Physical Chemistry Research
Volume:7 Issue: 3, Summer 2019

In this research paper, chemically activated Thuja Occidentalis leaves carbon (CATLC) is used as an adsorbent for the removal of calcium (Ca2+) ion from aqueous solution. CATLC is prepared and characterized by FTIR, SEM and EDX. The impact of pH, adsorbent dosage, contact period and initial concentration of Ca2+ on the adsorption performance of CATLC for Ca2+ removal are examined by batch studies. The results disclose that CATLC has a high potential to adsorb Ca2+ (91% removal) at pH 7.00. To know the equilibrium behaviour of Ca2+ adsorption, Freundlich and Langmuir models are investigated, and the data discloses that Langmuir model (maximum adsorption capacity ‘Qm’ obtained is of 51.28mg/g and R2= 0.9953) fits better than Freundlich model(R2 =0.8723). The Kinetic studies indicate that pseudo-second-order(R2= 0.9909) is the best fit rather than pseudo-first order, intra particle and Elovich models and chemisorptions are the rate-limiting steps for the Ca2+ adsorption using CATLC adsorbent. Regeneration studies showed that CATLC can be regenerated easily and reused for several adsorption cycles, with sodium chloride solution as a regenerating agent. The application of CATLC adsorbent is useful to reduce the hardness concentration in groundwater samples to meet the allowable limit according to WHO-2011 standards.

We developed an equation of state (EOS) by Ihm, Song, and Mason (ISM) for polar fluids. The model consists of four parameters, namely, the second virial coefficient, an effective van der Waals co-volume, a scaling factor, and the reduced dipole moment. The second virial coefficient is calculated from a correlation that uses the heat of vaporization, and the liquid density at the normal boiling point. The reduced dipole moment is calculated from experimental dipole moments data and other parameters were obtained by regressing against saturated liquid density data. In this work, we generalized this equation to calculate the saturated liquid density of n-alkanol, water, and ammonia. The calculated results are also compared with SAFT equation of state and show that the saturated liquid density can be predicted within about 1.2%.

Dyes in the textile industry are the most significant source of pollutants, which cause damaging effects to people’s health. Reactive black 5 (RD5) is an anionic color that is currently used in the textile industry. This study is designed to provide the strategies to synthesize and characterize the new family of functionalized magnetite nanoparticles via a chemical co-precipitation method with polyaniline modification groups on the surface. The effect of various parameters including pH, the initial concentration of RD5, the mass of adsorbent, contact time, temperature and ionic strength has been studied. Under optimal conditions, 10 mL of RD5 solution with a concentration of 30 mg/L, 20 mg of adsorbent, pH of 7 and contact time of 10 minutes, the color was completely removed. The results also showed that adsorption followed Langmuir isotherm (R2=0.998) and the maximum adsorption capacity was 63.69 mg/g. The results of kinetic studies also showed that the RD5 removal followed the pseudo-second-order equation with the correlation coefficient of R2=0.9984. The ΔG0 was negative at all temperatures which shows that the adsorption process was spontaneous. Conforming to our results, adsorption process by designed magnetic nano-adsorbent is an efficient and affordable method for eliminating RD5 from the industry.

As a green material, used date pits oil is increasingly utilized as inexpensive feedstock for ethyl ester (biodiesel) production. Waste date pits as a raw material are one of the highly produced agricultural wastes in Iran. This study investigated the effect of several procedure parameters including the ethanol/oil molar ratio, reaction temperature and amount of catalysts on the yield of the produced ethyl ester. The activity of date pits oil can be considered a method of second-generation biofuels production including green diesel fractions. Efficient from waste date pits and synthesis of ethyl ester have made a breakthrough in biodiesel production. Gas chromatography/mass spectrometry (GC-MS) and Fourier Transform Infrared (FT-IR) were employed to determine the composition of production. The optimized ethyl ester yield obtained was 92% when the procedure temperature was 65 ℃, within 6h, with 7:1 ethanol/oil molar ratio with 0.75 wt.% of catalyst (KOH). Waste date pits oil as feedstock can be an efficient platform for ethyl ester production. The purified ethyl ester satisfies the stringent quality standards imposed by ASTM D-6751 (USA standard) and EN-14214 (European standard).

The Fischer-Tropsch synthesis is a catalytic process that can produce a fuel similar to fossil fuels by using primary sources such as agricultural waste and carbon sources that can convert into synthesis gas by superheated steam. All fuel derivatives can be supplied through the Fischer-Tropsch reaction. The synthesis produces a variety of hydrocarbons via parallel and sequential reactions. However, achieving a particular product requires different operating conditions. It’s necessary to notice that, the terms of time and cost will increase by any change in operating conditions even on the laboratory scale, so it will not be cost-effective. For this purpose, in this study, adopting the method of modeling was investigated for the manufacturing of products of the Fischer-Tropsch process on Cobalt-based catalyst under the following operating conditions: TOS=20-150 h, T=190-225°C, P=2-6 MPa and H2/CO ratio of 1-5. Then, the models of selectivity and the optimal conditions for the reaction products were determined.

Substitution effects are probed for novel N-heterocyclic stannylenes (NHSns), including 1,4-di(R)-tetrazole-5-stannylenes (1R), and 1,3-di(R)-tetrazole-5-stannylenes (2R), using B3LYP/6-311++G** level of theory. Nucleophilicity, multiplicity, and stability of 1R and 2R are calculated; with R = H, methyl, ethyl, i-propyl, t-butyl, Ph, OH, methoxy, NO2, CN and CF3. Asymmetric 2H appears more nucleophilic (N ̴ 4) than its corresponding symmetric 1H isomer (N ̴ 3), mostly due to the formers higher separation of charge. The N is more sensitive to electronic effects in 1R stannylenes than those in the 2R series. Electron donating R groups increase N with Hammett ρ constants of -3.3 and -2.7 for 1R and 2R, respectively. Stannylene 2H is slightly more aromatic (NICS (1) = -10.31) than 1H (NICS (1) = -10.25). Every 1R is more stable than its corresponding 2R isomer. Every 2R is generally more nucleophilic and aromatic than its corresponding 1R. In addition the former is less electrophilic with a larger band gap and narrower stannylene bond angle. Substituent effects are probed on N by devising proper isodesmic reactions. The trend for N is: 2t-buthyl> 2iso-propyl> 2ethyl> 2methyl> 2ph> 2OMeth >1t-buthyl> 2OH> 2H >1Ph> 1iso-propyl> 1OH >1ethyl >1methyl >1OMeth >1H >2CF3 >2NO2> 2CN> 1CF3> 1CN> 1NO2.

The Cyclic Voltammetric (CV) behavior of Alizarin Red-S (ARS), which is an Anthraquinone dye was examined by utilizing TX-100 modified carbon nanotube paste electrode (TX-100MCNTPE). The surfactant utilized is TX-100, and it has been found that it has good electrocatalytic activity towards ARS. Distinctive parameters like pH, scan rate, detection limit have been studied in the potential range of 0.4 V to 1.0 V by using 0.2 M phosphate buffer solution (PBS) as supporting electrolyte. From these studies, it was clear that ARS shows well characterized irreversible oxidation peak in the solution of pH 6.5 at a scan rate of 0.1 V/s. Scan rate studies reveal that the entire process is adsorption controlled. Oxidation peak current rises linearly with the increase in the concentration of ARS. Two linear range is observed in the array of 2 × 10-6 to 10 × 10-6 M and 15 × 10-6 to 35 × 10-6 M. First linear range with a limit of detection (LOD) and limit of quantification (LOQ) of 1×10-6 and 3×10-6 M respectively was considered. The fabricated sensor can be productively employed for the simultaneous determination of ARS and Tartrazine (TZ).

Ni/Al-HMS/HZSM-5 catalysts with varying amounts of Si/Al ratios were prepared via the impregnation method and evaluated for the hydrogenation of benzene at 130−190 °C. To study the catalyst characterization, various methods were used as X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, temperature-programmed desorption of ammonia, H2 chemisorption, N2 adsorption-desorption, and thermogravimetric analysis. The effect of reaction temperature and residence time on catalytic performance was considered and kinetic of this reaction was investigated under different pressures. The results demonstrated that the composite catalysts have high benzene conversion (~80%), medium to low toluene and xylene conversion (16–80%), moderate benzene selectivity (~50%) in the mild reaction condition, and good catalytic stability against the coke deposition.

In this research, at first ordinary Aloe Vera micropowder (OAMP) and its impregnated form (IAMP) as the natural sorbents were prepared and then characterized by several techniques such as Fourier transform spectrophotometry (FT-IR), Scanning electron microscopy (SEM), Elemental analysis (EA), Brunauer–Emmett–Teller and Barrett-Joyner-Halenda (BET/BJH) essay and X-ray powder diffraction (XRD). The removal efficiencies of the prepared adsorbents were assessed upon their capacities for removing Reactive violet 8 (RV8) and Congo red (CR) dyes as the organic pollutants. Our preliminary adsorption experiments showed that the OAMB ability for removing RV8 and CR is very less than the IAMP form, so we focused on the IAMP removal ability and we used it as a fairy powerful adsorbent in this study. The effect of several parameters such as initial adsorbate concentration (C0), adsorbent dosage, contact time, temperature and solution pH on the adsorption capacity of IAMP adsorbent were investigated and then several isotherm models were examined to fit the experimental results. Consequently, we concluded that the Langmuir and Freundlich models fit reasonably the experimental results. In addition, thermodynamic and kinetic studies of the adsorption process were also done and the corresponding thermodynamic and kinetic parameters were concluded and reported.

AChE is an enzyme that is predominate in a healthy brain, while BChE is considered to play a minor role in regulating the levels of ACh (memory molecule) in the brain. In addition to setting the ACh level, these two enzymes also facilitate Aβ aggregation by forming stable complexes and participate in the abnormal phosphorylation of the tau protein, which also contribute to the development of Alzheimer’s disease (AD). Trace elements including Zn2+, Cu2+, and Fe2+ are found in the brain plaques of Alzheimer’s patients. This study employed tacrine as an efficient inhibitor of cholinesterase and quercetin as a natural metal chelating agent to design a new multi-target-directed ligand, which has been named Tac-Quer. The chelating properties of this ligand have been studied by quantum calculations. The Tac-Quer/Metal binding energies for Zn2+, Cu2+, and Fe2+ are -939. 08, -917.62, and - 694.103 kcal.mol-1, respectively. The cholinesterase enzyme inhibitory activity of the Tac-Quer ligand has been evaluated via molecular dynamic simulations. The free energies for the AChE/Tac-Quer and BChE/Tac-Quer complexes are -17.17 and -29.16 kcal.mol-1, respectively. Based on the results of this investigation, Tac-Quer is introduced as a potent multi-target-directed ligand that can be recognized as a promising treatment for AD.

The purpose of this study is to investigate the interaction of Etofylline as an established drug for asthma remedy, with the major transport protein in human blood circulation, the human serum albumin (HSA). In this respect, the fluorescence and circular dichroism (CD) spectroscopy techniques, along with the molecular docking and molecular dynamics simulation methods were employed. Analysis of the fluorescence quenching data with the Stern-Volmer equation, confirmed the static quenching mechanism due to the Etofylline-HSA complex formation. Calculated thermodynamics parameters (ΔH 0) indicated that the binding mechanism is both enthalpy and entropy driven, while simultaneous hydrophobic and hydrogen bonding interactions are involved in the Etofylline-HSA interaction. The CD spectrum demonstrated some conformational alterations of HSA upon Etofylline addition. Moreover, the distance between tryptophan residue of HSA and Etofylline was calculated by the Forster′s non-radiative energy transfer theory (FRET). The result was in good accordance with the molecular docking outcome.

By coupling of Fe2O3@SiO2 particles with metal organic Framework (MOF) the magnetic MOF structure was fabricated. Precipitation and hydrothermal methods were applied for synthesis of core and MOF. Silver nanoparticles were deposited on nickel based metal organic framework surface and magnetic Fe2O3@SiO2@MOF@Ag was obtained. Because of strong coupling between silver nanoparticles and metal organic framework, the catalyst demonstrated high catalytic activity and selectivity in aerobic oxidation of alkenes under mild conditions. The nanostructure, exhibited high catalytic activity. Alkenes oxides (epoxy alkanes) were the main products with more than 89.9 % selectivity. Composite system of silver nanoparticles supported on Fe2O3@SiO2@Metal Organic Framework has potential to be an active catalysts for aerobic oxidation of alkenes under mild conditions.