumping area is important to analyse because the degradation process changes with time. The degradation process are called power creep function. Power Creep Function (PCF) is time dependent deformation which is under constant stress. The two constant variables which are M’ and N’. M’ is the compressibility constant and N’ is rate of compression varies with age placement condition. The input parameters for PCF are H0, ∆σ, t, Tr, M’ and N’. These parameters are simulated based on two cases whereby, case 1 where M’ and N’ are kept constant and time (t) increases from 25 days to 75 days. Tr is kept constant at 1 day. Case 2 is where M’, N’ and Tr are kept constant and time (t) increases from 240 days to 730 days. The settlement prediction at the dumping area for Case 1 is 0.024 meters to 0.042 meters and for Case 2 the settlement is in the range of 0.074 meters to 0.130 meters. The prediction of total settlement for dumping area would be used to determine the depth of foundation for the new development at the dumping area.