Ammar Houas

Fabrication of a TiO2 nanoparticles impregnated titanium mesh filter and its application for environmental purification

A novel photocatalytic filter, titanium-mesh sheet modified with TiO2 (TMiP), was fabricated and applied for environmental purification. The high flexibility of TMiP allows for an easy to design and fabricate photocatalytic reactor. Moreover, TMiP provides an excellent air or water pass-through while maintaining a high level of surface contact with UV irradiation.

Zinc oxide incorporating iron nanoparticles with improved conductance and capacitance properties

Iron nanoparticles were incorporated into zinc oxide powders by an in situ dispersion method. The products were fully characterized by X-ray diffractometry, diffuse reflectance, FTIR spectrophotometry and complex impedance spectroscopy. The XRD patterns agreed with that of the ZnO typical wurtzite structure, the sharp diffraction peaks indicating good crystallinity of ZnO and ZnO-Fe nanoparticles. The average particle size determined by the Scherrer equation showed an increase from 20 to 25xa0nm for ZnO and ZnO-Fe respectively. The UV peak positions of the modified samples shifted to a longer wavelength compared to pure ZnO, providing evidence of changes in the acceptor level induced by iron nanoparticles. The optical band gap of the samples was found to be 3.14xa0eV for ZnO and 3.04xa0eV for ZnO-Fe. The electrical properties were investigated between 273 and 413xa0K, at several frequencies. Besides, a detailed analysis of the impedance spectrum showed an appreciable improvement of the conductivity due to the addition of iron nanoparticles. The incorporation of Fe-NPs appears to be responsible for conductance variations, charge transfer and capacitance improvement. The above properties make these materials to be regarded as very promising electrode materials for high-efficiency energy storage.

Development of a fixed bed gasifier model and optimal operating conditions determination

The main objective of this study was to develop a fixed bed gasifier model of palm waste and to identify the optimal operating conditions to produce electricity from synthesis gas. First, the gasifier was simulated using Aspen PlusTM software. Gasification is a thermo-chemical process that has long been used, but it remains a perfectible technology. It means incomplete combustion of biomass solid fuel into synthesis gas through partial oxidation. The operating parameters (temperature and equivalence ratio (ER)) were thereafter varied to investigate their effect on the synthesis gas composition and to provide guidance for future research and development efforts in process design. The equivalence ratio is defined as the ratio of the amount of air actually supplied to the gasifier and the stoichiometric amount of air. Increasing ER decreases the production of CO and H2 and increases the production of CO2 and H2O while an increase in temperature increases the fraction of CO and H2. The results show that the o...

Synthesis of Li-doped ZnO via sol–gel process: structural, optical and photocatalytic properties

In this work, the sol–gel technique was carried out to prepare lithium doped ZnO materials with a controlled percentage (3–10xa0%). The changes in structural, optical and photocatalytic properties were investigated using X-ray powder diffraction, FT-IR spectroscopy, diffuse reflectance UV–visible and scanning/transmission electron microscope. X-ray diffraction showed that ZnO nanoparticles exhibit hexagonal wurtzite structure. The calculated average crystalline size increases from 30xa0nm of ZnO and 40xa0nm of ZnO–Li (10xa0%). The UV peaks positions of the modified samples shifted towards the longer wavelength compared to pure ZnO. The optical band gap of the samples was found to be 3.24xa0eV for ZnO–Li (3xa0%) and 3.28xa0eV for ZnO–Li (10xa0%), which proves the change in the acceptor level induced by the Li atoms. For the application, the evaluation of the photocatalytic activity is carried out using p-nitrophenol (p-NP) as a model of chemical pollutants. As result, Li doped ZnO materials displayed photocatalytic activity is less than pure ZnO, due to the Li atom that increases the recombination rate of electron–hole pairs, which decreases the photocatalytic activity.