Ottó Berkesi

ASPHALTENE ADSORPTION ON CLAYS AND CRUDE OIL RESERVOIR ROCKS

Abstract The adsorption of asphaltene on different clay minerals (kaolinite, illite, montmorillonite) and mineral oil reservoir rocks was studied. In toluene solution, specific adsorption was observed on kaolinite and a decrease in adsorption was found in the order illite-montmorillonite. In toluene/n-heptane mixtures a two-stage isotherm was recorded on the surface of the adsorbents. Surface modification by the adsorption of asphaltenes was characterized by a variety of structure-probing methods such as N2-adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS) measurements, and FTIR spectroscopy. The hydrophobizing effect of asphaltene on clays was also checked by immersion microcalorimetry. According to XRD studies, no intercalation of asphaltene occurs in toluene and toluene/n-heptane mixture on montmorillonites. SAXS scattering curves measured on kaolinite samples deviate from each other in the angle range close to primary scattering, because of the preferential adsorption of asphaltene. The aggregation of clays by asphaltene also manifests itself in a decrease of specific surface areas determined by N2-adsorption.

Formation of spherical iron(III) oxyhydroxide nanoparticles sterically stabilized by chitosan in aqueous solutions

The interactions between the cationic polymer chitosan (Chit) and iron(III) were investigated. The solution properties were studied by pH-metry, viscometry and dynamic light scattering. Solid state iron(III)-Chit samples were also prepared and characterized by IR spectroscopy and electron microscopy. In aqueous solutions, the precipitation pH of the iron(III) oxyhydroxide (FeOOH) is significantly shifted towards the higher pH values in the presence of Chit indicating that some interaction takes place between the iron(III) and the polymer. However, the additivity of the pH-metric titration curves, the lack of variation both in the viscometric and IR spectra of Chit in the presence and absence of iron(III), indicate the lack of direct complexation between the Chit and ferric ions. Isolated FeOOH nanospheres of 5-10 nm diameter were observed on the transmission electron microscopic pictures of samples obtained from solutions containing iron(III) and Chit, while from DLS measurements hydrodynamic units with a few hundred nm in diameter were identified. Our data support that Chit acts as steric stabilizer and inhibits the macroscopic aggregation of the subcolloidal FeOOH particles. Thus the iron(III)-Chit interactions offer a simple and economic way to fabricate nanometric size FeOOH spheres, morphologically similar to the core of iron(III)-storage protein, ferritin.

DSC, X-ray and FTIR studies of a gemfibrozil/dimethyl-β-cyclodextrin inclusion complex produced by co-grinding.

The steps of formation of an inclusion complex produced by the co-grinding of gemfibrozil and dimethyl-β-cyclodextrin were investigated by differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD) and Fourier transform infrared (FTIR) spectroscopy with curve-fitting analysis. The endothermic peak at 59.25°C reflecting the melting of gemfibrozil progressively disappeared from the DSC curves of the products on increase of the duration of co-grinding. The crystallinity of the samples too gradually decreased, and after 35min of co-grinding the product was totally amorphous. Up to this co-grinding time, XRPD and FTIR investigations indicated a linear correlation between the cyclodextrin complexation and the co-grinding time. After co-grinding for 30min, the ratio of complex formation did not increase. These studies demonstrated that co-grinding is a suitable method for the complexation of gemfibrozil with dimethyl-β-cyclodextrin. XRPD analysis revealed the amorphous state of the gemfibrozil-dimethyl-β-cyclodextrin product. FTIR spectroscopy with curve-fitting analysis may be useful as a semiquantitative analytical method for discriminating the molecular and amorphous states of gemfibrozil.

Polymer-bound osmium oxide catalysts

Abstract Polymer-supported oxidic osmium catalysts based on cross-linked poly(4-vinyl pyridine) were synthesized by various routes and characterized by a number of physical techniques (Raman, IR, XPS, 13 C and 15 N solid-state NMR spectroscopy). Model compounds of type Os 2 O 6 L 4 (L = pyridine, 4- iso -propyl pyridine, and 4- tert -butyl pyridine) were obtained under the conditions of the catalyst synthesis. The catalytic systems were successful in the dihydroxylation of alkenes.

Water-soluble loratadine inclusion complex: analytical control of the preparation by microwave irradiation.

The majority of active pharmaceutical ingredients are poorly soluble in water. The rate-determining step of absorption is the dissolution of these drugs. Inclusion complexation with cyclodextrin derivatives can lead to improved aqueous solubility and bioavailability of pharmacons due to the formation of co-crystals through hydrogen-bonding between the components. Inclusion complexes of loratadine were prepared by a convenient new method involving microwave irradiation and the products were compared with those of a conventional preparation method. Dissolution studies demonstrated that the solubility and rate of dissolution of loratadine increased in both of the methods used. The interactions between the components were investigated by thermal analysis and Fourier Transform Infrared studies. The microwave treatment did not cause any chemical changes in the loratadine molecule.

Hydrogen bonding interactions of benzylidene type Schiff bases studied by vibrational spectroscopic and computational methods

The structural features of four benzylidene type Schiff bases [(E)-benzaldehyde-N-phenyl imine, (A) (E)-2-hydroxybenzaldehyde-N-phenyl imine (B) (E)-benzaldehyde-N-2-hydroxyphenyl imine (C) (E)-2-hydroxybenzaldehyde-N-2-hydroxyphenyl imine (D)] were studied by FT-IR spectroscopy in solution, photoacoustic and Raman spectroscopies in the solid state and quantum chemical calculations. It was found that molecule D dimerised in the solid state with concomitant loss of aromaticity in the benzylidene ring. Beside the intermolecular C=O...HO hydrogen bonds, intramolecular N-H...C=O hydrogen bonds could be found experimentally as well as computationally. Spectra taken in solution and ab initio quantum chemical calculation helped to identify hydrogen bonding interactions occurring for compounds B and C. Intramolecular OH...N hydrogen bond predominated in molecule B, while this interaction, although it existed, was weaker.

Pénétration enhancer effect of sucrose laurate and Transcutol on ibuprofen

The aim of this study was to develop transdermal gel formulations for ibuprofen, which ensure good skin permeation into the deeper layers, hereby achieving effective pain and inflammation relief locally. Transcutol and a new generation surfactant, a sucrose ester, were used as penetration enhancer. Ibuprofen diffusion was investigated across synthetic membrane (in vitro), and permeation was examined through excised human epidermis (ex vivo) and hairless mice (in vivo) too. Our investigations revealed that Transcutol is an effective diffusion increaser for ibuprofen, but it could not enhance its skin permeation. However, the sucrose ester promoted skin permeation of ibuprofen 2.15 fold. From our study, it seems that it is not enough to make in vitro membrane diffusion measurements by testing newly developed transdermal preparations, but it is also indispensable to complete the examinations with ex vivo skin permeation method. Our investigations show that sucrose laurate seems to be an appropriate and effective penetration and permeation enhancer for ibuprofen.

Ibuprofen penetration enhance by sucrose ester examined by ATR-FTIR in vivo.

The aim of this work was to investigate the skin penetration enhancer effect of a sucrose ester (SE) in an Ibuprofen (IBU) containing hydrogel and to examine its influence on the special lipid bilayer of the stratum corneum (SC). ATR-FTIR spectroscopic measurements were performed combined with tape stripping method on hairless mice in vivo. A SE containing gel was compared to another gel without SE. It was found that the preparations caused only minimal modifications in the lipid and the protein structure, promoting the skin hydration and therefore also the penetration of IBU. Although the degree of moisturization and penetration were more intense in the case of the SE containing gel treatment, it did not cause greater alterations in the SC structure than the gel without SE. It has been proven that SE acts as an effective and non-irritating hydration and penetration enhancer for IBU through skin.

The significance of colloidal hydrocarbons in crude oil production Part 1. New aspects of the stability and rheological properties of water-crude oil emulsions

Abstract The compositions of paraffinic deposits obtained from oil wells and pipelines were studied. It was established that, besides the well-known asphaltene, malthene, resin and paraffin, a hydrophobic paraffin derivative (solid hydrophobic fraction) of higher molar mass and melting point, containing polar end-groups (CO and COO−), can also be isolated. X-ray analyses showed this material to be an organocolloid of lamellar structure. Small angle X-ray scattering measurements demonstrated that the substance readily swells in toluene. When its solutions and its suspensions prepared by cooling are studied in aromatic aliphatic solvent mixtures, they exhibit a great variety of structural characteristics. Optical measurements indicate that its tendency to aggregate is very sensitively affected by the polarity of the hydrocarbon mixture, and by temperature. Its presence at a concentration of 1–2% stabilizes water-in-oil emulsions, which is explained by changes in the colloidal state of the paraffin derivative.

On the unexpected cation exchange behavior, caused by covalent bond formation between PEDOT and Cl- ions: Extending the conception for the polymer-dopant interactions

The ionic motion in connection with the redox transformation of poly(3,4-ethylenedioxythiophene) (PEDOT) conjugated polymer have been studied by both experimental-electrochemical (electrochemical quartz crystal nanobalance, EQCN) and spectroscopic (infrared spectroscopy, IR-ATR)-and theoretical methods. The observations have been completed by direct, semiquantitative analytical data, provided by energy dispersive X-ray (EDX) microanalysis. The EQCN results suggested an anomalous behavior, since only cationic movements have been observed for films deposited from chloride solutions. Chloride ions were proved to be immobile also when bulky tetrabutylammonium (Bu(4)N(+)) cations were substituted with even larger (hexadecyltrimethylammonium) cations. Since PEDOT films synthesized in the presence of other spherical, not too large anions-such as perchlorate and tetrafluoroborate-endowed mixed ion exchange behavior together with the Bu(4)N(+) cation, the possibility of a special interaction between chloride and the polymeric chain has been assumed. Semiempirical and DFT calculations indicated that chloride ions interact with the α carbon atoms of the thiophene rings of the oxidized EDOT oligomers, creating sp(3) type perturbations in the polymer chain. FTIR-ATR spectra evidenced the appearance of C-Cl bonds. Elementary analysis, performed by EDX spectroscopy with eight polymer samples at different doping levels clearly showed the permanent presence of constant amount of chlorine, independently of the oxidation state of the PEDOT layer. Finally, the presented observations call attention to the fact that unique dopant-polymer interactions during the electrochemical polymerization are of prime importance, being able to rule over conventions for the charge compensation of conjugated polymers, often solely based on steric parameters.