Oman Zuas

Synthesis of Nanostructured Copper-doped Titania and Its Properties

Nanostructured pure-TiO2 and Cu3%-TiO2 were successfully synthesized via co-precipitation method. The X-ray diffraction (XRD) result proves that the synthesized sample were predominantly in anatase phase with size in the range of 8∼16 nm, which are in good agreement with the transmission electron microscopy data. Owing to doping of copper, not only did the thermal stability of the TiO2 decrease, but also a significant decrease in its particle size and a shift of the adsorption edge to a higher wavelength region appear. The activity of both pure-TiO2 and Cu3%-doped TiO2 was tested to study their ability to decolorize congo red (CR) dye in aqueous solution. We observed that the CR dye was decolorized faster by Cu3%-TiO2 than pure-TiO2. Results of this study demonstrate a potential application of the synthesized sample for decolorizing dye pollutants from aqueous waste.

Measurement of HDO Products Using GC-TCD: Towards Obtaining Reliable Analytical Data

Abstract This paper reported the method development and validation of a gas chromatography with thermal conductivity detector (GC-TCD) method for the measurement of the gaseous products of hydrodeoxygenation (HDO). The method validation parameters include selectivity, precision (repeatability and reproducibility), accuracy, linearity, limit of detection (LoD), limit of quantitation (LoQ), and robustness. The results showed that the developed method was able to separate the target components (H2, CO2, CH4 and CO) from their mixtures without any special sample treatment. The validated method was selective, precise, accurate, and robust. Application of the developed and validated GC-TCD method to the measurement of by-product components of HDO of bio-oil revealed a good performance with relative standard deviation (RSD) less than 1.0% for all target components, implying that the process of method development and validation provides a trustworthy way of obtaining reliable analytical data.

Gravimetric dilution of calibration gas mixtures (CO2, CO, and CH4 in He balance): Toward their uncertainty estimation

Uncertainty estimation for the gravimetric dilution of four calibration gas mixtures [carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) in helium (He) Balance] have been carried out according to the International Organization for Standardization (ISO) of “Guide to the Expression of Uncertainty in Measurement”. The uncertainty of the composition of gas mixtures was evaluated to measure the quality, reliability, and comparability of the prepared calibration gas mixtures. The analytical process for the uncertainty estimation is comprised of four main stages such as specification of measurand, identification, quantification of the relevant uncertainty sources, and combination of the individual uncertainty sources. In this study, important uncertainty sources including weighing, gas cylinder, component gas, certified calibration gas mixture (CCGM) added, and purity of the He balance were examined to estimate the final uncertainty of composition of diluted calibration gas mixtures. The results shows that the uncertainties of gravimetric dilution of the four calibration gas mixtures (CO2, CO, and CH4 in He Balance) were found in the range of 5.974% - 7.256% that were expressed as %relative of expanded uncertainty at 95% of confidence level (k=2). The major contribution of sources uncertainty to the final uncertainty arose from the uncertainty related to the certified calibration gas mixture (CCGM) which was the uncertainty value stated in the CCGM certificate. The verification of calibration gas mixtures composition shows that the gravimetric values of calibration gas mixtures were consistent with the results of measurement using gas chromatography flame ionization detector equipped by methanizer.Uncertainty estimation for the gravimetric dilution of four calibration gas mixtures [carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) in helium (He) Balance] have been carried out according to the International Organization for Standardization (ISO) of “Guide to the Expression of Uncertainty in Measurement”. The uncertainty of the composition of gas mixtures was evaluated to measure the quality, reliability, and comparability of the prepared calibration gas mixtures. The analytical process for the uncertainty estimation is comprised of four main stages such as specification of measurand, identification, quantification of the relevant uncertainty sources, and combination of the individual uncertainty sources. In this study, important uncertainty sources including weighing, gas cylinder, component gas, certified calibration gas mixture (CCGM) added, and purity of the He balance were examined to estimate the final uncertainty of composition of diluted calibration gas mixtures. The results shows...

Copper-Zinc-Titania Nanocomposite as Catalyst for CO2 Photo-Reduction: A Surface Deactivation Study

In this paper, a surface deactivation study of Cu1.0-Zn0.5-Ti98.5 oxide nanocomposite (CZT-ONC) as catalyst for photo-reduction of CO2 in aqueous solution is reported. The photo-reduction experiments were conducted through five experimental cycles. The results demonstrated that the activity of the CZT-ONC decreased by increasing the number of testing cycle. The causes for declining the activity of the CZT-ONC catalyst was studied by investigating the surface condition of the catalyst before and after used by mean X-ray photoelectron spectroscopy (XPS) and field emission-scanning electron spectroscopy (FE-SEM) techniques and the results are discussed. It was found that the surface conditions (chemical state of the elements and morphology) of the CZT-ONC catalyst have been critically altered. Change in surface condition pointed that the deactivation process on the surface of the CZT-ONC was occurred and it could be considered to be the reasons for declining of the activity.