Shawaluddin Tahiruddin

Sludge palm oil as a renewable raw material for biodiesel production by two-step processes

In this study, biodiesel was produced from sludge palm oil (SPO) using tolune-4-sulfonic monohydrate acid (PTSA) as an acid catalyst in different dosages in the presence of methanol to convert free fatty acid (FFA) to fatty acid methyl ester (FAME), followed by a transesterification process using an alkaline catalyst. In the first step, acid catalyzed esterification reduced the high FFA content of SPO to less than 2% with the different dosages of PTSA. The optimum conditions for pretreatment process by esterification were 0.75% (w/w) dosage of PTSA to SPO, 10:1 M ratio, 60 °C temperature, 60 min reaction time and 400 rpm stirrer speed. The highest yield of biodiesel after transesterification and purification processes was 76.62% with 0.07% FFA and 96% ester content. The biodiesel produced was favorable as compared to EN 14214 and ASTM 6751 standard. This study shows a potential exploitation of SPO as a new feedstock for the production of biodiesel.

Controllable Growth of Vertically Aligned Aluminum-Doped Zinc Oxide Nanorod Arrays by Sonicated Sol--Gel Immersion Method depending on Precursor Solution Volumes

Aluminium (Al)-doped zinc-oxide (ZnO) nanorod arrays have been successfully prepared using a novel and low-temperature sonicated sol–gel immersion method. The photoluminescence (PL) spectrum reveals the appearance of two emission peaks from the nanorod that are centred at 381 and 590 nm. The nanorod has a hexagonal structure with a flat-end facet, as observed using field-emission electron microscopy (FESEM). Interestingly, all samples have similar surface morphologies and diameter sizes of 40 to 150 nm after immersion in different precursor-solution volumes. The thickness-measurement results show that the thicknesses of the samples increase after immersion in higher precursor-solution volumes. We show for the first time that the growth of nanorod arrays along the c-axis can be controlled using different precursor volumes, and its growth mechanism is discussed. X-ray diffraction (XRD) spectra indicate that the prepared nanorods are ZnO with a hexagonal wurtzite structure that grows preferentially along the c-axis.

Effect of Temperature on the Growth of Vertically Aligned Carbon Nanotubes from Palm Oil

The effects of synthesis temperature on the quality and quantity of vertically aligned carbon nanotubes (VACNT) were studied using high resolution scanning electron microscopy, and micro-Raman spectroscopy. The VACNT was synthesized by Fe catalytic decomposition of palm oil deposited on silicon substrate by thermal chemical vapour deposition method. The analysis shows that the growth rate increases from 3.8 to 5.5 µm/min as the temperature was increased from 750 to 800°C. The nanotube diameters were observed bigger at low temperature range. Smaller and uniform diameter (~15 nm) was found at 750°C and the increment in diameter size was seen at higher temperature range. Smaller graphite Raman “G” peak width, low ID/IG ratio (~0.52) indicated higher crystallinity of the nanotube and moderate I2D1/ I2D2 ratio for second order Raman peak was also detected at synthesis temperature of 750°C. These results indicated that the optimum synthesis temperature for higher quality VACNT production was at 750°C.

The Effect of Precursor Vaporization Temperature on the Growth of Vertically Aligned Carbon Nanotubes Using Palm Oil

Carbon nanotubes (CNTs) were fabricated from palm oil using the thermal chemical vapor deposition technique utilizing a two furnace system. The effect of precursor vaporization temperature of the first furnace, in the range of 300-600°C was systematically studied with the synthesis temperature (second furnace) fixed at 750°C for a total time of 30 min. The samples were characterized using field emission scanning electron microscopy and micro-Raman spectroscopy. CNTs of various packing densities and diameters were synthesized with the varying precursor vaporization temperature. Based on micro-Raman measurements nanotube defect level and the presence of SWCNT were dependent on the vaporization temperature. Vertically aligned CNTs (VACNTs) were found to grow within the vaporization temperature range of 400-500°C, with well graphitized and higher yield obtained at 450°C with excellent lateral alignment, uniform nanotubes diameter (~15 nm), orientation and distribution within the CNT bundles. At vaporization temperatures of 300-350°C and 500-600°C, lower growth rate, bigger nanotubes diameter and higher ID/IG ratio were observed which indicated lower nanotubes quality that produced at both temperature ranges.

Thermogravimetric analysis of Silantek coal, Palm Kernel Shell, Palm Kernel Shell char and their blends during combustion

Preliminary thermogravimetric studies of Silantek coal (SL), Palm Kernel Shell (PKS), PKS char and their blends have been performed in a Thermogravimetry Analyser(TGA). PKS char were produced using microwave irradiation carbonization system at power of 300 Watt, with nitrogen flow rate of 150 mL/min for 30 minutes. Combustion tests of raw and blends samples were carried out in purified air atmosphere conditions at heating rates of 20 °C/min. The SL/ PKS and SL/ PKS char blends were prepared in the weight ratios of 80:20, 60:40, 50:50, 40:60 and 20:80. Derivative thermogravimetric (DTG) results which represent the decomposition of volatile matters and char showed that raw PKS has higher reactivity than SL during combustion process. The thermal profiles of the SL: PKS blends correlated with the percentage of PKS added in the blends, representing lack of synergic effect between both samples. SL and PKS char blends results in single evolution peak, indicated possibility to be used as alternative fuel for combustion. These findings may be useful for the power generation industry in the development of future co-firing plants using coal/ biomass; however, significant development work is required before large-scale implementation can be done.