scholarly journals Adsorption Wave of Vanadium Complex with 2,3–Dihydroxybenzaldehyde

2009 ◽  
Vol 4 (2) ◽  
pp. 24-27
Author(s):  
Ludmila Kiriyak ◽  
Natalia Cecoi ◽  
Tatiana Cazac ◽  
Mihail Revenco
Keyword(s):  
Adsorption Energy ◽  
Adsorption Equilibrium ◽  
Surface Concentration ◽  
Electrode Process ◽  
Vanadium Complex ◽  
Polarographic Behavior ◽  
Adsorption Parameters ◽  
Adsorbed Complex ◽  
Adsorption Wave ◽  
Attraction Constant

The polarographic behavior of the complex formed by V(V) and 2,3–dihydroxybenzaldehyde (2,3–DHBA) in the solution containing acetate buffer (pH 5,2) has been investigated. By means of a.c. polarography, chronovoltammetry and other techniques, it has been shown that the electrode process is complicated by the adsorption of 2,3-DHBA and its vanadium complex. The kinetic and adsorption parameters of the electrode process have been determined: adsorption equilibrium constant B= 1,32⋅105 mol-1⋅dm3, the attraction constant γ = 1,2, the maximum surface concentration Гmax = 9,10⋅10-11 mol⋅ cm-2; the share of the electrode surface occupied by one particle of the adsorbed complex S = 1,81 nm2 and the free adsorption energy ΔG = - 39,1 kJ· mol-1.

scholarly journals Modified Dual-Site Langmuir Adsorption Equilibrium Models from A GCMC Molecular Simulation

2020 ◽  
Vol 10 (4) ◽  
pp. 1311
Author(s):  
Junchao Wang ◽  
Yongjie Wei ◽  
Zhengfei Ma
Keyword(s):  
Molecular Simulation ◽  
Adsorption Energy ◽  
Pressure Swing Adsorption ◽  
Adsorption Equilibrium ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Adsorption Energies ◽  
Pressure Swing ◽  
Adsorption Equilibrium Data ◽  
Dual Site

In the modern industrial separation process, the pressure swing adsorption technology is widely used to separate and purify gases due to its low energy consumption, low cost, convenience, reliability, and environmental benignity. The basic elements of the design and application of the pressure swing adsorption process are adsorption isotherms at different temperatures for adsorbents. The dual-site Langmuir (DSL) adsorption equilibrium model is the mostly used model; however, this model is based on the assumption that the adsorption energy on the surface of an adsorbent is uniform and remains unchanged. Here, a grand canonical Monte Carlo (GCMC) molecular simulation was used to calculate the CO2 adsorption equilibrium on MIL-101 (Cr) at 298 K. MIL-101 (Cr) was chosen, as it has more a general pore structure with three different pores. The calculation results showed that the adsorption energies with different adsorption pressures fitted a normal distribution and the relationship of the average adsorption energies, E with pressures had a linear form described as: E = aP + c. With this relationship, the parameter b = k·exp(E/RT) in the DSL model was modified to b = k·exp((aP + c)/RT), and the modified DSL model (M-DSL) was used to correlate the adsorption equilibrium data on CO2-MIL-101 (Cr), C2H4-HHPAC, CH4-BPL, and CO2-H-Mordenite, showing better correlations than those of the DSL model. We also extended the parameter qm in the M-DSL model with the equation qm = k1 + k2T to adsorption equilibrium data for different temperatures. The obtained model (M-TDSL) was checked with the abovementioned adsorption equilibrium systems. The fitting results also indicated that the M-TDSL model could be used to improve the correlation of adsorption equilibrium data for different temperatures. The linear relationship between the average adsorption energy and adsorption pressure could be further tested in other adsorption equilibrium models to determine its universality.

scholarly journals Enhancing the Sensing Performance of Zigzag Graphene Nanoribbon to Detect NO, NO2, and NH3 Gases

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3932 ◽  
Author(s):  
Ehab Salih ◽  
Ahmad I. Ayesh
Keyword(s):  
Charge Transfer ◽  
Gas Sensors ◽  
Adsorption Energy ◽  
Gas Adsorption ◽  
Epoxy Group ◽  
Graphene Nanoribbon ◽  
Hydroxyl Group ◽  
Adsorption Parameters ◽  
Oh Groups ◽  
Sensing Performance

In this article, a zigzag graphene nanoribbon (ZGNR)-based sensor was built utilizing the Atomistic ToolKit Virtual NanoLab (ATK-VNL), and used to detect nitric oxide (NO), nitrogen dioxide (NO2), and ammonia (NH3). The successful adsorption of these gases on the surface of the ZGNR was investigated using adsorption energy (Eads), adsorption distance (D), charge transfer (∆Q), density of states (DOS), and band structure. Among the three gases, the ZGNR showed the highest adsorption energy for NO with −0.273 eV, the smallest adsorption distance with 2.88 Å, and the highest charge transfer with −0.104 e. Moreover, the DOS results reflected a significant increase of the density at the Fermi level due to the improvement of ZGNR conductivity as a result of gas adsorption. The surface of ZGNR was then modified with an epoxy group (-O-) once, then with a hydroxyl group (-OH), and finally with both (-O-) and (-OH) groups in order to improve the adsorption capacity of ZGNR. The adsorption parameters of ZGNR were improved significantly after the modification. The highest adsorption energy was found for the case of ZGNR-O-OH-NO2 with −0.953 eV, while the highest charge transfer was found for the case of ZGNR-OH-NO with −0.146 e. Consequently, ZGNR-OH and ZGNR-O-OH can be considered as promising gas sensors for NO and NO2, respectively.

Designing and Encapsulation of Inorganic Al12N12 Nanoclusters with Be, Mg, and Ca Metals for Efficient Hydrogen Adsorption: A Step Forward Towards Hydrogen Storage Materials

2021 ◽  
pp. 1-19
Author(s):  
Muhammad Yasir Mehboob ◽  
Riaz Hussain ◽  
Zobia Irshad ◽  
Ume Farwa ◽  
Muhammad Adnan ◽  
...  
Keyword(s):  
Optical Properties ◽  
Hydrogen Storage ◽  
Adsorption Energy ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Energy Gap ◽  
Earth Metal ◽  
Partial Density ◽  
Geometrical Parameters ◽  
Adsorption Parameters

Nanoclusters such as Al[Formula: see text]N[Formula: see text] have received increased attention due to their diverse applications in the fields of optoelectronics and energy storage. In this paper, we have investigated a series of alkaline earth metal (AEM)-encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters for hydrogen adsorption. Thermodynamic adsorption parameters, optical and nonlinear optical properties were investigated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. Encapsulation of AEMs (Be, Mg and Ca) is an effective strategy to improve the NLO reaction and thermodynamic and adsorption properties of Al[Formula: see text]N[Formula: see text] nanoclusters. The adsorption energies ranging from [Formula: see text]26.57[Formula: see text]kJ/mol to [Formula: see text]213.33[Formula: see text]kJ/mol for the three guests (Be, Mg and Ca) capsulated Al[Formula: see text]N[Formula: see text] nanoclusters are observed. The adsorption energy is affected by the size of the nanocage. Therefore, Ca- and Mg-encapsulated cages show higher values of adsorption energy. Overall, an increase in adsorption energy ([Formula: see text][Formula: see text]kJ/mol to [Formula: see text]91.06[Formula: see text]kJ/mol) is observed for (Be, Mg and Ca) encapsulated Al[Formula: see text]N[Formula: see text] nanoclusters compared to untreated Al[Formula: see text]N[Formula: see text] and H2-Al[Formula: see text]N[Formula: see text] cages. Moreover, adsorption of hydrogen on AEMs encapsulated in Al[Formula: see text]N[Formula: see text] leads to a decrease in the HOMO-LUMO energy gap with an enhancement of linear and nonlinear hyperpolarizability. All hydrogen-adsorbed AEMs Al[Formula: see text]N[Formula: see text] nanocages exhibit large [Formula: see text] and [Formula: see text] values, suggesting that these systems are potential candidates for optical materials. Various geometrical parameters such as frontier molecular orbitals (FMOs), partial density of states, global quantum descriptor of reactivity, natural bond orbital testing and molecular electrostatic strength analyses were performed to investigate the thermodynamic stability of all the studied systems. The results obtained confirmed that the designed systems are suitable for hydrogen storage. Therefore, we recommend that these systems be investigated for their hydrogen storage and optical properties.

Methylene Blue Adsorption onto NaOH Treated Leucaena leucocephala Leaf Power

2015 ◽  
Vol 752-753 ◽  
pp. 251-256
Author(s):  
Megat Ahmad Kamal Megat Hanafiah ◽  
Noor Fhadzilah Mansur ◽  
Wan Mohd Nazri Wan Ab Rahman ◽  
Mardhiah Ismail
Keyword(s):  
Methylene Blue ◽  
Industrial Wastewater ◽  
Adsorption Equilibrium ◽  
Langmuir Model ◽  
Maximum Adsorption Capacity ◽  
Order Model ◽  
Adsorption Parameters ◽  
Leaf Powder ◽  
Pseudo Second Order ◽  
Kinetics And Isotherms

The potential of sodium hydroxide (NaOH) modified Petai Belalang (Leucaenaleucocephala) leaf powder as a biosorbent for methylene blue removal from aqueous solutions was investigated. Adsorption parameters studied include initial dye concentration, pH, dosage, kinetics and isotherms. The pHzpc of chemically treated Leucaenaleucocephala leaf powder was 7.50 and adsorption equilibrium time was achieved after 60 min. The kinetic data was best represented by the pseudo-second order model. The maximum adsorption capacity predicted from Langmuir model was 208.33 mg g-1. This work indicated that NaOH treated Leucaenaleucocephala leaf powder can be an attractive biosorbent for MB removal from diluted industrial wastewater.

Surface behaviour of tetrapropylammonium cation at the mercury/solution interface measured by use of controlled convective adsorptive accumulation

1985 ◽  
Vol 50 (11) ◽  
pp. 2525-2534 ◽  
Author(s):  
Ladislav Novotný ◽  
Ivan Smoler
Keyword(s):  
Surface Tension ◽  
Adsorption Isotherms ◽  
Adsorption Energy ◽  
Surface Coverage ◽  
Adsorption Parameters ◽  
Surface Tension Data ◽  
Solution Interface ◽  
Constant Potential ◽  
Drop Time ◽  
Constant Charge

Using drop time technique with long drop times and a controlled convection of the solution the surface tension data of Hg with tetrapropylammonium perchlorate in 0.1 mol l-1 NaClO4 in the concentration range 4 . 10-6 - 3 . 10-3 mol l-1 have been obtained. The corresponding adsorption parameters have been evaluated from the Frumkin isotherm both at constant potential E and at constant charge q. Both E and q could be chosen as an independent electrical variable. The maximum free adsorption energy amounts to approx. -36.5 kJ mol-1. The congruence of adsorption isotherms with respect to E and with respect to q was very well fulfilled for the surface coverage Θ ⪬ 0.6-0.7.

Role of the solvent in the oxidative process of a Hg electrode in the presence of thiopyrimidine derivatives

2005 ◽  
Vol 83 (8) ◽  
pp. 1132-1136
Author(s):  
Souad Bakari ◽  
Marco Borsari ◽  
Maria Cannio ◽  
Giovanna Gavioli ◽  
Antonio Ranieri ◽  
...  
Keyword(s):  
Solvent Effect ◽  
Electrochemical Oxidation ◽  
Electrochemical Process ◽  
Oxidative Process ◽  
Adsorption Model ◽  
Adsorption Parameters ◽  
Adsorption Wave ◽  
Adsorption Phenomena ◽  
Solvent Properties

The electrochemical oxidation of a Hg electrode in the presence of thiopyrimidine derivatives has been investigated in a collection of organic solvents using voltammetric and polarographic techniques. Remarkable adsorption phenomena control the electrochemical process, which in all cases gives rise to a Hg(I) complex. The Laviron adsorption model is found to describe well the polarographic adsorption wave. Some correlations between adsorption parameters and solvent properties have also been observed and discussed.Key words: polarography, voltammetry, thiopyrimidine, solvent effect, adsorption.

Etude polarographique des méthoxyhydroperoxydes

1969 ◽  
Vol 47 (18) ◽  
pp. 3333-3343 ◽  
Author(s):  
Jean Renard ◽  
Sándor Fliszár
Keyword(s):  
Quantitative Determination ◽  
Electrode Process ◽  
Analytical Application ◽  
Polarographic Behavior

The polarographic behavior of selected α-methoxyhydroperoxides, produced by ozonization of olefins in methanol, has been studied. A mechanism is proposed for the electrode process. An analytical application for the quantitative determination of these methoxyhydroperoxides and for the study of the mechanism of ozonolysis of unsymmetrical olefins is described.

Adsorption of humic and fulvic acid on copper surfaces

2010 ◽  
Vol 10 (6) ◽  
pp. 915-922
Author(s):  
Arturo Reyes ◽  
María Victoria Letelier ◽  
Gustavo Lagos
Keyword(s):  
Fulvic Acid ◽  
Natural Organic Matter ◽  
Adsorption Equilibrium ◽  
Copper Surface ◽  
Adsorption Parameters ◽  
Copper Surfaces ◽  
Langmuir Adsorption ◽  
Copper Foils ◽  
Pseudo Second Order ◽  
Main Components

The presence of natural organic matter (NOM) in drinking water can increase the levels of copper released from copper pipes to water and inhibit the formation of protective deposits such as malachite. Since adsorption of NOM on copper pipes surfaces is believed to be one of mechanisms that explains this phenomenom, the objective of this study was to determine kinetics and the adsorption equilibrium of main components of NOM, humic acid (HA) and fulvic acid (FA), onto copper surfaces. The kinetics and equilibrium adsorption of HA and FA on copper foils were examined using batch experiments at 22°C. HA and FA followed pseudo second-order kinetics adsorption. Rate constants measured were 2.59 × 10−1 (mgTOC cm−2 h−1) for HA and 3.13 × 10−1 (mgTOC cm−2 h−1) for FA. The adsorption behavior of HA and FA on the copper surface is in accordance with the Langmuir adsorption isotherm. Langmuir adsorption constants measured were 5.98 × 10−2 L mg−1 for HA and 4.78 × 10−2 L mg−1 for FA. The copper foils exposed during five months to FA formed malachite deposits, whereas those exposed to HA did not and just cuprite was found. The results of this study showed that both HA as well as FA adsorption on copper surfaces is favored and no significant differences were found in the adsorption parameters calculated for both compounds. However, the inhibition of the malachite precipitation could be attributed to the HA adsorption.

STUDY OF ADSORPTION EQUILIBRIUM OF SOME WET AIRCOMPOSITE MATERIAL SYSTEMS

2009 ◽  
Vol 8 (2) ◽  
pp. 253-257 ◽  
Author(s):  
Stelian Petrescu ◽  
Ioan Mamaliga ◽  
Constantin Baciu
Keyword(s):  
Adsorption Equilibrium ◽  
Material Systems

Kinetic and thermodynamic study of the adsorption of calcium onto sugar beet pulp

2016 ◽  
pp. 565-570
Author(s):  
Huang Qin ◽  
Zhu Si-ming ◽  
Zeng Di ◽  
Yu Shu-juan
Keyword(s):  
Sugar Beet ◽  
Adsorption Equilibrium ◽  
Ph Value ◽  
Hard Water ◽  
Sugar Beet Pulp ◽  
Order Kinetic ◽  
Factors Affecting ◽  
Isotherm Equation ◽  
Equilibrium Data ◽  
Beet Pulp

Sugar beet pulp (SBP) was used as low value adsorbent for the removal of calcium from hard water. Batch experiments were conducted to determine the factors affecting adsorption of the process such as pH value and Ca concentration. The adsorption equilibrium of Ca2+ by the SBP is reached after 100min and a pseudo second-order kinetic model can describe the adsorption process. The initial concentrations of Ca varied from 927 to 1127mgCa2+/L. A dose of 30g/L sugar beet pulp was sufficient for the optimum removal of calcium. The overall uptake of Ca ions by sugar beet pulp has its maximum at pH=8. The adsorption equilibrium data fitted well with the Langmuir adsorption isotherm equation.

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