Combined experimental and quantum chemical study on the adsorption mechanism of phosphorous anions on the hydrotalcite surfaces

2016 ◽  
Vol 09 (05) ◽  
pp. 1650061 ◽  
Author(s):  
Kenji Mishima ◽  
Shuang Zhang ◽  
Sho Minagawa ◽  
Naoki Kano
Keyword(s):  
Quantum Chemistry ◽  
Adsorption Mechanism ◽  
Reaction Pathway ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Phosphate Removal ◽  
Experimental Result ◽  
Stable States ◽  
Quantum Chemistry Calculations ◽  
Sorbent Materials

In the present work, the hydrotalcite-like compound [Mg6Al2(OH)[Formula: see text]]CO[Formula: see text] [Formula: see text]H2O (shorted as MgAl–CO[Formula: see text] is synthesized and the adsorption of phosphorous anions, their adsorption performance on the surface of hydrotalcites, and its mechanism are analyzed. To theoretically clarify the adsorption mechanism and adsorption structures, we perform quantum chemistry calculations of reactants, locally stable states, transition states, and products among phosphorous anion, water, and hydrotalcite in a variety of pH ranges. The experimental result shows that the efficiency of phosphate removal does not depend on pH of the solution, with which the numerical results are consistent. In particular, we identify the factors of influencing the adsorption ratio in different pH ranges from the quantum chemistry calculations: the stability of locally stable states, and the energies and locations of potential barriers along the reaction pathway relative to those of the locally stable states. The results suggest that hydrotalcites synthesized in this work are suitable as sorbent materials for the adsorption and removal of phosphorous anions from aqueous solutions.

scholarly journals Adsorption and Desorption Mechanisms of Rare Earth Elements (REEs) by Layered Double Hydroxide (LDH) Modified with Chelating Agents

2019 ◽  
Vol 9 (22) ◽  
pp. 4805 ◽  
Author(s):  
Shuang Zhang ◽  
Naoki Kano ◽  
Kenji Mishima ◽  
Hirokazu Okawa
Keyword(s):  
Rare Earth ◽  
Quantum Chemistry ◽  
Rare Earth Elements ◽  
Adsorption Capacity ◽  
Density Functional ◽  
Stable State ◽  
Experimental Result ◽  
Adsorption And Desorption ◽  
Adsorption Affinity ◽  
Quantum Chemistry Calculations

In order to obtain the adsorption mechanism and adsorption structures of Rare Earth Elements (REEs) ions adsorbed onto layered double hydroxides (LDH), the adsorption performance of LDH and ethylenediaminetetraacetic acid (EDTA) intercalated LDH for REEs was investigated by batch experiments and regeneration studies. In addition to adsorption capacity, the partition coefficient (PC) was also evaluated to assess their true performance metrics. The adsorption capacity of LDH increases from 24.9 μg·g−1 to 145 μg·g−1 for Eu, and from 20.8 μg·g−1 to 124 μg·g−1 for La by intercalating EDTA in this work; and PC increases from 45.5 μg·g−1·uM−1 to 834 μg·g−1·uM−1 for Eu, and from 33.6 μg·g−1·μM−1 to 405 μg·g−1·μM−1 for La. Comparison of the data indicates that the adsorption affinity of EDTA-intercalated LDH is better than that of precursor LDH no matter whether the concept of adsorption capacity or that of the PC was used. The prepared adsorbent was characterized by XRD, SEM-EDS and FT-IR techniques. Moreover, quantum chemistry calculations were also performed using the GAUSSIAN09 program package. In this calculation, the molecular locally stable state structures were optimized by density functional theory (DFT). Both the quantum chemistry calculations and the experimental data showed that REEs ions adsorbed by EDTA-intercalated LDH are more stable than those adsorbed by precursor LDH. Furthermore, the calculation results of adsorption and desorption rates show that adsorption rates are larger for Eu(III) than for La(III), which agrees with the experimental result that Eu(III) has a higher adsorption ability under the same conditions. The LDHs synthesized in this work have a high affinity for removing REEs ions.

scholarly journals Lactamomethylation of alkylphenols: synthesis and quantum-chemical study of the reaction pathway

2021 ◽  
pp. 103424
Author(s):  
Stepan V. Vorobyev ◽  
Olga V. Primerova ◽  
Sergey Yu. Bylikin ◽  
Vladimir N. Koshelev
Keyword(s):  
Quantum Chemical ◽  
Reaction Pathway ◽  
Quantum Chemical Study ◽  
Chemical Study

A Quantum-chemical Study of the Corrosion Inhibition of Iron by Means of Aniline Derivatives in Hydrochloric Acid

CORROSION ◽  
1976 ◽  
Vol 32 (5) ◽  
pp. 183-187 ◽  
Author(s):  
JAN VOSTA ◽  
JAROSLAV ELIASEK ◽  
PETR KNIZEK
Keyword(s):  
Hydrochloric Acid ◽  
Quantum Chemistry ◽  
Organic Compounds ◽  
Corrosion Inhibition ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Electrochemical Corrosion ◽  
Chemical Study ◽  
Substituted Anilines ◽  
Inhibition Process

Abstract When various properties of organic compounds are to be expressed, it is necessary to explore the connection between their experiment and theory. To determine the mechanism of the inhibition process by organic materials, the electron structure of a set of organic compounds is studied and correlated with their electrochemical corrosion measurements. This paper discusses the inhibition of corrosion in 5% hydrochloric acid by means of p-substituted anilines with respect to quantum chemistry.

scholarly journals Quantum-chemical study of mechanisms of sulfonation of benzoic and benzenesulfonic acids hydrazides in the gas phase

2020 ◽  
Vol 62 (5) ◽  
pp. 107-115
Author(s):  
Ludmila B. Kochetova ◽  
◽  
Tatyana P. Kustova ◽  
Alyona A. Kruglyakova ◽  
◽  
...  
Keyword(s):  
Transition State ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Potential Energy Surfaces ◽  
Reaction Pathway ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Attack Angle ◽  
Nucleophilic Attack ◽  
Single Transition

Quantum-chemical simulation of the mechanisms of 3-nitrobenzenesulfonyl chloride interaction with benzhydrazide (RHF/6-31G(d)) and benzenesulfohydrazide (DFT//B3LYP/6 311G(d,p)) in the gas phase was carried out. Three-dimensional potential energy surfaces of these processes are calculated in the coordinates of the angle of attack of the nucleophile and the distance between the reacting molecules. It has been established that in the both cases considered, reactions can proceed in the gas phase along a single route, through a single saddle point corresponding to a single transition state; processes begin as an axial attack of nucleophile, which subsequently proceeds with a decrease in the attack angle as the reagents molecules approach each other. It was shown that the both studied processes proceed in accordance with the bimolecular concerted mechanism of nucleophilic substitution SN2, which involves the formation of a single transition state in a reaction pathway and the absence of intermediates on it. Scanning the internal coordinate of benzhydrazide reaction with 3-nitrobenzenesulfonyl chloride made it possible to confirm the reaction route and mechanism of the process pointed out and to clarify the structure of its products and reagents. It was found that the geometric structure of the reaction center in the reactions transition states is medium between the trigonal-bipyramidal and tetragonal-pyramidal, which is due to the change in the nucleophilic attack angle when the reagents molecules approach each other. It was found that in reactions involving hydrazides a “synchronous” transition state is formed in which a new S-N bond is formed simultaneously with the loosening of the old S-Cl bond. The activation energies of the reactions are calculated; they amounted to 173 and 113 kJ/mol, respectively. The high values obtained are explained by the fact that the simulation was carried out for processes occurring in a gas hase. It was shown that the decrease in the activation energy of the reaction involving benzenesulfohydrazide as compared to the benzhydrazide reaction is due to a decrease in steric hindrances during nucleophilic attack created by the lone electron pair of the benzenesulfohydrazide secondary amino group as compared to the benzhydrazide molecule. The calculated values of charges on the nitrogen atoms of the –NH– groups in the hydrazides molecules indicate a weakening of the α-effect upon the transition from benzenesufohydrazide to benzhydrazide.

A quantum chemical study of the acidity of acetylene and 1,2-dihydrobuckminsterfullerene de-rivatives

2018 ◽  
Vol 59 (1) ◽  
pp. 51-53
Author(s):  
M. V. Makarova ◽  
◽  
S. G. Semenov ◽  
R. R. Kostikov ◽  
◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study
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