TiO2 thin film photocatalyst was successfully synthesized and immobilized on glass reactor tube using sol-gel method. The synthesized TiO2 coating was transparent, which enabled the penetration of ultra-violet (UV) light to the catalyst surface. Two photocatalytic reactors with different operating modes were tested: (a) tubular photocatalytic reactor with re-circulation mode and (b) batch photocatalytic reactor. A new proposed TiO2 synthesized film formulation of 1 titanium isopropoxide: 8 isopropanol: 3 acetyl acetone: 1.1 H2O: 0.05 acetic acid (in molar ratio) gave excellent photocatalytic activity for degradation of phenol and methylene blue dye present in the water. The half-life time, t1/2 of photocatalytic degradation of phenol was 56 min at the initial phenol concentration of 1000 microM in the batch reactor. In the tubular photocatalytic reactor, 5 re-circulation passes with residence time of 2.2 min (single pass) degraded 50% of 40-microM methylene blue dye. Initial phenol concentration, presence of hydrogen peroxide, presence of air bubbling and stirring speed as the process variables were studied in the batch reactor. Initial methylene blue concentration, pH value, light intensity and reaction temperature were studied as the process variables in the tubular reactor. The synthesized TiO2 thin film was characterized using SEM, XRD and EDX analysis. A comparative performance between the synthesized TiO2 thin film and commercial TiO2 particles (99% anatase) was evaluated under the same experimental conditions. The TiO2 film was equally active as the TiO2 powder catalyst.
ZnO nanowires have been synthesized using a catalyst-free carbothermal reduction approach on SiO2-coated Si substrates in a flowing nitrogen atmosphere with a mixture of ZnO and graphite as reactants. The collected ZnO nanowires have been characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and photoluminescence spectroscopy. Controlled growth of the ZnO nanowires was achieved by manipulating the reactants heating temperature from 700 to 1000 oC. It was found that the optimum temperature to synthesize high density and long ZnO nanowires was about 800 0C. The possible growth mechanism of ZnO nanowires is also proposed.
Even though a lot of new advanced materials have been developed nowadays, steel remains a major material in construction, automobiles, appliances, industrial machinery as well as in the nuclear industry. Due to steel easily corroded, a proper surface protection is required to avoid any failures and extended the life cycle of the components. Surface coating is an efficient and economical method to obtain desirable material surfaces properties. Hot dip aluminizing technique was utilized in this study. Experiments have been conducted on the mild steel substrates with 12mm diameter. Prior to hot dipping process, observation on grain growth at three different temperatures had also been conducted to understand the behaviour of steel under application of heat. The substrates were heated at 700ºC, 800ºC and 900ºC for 1 hour and the microstructure was analyzed. The temperature of 800C was chosen for hot dipping. The substrates were dipped into the molten aluminum maintained at temperature 800ºC for 2,4,6,8,10,15 and 20 minutes. Optical microscopy and energy dispersive X-ray spectroscopy were used in this investigation. From the microstructure observation, it showed the appearance of intermetallic layer covered by the top layer of Al on the mild steel substrate increased with the increase in dipping time ranging from 36 to 282μm. The result of EDX analysis revealed the existence of Fe and Al in form of Fe2Al5 phase for all the dipping time.
This study aims to investigate the behaviour of Malaysian sub-bituminous coal (Mukah Balingian), oil palm biomass (empty fruit bunches (EFB), kernel shell (PKS) and mesocarp fibre (PMF)) and their respective blends during pyrolysis using thermogravimetric analysis (TGA). The coal/palm biomass blends were prepared at six different weight ratios and experiments were carried out under dynamic conditions using nitrogen as inert gas at various heating rates to ramp the temperature from 25 degrees C to 900 degrees C. The derivative thermogravimetric (DTG) results show that thermal decomposition of EFB, PMF and PKS exhibit one, two and three distinct evolution profiles, respectively. Apparently, the thermal profiles of the coal/oil palm biomass blends appear to correlate with the percentage of biomass added in the blends, thus, suggesting lack of interaction between the coal and palm biomass. First-order reaction model were used to determine the kinetics parameters for the pyrolysis of coal, palm biomass and their respective blends.
Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions.
In the effort to find alternative low cost adsorbent for volatile organic vapors has prompted this research in assessing the effectiveness of activated carbon produced from durian shell in removing toluene vapors. Durian shells were impregnated with different concentrations of H3PO4 followed by carbonization at 500 °C for 20 min under nitrogen atmosphere. The prepared durian shell activated carbon (DSAC) was characterized for its physical and chemical properties. The removal efficiency of toluene by DSAC was performed using different toluene concentrations. Results showed that the highest BET surface area of the produced DSAC was 1404 m2/g. Highest removal efficiency of toluene vapors was achieved by using DSAC impregnated with 30% of acid concentration heated at 500 °C for 20 min heating duration. However, there is insignificant difference between removal efficiency of toluene by DSAC and different toluene concentrations. The toluene adsorption by DSAC was better fitted into Freundlich model.
Gasification of palm empty fruit bunch (EFB) was investigated in a pilot-scale air-blown fluidized bed. The effect of bed temperature (650-1050 °C) on gasification performance was studied. To explore the potential of EFB, the gasification results were compared to that of sawdust. Results showed that maximum heating values (HHV) of 5.37 and 5.88 (MJ/Nm3), dry gas yield of 2.04 and 2.0 (Nm3/kg), carbon conversion of 93% and 85 % and cold gas efficiency of 72% and 71 % were obtained for EFB and sawdust at the temperature of 1050 °C and ER of 0.25. However, it was realized that agglomeration was the major issue in EFB gasification at high temperatures. To prevent the bed agglomeration, EFB gasification was performed at temperature of 770±20 °C while the ER was varied from 0.17 to 0.32. Maximum HHV of 4.53 was obtained at ER of 0.21 where no agglomeration was observed.
PURPOSE: To determine the prevalence of and risk factors for AcriFlex 50CSE hydrophilic acrylic intraocular lens (IOL) opacification approximately 3 years after implantation.
SETTING: Selayang Hospital, Selangor, Malaysia.
DESIGN: Cross-sectional study.
METHODS: Patients who had AcriFlex 50CSE IOL implantation in 2005 and 2006 were identified from operating logbooks and recalled via telephone and letters. Opaque IOLs were explanted and sent for scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS).
RESULTS: The review showed that 18 patients had died and 67 had declined examination or could not be contacted, leaving 239 eyes for evaluation. The age of the patients ranged from 25 to 85 years. Of the patients, 83 (34.7%) were Malay, 127 (53.1%) Chinese, and 29 (12.1%) East Indian. The male:female ratio was 1:1. Fourteen eyes of 13 patients (5.4%) had IOL opacification; 1 had bilateral opacification. Five eyes had fine deposits, and 9 eyes had dense opaque deposits. Seven opaque IOLs required explantation. There was no correlation between age (P=.645), sex (P=.319), or race (P=.860) and IOL opacification. Pearson chi-square analysis showed a strong association between diabetes mellitus and IOL opacification (P=.019). Nine (69.2%) of the 13 patients with opacification had diabetes. Scanning electron microscopy and EDS showed calcium and phosphate deposits on the optic surface and intralenticularly near the anterior surface of the optic.
CONCLUSIONS: Results indicate that diabetes mellitus is a risk factor for AcriFlex hydrophilic acrylic IOL opacification. In some cases, opacification affected vision, necessitating explantation. The pathophysiology of this complication is unknown.
FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.
Nanocrystalline SnO(x) (x = 1-2) thin films were prepared on glass substrates by a simple chemical bath deposition method. Triethanolamine was used as complexing agent to decrease time and temperature of deposition and shift the pH of the solution to the noncorrosive region. The films were characterized for composition, surface morphology, structure and optical properties. X-ray diffraction analysis confirms that SnO(x) thin films consist of a polycrystalline structure with an average grain size of 36 nm. Atomic force microscopy studies show a uniform grain distribution without pinholes. The elemental composition was evaluated by energy dispersive X-ray spectroscopy. The average O/Sn atomic percentage ratio is 1.72. Band gap energy and optical transition were determined from optical absorbance data. The film was found to exhibit direct and indirect transitions in the visible spectrum with band gap values of about 3.9 and 3.7 eV, respectively. The optical transmittance in the visible region is 82%. The SnO(x) nanocrystals exhibit an ultraviolet emission band centered at 392 nm in the vicinity of the band edge, which is attributed to the well-known exciton transition in SnO(x). Photosensitivity was detected in the positive region under illumination with white light.
There are many essential and non-essential elements including metals and radionuclides present in vegetables. Howeve r, the accumulation of the several metals and radionuclides might cause the contamination to vegetables itself. Green m ustard (Brasissca rapa var. Parachinesis L.) was selected to represent the vegetable in this study. Objectives of this stud y are to determine the concentration of metals and radionuclides in the samples and to calculate the enrichment factor ( EF) and also to estimate the uptake, base on biological accumulation coefficient (BAC), for the various parts of selecte d vegetables. Three farmlands in the Cameron Highlands were studied namely Bharat, Kg Raja and Bertam area. The g reen mustard and soil samples were collected during the harvest season. Samples were dried, ground and sieved prior t o analysis. Analyses for both samples were done by using X-rays Fluorescence Spectroscopy (XRF) to measure the conc entration of Fe, Zn, Hg, U and Th. The concentration of all elements in the soils is lower than their concentration in the control soil, except for Zn, U and Th. The concentration of all elements in Green Mustard is lower than their concentrat ion in the soil where it was grown. The EF values in the Brasissca rapa var. Parachinesis L are lower than 2 except for U and Th, indicating some degree of contamination due to anthropogenic activities or naturally origin. The BAC values show that Zn and Hg were accumulated in the green mustard, depending on where the plant grows.
In this work, untreated bovine cortical bones (BCBs) were exposed to a range of heat treatments in order to determine at which temperature the apatite develops an optimum morphology comprising porous nano hydroxyapatite (nanoHAp) crystals. Rectangular specimens (10 mm × 10 mm × 3-5 mm) of BCB were prepared, being excised in normal to longitudinal and transverse directions. Specimens were sintered at up to 900 °C under ambient pressure in order to produce apatites by two steps sintering. The samples were characterized by thermogravimetric analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) attached to an energy-dispersive X-ray spectroscopy detector. For the first time, morphology of the HAp particles was predicted by XRD, and it was verified by SEM. The results show that an equiaxed polycrystalline HAp particle with uniform porosity was produced at 900 °C. It indicates that a porous nanoHAp achieved by sintering at 900 °C can be an ideal candidate as an in situ scaffold for load-bearing tissue applications.
Ultrahigh-molecular-weight polyethylene/high-density polyethylene (UHMWPE/HDPE) blends prepared using polyethylene glycol PEG as the processing aid and hydroxyapatite (HA) as the reinforcing filler were found to be highly processable using conventional melt blending technique. It was demonstrated that PEG reduced the melt viscosity of UHMWPE/HDPE blend significantly, thus improving the extrudability. The mechanical and bioactive properties were improved with incorporation of HA. Inclusion of HA from 10 to 50 phr resulted in a progressive increase in flexural strength and modulus of the composites. The strength increment is due to the improvement on surface contact between the irregular shape of HA and polymer matrix by formation of mechanical interlock. The HA particles were homogenously distributed even at higher percentage showed improvement in wetting ability between the polymer matrix and HA. The inclusion of HA enhanced the bioactivity properties of the composite by the formation of calcium phosphate (Ca-P) precipitates on the composite surface as proven from SEM and XRD analysis.
In this study, the biosorption of copper and zinc ions by Chlorella sp. and Chlamydomonas sp. isolated from local environments in Malaysia was investigated in a batch system and by microscopic analyses. Under optimal biosorption conditions, the biosorption capacity of Chlorella sp. for copper and zinc ions was 33.4 and 28.5 mg/g, respectively, after 6 hr of biosorption in an immobilised system. Batch experiments showed that the biosorption capacity of algal biomass immobilised in the form of sodium alginate beads was higher than that of the free biomass. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that copper and zinc were mainly sorbed at the cell surface during biosorption. Exposure to 5 mg/L of copper and zinc affected both the chlorophyll content and cell count of the algal cells after the first 12 hr of contact time.
This work presents a study of human hair as a bio-indicator for detection of heavy metals as part of environmental health surveillance programs project to develop a subject of interest in the biomedical and environmental sciences. A total of 34 hair samples were analyzed that consisting of 29 samples from sanitation workers and five samples from students. The hair samples were prepared and treated in accordance to the International Atomic Energy Agency (IAEA) recommendations. The concentrations of heavy metals were analyzed using the energy dispersive X-ray fluorescence (EDXRF) technique by X-50 Mobile X-ray Fluorescence (XRF) at Oceanography Institute, Universiti Malaysia Terengganu. The performance of EDXRF analyzer was tested by Standard Reference Material (SRM 2711) Montana Soil which was in good agreement with certified value within 14% deviations except for Hg. While seven heavy metals: Mn, Fe, Ni, Cu, Zn, Se, and Sb were detected in both groups, three additional elements, i.e. As, Hg and Pb, were detected only in sanitation workers group. For sanitation workers group, the mean concentration of six elements, Mn, Fe, Cu, Zn, Se, and Sb, shows elevated concentration as compared to the control samples concentration. Results from both groups were compared and discussed in relation to their respective heavy metals concentrations.
Five species of white rot fungi were screened for their capability to synthesize Ag nanoparticles (AgNPs). Three modes of AgNP bioreduction were developed. Pycnoporus sanguineus is found as a potential candidate for the synthesis of AgNPs with a yield at 98.9%. The synthesized AgNPs were characterized using UV-vis spectroscopy, DLS, FTIR, TEM, and SEM. Results showed that AgNP absorption band was located at a peak of 420 nm. Both the SEM and TEM confirmed that the formation of AgNPs were mainly spherical with average diameters of 52.8-103.3 nm. The signals of silver atoms' presence in the mycelium were observed by SEM-EDS spectrum.
Measurement of major cation such as Na+, K+, and Ca2+ in water are normally carried out using
AAS, ICP-OES or flame photometry. In this study, an attempt was made to measure these cations
using Energy Dispersive X-ray Fluorescent Spectrometry (EDXRF). Hot spring s water was taken from varies hot spring in Selangor and divided into two portions that is filtered and unfiltered. 5 mL of water samples were pipette into a special liquid cups (sample holders) which has a thin mylar film underneath. The MiniPal4 XRF instrument was used in this study. The resolution for the instrument use is 145 keV with energy resolution at 5.9 keV. The spectrum of cations were analysed by using MiniPal/MiniMate software to determine the cations concentration. For K+ and Ca2+, Al-thin filter was used and default filter was used for Na+. The concentration of Na+ obtained for filtered and unfiltered samples were ranged from 38.00 to 66.05 and 43.26 to 76.95 ppm. Meanwhile, concentrations of K+ for filtered and unfiltered samples were ranged from 2.42 to 8.07 and 6.18 to 29.28 ppm. Concentrations of Ca2+ for filtered and unfiltered samples were ranged from 2.59 to 10.94 and 3.18 to 12.99 ppm.
The effect of corrosion inhibition of low carbon steel in water based medium containing lignin was investigated via weight loss method. The evolution of surface morphology has been carried out for 7 to 42 days via optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron microscopy (XPS). Immersion of metal specimen without lignin shows that significant increase in the surface roughness. The longer the immersion time, the more the oxide crust formed. The surface degradation of metal specimen was well protected by immersion in lignin solution. A protective layer containing of lignin was formed on the surface of metal specimens after 7 and 21 days immersion. The corrosion inhibition gives about 13 and 53% inhibition for both 7 and 21 days immersion, respectively. The protective layers were spalling and separated from the metal surface after 42 days immersion in lignin solution possibly due to the increase in corrosion attack after long time immersion according to the increase in dissolved oxygen and may also due to the thermal mismatch between oxide and substrate. The adsorption of protective layer containing lignin was temporary adsorbed on the surface.