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Vogel P, Palberg T. Electrokinetic effects of ambient and excess carbonization of dielectric surfaces in aqueous environments. J Colloid Interface Sci 2023; 656:280-288. [PMID: 37995398 DOI: 10.1016/j.jcis.2023.10.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 11/25/2023]
Abstract
The charge state of surfaces in contact with aqueous electrolytes is crucial for the performance and stability of dielectric surfaces in general and lyophobic colloids in particular. Thus far the role of adsorbed molecular CO2 remained largely unexplored. The aim of the present investigation is to study the de-charging and re-charging for two model surfaces upon addition of CO2 and/or 1:1 electrolytes (NaCl, HCl) under precisely controlled boundary conditions up to millimolar concentrations of additives. Starting from the salt- and CO2-free state, the ζ-potential magnitudes drop linearly with the logarithm of the CO2-concentrations over several orders of magnitude in CO2-concentrations. Hydrophobic Polystyrene nearly fully discharges, hydrophilic SiO2 reveals a 60% charge reduction. From the surface specific effects of instead adding NaCl or HCl, we discriminate and parameterize empirically the relative contribution of three individual mechanisms for decreasing the ζ-potential magnitudes (screening, pH-driven charge regulation, dielectric charge regulation) combining during CO2-addition. Moreover, depending on the achieved CO2-induced de-charging, the behavior upon subsequent addition of NaCl and HCl switches between two limiting cases. Screening dominates for surfaces in the native state without CO2, but a significant re-charging is observed for surfaces conditioned under excess CO2-concentrations.
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Affiliation(s)
- Peter Vogel
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany.
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
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2
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Vogel P, Möller N, Qaisrani MN, Bista P, Weber SAL, Butt HJ, Liebchen B, Sulpizi M, Palberg T. Charging of Dielectric Surfaces in Contact with Aqueous Electrolytes─the Influence of CO 2. J Am Chem Soc 2022; 144:21080-21087. [DOI: 10.1021/jacs.2c06793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Peter Vogel
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
| | - Nadir Möller
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
| | | | - Pravash Bista
- Max Planck Institute for Polymer Research, 55128Mainz, Germany
| | | | | | - Benno Liebchen
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289Darmstadt, Germany
| | - Marialore Sulpizi
- Department of Physics, Ruhr Universität Bochum, 44780Bochum, Germany
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128Mainz, Germany
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3
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Delgado AV, Ahualli S, Arroyo FJ, Jiménez ML, Carrique F. Electrokinetic detection of the salt-free condition in colloids. Application to polystyrene latexes. Adv Colloid Interface Sci 2022; 299:102539. [PMID: 34610864 DOI: 10.1016/j.cis.2021.102539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 09/28/2021] [Accepted: 09/28/2021] [Indexed: 01/06/2023]
Abstract
Because of their singular phenomenology, the so-called salt-free colloids constitute a special family of dispersed systems. Their main characteristic is that the dispersion medium ideally contains only the solvent and the ions compensating exactly the surface charge of the particles. These ions (often called released counterions) come into the solution when the surface groups responsible for the particles charge get ionized. An increasing effort is nowadays dedicated to rigorously compare theoretical model predictions for ideal salt-free suspensions, where only the released counterions are supposed to be present in solution, with appropriately devised experiments dealing with colloids as close as possible to the ideal salt-free ones. Of course, if the supporting solution is aqueous, the presence of atmospheric contamination and any other charged species different from the released counterions in the solution must be avoided. Because this is not an easy task, the presence of dissolved atmospheric CO2 and of H+ and OH- from water dissociation cannot be fully discarded in aqueous salt-free solutions (often denominated realistic in such case). Ultimately, at some point, the role of the released counterions will be comparable or even larger in highly charged concentrated colloids than that of added salts. These topics are covered in the present contribution. The model results are compared with experimental data on the dynamic mobility and dielectric dispersion of polystyrene spheres of various charges and sizes. As a rule, it is found that the model correctly predicts the significance of alpha and Maxwell-Wagner-O'Konski relaxations. Positions and amplitudes of such relaxations are well predicted, although it is necessary to assume that the released counterions are potassium or sodium instead of protons, otherwise the frequency spectra of experimental mobility and permittivity differ very significantly from those theoretically calculated. The proposed electrokinetic evaluation is an ideal tool for detecting in situ the possible contamination (or incomplete ion exchange of the latexes). A satisfactory agreement is found when potassium counterions are assumed to be in solution, mostly if one considers that the comparison is carried out without using any adjustable parameters.
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Affiliation(s)
- A V Delgado
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain.
| | - S Ahualli
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain
| | - F J Arroyo
- Departamento de Física, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071 Jaén, Spain
| | - M L Jiménez
- Departamento de Física Aplicada, Facultad de Ciencias, and MNat Unit of Excellence, Universidad de Granada, 18071 Granada, Spain
| | - F Carrique
- Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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Carrique F, Ruiz-Reina E, Arroyo FJ, Delgado AV. Influence of ion size effects on the electrokinetics of aqueous salt-free colloids in alternating electric fields. Phys Rev E 2020; 102:032614. [PMID: 33076032 DOI: 10.1103/physreve.102.032614] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/31/2020] [Indexed: 11/07/2022]
Abstract
Electrokinetics is the science of the physical phenomena appearing at the solid-liquid interface of dispersed particles subjected to external fields. Techniques based on electrokinetic phenomena constitute an important set of tools for the electrical characterization of colloids because of their sensitivity to the properties of particle-solution interfaces. Their rigorous description may require inclusion of the effects of finite size of chemical species in the theoretical models, and, particularly in the case of salt-free (no external salt added) aqueous colloids, also consideration of water dissociation and possible carbon dioxide contamination in the aqueous solution. A new ac electrokinetic model is presented for concentrated salt-free spherical colloids for arbitrary characteristics of the particles and aqueous solution, including finite-size effects of chemical species by appropriate modifications of the chemical reaction equations to include such non-ideal aspects. The numerical solution of the electrokinetic equations in an alternating electric field has also been carried out by using a realistic non-equilibrium scenario accounting for association-dissociation processes in the chemical reactions. The results demonstrate the importance of including finite-size effects in the electrokinetic response of the colloid, mainly at high frequencies of the electric field, and for highly charged colloids. Findings of previous models for pointlike ions or for ideal salt-free colloids including finite ion size effects are recovered with the present model, for the appropriate limiting conditions.
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Affiliation(s)
- F Carrique
- Departamento de Física Aplicada II, Facultad de Ciencias Universidad de Málaga, 29071 Málaga, Spain
| | - E Ruiz-Reina
- Departamento de Física Aplicada II, Facultad de Ciencias Universidad de Málaga, 29071 Málaga, Spain
| | - F J Arroyo
- Departamento de Física, Facultad de Ciencias Experimentales Universidad de Jaén, 23071 Jaén, Spain
| | - A V Delgado
- Departamento de Física Aplicada, Facultad de Ciencias Universidad de Granada, 18071 Granada, Spain
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Ahualli S, Bermúdez S, Carrique F, Jiménez ML, Delgado ÁV. AC Electrokinetics of Salt-Free Multilayered Polymer-Grafted Particles. Polymers (Basel) 2020; 12:E2097. [PMID: 32942664 PMCID: PMC7569943 DOI: 10.3390/polym12092097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 11/20/2022] Open
Abstract
Interest in the electrical properties of the interface between soft (or polymer-grafted) nanoparticles and solutions is considerable. Of particular significance is the case of polyelectrolyte-coated particles, mainly taking into account that the layer-by-layer procedure allows the control of the thickness and permeability of the layer, and the overall charge of the coated particle. Like in simpler systems, electrokinetic determinations in AC fields (including dielectric dispersion in the 1 kHz-1 MHz frequency range and dynamic electrophoresis by electroacoustic methods in the 1-18 MHz range) provide a large amount of information about the physics of the interface. Different models have dealt with the electrokinetics of particles coated by a single polymer layer, but studies regarding multi-layered particles are far scarcer. This is even more significant in the case of so-called salt-free systems; ideally, the only charges existing in this case consist of the charge in the layer(s) and the core particle itself, and their corresponding countercharges, with no other ions added. The aims of this paper are as follows: (i) the elaboration of a model for the evaluation of the electrokinetics of multi-grafted polymer particles in the presence of alternating electric fields, in dispersion media where no salts are added; (ii) to carry out an experimental evaluation of the frequency dependence of the dynamic (or AC) electrophoretic mobility and the dielectric permittivity of suspensions of polystyrene latex spherical particles coated with successive layers of cationic, anionic, and neutral polymers; and (iii) finally, to perform a comparison between predictions and experimental results, so that it can be demonstrated that the electrokinetic analysis is a useful tool for the in situ characterization of multilayered particles.
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Affiliation(s)
- Silvia Ahualli
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Sara Bermúdez
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Félix Carrique
- Department of Applied Physics I, School of Sciences, University of Málaga, 23071 Málaga, Spain;
| | - María L. Jiménez
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
| | - Ángel V. Delgado
- Department of Applied Physics, School of Sciences, University of Granada, 18071 Granada, Spain; (S.B.); (M.L.J.)
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Botin D, Carrique F, Ruiz-Reina E, Palberg T. Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions. J Chem Phys 2020; 152:244902. [PMID: 32610949 DOI: 10.1063/5.0010692] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO2. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms.
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Affiliation(s)
- Denis Botin
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
| | - Felix Carrique
- Institute Carlos I for Theoretical and Computational Physics (iC1), Departamento de Física Aplicada I, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - Emilio Ruiz-Reina
- Institute Carlos I for Theoretical and Computational Physics (iC1), Departamento de Física Aplicada II, Escuela de Ingenierías Industriales, Universidad de Málaga, Campus de Teatinos, 29071 Málaga, Spain
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany
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Ramos-de-la-Peña AM, Aguilar O. Electrokinetic assessment of RNase A species and innovative PEG-grafted agarose-based resins used in downstream processing of PEGylated proteins. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.06.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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8
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Ionic coupling effects in dynamic electrophoresis and electric permittivity of aqueous concentrated suspensions. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ahualli S, González MA, Delgado AV, Jiménez ML. Dynamic electrophoretic mobility and electric permittivity of concentrated suspensions of plate-like gibbsite particles. J Colloid Interface Sci 2017; 502:112-121. [PMID: 28478218 DOI: 10.1016/j.jcis.2017.04.072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/21/2017] [Accepted: 04/23/2017] [Indexed: 11/17/2022]
Abstract
In this paper we present experimental results on the electrokinetic behavior of planar gibbsite particles in concentrated suspensions. The dc electrophoretic mobility measurements are in this case of little significance, as they are scarcely informative. In the present investigation, we show that the dielectric dispersion and dynamic electrophoresis can in contrast provide such information. The complicating factors are of course the non-spherical shape and the finite particle concentration, as no complete theory of these phenomena exists for such systems. We propose to use first of all a model of dynamic electrophoresis of spheroids in which the effect of volume fraction is considered by means of an approximate theory previously obtained for spheres, based on the evaluation of electrical and hydrodynamic interactions between particles. In addition, the role of volume fraction on the high frequency inertial relaxation is also ascertained and used to obtain a volume fraction-independent radius of the gibbsite spheroids. A similar approach is used for the evaluation of dielectric dispersion data. Both the dynamic mobility and dielectric constant dependencies on frequency were obtained for gibbsite suspensions of different volume fractions in 0.5mMKCl. The theoretical treatments elaborated were applied to these data, and a coherent picture of the geometrical and electrical characteristics of the particles was obtained.
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Affiliation(s)
- S Ahualli
- Department of Applied Physics, School of Science, University of Granada, 18071 Granada, Spain
| | - M A González
- Department of Applied Physics, School of Science, University of Granada, 18071 Granada, Spain
| | - A V Delgado
- Department of Applied Physics, School of Science, University of Granada, 18071 Granada, Spain
| | - M L Jiménez
- Department of Applied Physics, School of Science, University of Granada, 18071 Granada, Spain.
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Botin D, Mapa LM, Schweinfurth H, Sieber B, Wittenberg C, Palberg T. An empirical correction for moderate multiple scattering in super-heterodyne light scattering. J Chem Phys 2017; 146:204904. [PMID: 28571383 PMCID: PMC5444921 DOI: 10.1063/1.4983688] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/04/2017] [Indexed: 11/14/2022] Open
Abstract
Frequency domain super-heterodyne laser light scattering is utilized in a low angle integral measurement configuration to determine flow and diffusion in charged sphere suspensions showing moderate to strong multiple scattering. We introduce an empirical correction to subtract the multiple scattering background and isolate the singly scattered light. We demonstrate the excellent feasibility of this simple approach for turbid suspensions of transmittance T ≥ 0.4. We study the particle concentration dependence of the electro-kinetic mobility in low salt aqueous suspension over an extended concentration regime and observe a maximum at intermediate concentrations. We further use our scheme for measurements of the self-diffusion coefficients in the fluid samples in the absence or presence of shear, as well as in polycrystalline samples during crystallization and coarsening. We discuss the scope and limits of our approach as well as possible future applications.
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Affiliation(s)
- Denis Botin
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | | | | | - Bastian Sieber
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
| | | | - Thomas Palberg
- Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany
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