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Physical Chemistry
Number of Followers: 2  Open Access journalISSN (Print) 2167-7042 - ISSN (Online) 2167-7069 Published by SAP  [105 journals]
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- Study of Particle Size in Natural and Technological Water Suspensions
Using Photon Cross Correlation Spectroscopy with Nanophox
Abstract: Publication year: 2020Source: Physical Chemistry, Volume 10, Number 1G. Oyungerel, G. Batdemberel, G. MunkhsaikhanPhoton cross-correlation spectroscopy (PCCS) has become a novel light-scattering technique allowing for precise measurement of particle sizing and size distribution of suspensions colloids.The size and distribution of particles of suspensions including natural and technological water samples are studied by Photon Cross-Correlation Spectroscopy. The mean diameter, the size distribution range, the specific surface area of the particles in natural spring named Janchivlan are found to be 963±8 nm, 708 nm-1.4 µm and 6.27±0.01 m2/cm3, respectively. On the other hand, these values corresponding to the particles in snow samples from the industrial zone of Ulaanbaatar city are determined to be 1.4 µm ±70 nm, 947 nm-2.4 µm and 4.16±0.1 m2/cm3. It can be assumed that high values in the mean diameter of natural spring and snow samples are related to composition of minerals and PM2.5 and PM10 particles.
- Thermal Study of Aluminum Trifluoromethyl Sulfonate as Effective Catalyst
for the Polymerization of Epoxidized Linseed Oil
Abstract: Publication year: 2019Source: Physical Chemistry, Volume 9, Number 1Ethnice Dehonor Márquez, Enrique Vigueras Santiago, Susana Hernández LópezIt was studied the Aluminum Trifluoromethyl Sulfonate ((Al(OTf)3) as a very effective catalyst to polymerize Epoxidized Linseed Oil (ELO) in bulk, in a very wide range of temperatures, from room temperature (25°C) to the peak temperature of the exothermal curve of polymerization. Those temperatures and times of polymerization were depending on the amount of catalyst, which was evaluated in a very wide range of loads, from 0.5 x10-3 to 70 x10-3 molar percent. As an instance, a 55 x10-3 molar percent of catalyst showed at exothermic curve from 82 to 187°C with the peak temperature at 120.3°C. This preparation allows to ELO polymerize at 25°C in 24 hrs, at 60°C in 1hr and at 80°C in 20 min and only takes 7 min to polymerize at peak temperature. The study of the opening of the epoxy ring and polymerization of ELO was made by DSC and FTIR-HART analysis. Also was evidenced by 1H-NMR that no side reactions are promoted by this catalyst at least in the first minutes of reaction.
- Densities, Excess and Partial Molar Volumes of (DFM + n-pentane or
n-hexane or n-heptane or n-octane) Binary Mixtures at (T = 293.15, 298.15
and 303.15) K and Atmospheric Pressure
Abstract: Publication year: 2018Source: Physical Chemistry, Volume 8, Number 1Wilfred Ddamba, Belcher Fulele, Misael Silas Nadiye -TabbirukaDensities (ρ) of pure difuryl methane (DFM), n-pentane or n-hexane or n-heptane or n-octane and those of (DFM + n-pentane or n-hexane or n-heptane or n-octane) binary mixtures over the entire composition range, have been measured at (T = 293.15, 298.15 and 303.15) K and atmospheric pressure. Excess molar volumes
of each binary system were determined and correlated by the Redlich-Kister equation. The 
vs x2isothermsfor the (DFM + n-pentane or n-hexane or n-heptane) binary mixtures exhibit a sigmoidal behavior while that for the (DFM + n-octane) binary system positive deviation for 
function was observed. The 
values decreased with temperature increase for each binary systems which suggested a possible structural effects. The 
data have been used to derive excess partial molar volumes (
). Results are discussed in terms of possible geometrical and dispersive intermolecular interactions.
- Role of Anion in the Electrochemical Dissolution of Copper and Its
Inhibition by Diethyl Dithiocarbamate in Neutral Aqueous Solutions
Abstract: Publication year: 2018Source: Physical Chemistry, Volume 8, Number 1B. A. Abd-El-Nabey, A. Eldissouky, H. A. Fetouh, M. E. MohamedElectrochemical dissolution of copper in 0.5M aqueous solution of NaNO3, Na2SO4, NaCl or NaI in absence and presence of different concentrations of diethyl dithiocarbamate (DEDTC) has been studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and cyclic voltametry techniques. In absence of DEDTC, the results indicated that oxidation of copper greatly depends on the kind of anion of the electrolyte. In NaNO3 and Na2SO4 solutions, oxidation of copper takes place through a two-electron transfer step Cu
Cu(II), however in NaCl and NaI solutions, oxidation of copper occurs through two consecutive one-electron transfer steps Cu 
Cu(I) and Cu (I) 
Cu(II). These results were discussed on the basis that the mechanism of oxidation of copper depends on the adsorbability of the anion of the electrolyte at the Cu/solution interface which affects each of the potential of zero charge (PZC) and the surface charge of the metal. In presence of DEDTC, the results indicated that its inhibition efficiency for corrosion of copper decreases in the electrolytes containing adsorbable anions due to the competitive adsorption between the anion of the electrolyte and that of DEDTC. Theoretical fitting of the Langmuir isotherm and the Kinetic-thermodynamic model for the adsorption of DEDTC on the copper surface in the four examined electrolytes are tested to clarify the nature of adsorption. The results showed that the value of the standard free energy change of adsorption (∆Goads) for the tested four electrolytes equal (-35.55 to -39.70 kj/mol.) indicating that the adsorption process of DEDTC on the copper surface is comprehensive (chemical and physical adsorption).
- Adsorption Kinetics and Isotherms of Methylene Blue by Geopolymers Derived
from Common Clay and Rice Husk Ash
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 4F. M. Maingi, H. M. Mbuvi, M. M. Ng’ang’a, H. MwangiWith the onset of industrialization mankind has witnessed various environmental issues in the society. Industrialization has not only brought development and prosperity but eventually disturbed the ecosystem. It is currently estimated that 1.1 billion people in the world lack access to enhanced clean water supplies. Consequently, pursuance of sustainable materials and technologies for wastewater remediation is critical. Use of adsorbents for wastewater treatment is preferable due to their simplicity and cheap materials involved. Geopolymers are synthesized hydrothermally using alumina and silica which possesses amorphous surface for use as adsorbents. There is adequate information and reports in literature that indicate clay contain alumina and silica. Similarly, findings have shown that rice husk ash contains substantial amounts of silica. This work reports synthesis of geopolymers GP-1, GP-2 and GP-3 prepared by using different SiO2/Al2O3 ratios and consequently equilibrium and kinetics behaviour of adsorption of methylene blue. The geopolymers were characterized using FT-IR, EDS, XRD and SEM. Geopolymer adsorbents were subjected to methylene blue batch sorption experiments that indicated the adsorption of MB increased with increased Si/Al ratio in geopolymers. The adsorption isotherms were described by Langmuir, Freundlich, Temkin and Sips isotherms. Data for adsorption of MB onto geopolymers fitted best in Sips adsorption model. Kinetic studies showed that Pseudo -second order model were more suitable than the Pseudo- first order model in explaining the kinetics of adsorption.
- Effect of Surfactants on the Protection Efficiency of Zn-Phosphate Coat on
Steel
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 4B. A. Abd-El-Nabey, S. El-Housseiny, H. M. El-Kshlan, M. A. Abd-El-FatahPotentiodynamic polarization, electrochemical impedance spectroscopy, SEM study and EDX analysis have been used to investigate effect of Tween-80, Cetyl trimethyl ammonium bromide (Cetrimide), and Sodium Louryl Sulphate (SLS) surfactants on the corrosion resistance, porosity, structure and composition of Zn-phosphate coat on steel. Electrochemical results indicated that the presence of 0.01M surfactants in the coating solution caused a decrease in the porosity and an increase of the protection efficiency of the coat up to about 90%. The results proved that the coating process was controlled by adsorption of the surfactant molecules on the steel surface. Application of the adsorption isotherms and Kinetic-Thermodynamic model to fit the experimental data indicated that Langmuir isotherm is not applicable, however, Flory-Huggins isotherm and Kinetic-Thermodynamic model are applicable, and the three surfactants are chemisorbed on the steel surface. SEM study and EDX analysis gave very good support to the electrochemical data.
- A Study of Nanoparticle Sizes and Their Distribution along a Main Road in
Ulaanbaatar City
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 3G. Oyungerel, G. Batdemberel, Sh. Chadraabal, D. SangaaThe size and distribution of particles along a main road in Ulaanbaatar city are studied by Photon Cross Correlation Spectroscopy (PCCS) NANOPHOX (Sympatec GmbH, Germany). The mean diameter, the size distribution range, the specific surface area of the aerosol particles are found to be equal to 1.1-2.5 μm, 74 nm-4.0 μm and 2.38-5.43 m2/cm3, respectively. On the other hand, the particles distribution is Gaussian with density of 0.02-8.15 (q3lg) in the range of 790 nm-3.8 μm. However, nanoparticles with diameters less than 74 nm was not observed. The results reveal that samples contain 0.02% in volume ultrafine particles or nanoparticles in the range of 74-100 nm, 83.73% fine particles (PM2.5) in the range of 100 nm-2.4 μm and 16.25% coarse particles (PM10) in the range of 2.4-4.0 μm. It can be concluded that a high percentage of PM2.5 particles is present in an aerosol sample along a main road of Ulaanbaatar city.
- Internal Energy Functions of Thermodynamic Systems
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 3Xiaofu WuThe present work presents a different angle to look into the concepts of internal energy functions of thermodynamic systems. The argument presented is that the total internal energy U of a thermodynamic system consists of two basic components, Uk, the kinetic energy of the material particles moving in the interior space of the system, and Um, the energy stored in other forms inside the materials contained by the system. Internal energy is matter-dependent and energy exchange is thus a process of matter exchange. The expression of U as a function of pressure P or temperature T given volume V does not take Um into account. The relation ∆U=q-w is a path function for closed systems without matter exchange. Work (w) as a path function is not quantitatively related to the change in U as the work done by a system on its surroundings should be equal to the work done by the surroundings on the system. Heat (h) can be either absorbed or released, and heat transfer is a process of mass transfer. The connections of Uk and Um with enthalpy H, entropy S, Helmholtz free energy A and Gibbs free energy G are Uk=H=TS, Um=A=G and U=TS+G.
- Development and Validation of a Modern and Stability-Indicating Method for
the Quantification of Ceftriaxone Sodium in Powder for Injection by
Infrared Spectroscopy
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 3Mariana Teixeira da Trindade, Hérida Regina Nunes SalgadoThis paper proposed the validation of a modern and useful analytical method for the quantification of ceftriaxone sodium in powder for injection, using Fourier-transform infrared (FT-IR) transmission spectroscopy. This technique has great advantage because it does not use organic solventes and it is in accordance with the International Conference on Harmonisation guidelines (ICH), contributing to the reduction of the generation of waste of organic solvents by the industry and minimizing the impact of its activities on the environment. The method was quantified by measuring the absorbance of the band corresponding to the carbonyl present in the drug molecule, in the region between 1800 and 1700 cm-1, showing to be linear, accurate, precise, selective and robust. It was linear over the concentration range of 0.4-1.2 mg with correlation coefficient of 0.9983 and limits of detection and quantification of 0.016 and 0.049 mg, respectively. The validated method is able to quantify ceftriaxone sodium powder for injection preparation, it is an environmentally-friendly and low cost method and can be applied in the routine quality control of the pharmaceutical industry.
- Toward Visible-Light Responsive Photocatalysts: Nano-Potassium Doping Zinc
Oxide (K-ZnO) for Degradation of 2-Naphthol
Abstract: Publication year: 2017Source: Physical Chemistry, Volume 7, Number 2Taha M. ElmorsiPhotocatalytic properties of photocatalysts depend generally on techniques employed for preparing nanostructures and doping processes. Nanostructured zinc oxides (ZnO) are promising photocatalysts due to their high stability, high surface activity, and low costs. This study highlights a simple method of a co-precipitation for synthesizing ZnO and potassium doped ZnO (K-ZnO). In this research, surface functionalization with high quality explored by multiple surface analytical methods such as crystal structural, morphology analysis, inductively coupled plasma-atomic emissions spectroscopy (ICP-AES) and scanning electron microscopy (SEM) attached with energy dispersive x-ray (SEM/EDX). The approach is well suited to produce crystalline K-ZnO, which possesses a shape of nanorods (35.2 to 48.9 nm) and acts as an efficient visible light responsive photocatalyst. The results indicated that the K-ZnO is more responsive to the visible light than pure ZnO. The degradation efficiency of 2-naphthol in aqueous solution in the presence of K-ZnO and sunlight was found to be 95% in 70 min at pH 10.5. In contrast, negligible degradation of 2-naphthol occurred in the absence of K-ZnO. Mechanism and type of photoreaction were identified by employing hydroxyl radical scavengers (e.g. tert-butyl alcohol and Cu2+/Ag+ ion) and electron
scavengers (e.g. Ag+ ions and molecular oxygen). The kinetic analysis of the photodegradation process using a Langmuir-Hinshelwood model suggests that the reaction has occurred on the surface of the photocatalyst. Also, the reaction is influenced by hydroxyl radical scavengers supporting a photooxidation pathway, whereas electron scavengers showed minor effect. Mineralization of 2-naphthol using K-ZnO in presence of sunlight was confirmed by ultra-performance liquid chromatography equipped with mass spectrometry (UPLC/MS).
