Solubility and thermodynamics of lamotrigine in ternary mixtures of ionic liquids ([OMIm][Br]+[HMIm][Br]+water) at different temperatures

Experimental mole fraction solubility of lamotrigine (LTG) in ternary aqueous mixtures of two ionic liquids (ILs), 1-hexyl and 1-octyl-3-methylimidazolium bromide,[HMIm][Br] and [OMIm][Br] were reported at several temperatures T=(293.15 to 313.15) K. The van't Hoff and (Jouyban-Acree-van't Hoff, E-Jouyban-Acree-van't Hoff, e-NRTL, UNIQUAC and Wilson) models were used to correlate the solubility data. The comparison of the models with temperature and solvent composition dependencies shows that the Wilson model has the minimum ARD which are relatively close to those obtained from Jouyban-Acree-van't Hoff and E-Jouyban-Acree-van't Hoff models and maximum ARD belonged to the UNIQUAC model. The order of ARDs for these models is:Wilson < Jouyban-Acree-van't Hoff, E-Jouyban-Acree-van't Hoff < e-NRTL < UNIQUAC. Moreover, the apparent thermodynamic functions, Gibbs free energy, enthalpy and entropy of dissolution and mixing were calculated based on the van't Hoff and Gibbs free energy equations. The strong LTG-ILs interactions and enthalpic contribution of the dissolution process resulted from the calculated thermodynamic functions.     

Density, viscosity, and surface tension of water+ethanol mixtures from 293 to 323K

Density, viscosity, and surface tension of liquids are important physicochemical properties which affect mass and heat transfer in solutions. The density, viscosity, and surface tension of binary mixture of water+ethanol at 293, 298, 303, 308, 313, 318, and 323 K are reported and compared with the available literature data. The findings of these comparisons show how the measured data are reproducible from different laboratories. The molar volume of water+ ethanol mixtures are also calculated using measured density values. The Jouyban-Acree model was used for mathematical correlation of the data. The relative deviation (RD) was used as an error criterion and the RD values for correlation of density, viscosity, surface tension and molar volume data at investigated temperatures are 0.1±0.1%, 10.4±9.5%, 4.2±3.6%, and 0.3±0.3%, respectively. The corresponding RDs for the predicted properties after training using the experimental data at 298 K are 0.2±0.2%, 14.1±15.8%, 5.4±4.6% and 0.4±0.3%, respectively, for density, viscosity, surface tension, and molar volume data. This study shows that the Jouyban-Acree model can correlate/predict physicochemical properties of the mixtures of solvents at different temperatures with acceptable error in calculation.     

Electronic structure and bandgap of gamma-Al2O3 compound using mBJ exchange potential

ABSTRACT: gamma-Al2O3 is a porous metal oxide and described as a defective spinel with some cationic vacancies. In this work, we calculate the electronic density of states and band structure for the bulk of this material. The calculations are performed within the density functional theory using the full potential augmented plan waves plus local orbital method, as embodied in the WIEN2k code. We show that the modified Becke-Johnson exchange potential, as a semi-local method, can predict the bandgap in better agreement with the experiment even compared to the accurate but much more expensive green function method. Moreover, our electronic structure analysis indicates that the character of the valence band maximum mainly originates from the p orbital of those oxygen atoms that are close to the vacancy. The charge density results show that the polarization of the oxygen electron cloud is directed toward aluminum cations, which cause Al and O atoms to be tightly connected by a strong dipole bond.     

Spectrofluorimetric determination of buparvaquone in biological fluids,food samples and a pharmaceutical formulation by using terbium–deferasirox probe

A simple spectrofluorimetric method is described for the determination of buparvaquone (BPQ), based on its quenching effect on the fluorescence intensity of Tb³⁺–deferasirox (DFX) complex as a fluorescent probe. The excitation and emission wavelengths were 328 and 545 nm, respectively. The optimum conditions for determination of BPQ were investigated considering the effects of various affecting parameters. The variations in fluorescence intensity of the system showed a good linear relationship with the concentration of BPQ in the range of 10–1500 μg L⁻¹, its correlation coefficient was 0.999 with the detection and quantification limits of 1.1 and 3.4 μg L⁻¹, respectively. Linearity, reproducibility, recovery, limits of detection and quantification made the method suitable for BPQ assay in biological fluids, meat, dairy products and BPQ parenteral solutions (vials). The method was applied to real samples of serum and milk of three cows receiving BPQ.     

One-pot synthesis of N-phenyl-N′-(arylcarbonothioyl)-N-arylhydrazide derivatives from hydrazonoyl chlorides with sodium sulfide and aryldiazonium salts

The one-pot synthesis of N-phenyl-N′-(arylcarbonothioyl)-N-arylhydrazides is described by the reaction between two equiv. of hydrazonoyl chloride and sodium sulfide in the presence of aryldiazonium fluoroborates in DMF at room temperature.     

Evaluation of the performance of heat pump-assisted distillation of an ethanol–water mixture

The process of separation of an ethanol–water mixture was simulated. A heat pump system was then implemented on the distillation column with the highest energy requirements in the process. Complete elimination of hot and cold utilities of the pretreatment column was obtained through an improved system by application of a heat pump at a compressor work of 406.6 kW. Installation of the heat pump system on the pretreatment column of the system results in a reduction of 10.7% of annual operating costs and 6.6% of the total annual costs (TAC). However, the capital costs of the process will enhance by 22.6%.