Masoud Arabieh - Academia.edu (original) (raw)
Papers by Masoud Arabieh
Application of response surface methodology for modelling the enzymatic assay of hydrogen peroxide by Emerson–Trinder reaction using 4-iodophenol
International Journal of Environmental Analytical Chemistry, Dec 20, 2006
In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) we... more In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) were combined for modelling and optimizing the experimental parameters of the enzymatic Emerson–Trinder reaction, for the determination of hydrogen peroxide. This spectrophotometric indicator reaction is currently used in biotechnology for the determination of phenolic compounds (e.g. in industrial samples) and also for determination of various substrates (e.g. in clinical chemistry). Using 4-iodophenol as a hydrogen donor in this reaction, the quality of the generated second-order polynomial response model equation was checked by the kinetic assay of H2O2 in real samples (e.g. cosmetic and human pooled serum samples), where their resulting satisfactory analytical characteristics were reported.
Journal of Water Chemistry and Technology, Sep 1, 2018
Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extra... more Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extraction of lead in water. A mixture of extraction solvent (1-decanol) and disperser solvent (acetone) containing dithizone as chelating agent is injected into microextraction cell. Then an aqueous sample is injected into microextraction cell until the mixture of solvent forms initial state a homogeneous solution and then forms an emulsion consisting of fine droplets of the extraction solvent, disperser solvent and water. Using air flotation, the extraction solvent is transferred to the surface of the mixture and is collected by means of a micro-syringe. Then 25 µl of the collected organic solvent is diluted with 800 µl decanol and is analyzed with spectrophotometer in 520 nm wavelength. Also, the thermochemistry of complexation reactions was investigated at PM6 and B3LYP/6-31G* computational level.
Journal of the Brazilian Chemical Society, 2014
A determinação de chumbo e cádmio por espectrometria de absorção atômica de chama após a extração... more A determinação de chumbo e cádmio por espectrometria de absorção atômica de chama após a extração de fase sólida do óxido de grafeno (GO) utilizando o 4-acetamidotiofenol (ATP) como reagente quelante foi descrita. PM6 semi-empírico e a teoria de densidade funcional PBE foram os métodos usados na investigação do mecanismo de adsorção dos complexos em folhas de GO. Os principais fatores que influenciam a pré-concentração e determinação de analitos (pH, quantidade de ATP, tipo e concentração de eluente, fluxo e volume de amostra) foram examinados em detalhe. O efeito de íons interferentes no fator separação-pré-concentração também foi investigado. Para soluções de Pb(II) e Cd(II) 1,0 µg L −1 , o fator de pré-concentração chegou a 250 (em condições otimizadas). Os limites de detecção para Pb(II) e Cd(II) foram 170 e 80 ng L −1 , respectivamente. A validade do método proposto foi checada com materiais de referência padrão e foi aplicado com sucesso na determinacao de traços de Pb(II) e Cd(II) em amostras de água, ervas e peixe com recuperação de 99,4-103,5%. The determination of lead and cadmium by flame atomic absorption spectrometry after solid phase extraction on graphene oxide column with use of 4-acetamidothiophenol (ATP) as chelating reagent was described. PM6 semi-empirical and PBE density functional theory methods were used to investigation of adsorption mechanism of the complexes on GO sheet. The main factors influencing the preconcentration and determination of the analytes (pH, ATP amount, eluent type and concentration, flow rate and sample volume) were examined in detail. The effect of interfering ions on the separation-preconcentration of analytes was also investigated. For Pb(II) and Cd(II) solutions of 1.0 µg L −1 , the preconcentration factor was as high as 250 (under the optimized conditions). The detection limits for Pb(II) and Cd(II) were 170 and 80 ng L −1 , respectively. The validity of the proposed method was checked with standard reference materials and it has been successfully applied for the determination of trace Pb(II) and Cd(II) in water, herbal and fish samples with the recoveries of 99.4-103.5%.
Journal of Radioanalytical and Nuclear Chemistry, 2018
Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been ... more Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been investigated using a dioxa-diazamacrocycle and oleic acid as carrier and synergistic agents, respectively. Quantitative transport of uranyl ion was achieved within 4 h when the pH of source solution was kept at 5.0-6.0 and mole ratio of carrier to synergistic agent was 1/15. It was found that overall rate and selectivity of the transport is governed by the stripping step. Finally, the influence of some foreign competitor ions including Al 3? , Ca 2? , CO 3 2-, Cu 2? , Mg 2? , Pb 2? , Zn 2? and Th 4? and also the ionic strength on the transport efficiency has been evaluated.
Journal of Water Chemistry and Technology, 2018
Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extra... more Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extraction of lead in water. A mixture of extraction solvent (1-decanol) and disperser solvent (acetone) containing dithizone as chelating agent is injected into microextraction cell. Then an aqueous sample is injected into microextraction cell until the mixture of solvent forms initial state a homogeneous solution and then forms an emulsion consisting of fine droplets of the extraction solvent, disperser solvent and water. Using air flotation, the extraction solvent is transferred to the surface of the mixture and is collected by means of a micro-syringe. Then 25 µl of the collected organic solvent is diluted with 800 µl decanol and is analyzed with spectrophotometer in 520 nm wavelength. Also, the thermochemistry of complexation reactions was investigated at PM6 and B3LYP/6-31G* computational level.
Quarterly Journal of Applied Chemical Research, 2017
The present work was undertaken to evaluate the feasibility of nickel (II) removal from aqueous s... more The present work was undertaken to evaluate the feasibility of nickel (II) removal from aqueous solution by adsorption onto a biopolymer adsorbent. The adsorbent was prepared using modification of mesoporous silicate SBA-15 with alginate biopolymer (alginateSBA-15) by encapsulation method. Morphological structure of the obtained nanocomposite adsorbent was characterized by XRD, scanning electron microscopy, nitrogen porosimetry technique, and fourier transform infrared spectroscopy. Batch adsorption experiments were carried out to investigate influence of operational parameters such as pH, contact time and initial concentration on alginate-SBA-15 adsorption behavior. Kinetics study revealed that the pseudo-second-order model provided well mathematical description of the experimental data. Out of several isotherm models, the Langmuir, Ferundlich, Dubinin-Radushkevich, RedlichPeterson, and Temkin models were applied to adsorption data to estimate adsorption capacity. The equilibrium a...
International Journal of Engineering, 2016
Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence ... more Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence of sulfate anions was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on Amberlite IRA910 sorption behavior. Experiments revealed that uranium adsorption was fulfiled at pH>3 and 50 min to amount of 80%. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one. Freundlich isotherm was also provided well mathematical description of sorption process than the Langmuir one. Uranium adsorption capacity of the sorbent was 1666.6 mmol g -1 . It was also revealed that the existence of various anion species in the solution could strongly affect the sorption of uranium using the Amberlite IRA910 anion exchanger resin.
Selective Nanopores in Graphene Sheet for Separation I-129 Isotope from Air
Journal of Advanced Physics, 2017
Molecular dynamic simulation was used to investigate the ability of nanoporous graphene membrane ... more Molecular dynamic simulation was used to investigate the ability of nanoporous graphene membrane in gas separation process. Three di-atomic gases (I2, N2 and O2) were considered, in which different pore sizes were modeled on graphene. The structure contains an impermeable movable wall (piston) to push the mixture gases toward the nanoporous graphene membrane. Two different simulations were carried out, with two different piston velocities. Two key factors in gases separation process are the pore size of graphene and the velocity of movable wall. The results revealed that I-129 separation was improved by using proper size of pore and by decreasing the velocity of movable wall. It was also found that the I-129 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-12 graphene configuration. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while I-129 was not adsorbed.
Simulation studies of the separation of Kr-85 radionuclide gas from nitrogen and oxygen across nanoporous graphene membranes in different pore configurations
The European Physical Journal Plus, 2016
Abstract.Separating molecular species is an important precursor for various applications. In this... more Abstract.Separating molecular species is an important precursor for various applications. In this work, we have utilized molecular dynamics (MD) simulations to examine how pore radius and structure affect the separation process. We show from MD simulations that 2-D graphene sheets with designed sub-nanometer pores can efficiently separate the Kr-85 radionuclide gas from an N2/O2 mixture. Three species of gases (Kr-85, N2 and O2 were considered in the simulation box in which different sizes and geometries of pores were modeled on the graphene sheet. The ( $ 30\times 30\times 80$ Å^3 simulation box contains a nanoporous graphene membrane in the middle of the box and two fixed walls with equal distances on both sides of the nanoporous graphene. The results revealed that Kr-85 separation was improved by using an optimized pore structure. It was also found that the Kr-85 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-7 configuration. Restriction of the molecular orientation largely prohibited the permeation of nitrogen molecules. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while krypton was not adsorbed.
Molecular Perspective of Radionuclides Separation by Nanoporous Graphene Oxide Membrane
Chemical Product and Process Modeling, 2016
Graphene-derived membranes has gained much interest recently due to its promising potential in fi... more Graphene-derived membranes has gained much interest recently due to its promising potential in filtration and separation applications. Molecular Sieving phenomena of gas molecules in the interlayer of graphene oxide nanopore have been investigated using molecular dynamic (MD) simulation. We explore I-129 gas radionuclides sequestration from natural air in nanoporous graphene oxide membranes in which different sizes and geometries of pores were modeled on the graphene oxide sheet. In the present work, mean-squared displacement (MSD), diffusion, flow of gas and the number of crossed gas molecules through graphene oxide nanopore membrane have been calculated and the results showed, selective proper nanopores in graphene oxide membrane could dramatically improve separation. The aim of this paper is to show that for the well-defined pore size called P-12, it is possible to separate I-129 from a gas mixture containing I-129, O
Low-energy conformers of pamidronate and their intramolecular hydrogen bonds: a DFT and QTAIM study
Journal of Molecular Modeling, 2012
Extensive DFT and ab initio calculations were performed to characterize the conformational space ... more Extensive DFT and ab initio calculations were performed to characterize the conformational space of pamidronate, a typical pharmaceutical for bone diseases. Mono-, di- and tri-protic states of molecule, relevant for physiological pH range, were investigated for both canonical and zwitterionic tautomers. Semiempirical PM6 method were used for prescreening of the single bond rotamers followed by geometry optimizations at the B3LYP/6-31++G(d,p) and B3LYP/6-311++G(d,p) levels. For numerous identified low energy conformers the final electronic energies were determined at the MP2/6-311++G(2df,2p) level and corrected for thermal effects at B3LYP level. Solvation effects were also considered via the COSMO and C-PCM implicit models. Reasonable agreement was found between bond lengths and angle values in comparison with X-ray crystal structures. Relative equilibrium populations of different conformers were determined from molecular partition functions and the role of electronic, vibrational and rotational degrees of freedom on the stability of conformers were analyzed. For no level of theory is a zwitterionic structure stable in the gas-phase while solvation makes them available depending on the protonation state. Geometrically identified intramolecular hydrogen bonds were analyzed by QTAIM approach. All conformers exhibit strong inter-phosphonate hydrogen bonds and in most of them the alkyl-amine side chain is folded on the P-C-P backbone for further hydrogen bond formation.
Investigation of origin of stereo-selectivity of BF3·Et2O-promoted allylboration of aldehydes in the presence of (R)-pinanediol by computational method
Computational and Theoretical Chemistry, 2012
ABSTRACT The effect of position of BF3 on the BF3·Et2O-promoted allylboration of aldehydes in the... more ABSTRACT The effect of position of BF3 on the BF3·Et2O-promoted allylboration of aldehydes in the presence of (R)-pinanediol have been investigated. The results showed that the energy differences between TS-b2 and TS-a which has been regarded as two competing TS structures is very low, and TS-b2 is favorable only by about 0.9 and 2.5 kcal/mol in the gas phase and the solvent, respectively. Lack of 1,3-syn-pentane interaction in the TS-b2 case, and the withdrawing effect of BF3 as a Lewis acid could explain this phenomenon. NBO analysis showed that the coordination site is crucial in the amount of interaction between the O atom of aldehyde moiety with the B atom of chiral ligand. Attaching BF3 to the aldehyde moiety causes less interaction between the aforementioned two atoms. When BF3 is attached to the chiral ligand this interaction is increased. In this study acetaldehyde was used as a model instead of Ph(CH2)2CHO which was used in experimental work by Chen and Roush [Org. Lett. 12 (2010) 2706–2709].
Protective effect of rutin (vitamin p) against heme oxidation: A quantum mechanical approach
Computational and Theoretical Chemistry, 2012
ABSTRACT The methemoglobin (FeIIIHb) is product of the auto-oxidation of hemoglobin which cannot ... more ABSTRACT The methemoglobin (FeIIIHb) is product of the auto-oxidation of hemoglobin which cannot transport oxygen. Rutin (vitamin p) is one of the most important bioflavonoid with antioxidant activity in vivo and in vitro. Here, a systematic study of several interactions and arrangements between rutin, corresponding radical of rutin and methemoglobin (FeIIIHb) has been undertaken. Density Functional Theory (DFT) calculations by using B3LYP/6-31G* method were employed to calculate interaction energies, electronic states, and geometrical arrangements for the complex between the methemoglobin and rutin. Analysis of the theoretical bond dissociation enthalpy (BDE) values, for all OH sites of rutin, clearly shows the importance of the B-ring and the 3′-OH and 4′-OH groups in antioxidant reactivity. The results of calculations indicate that rutin and corresponding radical interact with methemoglobin with considerable stabilization energy and reduce the Fe(III) in the methemoglobin to Fe(II). Thus, rutin molecule plays a safeguard role against oxidative degradation of hemogolobin.
Computational and Theoretical Chemistry, 2012
Density functional theory (DFT) using B3LYP and split-valance 6-31G Ã basis set have been employe... more Density functional theory (DFT) using B3LYP and split-valance 6-31G Ã basis set have been employed to calculate the details of electronic structure and electronic energy of carbonic anhydrase enzyme active center (CA), six inhibitors of this enzyme including topiramate and its derivatives and its analogue, and complex between these inhibitors and active center of carbonic anhydrase. Also thermodynamic functions such as deprotonation enthalpy of inhibitors, standard enthalpies of formation ðDH f Þ, standard entropy of formation ðDS f Þ and standard Gibbs free energy of formation ðDG f Þ for six CA-inhibitor complexes are evaluated. The calculated results indicate that deprotonated inhibitors are coordinated to the Zn 2+ ion and all the complexes have tetrahedral geometry. According to the calculated thermodynamic functions substitution of sulfonamide group with hydroxyl reduces the tendency of inhibitor to bind to the active center of carbonic anhydrase. In all calculations solvent effects have been considered in water using SCRF method.
Australian Journal of Chemistry, 2012
The reactions of the HBr molecule with CH2CH2Cl (reaction R1), CH2CHCl2 (R2), CH2CH2Br (R3) and C... more The reactions of the HBr molecule with CH2CH2Cl (reaction R1), CH2CHCl2 (R2), CH2CH2Br (R3) and CH2CHBr2 (R4) are investigated by a dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points were calculated at the MPW1K/6–311+G(d,p) and BMK/6–311+G(d,p) levels. To refine the reaction enthalpy and energy barrier height of each reaction, single-point energy calculations were carried out by the G2M(RCC5) method based on the geometries optimized at the above-mentioned two levels. Using the canonical variational transition state theory or the canonical variational transition state theory with the small-curvature tunneling correction, the rate constants of HBr with CH2CH2Cl (R1), CH2CHCl2 (R2), CH2CH2Br (R3), and CH2CHBr2 (R4) were calculated over a wide temperature range of 200–2000 K at the G2M(RCC5)//MPW1K/6–311+G(d,p) level. The effect of chlorine or bromine substitution on the ethyl radical reactivity is discussed. Finally, the total rate con...
DFT exploration of adsorptive performances of borophene to small sulfur-containing gases
Journal of Molecular Modeling
Computational and Theoretical Chemistry, 2012
B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory has been used to investigate the ring size ef... more B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory has been used to investigate the ring size effect on the Bellus-Claisen rearrangement. The results show the reaction has a high asynchronous character and there is no direct relationship between ring size and E a ; for example, the E a is almost the same amount for three-and five-member rings. Four-member rings however, have an unexpectedly higher E a. Reactants which have nitrogen as a heteroatom in their structures have lower E a in comparison to oxygen containing rings. The effect of solvent on the E a is considerable. In all of the cases, by increasing the polarity of solvents, the amount of E a decreases. The results show that the effect of solvent on E a for N as heteroatom is more than that of O. There is an inverse relation between solvent polarity and E a. This can be interpreted as higher stabilization effect of the polar solvents on TSs' structures comparing to less polar solvents which leads to lower E a .
Application of Response Surface Methodology to Optimize Photocatalytic Degradation Rate of Methylorange Using Nanoparticles of Nd Doped TiO 2
Energy and Environment Focus, 2016
A density functional theory study on the interaction of dipicolinic acid with hydrated Fe2+ cation
Computational and Theoretical Chemistry, 2016
The most feasible complexes formed between dipicolinic acid and hydrated Fe 2+ cation (namely, [F... more The most feasible complexes formed between dipicolinic acid and hydrated Fe 2+ cation (namely, [FeL(H 2 O) 3 ] and [FeL 2 ]) have been modeled using density functional theory. A comparison among several computational levels of theory and available X-ray data showed that the B3LYP/6-311G(d) computational level provides accurate geometrical parameters for geometry optimization of complexes. The energetics and thermochemistry of complexation reactions in the gas phase and solvated medium (PCM) were evaluated at the B3LYP/6-311G(d) and B3LYP/6-311++G(2df,pd)//B3LYP/6-311G(d) levels of theory. The calculated thermochemistry data exhibited high complexation energies for both complexes and decreasing in the exothermicity of complexation reactions when PCM model was included in the calculations. The calculated free energy changes of complexation reactions pointed to spontaneous procedures. Detailed analysis of energy levels and major composition of selected frontier orbitals were performed ...
The effect of external electric field and metal impurities on the interaction of HF and boraphene: a computational study
Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structur... more Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structure of boraphene (B 36 ) were investigated. The results show the highest change in electronic structure of doped-B 36 systems belongs to Al-B 36 structures wherein the gap energy of the system is decreased by 17.92%. DOS diagrams and absorption spectra of doped B 36 are compared to pristine and discussed. The capability of pristine and modified B 36 in the field of detection/adsorption of HF molecule has been evaluated. The calculated values of adsorption energies of 0.13, 0.63, 0.24, and 0.16 eV for adsorption of HF on pristine, Al-, Ga-, and P-B 36 and related DOS diagrams reveal that these systems are not superior host materials for detection/adsorption applications. It was found that the external electric field could increase the interaction between HF and B 36 systems leading to suggesting Al-B 36 as proper candidate for HF removal applications. Graphical abstract
Application of response surface methodology for modelling the enzymatic assay of hydrogen peroxide by Emerson–Trinder reaction using 4-iodophenol
International Journal of Environmental Analytical Chemistry, Dec 20, 2006
In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) we... more In this work, an initial-rate spectrophotometric method and response surface methodology (RSM) were combined for modelling and optimizing the experimental parameters of the enzymatic Emerson–Trinder reaction, for the determination of hydrogen peroxide. This spectrophotometric indicator reaction is currently used in biotechnology for the determination of phenolic compounds (e.g. in industrial samples) and also for determination of various substrates (e.g. in clinical chemistry). Using 4-iodophenol as a hydrogen donor in this reaction, the quality of the generated second-order polynomial response model equation was checked by the kinetic assay of H2O2 in real samples (e.g. cosmetic and human pooled serum samples), where their resulting satisfactory analytical characteristics were reported.
Journal of Water Chemistry and Technology, Sep 1, 2018
Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extra... more Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extraction of lead in water. A mixture of extraction solvent (1-decanol) and disperser solvent (acetone) containing dithizone as chelating agent is injected into microextraction cell. Then an aqueous sample is injected into microextraction cell until the mixture of solvent forms initial state a homogeneous solution and then forms an emulsion consisting of fine droplets of the extraction solvent, disperser solvent and water. Using air flotation, the extraction solvent is transferred to the surface of the mixture and is collected by means of a micro-syringe. Then 25 µl of the collected organic solvent is diluted with 800 µl decanol and is analyzed with spectrophotometer in 520 nm wavelength. Also, the thermochemistry of complexation reactions was investigated at PM6 and B3LYP/6-31G* computational level.
Journal of the Brazilian Chemical Society, 2014
A determinação de chumbo e cádmio por espectrometria de absorção atômica de chama após a extração... more A determinação de chumbo e cádmio por espectrometria de absorção atômica de chama após a extração de fase sólida do óxido de grafeno (GO) utilizando o 4-acetamidotiofenol (ATP) como reagente quelante foi descrita. PM6 semi-empírico e a teoria de densidade funcional PBE foram os métodos usados na investigação do mecanismo de adsorção dos complexos em folhas de GO. Os principais fatores que influenciam a pré-concentração e determinação de analitos (pH, quantidade de ATP, tipo e concentração de eluente, fluxo e volume de amostra) foram examinados em detalhe. O efeito de íons interferentes no fator separação-pré-concentração também foi investigado. Para soluções de Pb(II) e Cd(II) 1,0 µg L −1 , o fator de pré-concentração chegou a 250 (em condições otimizadas). Os limites de detecção para Pb(II) e Cd(II) foram 170 e 80 ng L −1 , respectivamente. A validade do método proposto foi checada com materiais de referência padrão e foi aplicado com sucesso na determinacao de traços de Pb(II) e Cd(II) em amostras de água, ervas e peixe com recuperação de 99,4-103,5%. The determination of lead and cadmium by flame atomic absorption spectrometry after solid phase extraction on graphene oxide column with use of 4-acetamidothiophenol (ATP) as chelating reagent was described. PM6 semi-empirical and PBE density functional theory methods were used to investigation of adsorption mechanism of the complexes on GO sheet. The main factors influencing the preconcentration and determination of the analytes (pH, ATP amount, eluent type and concentration, flow rate and sample volume) were examined in detail. The effect of interfering ions on the separation-preconcentration of analytes was also investigated. For Pb(II) and Cd(II) solutions of 1.0 µg L −1 , the preconcentration factor was as high as 250 (under the optimized conditions). The detection limits for Pb(II) and Cd(II) were 170 and 80 ng L −1 , respectively. The validity of the proposed method was checked with standard reference materials and it has been successfully applied for the determination of trace Pb(II) and Cd(II) in water, herbal and fish samples with the recoveries of 99.4-103.5%.
Journal of Radioanalytical and Nuclear Chemistry, 2018
Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been ... more Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been investigated using a dioxa-diazamacrocycle and oleic acid as carrier and synergistic agents, respectively. Quantitative transport of uranyl ion was achieved within 4 h when the pH of source solution was kept at 5.0-6.0 and mole ratio of carrier to synergistic agent was 1/15. It was found that overall rate and selectivity of the transport is governed by the stripping step. Finally, the influence of some foreign competitor ions including Al 3? , Ca 2? , CO 3 2-, Cu 2? , Mg 2? , Pb 2? , Zn 2? and Th 4? and also the ionic strength on the transport efficiency has been evaluated.
Journal of Water Chemistry and Technology, 2018
Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extra... more Homogeneous liquid-liquid microextraction via flotation assistance method was developed for extraction of lead in water. A mixture of extraction solvent (1-decanol) and disperser solvent (acetone) containing dithizone as chelating agent is injected into microextraction cell. Then an aqueous sample is injected into microextraction cell until the mixture of solvent forms initial state a homogeneous solution and then forms an emulsion consisting of fine droplets of the extraction solvent, disperser solvent and water. Using air flotation, the extraction solvent is transferred to the surface of the mixture and is collected by means of a micro-syringe. Then 25 µl of the collected organic solvent is diluted with 800 µl decanol and is analyzed with spectrophotometer in 520 nm wavelength. Also, the thermochemistry of complexation reactions was investigated at PM6 and B3LYP/6-31G* computational level.
Quarterly Journal of Applied Chemical Research, 2017
The present work was undertaken to evaluate the feasibility of nickel (II) removal from aqueous s... more The present work was undertaken to evaluate the feasibility of nickel (II) removal from aqueous solution by adsorption onto a biopolymer adsorbent. The adsorbent was prepared using modification of mesoporous silicate SBA-15 with alginate biopolymer (alginateSBA-15) by encapsulation method. Morphological structure of the obtained nanocomposite adsorbent was characterized by XRD, scanning electron microscopy, nitrogen porosimetry technique, and fourier transform infrared spectroscopy. Batch adsorption experiments were carried out to investigate influence of operational parameters such as pH, contact time and initial concentration on alginate-SBA-15 adsorption behavior. Kinetics study revealed that the pseudo-second-order model provided well mathematical description of the experimental data. Out of several isotherm models, the Langmuir, Ferundlich, Dubinin-Radushkevich, RedlichPeterson, and Temkin models were applied to adsorption data to estimate adsorption capacity. The equilibrium a...
International Journal of Engineering, 2016
Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence ... more Uranium (VI) sorption using an anionic exchanger resin, namely Amberlite IRA910, in the presence of sulfate anions was the subject of current study. Batch sorption experiments were carried out to evaluate the influence of operational parameters such as pH, contact time, initial concentration and existence of various anions (including phosphate, sulfate, chloride, fluoride, and nitrate) in the solution on Amberlite IRA910 sorption behavior. Experiments revealed that uranium adsorption was fulfiled at pH>3 and 50 min to amount of 80%. Kinetics study revealed that the pseudo-second-order model showed better curve-fitting regression of the experimental data than the pseudo-first-order one. Freundlich isotherm was also provided well mathematical description of sorption process than the Langmuir one. Uranium adsorption capacity of the sorbent was 1666.6 mmol g -1 . It was also revealed that the existence of various anion species in the solution could strongly affect the sorption of uranium using the Amberlite IRA910 anion exchanger resin.
Selective Nanopores in Graphene Sheet for Separation I-129 Isotope from Air
Journal of Advanced Physics, 2017
Molecular dynamic simulation was used to investigate the ability of nanoporous graphene membrane ... more Molecular dynamic simulation was used to investigate the ability of nanoporous graphene membrane in gas separation process. Three di-atomic gases (I2, N2 and O2) were considered, in which different pore sizes were modeled on graphene. The structure contains an impermeable movable wall (piston) to push the mixture gases toward the nanoporous graphene membrane. Two different simulations were carried out, with two different piston velocities. Two key factors in gases separation process are the pore size of graphene and the velocity of movable wall. The results revealed that I-129 separation was improved by using proper size of pore and by decreasing the velocity of movable wall. It was also found that the I-129 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-12 graphene configuration. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while I-129 was not adsorbed.
Simulation studies of the separation of Kr-85 radionuclide gas from nitrogen and oxygen across nanoporous graphene membranes in different pore configurations
The European Physical Journal Plus, 2016
Abstract.Separating molecular species is an important precursor for various applications. In this... more Abstract.Separating molecular species is an important precursor for various applications. In this work, we have utilized molecular dynamics (MD) simulations to examine how pore radius and structure affect the separation process. We show from MD simulations that 2-D graphene sheets with designed sub-nanometer pores can efficiently separate the Kr-85 radionuclide gas from an N2/O2 mixture. Three species of gases (Kr-85, N2 and O2 were considered in the simulation box in which different sizes and geometries of pores were modeled on the graphene sheet. The ( $ 30\times 30\times 80$ Å^3 simulation box contains a nanoporous graphene membrane in the middle of the box and two fixed walls with equal distances on both sides of the nanoporous graphene. The results revealed that Kr-85 separation was improved by using an optimized pore structure. It was also found that the Kr-85 gas radionuclides could be completely separated from nitrogen and oxygen molecules in the pore-7 configuration. Restriction of the molecular orientation largely prohibited the permeation of nitrogen molecules. It was also found that nitrogen was more strongly adsorbed onto the membrane than oxygen, while krypton was not adsorbed.
Molecular Perspective of Radionuclides Separation by Nanoporous Graphene Oxide Membrane
Chemical Product and Process Modeling, 2016
Graphene-derived membranes has gained much interest recently due to its promising potential in fi... more Graphene-derived membranes has gained much interest recently due to its promising potential in filtration and separation applications. Molecular Sieving phenomena of gas molecules in the interlayer of graphene oxide nanopore have been investigated using molecular dynamic (MD) simulation. We explore I-129 gas radionuclides sequestration from natural air in nanoporous graphene oxide membranes in which different sizes and geometries of pores were modeled on the graphene oxide sheet. In the present work, mean-squared displacement (MSD), diffusion, flow of gas and the number of crossed gas molecules through graphene oxide nanopore membrane have been calculated and the results showed, selective proper nanopores in graphene oxide membrane could dramatically improve separation. The aim of this paper is to show that for the well-defined pore size called P-12, it is possible to separate I-129 from a gas mixture containing I-129, O
Low-energy conformers of pamidronate and their intramolecular hydrogen bonds: a DFT and QTAIM study
Journal of Molecular Modeling, 2012
Extensive DFT and ab initio calculations were performed to characterize the conformational space ... more Extensive DFT and ab initio calculations were performed to characterize the conformational space of pamidronate, a typical pharmaceutical for bone diseases. Mono-, di- and tri-protic states of molecule, relevant for physiological pH range, were investigated for both canonical and zwitterionic tautomers. Semiempirical PM6 method were used for prescreening of the single bond rotamers followed by geometry optimizations at the B3LYP/6-31++G(d,p) and B3LYP/6-311++G(d,p) levels. For numerous identified low energy conformers the final electronic energies were determined at the MP2/6-311++G(2df,2p) level and corrected for thermal effects at B3LYP level. Solvation effects were also considered via the COSMO and C-PCM implicit models. Reasonable agreement was found between bond lengths and angle values in comparison with X-ray crystal structures. Relative equilibrium populations of different conformers were determined from molecular partition functions and the role of electronic, vibrational and rotational degrees of freedom on the stability of conformers were analyzed. For no level of theory is a zwitterionic structure stable in the gas-phase while solvation makes them available depending on the protonation state. Geometrically identified intramolecular hydrogen bonds were analyzed by QTAIM approach. All conformers exhibit strong inter-phosphonate hydrogen bonds and in most of them the alkyl-amine side chain is folded on the P-C-P backbone for further hydrogen bond formation.
Investigation of origin of stereo-selectivity of BF3·Et2O-promoted allylboration of aldehydes in the presence of (R)-pinanediol by computational method
Computational and Theoretical Chemistry, 2012
ABSTRACT The effect of position of BF3 on the BF3·Et2O-promoted allylboration of aldehydes in the... more ABSTRACT The effect of position of BF3 on the BF3·Et2O-promoted allylboration of aldehydes in the presence of (R)-pinanediol have been investigated. The results showed that the energy differences between TS-b2 and TS-a which has been regarded as two competing TS structures is very low, and TS-b2 is favorable only by about 0.9 and 2.5 kcal/mol in the gas phase and the solvent, respectively. Lack of 1,3-syn-pentane interaction in the TS-b2 case, and the withdrawing effect of BF3 as a Lewis acid could explain this phenomenon. NBO analysis showed that the coordination site is crucial in the amount of interaction between the O atom of aldehyde moiety with the B atom of chiral ligand. Attaching BF3 to the aldehyde moiety causes less interaction between the aforementioned two atoms. When BF3 is attached to the chiral ligand this interaction is increased. In this study acetaldehyde was used as a model instead of Ph(CH2)2CHO which was used in experimental work by Chen and Roush [Org. Lett. 12 (2010) 2706–2709].
Protective effect of rutin (vitamin p) against heme oxidation: A quantum mechanical approach
Computational and Theoretical Chemistry, 2012
ABSTRACT The methemoglobin (FeIIIHb) is product of the auto-oxidation of hemoglobin which cannot ... more ABSTRACT The methemoglobin (FeIIIHb) is product of the auto-oxidation of hemoglobin which cannot transport oxygen. Rutin (vitamin p) is one of the most important bioflavonoid with antioxidant activity in vivo and in vitro. Here, a systematic study of several interactions and arrangements between rutin, corresponding radical of rutin and methemoglobin (FeIIIHb) has been undertaken. Density Functional Theory (DFT) calculations by using B3LYP/6-31G* method were employed to calculate interaction energies, electronic states, and geometrical arrangements for the complex between the methemoglobin and rutin. Analysis of the theoretical bond dissociation enthalpy (BDE) values, for all OH sites of rutin, clearly shows the importance of the B-ring and the 3′-OH and 4′-OH groups in antioxidant reactivity. The results of calculations indicate that rutin and corresponding radical interact with methemoglobin with considerable stabilization energy and reduce the Fe(III) in the methemoglobin to Fe(II). Thus, rutin molecule plays a safeguard role against oxidative degradation of hemogolobin.
Computational and Theoretical Chemistry, 2012
Density functional theory (DFT) using B3LYP and split-valance 6-31G Ã basis set have been employe... more Density functional theory (DFT) using B3LYP and split-valance 6-31G Ã basis set have been employed to calculate the details of electronic structure and electronic energy of carbonic anhydrase enzyme active center (CA), six inhibitors of this enzyme including topiramate and its derivatives and its analogue, and complex between these inhibitors and active center of carbonic anhydrase. Also thermodynamic functions such as deprotonation enthalpy of inhibitors, standard enthalpies of formation ðDH f Þ, standard entropy of formation ðDS f Þ and standard Gibbs free energy of formation ðDG f Þ for six CA-inhibitor complexes are evaluated. The calculated results indicate that deprotonated inhibitors are coordinated to the Zn 2+ ion and all the complexes have tetrahedral geometry. According to the calculated thermodynamic functions substitution of sulfonamide group with hydroxyl reduces the tendency of inhibitor to bind to the active center of carbonic anhydrase. In all calculations solvent effects have been considered in water using SCRF method.
Australian Journal of Chemistry, 2012
The reactions of the HBr molecule with CH2CH2Cl (reaction R1), CH2CHCl2 (R2), CH2CH2Br (R3) and C... more The reactions of the HBr molecule with CH2CH2Cl (reaction R1), CH2CHCl2 (R2), CH2CH2Br (R3) and CH2CHBr2 (R4) are investigated by a dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points were calculated at the MPW1K/6–311+G(d,p) and BMK/6–311+G(d,p) levels. To refine the reaction enthalpy and energy barrier height of each reaction, single-point energy calculations were carried out by the G2M(RCC5) method based on the geometries optimized at the above-mentioned two levels. Using the canonical variational transition state theory or the canonical variational transition state theory with the small-curvature tunneling correction, the rate constants of HBr with CH2CH2Cl (R1), CH2CHCl2 (R2), CH2CH2Br (R3), and CH2CHBr2 (R4) were calculated over a wide temperature range of 200–2000 K at the G2M(RCC5)//MPW1K/6–311+G(d,p) level. The effect of chlorine or bromine substitution on the ethyl radical reactivity is discussed. Finally, the total rate con...
DFT exploration of adsorptive performances of borophene to small sulfur-containing gases
Journal of Molecular Modeling
Computational and Theoretical Chemistry, 2012
B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory has been used to investigate the ring size ef... more B3LYP/6-311++G(d,p)//B3LYP/6-31G(d) level of theory has been used to investigate the ring size effect on the Bellus-Claisen rearrangement. The results show the reaction has a high asynchronous character and there is no direct relationship between ring size and E a ; for example, the E a is almost the same amount for three-and five-member rings. Four-member rings however, have an unexpectedly higher E a. Reactants which have nitrogen as a heteroatom in their structures have lower E a in comparison to oxygen containing rings. The effect of solvent on the E a is considerable. In all of the cases, by increasing the polarity of solvents, the amount of E a decreases. The results show that the effect of solvent on E a for N as heteroatom is more than that of O. There is an inverse relation between solvent polarity and E a. This can be interpreted as higher stabilization effect of the polar solvents on TSs' structures comparing to less polar solvents which leads to lower E a .
Application of Response Surface Methodology to Optimize Photocatalytic Degradation Rate of Methylorange Using Nanoparticles of Nd Doped TiO 2
Energy and Environment Focus, 2016
A density functional theory study on the interaction of dipicolinic acid with hydrated Fe2+ cation
Computational and Theoretical Chemistry, 2016
The most feasible complexes formed between dipicolinic acid and hydrated Fe 2+ cation (namely, [F... more The most feasible complexes formed between dipicolinic acid and hydrated Fe 2+ cation (namely, [FeL(H 2 O) 3 ] and [FeL 2 ]) have been modeled using density functional theory. A comparison among several computational levels of theory and available X-ray data showed that the B3LYP/6-311G(d) computational level provides accurate geometrical parameters for geometry optimization of complexes. The energetics and thermochemistry of complexation reactions in the gas phase and solvated medium (PCM) were evaluated at the B3LYP/6-311G(d) and B3LYP/6-311++G(2df,pd)//B3LYP/6-311G(d) levels of theory. The calculated thermochemistry data exhibited high complexation energies for both complexes and decreasing in the exothermicity of complexation reactions when PCM model was included in the calculations. The calculated free energy changes of complexation reactions pointed to spontaneous procedures. Detailed analysis of energy levels and major composition of selected frontier orbitals were performed ...
The effect of external electric field and metal impurities on the interaction of HF and boraphene: a computational study
Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structur... more Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structure of boraphene (B 36 ) were investigated. The results show the highest change in electronic structure of doped-B 36 systems belongs to Al-B 36 structures wherein the gap energy of the system is decreased by 17.92%. DOS diagrams and absorption spectra of doped B 36 are compared to pristine and discussed. The capability of pristine and modified B 36 in the field of detection/adsorption of HF molecule has been evaluated. The calculated values of adsorption energies of 0.13, 0.63, 0.24, and 0.16 eV for adsorption of HF on pristine, Al-, Ga-, and P-B 36 and related DOS diagrams reveal that these systems are not superior host materials for detection/adsorption applications. It was found that the external electric field could increase the interaction between HF and B 36 systems leading to suggesting Al-B 36 as proper candidate for HF removal applications. Graphical abstract