Potentiometric Titrations as a Tool for Surface Charge Determination

Lützenkirchen, Johannes; Preočanin, Tajana; Kovačević, Davor; Tomišić, Vladislav; Lövgren, Lars; Kallay, Nikola

doi:10.5562/cca2062

Cited by 100 publications

(93 citation statements)

References 44 publications

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“…In comparison to potentiometric acid-base titrations, potentiometric mass titration is a method of choice in the case of the nonsymmetrical electrolyte adsorption but is valid only in the case when the sample is free from the impurities (acidic or basic impurities that remained from synthesis procedure). 33 Besides that, another advantage of performing the experiments at low ionic strength is that it is …”

Section: Potentiometric Mass Titrationmentioning

confidence: 99%

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials

et al. 2015

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The present research focuses on the comparative investigation of the acid-base surface properties (the isoelectric point, pH iep and point of zero charge, pH pzc ) of one-dimensional TiO 2 nanomaterials. Different one-dimensional TiO 2 nanomaterials, nanotubes (NTs) and nanowires (NWs) were prepared by an alkaline hydrothermal synthesis procedure. The structural properties of the synthesized TiO 2 nanomaterials were investigated with high-resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The NWs and NTs were characterized using Raman and Fourier transform infrared (FT-IR) spectroscopy as well as Brunauer-EmmettTeller (BET) measurements. Surface properties, i.e. pH iep and pH pzc of NWs and NTs were determined from electrokinetic measurements, potentiometric mass and electrolyte titrations. The relative acidity for the NWs is found to be in the interval 3 < pH iep < 4 in comparison with the NTs, with 4

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Section: Potentiometric Mass Titrationmentioning

confidence: 99%

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials

et al. 2015

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“…The relative surface charge densities were determined by dividing the number of moles of potential-determining ions on the surface by the total available surface area (Lützenkirchen et al, 2012).…”

Section: Filter Aid Titrationmentioning

confidence: 99%

Contributions of depth filter components to protein adsorption in bioprocessing

Khanal

Singh

Traylor

et al. 2018

Biotech & Bioengineering

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Depth filtration is widely used in downstream bioprocessing to remove particulate contaminants via depth straining and is therefore applied to harvest clarification and other processing steps. However, depth filtration also removes proteins via adsorption, which can contribute variously to impurity clearance and to reduction in product yield. The adsorption may occur on the different components of the depth filter, that is, filter aid, binder, and cellulose filter. We measured adsorption of several model proteins and therapeutic proteins onto filter aids, cellulose, and commercial depth filters at pH 5-8 and ionic strengths <50 mM and correlated the adsorption data to bulk measured properties such as surface area, morphology, surface charge density, and composition. We also explored the role of each depth filter component in the adsorption of proteins with different net charges, using confocal microscopy. Our findings show that a complete depth filter's maximum adsorptive capacity for proteins can be estimated by its protein monolayer coverage values, which are of order mg/m , depending on the protein size. Furthermore, the extent of adsorption of different proteins appears to depend on the nature of the resin binder and its extent of coating over the depth filter surface, particularly in masking the cation-exchanger-like capacity of the siliceous filter aids. In addition to guiding improved depth filter selection, the findings can be leveraged in inspiring a more intentional selection of components and design of depth filter construction for particular impurity removal targets.

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“…The end point is set at pH 3.0 [69]. SCDs are calculated following the procedure described by Lützenkirchen et al [70] with a specific surface area of 282 m 2 =g. Measurements are performed in triplicate to ensure reproducibility.…”

Section: Potentiometric Titrationsmentioning

confidence: 99%

Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

et al. 2016

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The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li þ , Na þ , K þ , and Cs þ ) in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

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Potentiometric Titrations as a Tool for Surface Charge Determination

Cited by 100 publications

References 44 publications

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials

Contributions of depth filter components to protein adsorption in bioprocessing

Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

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Potentiometric Titrations as a Tool for Surface Charge Determination

Cited by 100 publications

References 44 publications

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO2 Nanomaterials

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO2 Nanomaterials

Contributions of depth filter components to protein adsorption in bioprocessing

Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

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An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials

An Experimental and Theoretical Approach to Understanding the Surface Properties of One-Dimensional TiO₂ Nanomaterials