Nicolae Apostolescu

The physicochemical properties of polyurethane membranes determined by swelling measurements

In this work, we have dispersed SAPO-5 zeolite particles in polyurethane matrix for preparation of porous mixed matrix membranes. The goal of work is the determination of the cohesive energy density for unfilled- and zeolite - filled polyurethane membranes. Experimental determination of cohesive energy density values for the prepared membranes is obtained by measuring the swelling coefficients in water and several alcohols (methanol, ethanol, propanol and butanol). The solubility parameters of the membranes are also calculated. For the unfilled membranes the corresponded values of cohesive energy density and solubility parameter increase in comparison to those of the filled membranes. All the tested membranes show a tendency to swell with ethanol.

A Study of Combustion of Hydrogen-Enriched Gasoline in a Spark Ignition Engine

An investigation has been done on the influence of small amounts of hydrogen added to hydrocarbons-air mixtures on combustion characteristics. The effect of hydrogen addition to a hydrocarbon-air mixture was firstly approached in an experimental bomb, to measure the laminar burning velocity and the shift of lean flammability limit. Experiments carried out with a single-cylinder four stroke SI engine confirmed the possibility of expanding the combustion stability limit, which correlates well with the general trend of enhancing the rate of combustion. An increase of brake thermal efficiency has been obtained with a reduction of HC emissions; the NO{sub x} emissions were higher, except for very lean mixtures.

Effects of Gasoline-Air Enrichment with HRG Gas on Efficiency and Emissions of a SI Engine

The addition of hydrogen to the gasoline-air mixture may contribute significantly towards accelerating the combustion process, with the beneficial effects on engine performance and emissions. The present contribution describes the results of an experimental research where gasoline-air mixture was enriched with a Hydrogen Rich Gas (HRG) produced by the electrical dissociation of water. The HRG analysis shows the presence of hydrogen and oxygen together with some additional species. Experiments were carried out at engine light and partial load. Detailed results of the measurements are shown, namely engine torque and efficiency, exhaust emissions, cyclic variability, heat release rates and combustion duration. The possibilities of improving engine performance and emissions in correlation with the amount of HRG, the equivalence ratio and the engine operating condition are thus outlined.

The Effect of Storage Time on the Composition of the Olive and Sunflower Oils

The effect of storage time on the composition of the olive and sunflower oils has been investigated. It were studied parameters like free fatty acids (FFA), anisidine value (AV), iodine value (IV), saponification number (SN) and identification of the molecular structure through FT-IR method. During storage (48 months) an increasing in the values of parameters FFA and AV took place that measures the oxidative degradation of oils. The oxidative stability of olive oil stored at room temperature was less than of sunflower oil. Also, significant differences were found among the olive oil and sunflower oil during storage period.

A GREEN ROUTE TO SYNTHESIZE CeO2 NANOPARTICLES

The paper presents the surfactant-assisted solvo-thermal route to synthesize nanoparticles of cerium oxide with different shape and morphology. The precursor was calcined at 400°C for 4 h in order to obtain CeO2 nanoparticles. The obtained samples were characterized by means of thermal analysis and FTIR spectroscopy. The UV-Vis analysis was used to study the optical properties. The morphologies and nano-structures were characterized by scanning electron microscopy (SEM) and XRD. It was found that nature and concentration of template agents played important roles in the formation of the novel morphology. A possible formation mechanism was proposed based on the controlling reaction parameters.

Hydrotalcite-like anionic clays substituted with iron / laccase, composites for biosensors applications

Laccase - based biosensors are important for the selective determination of the phenolic compounds in the environmental matrices. The features of the enzyme immobilisation process and the characteristics of the inorganic porous matrix adsorbed on the electrode surface are both important for establishing the biosensor performances. This work presents the synthesis and physical-chemical characteristics of new hybrid materials based on iron containing layered double hydroxides / laccase. XRD and TGA-DTA analyses give information about the structural characteristics and thermal behaviour of the tested hybrids. The SEM images show the presence of a well crystallized texture of organized ensembles of platelets-like particles stacking on top of one another. The presence of iron in the substituted clay matrix is able to give rise to the specific redox properties that can be further used to tailor not only the laccase immobilisation process but also the biological sensing response of the biohybrid-transducer device.