Adsorption isotherms for coadsorption studies from solution

1986 ◽  
Vol 64 (2) ◽  
pp. 328-332 ◽  
Author(s):  
Panaghiotis Nikitas ◽  
Adriani Pappa-Louisi
Keyword(s):  
Adsorption Isotherms ◽  
Lattice Theory ◽  
Adsorption Layer ◽  
Statistical Thermodynamics ◽  
Bulk Solution ◽  
Regular Solutions ◽  
State Equations ◽  
Electrolyte Bulk ◽  
Thermodynamic Restrictions

The mixed adsorption of k adsorbates from solution on energetically homogeneous surfaces is studied by means of lattice statistical thermodynamics. The adsorption layer is considered to behave as a non-electrolyte bulk solution composed from k adsorbates and solvent. On the basis of this assumption the adsorption isotherms and their state equations are determined by means of the lattice theory of strictly regular solutions and Flory–Huggins statistics. The thermodynamic restrictions imposed when these models have to be applied to real systems are also determined and discussed.

Investigation of Ion Transport in Polypyrrole Modified Ultra-Microelectrodes During Scanning Electrochemical Microscopy

2016 ◽  
Author(s):  
Vinithra Venugopal ◽  
Vijay Venkatesh ◽  
Vishnu Baba Sundaresan
Keyword(s):  
Scanning Electrochemical Microscopy ◽  
Redox Mediator ◽  
Electrochemical Measurements ◽  
Bulk Solution ◽  
Electrochemical Technique ◽  
Diffusion Field ◽  
Faradaic Current ◽  
Constant Height ◽  
Electrolyte Bulk ◽  
Electrochemical Microscopy

Scanning electrochemical microscopy (SECM) is an electrochemical technique used to measure faradaic current changes local to the surface of a sample. The incorporation of shear force (SF) feedback in SECM enables the concurrent acquisition of topographical data of substrates along with electrochemical measurements. Contemporary SECM measurements require a redox mediator such as ferrocene methanol (FcMeOH) for electrochemical measurements; however, this could prove detrimental in the imaging of biological cells. In this article, nanoscale polypyrrole membranes doped with dodecylbenzene sulfonate (PPy(DBS)) are deposited at the tip of an ultra-microelectrode (UME) to demonstrate a novel modification of the contemporary SECM-SF imaging technique that operates in the absence of a redox mediator. The effect of distance from an insulating substrate and bulk electrolyte concentration on sensor response are examined to validate this technique as a tool for correlated topographical imaging and cation flux mapping. Varying the distance of the PPy(DBS) tipped probe from the substrate in a solution containing NaCl causes a localized change in cation concentration within the vicinity of the membrane due to hindered diffusion of ions from the bulk solution to the diffusion field. The cation transport into the membrane in close proximity to the substrate is low as compared to that in the electrolyte bulk and asymptotically approaches the bulk value at the sense length. At a constant height from the base, changing the bulk NaCl concentration from 5 mM to 10 mM increases the filling efficiency from 35% to 70%. Further, the sense length of this modified electrode in NaCl is about 440 nm which is significantly lower as compared to that of a bare electrode in ferrocene methanol (5–20 μm). It is postulated that this novel technique will be capable of producing high resolution maps of surface cation concentrations, thus having a significant impact in the field of biological imaging.

scholarly journals Studies of Some Properties and the Structure of Polyethylene Glycol (PEG) Macromolecules Adsorbed on a TiO2 Surface

2001 ◽  
Vol 19 (5) ◽  
pp. 397-407 ◽  
Author(s):  
S. Chibowski ◽  
M. Paszkiewicz
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
Surface Charge ◽  
Adsorption Layer ◽  
Bulk Solution ◽  
Ionic Structure ◽  
Solution Interface ◽  
Main Factors ◽  
Presence And Absence

In the studies presented, the influence of the molecular weight of polyethylene glycol (PEG) on the adsorption and electrical properties at the metal oxide/polymer solution interface has been determined. The main factors responsible for the observed changes in the zeta potential and surface charge of titania were determined on the basis of the data obtained. It was demonstrated that changes in the ionic structure of the Stern layer depend on the molecular weight of PEG and its conformation. A possible mechanism for the changes in zeta potential both with pH and molecular weight was proposed on the basis of values of the surface charge difference (Δσ0) and the diffuse layer charge difference (Δσd) as determined in the presence and absence of the polymer. The thickness of the adsorption layer (δ) on the surface of titania was calculated from the zeta potential changes, both in the presence and absence of the polymer. A distinct influence of the PEG molecular weight was noted on the values of the adsorption layer thickness (δ) determined. The structures of the macromolecules in solution and at the solid/solution interface were compared and from the dependencies obtained some changes in the shape and dimensions of the polymer coils on passing from the bulk solution to the interface were proposed.

scholarly journals Mixed adsorption of hexadecylpyridinium bromide and Triton X surfactants at graphitized carbon black

2020 ◽  
Vol 85 (6) ◽  
pp. 781-794
Author(s):  
Olga Kochkodan ◽  
Viktor Maksin
Keyword(s):  
Carbon Black ◽  
Adsorption Layer ◽  
Surfactant Molecule ◽  
Graphitized Carbon Black ◽  
Bulk Solution ◽  
Ionic Surfactant ◽  
Surfactant Mixtures ◽  
Graphitized Carbon ◽  
Experimental Values ◽  
Triton X

Adsorption of cationic 1-hexadecylpyridinium bromide (HDPB) and non-ionic p-(1,1,3,3-tetramethylbutyl)-phenoxypolyoxyethylene glycols surfactants of the Triton X series (Triton X-45, Triton X-100 and Triton X-305) from their single and mixed aqueous solutions at thermally graphitized carbon black (CB) was studied. It was shown that the adsorption of the non-ionic surfactant from its individual solution decreased when a number of ethylene oxide units in the surfactant molecule increased. Addition of the non-ionic surfactants increased the amount of HDPB adsorbed from HDPB/Triton X mixtures. At low solution concentrations it was found that in HDPB/Triton X mixtures, the experimental values of total surfactants adsorption are higher than the adsorption values calculated for the ideal surfactant mixtures. The composition of the mixed HDPB/Triton X adsorption layer and the parameters of the intermolecular interaction (?s), between the components in this layer, were calculated using the Rubingh-Rosen approach. It was shown that ?s parameters have negative values, which indicate notable interactions between Triton X molecules and HDPB ions in the mixed adsorption layer. It was found that the composition of the mixed adsorption layer at CB surface is notably different from the surfactants composition in the bulk solution. The mixed HDPB/Triton X adsorption layer is enriched with Triton X surfactant and the mole fraction of Triton X increases with decreasing of ethoxylation degree of its molecules.

Einfluß der Molekülgröße auf Adsorptionsisothermen

1995 ◽  
Vol 50 (2-3) ◽  
pp. 235-246
Author(s):  
C. Meyer ◽  
D. Hesse
Keyword(s):  
Computer Simulations ◽  
Adsorption Isotherms ◽  
Adsorption Process ◽  
Statistical Thermodynamics ◽  
Lateral Interaction ◽  
Interaction Forces ◽  
Partial Pressures ◽  
Special Parameter

Abstract Using methods of statistical thermodynamics, adsorption isotherms for the description of differ­ent-sized molecules are discussed by assuming the adsorbing surface to be energetically homoge­neous and by neglecting lateral interaction forces between the adsorbed particles. In this case, besides the temperature and the partial pressures, the adsorption process is mainly influenced by a geomet­rical interaction between the coadsorbed molecules which is modeled by a special parameter. Its value can be determined by geometrical considerations as well as by computer simulations.

scholarly journals Adsorption of Sodium Hexadecyl Sulfate and Triton X from Binary Aqueous Solutions at Thermally Graphitized Carbon Black

2020 ◽  
Vol 65 (1) ◽  
pp. 72-79
Author(s):  
Olga Kochkodan ◽  
Victor Maksin ◽  
Tetyana Semenenko
Keyword(s):  
Carbon Black ◽  
Aqueous Solutions ◽  
Nonionic Surfactant ◽  
Adsorption Layer ◽  
Nonionic Surfactants ◽  
Graphitized Carbon Black ◽  
Bulk Solution ◽  
Graphitized Carbon ◽  
Individual Solution ◽  
Triton X

Adsorption of anionic sodium hexadecyl sulfate (SHS) and nonionic Triton X surfactants with different ethoxylation degree: TX-45, TX-100 and TX-300 from their individual and mixed aqueous solutions at the surface of thermally graphitized carbon black (CB) was studied. It was found that at low solution concentrations addition of the nonionic surfactant increases the amount of SHS adsorbed from SHS/Triton X mixtures compared to SHS amount adsorbed from its individual solution. These findings might be explained by decreasing in electrostatic repulsion between SHS ions due to inclusion of the molecules of the nonionic surfactant in the mixed adsorption layer. At higher solution concentrations, adsorption of SHS decrease as a result of displacement of SHS ions from the mixed adsorption layer by Triton X molecules. It was established that the composition of the mixed adsorption layer at CB surface notably differ from the composition of the surfactant mixture in the bulk solution. The mixed adsorption layer is enriched with the molecules of the nonionic surfactants and this conclusion is confirmed by the results of measuring zeta potential of CB particles with the adsorbed surfactants.

Modeling of Adsorption Isotherms for Supercritical Hydrogen on A and X Zeolite

2012 ◽  
Vol 487 ◽  
pp. 719-723
Author(s):  
Xiao Ming Du
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Adsorption Isotherms ◽  
Lattice Theory ◽  
Analytic Solution ◽  
Hydrogen Adsorption ◽  
X Zeolite ◽  
Type Zeolite ◽  
Modeling Of Adsorption ◽  
Pressure Hydrogen

we give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside cylindric pores of adsorbents, and predict adsorption isotherms for hydrogen on A and X type zeolite at 77K. It is shown that the model reflects the peculiar features in adsorption isotherms of supercritical hydrogen in particular, a maximum in the adsorption with increasing pressure) .The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Modeling of Adsorption Isotherms for Hydrogen on Zeolite ZSM-5

2011 ◽  
Vol 391-392 ◽  
pp. 732-736
Author(s):  
Xiao Ming Du
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Adsorption Isotherms ◽  
Lattice Theory ◽  
Analytic Solution ◽  
Hydrogen Adsorption ◽  
Experimental Results ◽  
Slit Pores ◽  
Modeling Of Adsorption ◽  
Pressure Hydrogen

We give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside slit pores of adsorbents, and predict adsorption isotherms for hydrogen on microporous ZSM-5 zeolite at 77K,195K and 293K. The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Sign in / Sign up

Export Citation Format

Share Document