Hydroxyproline adsorption on a mercury electrode in neutral solution

1991 ◽  
Vol 69 (10) ◽  
pp. 1528-1534 ◽  
Author(s):  
M. M. Gómez
Keyword(s):  
Dipole Moment ◽  
Adsorption Process ◽  
Normal Component ◽  
Mercury Electrode ◽  
Hydroxyl Group ◽  
Neutral Solution ◽  
Pyrrolidine Ring ◽  
Adsorption Parameters ◽  
Gibbs Energies ◽  
Comparison Of The Results

The adsorption of hydroxyproline (HPRO) on mercury in aqueous solutions of 10−2 M KClO4 has been determined from electrocapillary and capacity measurements. Comparison of the results obtained for HPRO with those reported for proline (PRO) shows that the presence of a hydroxyl group in the molecule has a small effect on the adsorption process. The respective values for adsorption parameters are −7 and −5 μC cm−2 for the charges of maximum adsorption, −13.0 and −10.4 kj mol−1 for the standard Gibbs energies of adsorption at zero charge, and −1.28 and +0.6 for the α parameter in the Frumkin isotherms. According to the analysis carried out for the normal component of the dipole moment of HPRO, −0.8 D, the more probable orientation of this aminoacid adsorbed on mercury is with the pyrrolidine ring parallel to the electrode surface resting the OH group away from the surface. Key words: adsorption, double layer, aminoacids, hydroxyproline.

Effects of Langmuirian adsorption on the potentiostatic response at spherical and planar electrodes

1991 ◽  
Vol 56 (1) ◽  
pp. 42-59 ◽  
Author(s):  
María-Luisa Alcaraz ◽  
Jesús Gálvez
Keyword(s):  
Power Law ◽  
Adsorption Process ◽  
Asymptotic Solutions ◽  
Planar Electrodes ◽  
Comparison Of The Results

Equations for a potentiostatic reaction with an adsorption process following Langmuir’s isotherm have been derived for the expanding sphere with any power law electrode model. This model is very general and includes, among others, the following ones: (a) stationary plane; (b) stationary sphere; (c) expanding plane; and (d) expanding sphere. Characteristics of these solutions and the behavior of the corresponding asymptotic solutions are discussed. A comparison of the results obtained for plane and spherical electrodes has also been performed.

Studies of a Mixed Adsorption Layer of Butan-1-ol and o-Toluidine on Mercury Electrode

2002 ◽  
Vol 67 (11) ◽  
pp. 1579-1588 ◽  
Author(s):  
Dorota Sieńko ◽  
Dorota Gugała ◽  
Jolanta Nieszporek ◽  
Joanna Jankowska ◽  
Jadwiga Saba
Keyword(s):  
Thermodynamic Analysis ◽  
Adsorption Layer ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Interaction Constant ◽  
Repulsive Interaction ◽  
Surface Excess ◽  
Adsorption Parameters ◽  
Frumkin Isotherm ◽  
Adsorption Layers

The results of thermodynamic analysis of o-toluidine adsorption on a mercury electrode in the presence of various butan-1-ol amounts complete our previous studies on properties of mixed adsorption layers of toluidine isomers-butan-1-ol. The values of the relative surface excess Γ'°T obtained for o-toluidine show that adsorption of this compound decreases with increasing of butan-1-ol concentration. Analysis of adsorption parameters derived from the Frumkin isotherm indicates that in the presence of 0.33 M BuOH in 1 M NaClO4 with adjusted pH 3 as supporting electrolyte, ∆G0 values for o-toluidine are the highest and, at the same time, the strongest repulsive interaction occurs. In the presence of 0.11 M butan-1-ol, smaller values of ∆G0 for o-toluidine correspond to weaker repulsive interaction. Therefore the change of the Γ'°T value for o-toluidine as a function of butan-1-ol concentration is the result of mutual changes of ∆G0 and interaction constant A between adsorbate molecules.

scholarly journals Synthesis of Zeolite from Carbothermal Reduction Electrolytic Manganese Residue for the Removal of Macrolide Antibiotics from Aqueous Solution

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2133 ◽  
Author(s):  
Xuli Li ◽  
Yue Zeng ◽  
Fangyuan Chen ◽  
Teng Wang ◽  
Yixin Li ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Carbothermal Reduction ◽  
Adsorption Process ◽  
Hydroxyl Group ◽  
Macrolide Antibiotics ◽  
Adsorption Sites ◽  
Electrolytic Manganese ◽  
Electrolytic Manganese Residue ◽  
Pseudo Second Order ◽  
The Fourier Transform

Zeolite analcime (EMANA) was synthesized through the hydrothermal method by using carbothermal reduction electrolytic manganese residue (CR-EMR). The structural properties of EMANA and CR-EMR were studied using various characterization techniques. After hydrothermal synthesis, the CR-EMR became super-microporous, and the surface area increased by 4.76 times than before. Among the various synthesized zeolites, 6 h-synthesized EMANA was selected as the best adsorbent for macrolide antibiotics in aqueous solution. The adsorption performance of EMANA on the adsorption capacity was examined by using various experimental parameters, such as contact time (0–24 h), initial concentration (50–300 mg/L), temperature (30–50 °C) and pH (3–13). The experimental results were also analyzed by the Langmuir and Freundlich adsorption models, with the latter obtaining better representation. The adsorption process could be described well by the pseudo-second-order model, even under a low concentration (50 mg/L). This result suggests that the adsorption process of macrolide antibiotics is due to chemisorption. According to the Fourier Transform infrared spectroscopy (FT-IR) results, the adsorption of zeolite was mainly due to its hydroxyl group, which played an important role during the adsorption process. Moreover, EMANA is more suitable for treatment of roxithromycin (ROX) than azithromycin (AZM), because ROX has more adsorption sites for the hydroxyl group.

Optimization of the Adsorption Process of Bezaktiv Turquoise Blue «VG» Textile Dye onto Diatomite Using the Taguchi Method

2018 ◽  
Vol 762 ◽  
pp. 81-86 ◽  
Author(s):  
Hakim Aguedal ◽  
Abdelkader Iddou ◽  
Janis Locs
Keyword(s):  
Taguchi Method ◽  
Adsorption Capacity ◽  
Contact Time ◽  
Adsorption Process ◽  
Removal Rate ◽  
Textile Dye ◽  
Adsorption Parameters ◽  
Thermal Regeneration ◽  
Factors Affecting ◽  
Relevant Factors

A design of experiments based on the Taguchi method was used to evaluate the main parameters affecting the removal of textile dyes from aqueous solution. By using the adsorption capacity of textile dye as target response, several experiments were carried out using L27 orthogonal array, and the higher-the-better as quality characteristics was applied. The controlling factors, including initial dye concentration, contact time and pH of solution were assessed. Analysis of variance (ANOVA) was used to determine the effects of each factor on the adsorption capacity. The optimum adsorption conditions giving higher adsorption capacity were selected as initial dye concentration of 500 mg.L-1, contact time of 180 min and pH of solution of 2. The analysis results revealed that the most relevant factors affecting the adsorption process of textile dye are the initial dye concentration and pH of solution. After 3 cycles of thermal regeneration, the diatomite behavior did not change and more than 60 % of dye was eliminated from solution after regeneration at 600°C. From the obtained results, the Taguchi method was very successful to optimize of the adsorption parameters for maximum removal rate, and gives more credibility for industrial application.

Effect of Fe(III) on specific adsorption of aliphatic carbamide derivatives at the dropping mercury electrode

1983 ◽  
Vol 48 (11) ◽  
pp. 3253-3260
Author(s):  
Joanna Masłowska ◽  
Halina Czerwinska
Keyword(s):  
Adsorption Isotherms ◽  
Adsorption Process ◽  
Mercury Electrode ◽  
Specific Adsorption ◽  
Frumkin’S Isotherm ◽  
Dropping Mercury Electrode ◽  
Free Molecules

The specific adsorption of carbamide and its aliphatic derivatives (L) was studied by the droptime method in the system Fe(ClO4)3-L-HClO4-H2O, and the adsorption process was elucidated. From the calculated surface concentrations and adsorption isotherms, it was found that the adsorption of aliphatic carbamide derivatives is higher in the presence of Fe(III) ions than in their absence under the same conditions. In the presence of Fe(III) ions at the interface, free molecules of carbamide derivatives and the complexes [Fe(H2O)6-nLn]3+ as well as the complexes [Fe(H2O)5-nLnLads]3+ and [Fe(H2O)5-nLnLads]2+ formed with the adsorbed ligand are adsorbed. The adsorption was found to proceed according to the Frumkin's isotherm.

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.

Alternating current polarography of organic compounds. V. Quantitative treatment of the adsorption process

1956 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
B Breyer ◽  
HH Bauer
Keyword(s):  
Organic Compounds ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Mercury Electrode ◽  
Alternating Current ◽  
Qualitative Explanation ◽  
Calibration Curves ◽  
Adsorbent Surface ◽  
Dropping Mercury Electrode ◽  
Quantitative Treatment

Equations are derived to express the adsorption equilibrium subsisting at an adsorbent surface in the presence of two adsorbable species. These equations are applied to the case of the reduction of organic compounds at the dropping mercury electrode. It is well known that adsorption at the electrode can produce irreversibility in the D.C. step, and a qualitative explanation is provided. The same treatment is used to explain the shape of the A.C. calibration curves.

Studies on the adsorption and the association of cytidine sulphate at the dropping mercury electrode with phase-sensitive ac-polarography

1979 ◽  
Vol 57 (10) ◽  
pp. 1136-1140 ◽  
Author(s):  
Yassein M. Temerk
Keyword(s):  
Mercury Electrode ◽  
Threshold Value ◽  
Adsorption Potential ◽  
Buffer Solution ◽  
Adsorption Parameters ◽  
Solution Ph ◽  
Adsorbed Molecules ◽  
Oriented Molecules ◽  
Dropping Mercury Electrode ◽  
Phase Sensitive

The adsorption and association of cytidine sulphate have been studied by using phase-sensitive ac-polarography in acidic buffer solution (pH 3.24) at the dropping mercury electrode. At low bulk concentrations, adsorbed molecules of cytidine sulphate at maximal adsorption potential (−0.7 V) are orientated in 'dilute' adsorption layer planar to the electrode surface where the interaction of π-electrons with interface favours adsorption. At bulk concentrations above a threshold value (6.6 × 10−3 M), the stacking interactions between vertically oriented molecules lead to association and formation of a compact layer; and a pit is observed. The concentration dependence of the ac-capacity current at a maximal adsorption potential (−0.7 V) shows a two-step Frumkin isotherm due to association of the adsorbed molecules. The adsorption parameters are computed and discussed.

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