Hardware components wastes pyrolysis: energy recovery and liquid fraction valorisation

Pyrolysis of hardware components wastes consisting mainly in computers and television components was performed under nitrogen. The degradation products were separated in three fractions, solid, liquid and gaseous. Analyses of the three phases were carried out using gas chromatography (GC), mass spectrometry (MS), thermal analysis and infrared spectroscopy. The energetic content of the gas phase and the economic value of the liquid phase were also determined. The gas fraction produced was rich in light hydrocarbons and hydrogen. Consequently, its calorific value was high and widely sufficient to make the pyrolysis process self-sustained. The main products of the liquid phase were phenol and isopropylphenol (ca. 50–80 wt.%). The presence of Br-based compounds, deriving from the flame retardant employed in hardware components, were also detected. A controlled combustion of the solid phase permitted to obtain the glass fibres unaltered, which can be recycled.     

CH bond activation in the presence or absence of oxygen or nitrous oxide

The reaction of C₂H₆with lattice oxygen, O^2- (in the absence of gaseous oxygen), or “adsorbedℍ oxygen (in the presence of gaseous oxygen) over NiMoO₄ catalysts has been performed and compared to C₃H₈ activation. The results obtained indicate that adsorbed oxygen exhibits a higher reactivity to C₂H₆, while lattice oxygen is more reactive relative to C₃H₈. Kinetic studies of these two reactions in presence of molecular oxygen have indeed shown that the ethane oxidative dehydrogenation (ODH) is dependent on the oxygen partial pressure, whilst on the contrary propane ODH is not. In order to confirm the presence of “adsorbed” oxygen for ethane activation, ODH tests have been performed with N₂O. On increasing temperature, the O^- adsorbed species enhances the mild oxidation of ethane. The activation energy of ethane consumption E_C2H6, relative to propane (E_C3H8 = 133 kJ/mol) is 145 kJ/mol. A possible mechanism is proposed for the oxidative dehydrogenation of ethane. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis of Nickel Supported Catalysts for Hydrogen Production by Sol-Gel Method

SiO₂ and Al₂O₃ supported Ni catalysts were synthesized in the form of xerogels: the SiO₂ based materials were prepared starting from Ni propionate or glycolate salts and reacting them with tetraethoxysilane (TEOS) in propionic acid, Si(ethylene glycolate) or sodium silicate. The Al₂O₃ supported catalysts were prepared similarly from Ni propionate salts with Al iso-propoxide salts. Narrow metal particles and strong metal support interactions are observed in the sol-gel catalysts. The metal dispersion was higher for Al₂O₃ based materials than the SiO₂ ones and it deeply depends on the Ni precursor for the silica supported Ni. Wet impregnated oxides with similar Ni loading have higher metal surface area than those from sol-gel processing. The influence of surface differences on the catalytic activity of the materials was studied following the CH₄ and CO₂ reaction in dry reforming conditions by pulse reaction tests.     

Conventional hydrothermal process versus microwave-assisted hydrothermal synthesis of La1−xAgxMnO3+δ (x = 0, 0.2) perovskites used in methane combustion

A study on the synthesis of La_1−xAg_xMnO_3+δ (x = 0, 0.2) using a microwave process (MWhyd) has been carried out by comparing the heating time and reaction temperature with the same factor under conventional thermal process (CHhyd). Experiments have been conducted using the hydrothermal method at medium pressure (T = 200 °C, P = 20 atm) followed by a thermal treatment of the precursor at 700 °C (10 h).Structural and physico-chemical properties of the catalysts were investigated using X-ray diffraction (XRD), BET sorption, temperature-programmed reduction or desorption, mass spectrometry (TPR-MS and TPD-MS), and X-ray photoelectron spectroscopy (XPS). While CHhyd and MWhyd powder catalysts exhibited the same XRD patterns indexed as pure perovskite structure, their surface physico-chemical properties were found to be strongly influenced by the preparation method. The effect of the nature of oxygen species, their amount and mobility, evidenced by temperature programmed experiments, on the catalytic properties in methane combustion in the presence and in the absence of hydrogen sulphide has been studied. MWhyd-La_0.8Ag_0.2MnO_3+δ catalysts were found to exhibit a much better performance in methane combustion together with higher resistance to sulphur poisoning than CHhyd catalysts.     

About b-weakly compact operators on Banach lattices

We characterize Banach lattices on which each positive operators is b-weakly compact and we derive some characterizations of KB-spaces.     

Approaches for Mitigating Microbial Biofilm-Related Drug Resistance: A Focus on Micro- and Nanotechnologies

Biofilms play an essential role in chronic and healthcare-associated infections and are more resistant to antimicrobials compared to their planktonic counterparts due to their (1) physiological state, (2) cell density, (3) quorum sensing abilities, (4) presence of extracellular matrix, (5) upregulation of drug efflux pumps, (6) point mutation and overexpression of resistance genes, and (7) presence of persister cells. The genes involved and their implications in antimicrobial resistance are well defined for bacterial biofilms but are understudied in fungal biofilms. Potential therapeutics for biofilm mitigation that have been reported include (1) antimicrobial photodynamic therapy, (2) antimicrobial lock therapy, (3) antimicrobial peptides, (4) electrical methods, and (5) antimicrobial coatings. These approaches exhibit promising characteristics for addressing the impending crisis of antimicrobial resistance (AMR). Recently, advances in the micro- and nanotechnology field have propelled the development of novel biomaterials and approaches to combat biofilms either independently, in combination or as antimicrobial delivery systems. In this review, we will summarize the general principles of clinically important microbial biofilm formation with a focus on fungal biofilms. We will delve into the details of some novel micro- and nanotechnology approaches that have been developed to combat biofilms and the possibility of utilizing them in a clinical setting.     

Optical emissions of products sputtered from Fe, Fe2O3 and Fe3O4 powders

Powder iron has been bombarded by a 5 keV Kr⁺ ions in a vacuum better than 10^-7 torr and under few 10^-6 torr ultra pure oxygen partial pressure. The optical spectra of the sputtered particles were recorded between 340.0 nm and 410.0 nm. These spectra exhibit discrete lines, which are attributed to neutral excited atoms of iron. Two iron oxides, namely hematite (Fe₂O₃)_{3}) and magnetite (Fe₃O₄)_{4}), in powder form, were studied under the same experimental conditions and identical lines were observed in the obtained spectra. The absolute intensities of the spectral lines in all spectra were measured and the differences in the recorded yield photons were discussed in term of electron-transfer processes between the excited sputtered atom and the bombarded surface. In accordance with the proposed interpretation, we suggest values for the energy gaps and electronic affinities for the studied oxides and for the oxide layer that might be formed by the adsorption of oxygen atoms.     

Physicochemical and catalytic properties of sol gel-prepared copper-chromium oxides

Nanostructured copper-chromium oxides were prepared by the sol–gel process (SG) and were characterised by elemental analysis, thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and by their activity in methane combustion. A comparative study was made with copper chromites commercial catalysts. The as-synthesised copper chromites sample exhibited higher specific surface area (248 m² g⁻¹) with respect to commercial solids (42 m² g⁻¹). The surface quantitative analysis evidenced a Cr⁶⁺ enrichment for the SG catalyst (Cr⁶⁺/Cr³⁺=0.56) with respect to commercial sample (0.39), while the ratio of copper species Cu²⁺/(Cu° + Cu⁺) was the same in both solids. Catalytic activity of SG solids in methane combustion was found to be comparable to that of Pt/Al₂O₃ and superior to that of commercial copper chromites tested under the same conditions.     

Two new acridone alkaloids from Glycosmis macrantha

Extraction and chromatographic separation of the extracts of dried stem barks of Glycosmis macrantha lead to isolation of two new acridone alkaloids, macranthanine and 7-hydroxynoracronycine, and a known acridone, atalaphyllidine. The structures of these alkaloids were determined by detailed spectral analysis and also by comparison with reported data.