Gliclazide (GLC) inclusion complexes with β-cyclodextrin (βCD) were studied by UV-VIS and FT-IR spectroscopy. The recorded spectra confirmed the formation of GLC-βCD binary complexes and GLC-(βCD)2 ternary complexes in aqueous solutions. UV-VIS measurements carried out for a number of temperatures allowed to determine the binding constants of the complexation reactions. The bioavailability of GLC-βCD and GLC-(βCD)2 was determined using the n-octanol/water partition coefficient. Experimental studies were supplemented with theoretical calculations. Quantum-chemical calculations and classical molecular dynamics simulations were used to describe the interactions in the host-guest inclusion complexes.

In this work, Algerian natural bentonite was used in the preparation of a new adsorbent by impregnation with polyethylene glycol (PEG) for the removal of toluene from an aqueous solution. These interactions have been monitored by thermal method (thermogravimetric analysis) as well as by Fourier-transform infrared spectroscopy. The adsorption efficiency of natural and PEG-bentonite was examined for toluene removal by batch adsorption experiments under different operating conditions. Therefore, a multilayer perceptron (MLP) neural network was then used to predict the adsorption capacity of toluene. Different training algorithms were compared to determine the most suitable training algorithm. A single hidden with six neurons using a tangent sigmoid function transfer with the Levenberg-Marquardt backpropagation algorithm has been found the best predictive performance. The high value of coefficient determination (0.999) and low value of root mean square error (0.00074) proved that the MLP model can predict the adsorption capacity of toluene with reasonable accuracy. Furthermore, the sensitivity analysis based on the MLP model indicated that the contact time and the initial concentration of adsorbate with the same relative importance a round of 39% appeared to be the most influential parameter in the adsorption capacity of toluene, followed by adsorbent dose (20.99%).

In this work an Algerian natural bentonite was used in the preparation of new adsorbents by impregnation with different mass ratios of hexadecyltrimethylammonium bromide (HDTMA) surfactant. The HDTMA-bentonites adsorbents were prepared according to the HDTMA/bentonite cation exchange capacity (CEC) ratios (HDTMA/CEC). Five HDTMA/CEC ratios (25%, 50%, 100%, 150% and 200%) were used to investigate the effects on the physicochemical characteristics and the adsorptive power of these clays. The characteristics of these adsorbents were studied by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The adsorptive power of these clays was studied by batch adsorption of chlorobenzene from aqueous solutions. FTIR and TGA spectra confirm the modification of bentonites by intercalation with HDTMA. XRD spectra of these adsorbents exhibited interlayer spacings from 13 to 20 Å, with maximum interlayer spacing of 20 Å corresponding to the adsorbent with 100% HDTMA/CEC ratio. Adsorption experiments of chlorobenzene indicate that pseudo first order model was suitable for describing the kinetic results. Regarding the equilibrium results, both Langmuir and Freundlich isotherms were fitted well. The adsorbent impregnated with 100% HDTMA/CEC ratio, shows a high percentage of chlorobenzene removal compared to the other adsorbents.

Herein, preparation, characterization, and catalytic testing of a catalyst based on Algerian clay are presented. The Algerian bentonite is activated in a separated manner following three different acids (H2SO4, HNO3 and HClO4). The effects of the nature and the concentration of the activation acid, and the activation temperature were evaluated. The obtained catalyst samples were characterized by X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. All the prepared catalysts have revealed a high catalytic activity for the esterification reaction of acetic acid along with five different alcohols (methanol, ethanol, propanol-1, butanol-1, and tert-butanol). The catalyst prepared by activation with 3 M H2SO4 at 70 degrees C showed the highest catalytic activity with about 84, 25%.

Charge-transfer interactions (CT) between the electron donor gliclazide (GLC) and the pi-acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetracyanoethylene (TCNE) were studied in a chloroform solution and in the solid state. The CT complexes were discussed in terms of formation constants (K-CT), molar extinction coefficients (epsilon(CT)), standard reaction quantities (Delta G degrees, Delta H degrees, and Delta S degrees), oscillator strength (f), transition dipole moment (mu(EN)), and ionization potential (I-p). The limits of detection (LOD) and limits of quantification (LOQ) have also been reported, The stoichiometry of these complexes was found to be in a 1:1 M ratio. The formed solid CT complexes were also synthesized and characterized using electronic methods, FT-IR, H-1 and C-13 NMR spectroscopy. Thermogravimetric analysis techniques (TGA/DTA) and differential scanning calorimetry (DSC) were used to determine the thermal stability of the synthesized CT complex. The kinetic parameters (Delta G*, Delta H*, and Delta S*) were calculated from thermal decomposition data using the Coats-Redfern method. Moreover, density functional theory (DFT) studies are discussed for the charge transfer complex GLC-TCNE, using the B3LYP with 6-311++G (d, p) basis set. The harmonic vibrational frequencies were calculated, and the scaled values have been compared with experimental FT-IR spectra. The calculated H-1 and C-13 NMR chemical shifts using the GIAO method showed good correlations with the experimental data. The theoretical UV visible spectrum of the compound and the electronic properties, such as HOMO and LUMO energies, were performed using the time-dependent (TD-DFT) approach with CAM-B3LYP, employing the 6-311++G (d, p) basis set, and good agreement with the theoretical and experimental UV visible data was found. (C) 2018 Elsevier B.V. All rights reserved.

Charge transfer interactions (CT) between a gliclazide (GLC) donor and a picric acid (PA) π acceptor or iodine σ acceptor, were studied in a chloroform solution and in the solid state. UV-vis spectroscopy elucidated the formation of the complexes, and allowed determination of the stoichiometry, stability constants (K), and thermodynamic quantities (ΔG°, ΔH°, and ΔS°), and spectroscopic properties such as the molar extinction coefficient (εCT), oscillator strength (f), transition dipole moment (μEN), and ionization potential (Ip). Beer's law was obeyed over the 2-8 and 4-12 μg mL-1 concentration ranges for GLC with PA (method A) and I2 (method B), respectively, with correlation coefficients of 0.9986 and 0.9989. The limits of detection (LOD) and limits of quantification (LOQ) have also been reported. The 1:1 stoichiometric CT complexes were synthesized and characterized by FTIR, 1H, and 13C NMR spectroscopy. The results indicated a favorable proton migration from PA to the donor molecule, and an interaction between the NH of GLC and iodine. Thermogravimetric analysis techniques (TGA/DTA) and differential scanning calorimetry (DSC) were used to determine the thermal stability of the synthesized CT complex. The kinetic parameters (ΔG*, ΔH*, and ΔS*) were calculated from thermal decomposition data using the Coats-Redfern method.

This work is a continuation of our researches on the study of thermodynamic properties of organic compound mixtures and made up of two sections: an experimental section and a theoretical section. The experimental solid–liquid equilibrium diagrams of binary systems: piperidine + benzene and piperidine + n-octane, measured at atmospheric pressure, have been obtained by means of an apparatus derived from that of Smit. The advantage of this apparatus compared to that of Rossini and that of Jacob is the higher measurement accuracy and the low amount of product used. In the theoretical section, in addition to the calculation of the liquidus curves in the ideal case, the DISQUAC model and the Dortmund-UNIFAC method were applied to the two mixtures to predict the liquidus curves and make a comparison.

For the first time, nanoparticles enhanced ionic liquids (NEILs) were used to improve the capacity of ILs to extract sulfur compounds from aliphatic media. A study on six ternary systems containing {thiophene (1) + heptane (2) + NEILs} shows that NEILs composed of TiO2 or Fe2O3 nano particles and 1,3-dimethylimidazolium methylphosphonate, 1-ethyl-3-methylimidazolium thiocyanate, or 1-butyl-3-methylimidazolium thiocyanate increase up to 2.5 the solute distribution ratio values compared to results obtained with pure ionic liquids. Yet, the selectivity values of NEILS are lower than those obtained with pure ILs, but their value remains important. The dynamic light scattering measurements show that nanoparticles of Fe2O3 and TiO2 aggregate in ILs, and the size of nanoaggregates depends on the nature of nanoparticles and of ionic liquid.

The chemical composition of crude oil, and hence its physicochemical properties, may change during extraction, transportation and treatment. This study characterizes the asphaltene fraction of algerian petroleum collected at three stages of production, namely at the petroleum well, from deposits resulted after petroleum storage, and from the vacuum residuum obtained during the refining process. Mass spectrometry (LDI-TOF), 1H NMR spectroscopy and infrared absorption (FTIR) were used, along with elemental analysis to monitor the composition and average molecular structure of the asphaltene samples. Noticeable differences in chemical structure are found among the three types of samples. The asphaltenes from the storage deposit are particularly differentiated with respect to the other two ones, featuring a higher polarity, a greater heteroatom content, and a lower aromaticity involving a smaller number of substituted aromatic structures. These features must be taken into account when designing strategies to prevent precipitation throughout the production process.

The formation of inclusion complexes of β-cyclodextrin was studied at the melting temperature of guest compounds by differential scanning calorimetry. The complexes of long-chain n-alkanes, polyaromatics, and organic acids were investigated by calorimetry and IR spectroscopy. The complexation ratio of β-cyclodextrin was compared with results obtained in an aqueous environment. The stability and structure of inclusion complexes with various stoichiometries were estimated by quantum chemistry and molecular dynamics calculations. Comparison of experimental and theoretical results confirmed the possible formation of multiple inclusion complexes with guest molecules capable of forming hydrogen bonds. This finding gives new insight into the mechanism of formation of host–guest complexes and shows that hydrophobic interactions play a secondary role in this case.

The aim of this work is to study the properties of an activated carbon prepared from apricot stones by carbonisation for 1 h at 700 degrees C and chemical activation with a mixture of H3PO4 + HNO3 and compared to a commercial activated carbon. The adsorbent materials were characterised with FTIR spectroscopy, XRD, SEM/EDX and surface chemistry. The maximum uptake of MB and MO onto the ASAC and CAC under optimised conditions was determined to be 99.5%. The absorption processes of MB and MO by ASAC and CAC were endothermic and exothermic, respectively. Acidic conditions promote the transfer of anionic dye (MO) molecules onto the ASAC and CAC surface by electrostatic attraction. The adsorbents were better able to remove the cationic dye than the anionic dye. The competitive adsorption of dyes favoured the MB on ASAC and CAC in the mixture solution. The Langmuir isotherm model and the pseudo-second order kinetic model were observed to fit the adsorption data well. The mechanism of the adsorption process was determined based on an intraparticle diffusion model. The results of this study will be useful for future scale-up using this apricot stone material as a low-cost adsorbent for the removal of cationic and anionic dyes. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

A model, which allows analyzing compression isotherms of mono- and multi layered films formed with particles at the air-water or oil-water interface is here proposed. The number of contacts established between particles in the layer was linked to surface pressure. The parameters used in the model permit calculating the energy of layer formation, and area per particle in the mono- or multi-layered films. These data reflect particle-particle and particle-subphase interaction and, consequently, particle organization in the film.The model was tested with micrometric glass beads and used for calculating the diameters of particles formed at the interface. The excellent representation of the experimental compression isotherms shows that the model can be used for constructing films with defined properties. (C) 2015 Elsevier B.V. All rights reserved.

In this work we were concerned with interactions between ionic liquids (IL) and nanoparticles (NPs) dispersed in aqueous solutions leading to the formation of NP clusters of finite size. The NPs used were Al2O3 (d=80nm), TiO2 (d<100nm), and Fe3O4 (d<100nm). ILs were 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) and 1-methacryloyloxypropyl-3-methylimidazolium bromide, [mcpmim][Br]. The latter compound was a new IL synthesized in our laboratory. It was demonstrated that ILs actively participate in the formation of NP aggregates suspended in aqueous solution filling the inter-particle space. The aggregates saturated with IL were used as extractors making it possible for the elimination of compounds dissolved in water. Results of the extraction of anthracene and salicylic acid from aqueous solutions were presented.

Charge sensitivity analysis (CSA) in force-field atoms resolution was applied to describe the mutual polarization of reactants as well as charge-transfer (CT) effects. An inclusion complex of β-cyclodextrin with salicylic acid was used as a model system. Three CSA models were taken into account and verified on a Born–Oppenheimer molecular dynamics (BOMD) trajectory. The models differed in terms of the equilibrium conditions imposed on the system. It was demonstrated that mutual polarization is an important source of stabilization, in contrast to the results obtained from static charge calculations. The energy lowering induced by CT was small and comparable to the CT stabilization that occurs in hydrogen-bonded systems. All models correctly described the main topological features of the BOMD energy surface. CSA in force-field atoms resolution qualitatively reproduced the charge reorganization accompanying hydrogen-bond formation. It was shown that CSA parameters are very sensitive to the bond formation process, which suggests that they could be applied in reactive force fields as detectors of newly formed chemical bonds.

Despite some recent progress trustworthy methods to predict the flocculation onset in crude oils are still needed. In this article, different experimental methods, like the density measurement method, the optical and the spot techniques based on the mixture of crude oil + toluene or cyclohexane + n-heptane, respectively, are applied to assess changes of aggregation occurring in crude oil under influence of physical and chemical factors as well as under variable temperature conditions. The solubility parameters of Hildebrand have also been used to predict the flocculation threshold. It turned out that the findings achieved by the spot method and the optical technique are in excellent agreement with break points of the reduced density curves obtained by the density measurement method for crude oils of different geographical origins. Using the solubility parameters of Hildebrand leads to comparable results. All these achievements confirm the density measurement method as a new possibility for reliably determining the flocculation onset in crude oils systems. With respect to temperature effects, changes of the oil microstructure could be detected as function of the temperature by means of the differential scanning calorimetry. In particular the thermal curves behavior of certain crude oils confirmed the existence of aggregation processes.

The solubility of β-cyclodextrin (β-CD) in ionic liquids (ILs) and the activity coefficients at infinite dilution () of more than 20 solutes (alkanes, aromatic hydrocarbons, alcohols) were measured in four chosen ionic liquids, their mixtures with β-CD, and in the β-CD at high temperatures from 338 to 398 K using the inverse gas chromatography. The intermolecular interactions, inclusion complexes and the possible increasing of the solubility of β-CD in water using the IL are presented. The solubility of β-CD in ten chosen hydrophobic ILs at the temperature T = 423 K was detected. The solid-liquid phase diagrams (SLE) of {IL (1) + β-CD (2)} binary systems at the high mole fraction of the IL were measured for three systems (1-ethyl-3-methylimidazolium chloride, [EMIM][Cl], 1-ethyl-3-methylimidazolium bromide, [EMIM][Br]; and for 1-butyl-3-methylimidazolium chloride, [BMIM][Cl]). The eutectic points were determined at the high IL concentration for all binary systems. The intermolecular interaction and the possibility of inclusion complexes of the IL and/or solvents with β-CD were discussed. The infrared spectroscopy, IR was used for the description of the intermolecular interactions in the (β-CD + IL) systems. It was shown via the activity coefficients at infinite dilution results that the inclusion complexes are dependent on the temperature. The addition of β-CD to the IL does not improve the selectivity of the separation of the aliphatics from aromatics.

The solid–liquid equilibrium (SLE) phase diagrams of anthracene + 2-phenylimidazole, anthracene + 4,5-diphenylimidazole and anthracene + 2,4,5-triphenylimidazole, were measured using differential scanning calorimetry (DSC). These systems formed a simple eutectic diagrams. The eutectic composition in different mixtures has been determined by the Tammann's method. The curves of the liquidus in the ideal case were calculated and represented. The {anthracene + 2-phenylimidazole} system exhibits more non-ideal behavior than the two others. Thus, to illustrate the effect of steric hindrance, the eutectic composition and the eutectic temperature as a function of the phenyls number have been represented.

In this study is described the development of new adsorbents from lignocellulosic wastes of vegetable origin. Agricultural wastes such as coffee grounds (CG), melon seeds (MS) and orange peels (OP) were used for this purpose. The activated carbons obtained were characterised using infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The adsorption efficiency of these new materials was tested with two model organic pollutants: o-nitrophenol and p-nitrotoluene. The elimination ratio obtained with new adsorbents was in the range from 70% to 90%. The kinetics of adsorption of these compounds were measured and described using a pseudo-second-order model. The time necessary to attain the adsorption equilibrium was between 75 and 135 min. It was demonstrated that the adsorption kinetics as well as the maximum uptake of the pollutants were dependent mainly on the chemical properties of the adsorbates.

Polar fractions of Hassi-Messaoud asphaltenes were obtained by two different extraction/precipitation procedures. Properties of these fractions were studied using elemental analysis, LDI-TOF mass spectroscopy, and solid state 13C NMR. The aggregation and the flocculation onset of polar fractions were determined. It was demonstrated that the most polar fraction of asphaltenes that is soluble in highly polar solvents, such as N-methyl pyrrolidone and nonsoluble in mildly polar or nonpolar solvents is composed of small molecules, containing a high oxygen ratio. This fraction plays an important role in asphaltene aggregate formation. The understanding of this role would be helpful for designing new antiflocculation agents.