Carbon Nanotubes: Functionalisation And Their Application In Chemical Sensors

Carbon nanotubes (CNTs) have been recognised as a promising material in a wide range of applications, from safety to energy-related devices. However, poor solubility in aqueous and organic solvents has hindered the utilisation and applications of carbon nanotubes. As studies progressed, the methodology for CNTs dispersion was established. The current state of research in CNTs either single wall or multiwall/polymer nanocomposites has been reviewed in context with the various types of functionalisation presently employed. Functionalised CNTs have been playing an increasingly central role in the research, development, and application of carbon nanotube-based nanomaterials and systems. The extremely high surface-to-volume ratio, geometry, and hollow structure of nanomaterials are ideal for the adsorption of gas molecules. This offers great potential applications, such as in gas sensor devices working at room temperature. Particularly, the advent of CNTs has fuelled the invention of CNTbased gas sensors which are very sensitive to the surrounding environment. The presence of O2, NH3, NO2 gases and many other chemicals and molecules can either donate or accept electrons, resulting in an alteration of the overall conductivity. Such properties make CNTs ideal for nano-scale gas-sensing materials. Conductive-based devices have already been demonstrated as gas sensors. However, CNTs still have certain limitations for gas sensor application, such as a long recovery time, limited gas detection, and weakness to humidity and other gases. Therefore, the nanocomposites of interest consisting of polymer and CNTs have received a great deal of attention for gas-sensing application due to higher sensitivity over a wide range of gas concentrations at room temperature compared to only using CNTs and the polymer of interest separatel

Chemical Reduction Behavior of Zirconia Doped to Nickel at Different Temperature in Carbon Monoxide Atmosphere

The reduction behavior of nickel oxide (NiO) and zirconia (Zr) doped NiO (Zr/NiO) was investigated using temperature programmed reduction (TPR) using carbon monoxide (CO) as a reductant and then characterized using X-ray diffraction (XRD), nitrogen absorption isotherm using BET technique and FESEM-EDX. The reduction characteristics of NiO to Ni were examined up to temperature 700 °C and continued with isothermal reduction by 40 vol. % CO in nitrogen. The studies show that the TPR profile of doped NiO slightly shifts to a higher temperature as compared to the undoped NiO which begins at 387 °C and maximum at 461 °C. The interaction between ZrO2 with Ni leads to this slightly increase by 21 to 56 °C of the reduction temperature. Analysis using XRD confirmed, the increasing percentage of Zr from 5 to 15% speed up the reducibility of NiO to Ni at temperature 550 °C. At this temperature, undoped NiO and 5% Zr/NiO still show some crystallinity present of NiO, but 15% Zr/NiO shows no NiO in crystalline form. Based on the results of physical properties, the surface area for 5% Zr/NiO and 15% Zr/NiO was slightly increased from 6.6 to 16.7 m2/g compared to undoped NiO and for FESEM-EDX, the particles size also increased after doped with Zr on to NiO where 5% Zr/NiO particles were 110 ± 5 nm and 15% Zr/NiO 140 ± 2 nm. This confirmed that the addition of Zr to NiO has a remarkable chemical effect on complete reduction NiO to Ni at low reduction temperature (550 °C). This might be due to the formation of intermetallic between Zr/NiO which have new chemical and physical properties

Determination of palm biodiesel/petroleum diesel blend ratio through spectroscopic method / Alinda Samsuri

Biodiesel, defined as the alkyl esters (usually methyl esters) of vegetable oils, is miscible with conventional petroleum diesel fuel at all blend levels. Blends of biodiesel with conventional petroleum diesel fuel represent a common utilization of biodiesel. The Malaysian Government has initiated the implementation of palm biodiesel since 2007 and the proposed blend is B5. Accordingly, there is interest and need for the development of methods for determining or verifying the blend level of biodiesel in petroleum diesel. To date, the most widely used and acceptable method for determination of biodiesel blend levels is using IR spectroscopy. The present study investigated the determination of blend level of palm biodiesel in petroleum diesel fuel in accordance to European Standard EN 14078:2003. The method was established for the determination of fatty acid methyl esters (FAME) in middle distillates—Infrared spectroscopy method. Principal component analysis of the region 1670 cm-1 to 1820 cm–1 and maximum carbonyl (C=O) absorption peak at 1745 cm-1 ± 5 cm-1 could distinguish blends of petroleum diesel fuel with palm biodiesel. The calibration model was built by following the parameters specified in EN 14078:2003. The peak height was correlated against the FAME concentration in g/L, and the calibration is reported. In the present study, the linearity over the selected range is very good, as evidenced by the R2 value of 0.9999. By using the data from the calibration function, the blend level of palm biodiesel in petroleum diesel was determined easily. Up to 0.2 % error occurs between the measured and an estimated value when used this method to determining the FAME contents in the palm biodiesel-petroleum diesel fuel blend. The adulteration of biodiesel/petroleum diesel blends by palm cooking oil was also successful traced by using thin layer chromatography (TLC) method. Good separation between methyl ester and glycerol was traced using TLC silica gel plate and solvent system chloroform : hexane (1:1 v/v). The amount of acylglycerols adulteration as low as 0.05% can be detected. The detection of adulterant such as acylglycerols in palm biodiesel and petroleum diesel fuel blends via TLC method is a useful and rapid method. It is highly recommended for enforcement exercise during implementation of palm biodiesel blend as there is a high possibility that acylglycerols may be used as an adulterant due to the fact it is cheaper than FAME and it cannot be differentiated from FAME due to the presence of carbonyl functional group