Surfactant adsorption kinetics in microfluidics

Emulsions are metastable dispersions. Their lifetimes are directly related to the dynamics of surfactants. We design a microfluidic method to measure the kinetics of adsorption of surfactants to the droplet interface, a key process involved in foaming, emulsification, and droplet coarsening. The method is based on the pH decay in the droplet as a direct measurement of the adsorption of a carboxylic acid surfactant to the interface. From the kinetic measurement of the bulk equilibration of the pH, we fully determine the adsorption process of the surfactant. The small droplet size and the convection during the droplet flow ensure that the transport of surfactant through the bulk is not limiting the kinetics of adsorption. To validate our measurements, we show that the adsorption process determines the timescale required to stabilize droplets against coalescence, and we show that the interface should be covered at more than 90% to prevent coalescence. We therefore quantitatively link the process of adsorption/desorption, the stabilization of emulsions, and the kinetics of solute partitioning—here through ion exchange—unraveling the timescales governing these processes. Our method can be further generalized to other surfactants, including nonionic surfactants, by making use of fluorophore–surfactant interactions.

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Comparison of Oxalate, Citrate and Tartrate Ions Adsorption in the Hydroxyapatite/Aqueous Electrolyte Solution System

Colloids and Interfaces ◽

10.3390/colloids4040045 ◽

2020 ◽

Vol 4 (4) ◽

pp. 45

Author(s):

Władysław Janusz ◽

Ewa Skwarek

Keyword(s):

Adsorption Process ◽

Particle Distribution ◽

Aqueous Electrolyte ◽

Solution System ◽

Kinetics Of Adsorption ◽

Ion Desorption ◽

Three Stages ◽

Oxalate Ions ◽

Adsorption Desorption ◽

Kinetics Of

The kinetics of adsorption/desorption of oxalate, citrate and tartrate anions was investigated using hydroxyapatite from solutions at the initial concentrations of 0.000001 and 0.001 mol/dm3 anions. The adsorption process from a solution with a concentration of 0.001 mol/dm3 takes place in three stages and is well described by the multiexponential equation of adsorption kinetics. The process of tartrate and citrate ion desorption after increasing the pH to 10 is irreversible, while the oxalate ions undergo significant desorption with the increasing pH. The adsorption of oxalate ions decreases with the increasing pH. This effect is weaker in the adsorption of citrate and tartrate ions. Ion adsorption studies were supplemented with the measurements of zeta potential, FTIR and particle distribution of hydroxyapatite particles.

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Theoretical Approaches to the Kinetics of Adsorption, Desorption, and Reactions at Surfaces

Computational Methods in Surface and Colloid Science ◽

10.1201/9780429115813-9 ◽

2019 ◽

pp. 439-479

Author(s):

H. J. Kreuzer ◽

Stephen H. Payne

Keyword(s):

Kinetics Of Adsorption ◽

Theoretical Approaches ◽

Adsorption Desorption ◽

Kinetics Of

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Modified/Unmodified Nanoparticle Adsorbents of Cellulose Origin With High Adsorptive Potential for Removal of Pb(II) From Aqueous Solution

European Scientific Journal ESJ ◽

10.19044/esj.2017.v13n27p425 ◽

2017 ◽

Vol 13 (27) ◽

pp. 425

Author(s):

Azeh Yakubu ◽

Gabriel Ademola Olatunji ◽

Folahan Amoo Adekola

Keyword(s):

Aqueous Solution ◽

Adsorption Capacity ◽

Contact Time ◽

Adsorption Process ◽

Correlation Coefficients ◽

Solution Temperature ◽

Isotherm Models ◽

Maximum Adsorption Capacity ◽

Kinetics Of Adsorption ◽

Kinetics Of

This investigation was conducted to evaluate the adsorption capacity of nanoparticles of cellulose origin. Nanoparticles were synthesized by acid hydrolysis of microcrystalline cellulose/cellulose acetate using 64% H3PO4 and characterized using FTIR, XRD, TGA-DTGA, BET and SEM analysis. Adsorption kinetics of Pb (II) ions in aqueous solution was investigated and the effect of initial concentration, pH, time, adsorbent dosage and solution temperature. The results showed that adsorption increased with increasing concentration with removal efficiencies of 60% and 92.99% for Azeh2 and Azeh10 respectively for initial lead concentration of 3 mg/g. The effects of contact time showed that adsorption maximum was attained within 24h of contact time. The maximum adsorption capacity and removal efficiency were achieved at pH6. Small dose of adsorbent had better performance. The kinetics of adsorption was best described by the pseudo-second-Order model while the adsorption mechanism was chemisorption and pore diffusion based on intra-particle diffusion model. The isotherm model was Freundlich. Though, all tested isotherm models relatively showed good correlation coefficients ranging from 0.969-1.000. The adsorption process was exothermic for Azeh-TDI, with a negative value of -12.812 X 103 KJ/mol. This indicates that the adsorption process for Pb by Azeh-TDI was spontaneous. Adsorption by Azeh2 was endothermic in nature.

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Kinetic Studies of Adsorption Process of Zambian Kapiri Mposhi Zeolites

Oriental Journal Of Chemistry ◽

10.13005/ojc/370229 ◽

2021 ◽

Vol 37 (2) ◽

pp. 467-475

Author(s):

Marina G. Xavier

Keyword(s):

Adsorption Process ◽

Kinetic Studies ◽

Solute Concentration ◽

Exchange Property ◽

Batch Adsorption ◽

Reaction Conditions ◽

Kinetics Of Adsorption ◽

Calcination Temperatures ◽

Optimum Reaction ◽

Kinetics Of

Batch adsorption studies were done on aqueous solutions of Pb(NO3)2 at varying solute concentration, adsorbent dose, contact time, temperature, calcination temperatures and pH. Residual concentrations of the solute were found out using AAS and optimum conditions were studied. Adsorbent used in this study is locally available silicate rich mineral which closely resembles zeolites. The net negative charge on the framework of hydrated aluminosilicates is responsible for ion exchange property. Freundlich model was used to validate the results obtained from batch experiments plotting lnCe vs lnqe. Objective of this work is to study the kinetics of adsorption considering the interplay of particle diffusion in addition to proving the effectiveness as an adsorbent. A diffusion model also was also applied apart from kinetic model to analyze the experimental results more specifically. For maximizing the efficiency of the adsorption process and minimizing the time involved, variables like temperature, reactants and pH were manipulated using kinetic studies. It establishes the optimum reaction conditions for various experimental parameters in the process of adsorption.

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Correction: Barrier kinetics of adsorption–desorption of alcohol monolayers on water under constant surface tension

Soft Matter ◽

10.1039/c9sm90032b ◽

2019 ◽

Vol 15 (8) ◽

pp. 1890-1890 ◽

Cited By ~ 1

Author(s):

Ivan L. Minkov ◽

Dimitrinka Arabadzhieva ◽

Ibrahim E. Salama ◽

Elena Mileva ◽

Radomir I. Slavchov

Keyword(s):

Surface Tension ◽

Soft Matter ◽

Kinetics Of Adsorption ◽

Adsorption Desorption ◽

Alcohol Monolayers ◽

Kinetics Of

Correction for ‘Barrier kinetics of adsorption–desorption of alcohol monolayers on water under constant surface tension’ by Ivan L. Minkov et al., Soft Matter, 2019, DOI: 10.1039/c8sm02076k.

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