The production of high purity hexagonal MoO3 through the acid washing of as-prepared solids

Highly pure and crystalline h-MoO3 nanocrystals in the form of well-faceted straight hexagonal rods were successfully synthesised from an acid-base titration method. The formation of metastable h-MoO3 was due to the addition of a high H+concentration to a basic molybdenum solution. Precipitates were formed at a pH range of 1.95-2.10. X-ray diffraction (XRD)analysis confirmed that the obtained solids were hexagonal MoO3, while their morphology was observed using scanning electron microscopy (SEM). The fabricated rods have a BET total surface area of ~3m2g-1, with crystallite sizes ranging from 33 to 46 nm

Observation of cotton-like bismuth oxide (β-Bi2O2.5) prepared via pulsed laser ablation deposition

Monoclinic bismuth oxide (α-Bi2O3) nanoparticles were prepared via precipitation method and irradiated with a pulsed laser forming thin films. Their phase and surface morphological properties were investigated using x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HR-TEM). The XRD analysis shows the phase transformation to a partially crystalline tetragonal phase β-Bi2O3 thin film. The SEM micrograph of the nanoparticles, with an average crystal size of 72 nm, was seen to form a thin film with a peculiar structure, coined as “cotton-likeâ€�, is attributed to the high surface energy absorbed by the nanoparticles during ablation. The HR-TEM micrograph shows the particulate with a clearly defined interlayer spacing

Monitoring microwave dielectric properties during transesterification reaction for palm biodiesel production

Microwave energy offers a fast method to produce biodiesel with advantages of enhancing the reaction rate and improving the reaction separation. The dielectric properties at frequency range from 0.2 GHz to 20 GHz of a mixture during transesterification reaction which are used for producing palm biodiesel were presented. The monitoring was done by placing a dielectric probe at the upper level and lower level of the mixture to measure the dielectric properties during the formation of biodiesel and glycerin respectively. In the transesterification reaction, the mixture consisting of vegetable oil, methanol and sodium hydroxide was heated at a constant temperature of about 45-50 o C and stirred for homogeneity. Results of the measurement over the frequency range showed drastic changes on the dielectric properties in the first 3 minutes of the reaction and after 3 minutes, the dielectric properties slowly decreased and approached the dielectric properties of biodiesel or glycerin. This study gives valuable information on the optimum mixing time for microwave transesterification reaction. These properties could be used to estimate absorbed power by the mixture for application in microwave transesterification process as dielectric loss of the mixture changed from 20 to about 0.5 as the transesterification reaction was completed

Effect of calcination temperature on the characteristics of MoV oxides prepared via reflux method

In this study, MoV mixed oxides with a molar ratio of 10:3 were prepared by reflux method. The samples were subjected to various calcination temperatures in order to investigate the physicochemical properties of the oxide affected by the parameter. Samples were characterised by XRD, TG/DTA, BET surface area, SEM and TPR. By imposing various calcination temperatures, phase evolutions were observed. However, these changes do not significantly affect the morphology, surface area, particle size and reducibility of the oxide. Still, the best calcination temperature can be chosen to arrive at the effective catalyst necessary for the desired catalytic reaction

Influence of organic species on the characteristics of Mo-V oxide

This study investigates on the effect of organic species on the characteristics of molybdenum-vanadium mixed oxide catalysts. The MoV precursors were prepared by homogeneous precipitation method using urea hydrolysis. The oxides were later treated with three organic species namely polyvinyl alcohol (PVA), malic acid (MA) and adipic acid (AA). The solutions were refluxed in a prescribed time. The solid obtained were calcined and subsequently denoted as MoV(PVA), MoV(MA) and MoV(AA). Interesting results in which high surface area values (SBET) were obtained in the range between 10 to 20 m2 g-1. XRD reckoned the samples are in highly crystalline form. H2-Temperature programmed reduction analysis showed that the total number of oxygen removed are 1.4 x 1022 atoms g-1, 3.3 x 1022 atoms g-1 and 1.8 x 1022 atoms g-1 for MoV(PVA), MoV(MA) and MoV(AA) respectively

Bismuth oxide nanoparticles/chitosan/modified electrode as biosensor for DNA hybridization.

An electrochemical DNA biosensor based on nanoparticles bismuth oxide Bi2O3 for DNA immobilization and hybridization detection is presented. The nano Bi2O3/chitosan-modified gold electrode (AuE) was fabricated and oligonucleotides were immobilized onto the AuE surface with the use of activating reagents – water soluble 1-ethyl-3(3’-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxy sulfosuccinimide (NHS). Hybridization was induced by exposure of the ssDNA-containing AuE to complementary target DNA in solution. The electrochemical behavior of methylene blue (MB) on the ssDNA and dsDNA modified electrode were carefully monitored by cyclic voltammetry (CV) analysis. The increases in the anodic peak current of MB were observed upon hybridization of probe with the target complementary DNA. Selectivity and sensitivity of this assay were also investigated in order to determine the specificity of the hybridization detection. This is the first application of chitosan combined with nano Bi2O3 for the fabrication of an electrochemical DNA biosensor with a favorable performance for the detection of specific hybridization

Hydrocarbon sources for the carbon nanotubes production by chemical vapour deposition: a review

The synthesis of carbon nanotubes (CNTs) using a chemical vapour deposition (CVD) method requires the use of hydrocarbon as the carbon precursor. Among the commonly used hydrocarbons are methane and acetylene, which are both light gas-phase substances. Besides that, other carbon-rich sources, such as carbon monoxide and coal, have also been reportedly used. Nowadays, researches have also been conducted into utilising heavier hydrocarbons and petrochemical products for the production of CNTs, such as kerosene and diesel oil. Therefore, this article reviews the different kind of hydrocarbon sources for CNTs production using a CVD method. The method is used for it allows the decomposition of the carbon-rich source with the aid of a catalyst at a temperature in the range 600-1200°C. This synthesis technique gives an advantage as a high yield and high-quality CNTs can be produced at a relatively low cost process. As compared to other processes for CNTs production such as arc discharge and laser ablation, they may produce high quality CNTs but has a disadvantage for use as large scale synthesis routes

Synthesis of epoxidized palm oil-based trimethylolpropane ester by in situ epoxidation method

Palm oil-based Trimethylolpropane ester (TMP ester), with an iodine value of 66.4 g/100g, was epoxidized to produce epoxidized TMP esters. In situ epoxidation method was used with peracetic acid to eliminate fatty acid double bonds in palm oil-based TMP ester and change it into oxirane ring. This was done to improve the oxidative stability of trimethylolpropane ester which is a key concern limiting the useful service life in lubricants. The epoxidation was performed by reacting acetic acid as active oxygen carrier with concentrated hydrogen peroxide as oxygen donor and a small amount of homogeneous catalyst (sulphuric acid). The effects of various parameters on the rate of epoxidation (such as the ratio of mole acetic acid to ethylenic unsaturation, hydrogen peroxide to ethylenic unsaturation and acetic acid mole ratio, and amount of catalyst) were studied. The rate of oxidation was investigated by the percentage of oxirane oxygen analysis and iodine value

Chemical Constituents of Vitex ovata (Verbenaceae)

Three compounds, luteolin, ursolic acid and meta-hydroxybenzoic acid were isolated from the leaves of Vitex ovata. The structures of the compounds were identified using modern spectroscopic techniques

Carbon nanopipe catalysed by as-prepared NiO nanoparticles

Carbon nanopipes catalyzed by high purity nickel oxide (NiO) nanoparticles were reported. The nanocrystals catalysts were first prepared using precipitation technique and characterized using x-ray diffraction (XRD), energy dispersive x-ray (EDX) and scanning electron microscopy (SEM) and subsequently used as catalyst for the formation of nanotubes. Pure phase, rhombohedral nickel oxide formation was identified from the XRD data, with the major peak located at 43.29o of the 2θ degree corresponding to a (202) plane. A pulsed laser ablation deposition technique (PLAD) was used to produce the CNTs. From the SEM micrograph, deposited CNTs shows a web-like structure, while the HR-TEM reveals carbon nanopipes with a length of 10 micron and diameter of 430 nm, suggesting that the nanocrystals aggregate and forms bigger cluster consequence of the ablation process