Firdosa Nabi

Nanotoxicity: Dimensional and Morphological Concerns

Nanotechnology deals with the construction of new materials, devices, and different technological systems with a wide range of potential applications at the atomic and molecular level. Nanomaterials have attracted great attention for numerous applications in chemical, biological, and industrial world because of their fascinating physicochemical properties. Nanomaterials and nanodevices are being produced intentionally, unintentionally, and manufactured or engineered by different methods and released into the environment without any safety test. Nantoxicity has become the subject of concern in nanoscience and nanotechnology because of the increasing toxic effects of nanomaterials on the living organisms. Nanomaterials can move freely as compared to the large-sized particles; therefore, they can be more toxic than bulky materials. This review article delineates the toxic effects of different types of nanomaterials on the living organisms through different sources, like water, air, contact with skin, and the methods of determinations of these toxic effects.

Extraction of metal ions by ELM Separation Technology

The removal of toxic heavy metal ions is of great concern in the environmental field. Emulsion liquid membrane (ELM) technology has been proposed for the separation processes to enhance the extraction process and reduce the solvent and carrier requirement in comparison with other conventional solvent extractions techniques. Emulsion liquid membrane is an unsupported liquid membrane in which the membrane phase of an emulsion is dispersed into the feed phase to be treated. ELM technique is an accessible and easy way for the removal of different chemicals, metal ions, organic compounds, biomolecules, pollutants from aqueous feed phase and the transport them into desired receiving phases. This review article delineates the role of different parameters on the extraction process in ELM separation processes. These parameters strongly influence the percentage removal of metal ions and emulsion leakage. The optimum membrane properties can enhance the recovery of the desired phase and improves the stability of the ELM by minimizing the swelling and leakage of the membrane. The future direction of ELM technology can be the use of room temperature ionic liquids (RTILs) as stabilizers, carriers and can replace the conventional volatile toxic organic solvents.

ESTIMATION OF EXCESS MOLAR VOLUMES, THEORETICAL VISCOSITIES, AND ULTRASONIC SPEEDS OF BINARY LIQUID MIXTURES AT DIFFERENT TEMPERATURES

Excess molar volumes, , have been derived by using viscosity data for the binary mixtures of styrene (STY) with dimethylsulfoxide (DMSO), acetone (ACT), chlorobenzene (CB), and ethanol (EA) at different temperatures. From the literature data of viscosities, entropies, (ΔS*, and enthalpies, (ΔH*, of activation of viscous flow have been determined. Moreover, theoretical values of viscosities and ultrasonic speeds of the binary mixtures were calculated using different empirical relations and theories. The results were discussed in terms of deviations in experimentally and theoretically calculated values. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. The predicted properties show good accuracy in comparison with the experimentally derived properties.

Volumetric and Viscometric Studies of Molecular Interactions of Binary Liquid Mixtures of Styrene with Acetone and Dimethylsulphoxide at Different Temperatures

The present work reports the results of densities, ρ, viscosities, η, ultrasonic speeds, u, and refractive indices, n, of pure styrene (STY), acetone (ACT) and dimethylsulphoxide (DMSO) and of their binary liquid mixtures over the entire composition range at 298.15, 303.15, 308.15, and 313.15 K. The excess molar volumes, V E , excess intermolecular free lengths, , deviations in isentropic compressibilities, Δk s , viscosities, Δη, and in refractive indices, Δn were calculated from the experimental data. Partial molar volumes, , and partial molar compressibilities, , of ACT and DMSO in styrene at infinite dilution and at different temperatures have been evaluated. Apart from using density data for the calculation of V E , excess molar volumes have also been estimated by using the Florys statistical theory and refractive index measurements.

A review of molecular interactions in organic binary mixtures

The intention of this review article is to review the knowledge about interactions in organic binary liquid mixtures. Molecular interactions in organic binary liquid mixtures are interesting due to their extensive use in many fields of solution chemistry. The thermodynamics of component molecules present in various systems interacting are particularly interesting because they display fantastic results. Studies of different organic liquid mixtures represent the different modes of interactions prevailing in the component molecules. The number of parameters required describing the properties of a given class of mixtures increases sharply with the number of segment types involved. In recent years, the theoretical and experimental investigations of interactions between unlike molecules have been conveniently carried out using excess thermodynamic functions. The properties of liquid mixtures depend on the forces between molecules and on the nature and volume of these molecules, and change with the composition of the mixtures. This change, in turn, is reflected in the thermodynamic properties of the mixtures. The influence of significant contributions of a chemical, physical and geometrical nature that change excess thermodynamic properties is considered and explained in detail.

Densities, Refractive Indices and Ultrasonic Speeds of N,N-dimethylformamide + Acetone Binary Mixtures at Different Temperatures

Experimental densities, ρ, refractive indices, n, and ultrasonic speeds, u, at various compositions and at various temperatures from (298.15 to 313.15) K for N,N-dimethylformamide + acetone binary mixtures were measured. From these results excess molar volumes (), deviations in refractive indices (Δn), isentropic compressibilities (Δks), partial molar volumes (), and partial molar compressibilities (), of acetone in N,N-dimethylformamide were calculated. All the excess and deviation functions were fitted to Redlich–Kister polynomial equation to determine the fitting coefficients and the standard deviations. The values of and Δks showed negative deviations, whereas excess Δn showed positive values over the entire range of concentrations and temperatures. The observed variations of these parameters, with concentration and temperature are discussed in terms of the intermolecular interactions and structural effects between the unlike molecules of the binary mixtures.

Volumetric, Viscometric, and Ultrasonic Properties of Liquid Mixtures of Cyclohexane with Alkanols at Different Temperatures

The densities (ρ), viscosities (η), and ultrasonic speeds (u) of pure cyclohexane, 1-butanol, 2- butanol, and those of their binary mixtures, with cyclohexane as common component, covering the whole composition range have been measured at 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data the excess molar volume (VE), deviations in isentropic compressibility (Δks), deviations in viscosity (Δη), deviations in ultrasonic speed (Δu), deviations in acoustic impedance (ΔZ), deviations in internal pressure (ΔPi), excess Gibbs free energy of activation (ΔG*E), entropies (ΔS*), and enthalpies (ΔH*) of activation of viscous flow have been determined. The sign and magnitude of these parameters were found to be sensitive towards interactions prevailing in the studied systems. Partial molar volumes (V0φ,2) and partial molar compressibilities (K0φ,2) of 1-butanol and 2-butanol in cyclohexane have also been evaluated. Moreover, VE values were theoretically predicted by using Flory’s statistical theory. The variations of derived parameters mentioned above with composition offer a convenient method to study the nature and extent of interactions between the component molecules of the liquid mixtures, not easily obtained by other means

Micellar Catalysis on the Redox Reaction of Ascorbic Acid-Vanadium(V) System

Stoichiometry of the redox reaction of vanadium(V) by ascorbic acid (H2A) has been experimentally determined to be H2A + 2V(V) → A + 2V(IV) + 2H + . Evidence of induced polymerization of acrylonitrile and the reduction of mercuric chloride indicates that a free-radical mechanism operates during the course of reaction. Vanadium(V) is only reduced to vanadium(IV). The kinetics of this redox reaction have been investigated spectrophotometrically at 35°C in acidic media of H2SO4. In this kinetic study we have observed the nature of vanadium(V)-H2A interaction in presence of anionic surfactant of SDS. In V(V)-H2A system, the addition of anionic surfactant (SDS) enhanced the reaction rate and shows catalytic effect. This trend was explained by the incorporation/solubilization of vanadium(V) and ascorbic acid in the Stern layer.

Physico-Chemical Properties of Binary Liquid Mixtures of n-Hexane + Acrylic Esters (C4, C5, C6, C7) at Different Temperatures

Densities ρ, ultrasonic speeds u, and refractive indices n for pure n-hexane, methylacrylate (MA), ethylacrylate (EA), ethylmethacrylate (EMA), butylacrylate (BA), and of their 36 binary mixtures over the entire composition range were measured at 298.15, 303.15, 308.15, and 313.15 K. Using these data, the excess molar volumes, VE, deviations in isentropic compressibilities, Δks, deviations in molar refractions, ΔRm, and deviations in internal pressure, ΔPi, were calculated for the mixtures at given temperatures. Apparent molar volumes, Vϕ,2, and apparent molar compressibilities, Kϕ,2, of acrylic esters in n-hexane were also calculated. Partial molar volumes, , and partial molar isentropic compressibilities, , at infinite dilution were estimated. Moreover, the optical property and partial molar refraction, , of the systems at infinite dilution were examined. The variations of these parameters and of the optical property suggest that the strength of interactions in these mixtures follow the sequence: MA < EA < EMA < BA.

Prediction of viscosities and COSMO-RS analyses in binary mixtures of N,N-dimethylformamide with acetone

ABSTRACT Experimental viscosities, η, for pure N,N-dimethylformamide (DMF) and acetone (ACT) and their binary mixtures are measured over the whole composition range as a function of temperature between 298.15 and 313.15 K. The deviations in viscosity, ∆η, Gibbs free energy of activation ∆G, entropies ∆S*, enthalpies ∆H of activation of viscous flow have been calculated. The determination of excess molar volumes, VηE, was calculated from the experimental viscosities for the binary mixtures. The conductor-like screening model is applied to interpret the intermolecular forces. The σ-profile is computed for the N,N-DMF and ACT with conductor-like screening model for real solvents. The experimental results were found to be in good agreement with the theoretical predictions. Moreover, viscosity data were calculated from the theoretical equations of Grunberg and Nissan, Hind et al. and Wilke for the entire systems. All results obtained were averaged experimentally and theoretically in terms of average deviations.