Mohd Azlan Mohd Ishak

Kinetics of photocatalytic decolourization of cationic dye using porous TiO2 film

Abstract In this work, the kinetics of the photocatalytic decolourization of methylene blue (MB) is investigated using different surface morphologies of multilayer TiO2 coating onto a glass plate under irradiation from a 55-W household florescent lamp. A simple direct dip-coating technique was used, and the coating properties of TiO2 powder were improved by adding epoxidized natural rubber (ENR) as an organic binder in the coating formulation. The effects of the fundamental parameters that govern the kinetics of the photocatalytic decolourization of MB, such as the mass of TiO2 coated onto the glass plate, the pH and the TiO2 surface morphology, were also studied. The kinetics of the MB decolourization in all cases was found to be pseudo-first-order kinetics and was fitted to the Langmuir–Hinshelwood model. The degraded part of the ENR binder led to generating pores within the surface of the TiO2/ENR film and converting it into porous form, as confirmed by SEM analysis. Furthermore, TGA, FTIR and leachability analyses were conducted to further confirm the depletion of the ENR from the TiO2/ENR film. The kinetics of the MB decolourization and the efficiency of the MB colour removal indicated that the porous TiO2/ENR film becomes approximately twice as fast as the non-porous TiO2/ENR film.

New TiO2/DSAT Immobilization System for Photodegradation of Anionic and Cationic Dyes

A new immobilized TiO2 technique was prepared by coating TiO2 solution onto double-sided adhesive tape (DSAT) as a thin layer binder without adding any organic additives. Glass plate was used as support material to immobilized TiO2/DSAT. Two different charges of dyes were applied, namely, anionic reactive red 4 (RR4) and cationic methylene blue (MB) dyes. Photocatalytic degradation of RR4 and MB dyes was observed under immobilized TiO2/DSAT with the degradation rate slightly lower and higher, respectively, compared with TiO2 in suspension mode. It was observed that DSAT is able to provide a very strong intact between glass and TiO2 layers thus making the reusability of immobilized TiO2/DSAT be up to 30 cycles. In fact, a better photodegradation activity was observed by number of cycles due to increasing formation of pores on TiO2 surface observed by SEM analysis.

Liquefaction studies of low-rank Malaysian coal using high-pressure high-temperature batch-wise reactor

ABSTRACT Direct liquefaction of low-rank Malaysian coal from the Mukah Balingian (MB) area was successfully carried out in a 1000 ml high-temperature (360–450°C) high-pressure (4–13 MPa) batch-wise reactor system using tetralin as hydrogen donor solvent. The results indicated that the percent coal conversion obtained were in the range of 31–90%. At optimum conditions of 450°C and 4 MPa, the oil + gas, asphaltene and preasphaltene of the coal extract were 80%, 7%, and 2%, respectively. It was observed that heat plays an important role in comparison to pressure in contributing to high coal conversion, oil yield, and organic properties of the residues. The high coal conversion and oil yield correlate well with the high content of reactive macerals, i.e., vitrinite and exinite, in the coal. Other parameters that were also investigated include the effect of reaction time (0–120 min) and coal-to-solvent ratio. A high yield of asphaltene and preasphaltene was obtained at the longest reaction time (i.e., 120 min). Coal conversion and oil yield increase with increasing in coal-to-solvent ratio, with the optimal ratio being 1:5.

Microwave-assisted preparation of mesoporous-activated carbon from coconut (Cocos nucifera) leaf by H3PO4 activation for methylene blue adsorption

ABSTRACT Mesoporous-activated carbon was prepared from fallen coconut (Cocos nucifera) leaf, an agricultural waste through a microwave-induced H3PO4 activation process. The characterization of the coconut leaf–activated carbon (CAC) was evaluated through the iodine number, ash content, bulk density, and moisture content. Fourier transform infrared spectroscopy, scanning electron microscope, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction, and pHPZC. CAC has a mesopore content of 84% with an average pore size of 36.5 Å and a large BET surface area of 632 m2/g. The uptake properties of the CAC with methylene blue was evaluated at different CAC dosage levels (0.2–10 g/L), initial pH (3–10), methylene blue concentration (50–350 mg/L), and time (0–360 min) using batch mode operation. The kinetic profiles were described by the pseudo-second-order kinetics. The equilibrium data were well fitted to the Langmuir model with a maximum monolayer adsorption capacity of 250 mg/g at 30°C. Thermodynamic functions indicate a spontaneous and exothermic nature of the adsorption process. This study indicates that coconut leaves are a promising renewable precursor that can be utilized to develop an efficient mesoporous-activated carbon.

Pyrolysis of Jatropha curcas L. husk: Optimization solid, liquid and gas yield by using response surface methodology (RSM)

This study aimed to develop an optimal condition for production of solid and liquidproducts from the pyrolysis of Jatropha curcas L. husk. Response surface methodology (RSM) based on central composite rotatable design (CCRD) was applied to optimize the combination effect of three important reaction variables, i.e. reaction temperature (°C), heating rate (°C/min) and nitrogen gas flow rate (ml/min). The reaction was performed via vertical fixed-bed reactor. A total of 20 individual experiments were conducted. The results showed that the RSM based on CCRD is well adaptable for pyrolysis studied in this system. The predicted optimum conditions for production of solid and liquid yield from the pyrolysis of Jatropha curcas L. husk was at 400°C reaction temperature, 60 °C/min heating rate and 120 ml/min nitrogen gas flow rate with char, liquid and gas yield at 38 %, 28.9 % and 33.0% respectively.

Fabrication and Characterization of Porous Activated Carbon from Coconut Shell by Using Microwave-Induced KOH Activation Technique

Coconut shell-based activated carbon (CSAc) was prepared by chemical activation method using microwave-induced KOH technique. The activation process was successfully carried out with varying microwave power ranging from 100 to 1000 W and impregnation ratio of 1.0 to 3.0. The surface area, pore sizes, surface morphology and specific capacitance of the produced activated carbon were analyzed by using an automatic quantachrome instrument (Autosorb1C) volumetric sorption analyzer, scanning electron microscope (SEM) and automatic battery cycler. The optimum activation power and impregnation ratio were found at 600 W and 1.5, respectively. The resulted product, C3 has maximum surface area and specific capacitance value of 1768.8 m2 g-1 and 156.33 F g-1 respectively, with carbon yield of 58 %.

Co-liquefaction of low rank Malaysian coal and Palm Kernel Shell — The effect of temperature

The co-liquefaction of Mukah Balingian (MB) Malaysian coal with the Palm Kernel Shell (PKS) was studied to investigate the synergistic effect by comparing the conversion and product yields. Co-liquefaction results thus far indicate there exists an obvious synergestic effect between MB and PKS, which is depends on liquefaction temperature. Thus far, the results showed that the conversion and oil + gas yields were comparatively much higher than the liquefaction of the MB coal alone. The largest synergistic effect is obtained at low temperature of 400 °C and then decreases as temperature increase. The liquefaction conversion of 88.6 % and oil+gas of 77.6 % of the co-liquefaction at this optimal temperature are higher than that of corresponding values from the invidual liquefaction of MB coal.

Morphological and spectral analysis of polystyrene-block- polyisoprene-poly(Butyl acrylate) triblock copolymer

Polystyrene-block-polyisoprene-block-poly (butyl acrylate) or PS-b-PI-b-PBA triblock copolymer with different ratio (5:5 and 4:6) of styrene and isoprene unit have been synthesized by anionic polymerization. The product had been characterized by using Scanning Electron Microscopy (SEM) and N-Nuclear Magnetic Resonance (H-NMR). The results of SEM images reveal that more rubber matrix can be seen for 4:6 ratios as compared to 5:5 ratios due to high content of isoprene in the copolymer. H-NMR results indicate that the peaks of polystyrene, polyisoprene and butyl acrylate for ratio 5:5 exists at 6.50 – 7.28 ppm, 4.68 – 4.88 ppm, and 0.80 – 1.83 ppm. As for ratio 4:6, the peaks can be observed at 6.30 – 7.33 ppm, 5.19 – 5.70 ppm, and 1.18 – 1.78 ppm respectively. The H-NMR analysis of the copolymer microstructure confirms that both copolymer are primarily consists of polystyrene, polyisoprene and polybutyl acrylate segment.

Synthesis and Characterization of Strontium-Doped Lanthanum Cobaltite Cathode Material Prepared by a Modified Combined Complexing Method

A potential candidate for intermediate temperature solid oxide fuel cell (IT-SOFC) cathode material which is strontium-doped lanthanum cobaltite, La0.6Sr0.4CoO3-α (LSCO) has been synthesized by a complexing method. Citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) were used as a combined chelating agent and ethylene glycol (EG) was employed as surfactant. The obtained powder was characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). TGA results showed the thermal decomposition of the precursor gel was completed at 700 °C. A single perovskite phase of LSCO with cubic structure was obtained at calcination temperature of 1000 °C with heating/cooling rate of 10 °C min-1 as confirmed by XRD analysis. SEM result revealed that the morphology of the powder was spherical in shape with diameter ranging from 250 to 650 nm. Apparently, the bulk sample consists of almost homogeneous and identical particles.

Production of Biodiesel via In-Situ Supercritical Methanol Transesterification

Most energy that the world is using is derived from unrenewable fossil fuel that has a great impact on environments (Warabi et al., 2004). The demand of fossil fuels is increasing very rapidly and it is estimated that the remaining world reserves will be exhausted by the year 2020, with the current rate of consumption. There is an urgent need to seek for an alternative fuels to substitute the diesel due to gradual depletion of world crude oil reserves. Research is, therefore oriented for alternative energy. Biomass is one of its candidates, because biomass energy has some advantageous in reproduction, cyclic and carbon neutral properties (Warabi et al., 2004). Biodiesel fuel is one example of biomass energy, and it is generally made of methyl esters of fatty acids produced by the transesterification reaction of triglycerides with methanol with the help of a catalyst (Clark et al., 1984). Alcoholysis of vegetable oils produces fatty acids alkyl esters that are excellent substitutes for conventional fossil diesel fuels (Selmi and Thomas, 1998; De et al., 1999). The viscosity of alkyl esters is nearly twice that of diesel fuel instead of 10–20 times as in the case of neat vegetable oil (Rathore and Madras, 2007). The use of such edible oil to produce biodiesel is not feasible in view of big gap in the demand and supply of such oils in the country for dietary consumption. Increased pressure to augment the production of edible oils has also put limitations on the use of these oils for production of biodiesel (Sinha et al., 2008). Therefore, biodiesel is actually competing limited land availability with the food industry for the same oil crop. Thus, instead of arable land being utilized to grow food, it is now being used to grow fuel. This will then raise the price of edible oil making the biodiesel produced economically unfeasible as compared to petroleum-derived diesel. In order to overcome this issue, many researchers have begun searching for cheaper and non-edible oils to be used as alternative feedstock for biodiesel production (Kansedo et al., 2009). Few sources have been identified such as waste cooking oil (Wang et al., 2006; Chen et al., 2009) and oils from non-edible oil-producing plants such as Jatropha curcas (Heller, 1996; Herrera et al., 2006; Tiwari et al., 2007; Berchmans and Hirata, 2008; Chew, 2009), Pongamia pinnata (Meher et al., 2006; Naik et al., 2008; Pradhan et al., 2008), Calophyllum inophyllum (Sahoo et al., 2007), cottonseed (Demirbas, 2008; Qian et al., 2008; Rashid et al., 2009), rubber seeds (Ikwuagwu et al., 2000; Ramadhas et al., 2005) and tobacco seeds (Usta, 2005; Veljkovic et al., 2006). Obviously, developing nations have to focus their attention on oils of non-edible nature, which are cheaper (Sinha et al., 2008). In Malaysia, Jatropha curcas L. (JCL), could be utilized as a source for production of oil and can be grown in large scale on non-cropped marginal lands and waste lands.