Irmawati Ramli

Bismuth-Modified Vanadyl Pyrophosphate Catalysts

A 1 bismuth-doped VPO catalyst was prepared by refluxing Bi(NO3)3 and VOPO4 ⋅ 2H2O in isobutanol. The incorporation of Bi into the VPO lattice lowered the overall V oxidation state from 4.24 to 4.08. It also lowered both the peak maximum temperature for the desorption of oxygen from the lattice from 1001K (undoped) to 964K with a shoulder at 912K and the peak maxima for H2 temperature-programed reduction from 863, 1011 and 1143K (undoped) to 798, 906 and 1151K. The total oxygen desorbed from the Bi-doped catalyst was only one-fourth that of the undoped catalyst, while the amount of oxygen removed by TPR was roughly the same for both catalysts. These results suggest that in anaerobic oxidation, the Bi-doped catalyst will have roughly the same activity as in undoped catalyst in C4 hydrocarbon oxidation but will have a higher selectivity to products such as olefins and maleic anhydride.

Response Surface Methodology for Optimization of Epoxidized Trimethylolpropane Ester Synthesis from Palm Oil

To improve the oxidative stability of the palm oil-based biolubricant, the fatty acid double bonds in palm oil-based trimethylolpropane ester (TMP ester) was converted into an oxirane ring via an in-situ epoxidation method. The epoxidized TMP ester was produced from a reaction between TMP ester and peracetic acid which was prepared in-situ by reacting glacial acetic acid with hydrogen peroxide in the presence of concentrated sulphuric acid. The response surface methodology was applied using a central composite design technique to optimize the conditions of the epoxidation reaction to produce the epoxidized TMP ester. The effects of four independent variables namely concentration of acetic acid (0-2 mol), concentration of hydrogen peroxide (1.5-9.5 mol), temperature of reaction (30-110°C) and reaction time (0.5-26.5 h) on the three dependent variables; percentage of oxirane oxygen, iodine value, and hydroxyl value were studied. A second-order polynomial multiple regression model was employed to predict the three dependent variables under optimum conditions of 0.59 mol of glacial acetic acid, 7.5 mol of hydrogen peroxide concentration, at temperature of 50°C and reaction times of 7 h. The optimum values of percentage of oxirane oxygen, iodine value, and hydroxyl value were 4.01%, 1.94%, and 0.43% respectively. The analysis of variance yielded a high coefficient of determination value of 0.9395-0.9880, hence indicating the fitness of the second-order regression model to the experimental data.

Effect of kenaf and EFB fiber hybridization on physical and thermo-mechanical properties of PLA biocomposites

Kenaf/empty fruit bunch/polylactic acid (kenaf/EFB/PLA) hybrid biocomposites were prepared using hot press technique. The ratio of fiber to polylactic acid was set at 60:40 with 1:1 ratio between kenaf and empty fruit bunch fibers. Physical, mechanical and thermal properties of hybrid biocomposites were subsequently characterized using Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, tensile and water absorption tests. Test results indicated that mechanically stronger fiber was able to support the weaker fiber. Hybrid fiber biocomposite had higher crystallinity as compared to single fiber biocomposite. Water absorption of hybrid composite was higher as compared to single fiber composite. Thermal result revealed that hybridization of fiber was not significantly influence the thermal properties of composites. However, the presence of two different fibers proposed good wettability properties, which could reduce the formation of voids at the fibers-polymer interface and produce composites with high stiffness and strength.

Impact of Nanoclay on the Properties of Wood Polymer Nanocomposites

In this chapter, the influences of nanoclay on the attributes of tropical wood polymer nanocomposites (WPNCs) were discussed. The impregnation of wood samples with nanoclay and in situ polymerization were employed by vacuum-pressure method. The comparisons of improvement in different properties have been showed between the raw wood, wood plastic composites (WPC), and WPNC. The FTIR result confirmed the interaction and incorporation of nanoclay inside wood. The exfoliation of nanoclay has been identified by Transmission electron microscopy result. The formation of wood polymer nanocomposites was proven through X-ray diffraction (XRD) pattern and Scanning electron microscopy (SEM) images, respectively. Significant improvement in mechanical properties was found through nanoclay treatment. The Dynamic mechanical thermal analysis (DMTA) result also indicated the improvement of thermo-mechanical properties after nanoclay treatment. The storage modulus (E’) of the WPNC specimen also unveiled notable enhancement in both rubbery plateau and glassy region in alliance to their parallel wood polymer composites and raw wood samples. The wood’s Dynamic Young’s modulus (Ed) also indicated significant increment for PF-nanoclay impregnated WPNC samples. Whereas, the treatment by PF-nanoclay system seem to lower the damping (loss Tanδ) peaks of woods. Furthermore, the WPNC samples shown significant improved compared to WPC and raw ones against white-rot white-rot (polyporous versicolor) and brown-rot (postia placenta) exposed.

Purification of Carbon Nanotubes Synthesized by Catalytic Decomposition of Methane using Bimetallic Fe-Co Catalysts Supported on MgO

This work reports the synthesis of carbon nanotubes by catalytic decomposition of methane using bimetallic Fe-Co catalysts supported on MgO. Transmission electron microscopy (TEM) results show the as-prepared carbon nanotubes are multi-walled carbon nanotubes (MWCNTs) with diameter in the range of 15nm to 45nm. Purification of as-prepared MWCNTs was carried out by acid and heat treatment method. EDX results show the Fe, Co and MgO catalysts were successfully removed by refluxing the as-prepared MWCNTs in 3M H2SO4.

Electrochemical detection of DNA hybridization based on bismuth oxide nanoparticles/chitosan-modified electrodes with methylene blue as an electrochemical indicator

The detection of DNA hybridization is of central importance to the diagnostic and treatment of genetic diseases, for the detection of infectious agents, and for reliable forensic analysis [1]. The technique for the detection of DNA hybridization has attracted many attentions. Many methods for detecting hybridization have been developed, including electrochemical, optical, microgravimetric methods and surface plasma resonance. As compared with other detection techniques, the main advantages of electrochemical techniques are their low cost, small size, and convenience for integration and microminaturizaion. Hence, DNA electrochemical biosensors have been rapidly developed recently [2–7].