Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids
Potentiometric titrations have been routinely used to measure the proton-related surface charge density (SCD) of particles in solution. Here, we quantify the SCD of silica nanoparticles (NPs) that are commercially available as charge-stabilized colloids (by the addition of NaOH) in the presence of k...
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MDPI AG
2022-04-01
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Series: | Colloids and Interfaces |
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Online Access: | https://www.mdpi.com/2504-5377/6/2/23 |
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author | Alok Goel Johannes Lützenkirchen |
author_facet | Alok Goel Johannes Lützenkirchen |
author_sort | Alok Goel |
collection | DOAJ |
description | Potentiometric titrations have been routinely used to measure the proton-related surface charge density (SCD) of particles in solution. Here, we quantify the SCD of silica nanoparticles (NPs) that are commercially available as charge-stabilized colloids (by the addition of NaOH) in the presence of known amounts of added NaCl. The experimental results are simulated by surface complexation models (SCMs) of the electrical double layer (EDL). The modeling results suggest that involving only the added NaCl electrolyte yields poor agreement between the experiment and the best achievable fit. An increase in the Na concentration accounting for the colloid inherent salt (CIS) associated with these charge-stabilized colloids results in much better simulations. In the available literature, this CIS has often been disregarded. However, in the modeling, the total concentration of Na must be known for a consistent mole balance and derivation of reliable ion-pair binding constants. If the CIS is not accounted for or the original suspensions are not dialyzed, the presence of CIS renders the study of those colloids difficult, particularly when investigating specific ion effects, since the CIS always interferes. In the present work, we show that the SCM-estimated amount of CIS from varying the total salt and solid concentration agrees surprisingly well with the manufacturer specification. |
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issn | 2504-5377 |
language | English |
last_indexed | 2024-03-10T00:05:24Z |
publishDate | 2022-04-01 |
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spelling | doaj.art-879c647e3aaa4659a15a0be222fec3522023-11-23T16:09:10ZengMDPI AGColloids and Interfaces2504-53772022-04-01622310.3390/colloids6020023Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica ColloidsAlok Goel0Johannes Lützenkirchen1Laboratory for Surface Science and Technology, Department of Materials, ETH Zürich, 8093 Zurich, SwitzerlandInstitute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344 Karlsruhe, GermanyPotentiometric titrations have been routinely used to measure the proton-related surface charge density (SCD) of particles in solution. Here, we quantify the SCD of silica nanoparticles (NPs) that are commercially available as charge-stabilized colloids (by the addition of NaOH) in the presence of known amounts of added NaCl. The experimental results are simulated by surface complexation models (SCMs) of the electrical double layer (EDL). The modeling results suggest that involving only the added NaCl electrolyte yields poor agreement between the experiment and the best achievable fit. An increase in the Na concentration accounting for the colloid inherent salt (CIS) associated with these charge-stabilized colloids results in much better simulations. In the available literature, this CIS has often been disregarded. However, in the modeling, the total concentration of Na must be known for a consistent mole balance and derivation of reliable ion-pair binding constants. If the CIS is not accounted for or the original suspensions are not dialyzed, the presence of CIS renders the study of those colloids difficult, particularly when investigating specific ion effects, since the CIS always interferes. In the present work, we show that the SCM-estimated amount of CIS from varying the total salt and solid concentration agrees surprisingly well with the manufacturer specification.https://www.mdpi.com/2504-5377/6/2/23silicapotentiometric titrationsurface charge densitycolloid inherent saltspecific ion effects |
spellingShingle | Alok Goel Johannes Lützenkirchen Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids Colloids and Interfaces silica potentiometric titration surface charge density colloid inherent salt specific ion effects |
title | Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids |
title_full | Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids |
title_fullStr | Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids |
title_full_unstemmed | Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids |
title_short | Relevance of Colloid Inherent Salt Estimated by Surface Complexation Modeling of Surface Charge Densities for Different Silica Colloids |
title_sort | relevance of colloid inherent salt estimated by surface complexation modeling of surface charge densities for different silica colloids |
topic | silica potentiometric titration surface charge density colloid inherent salt specific ion effects |
url | https://www.mdpi.com/2504-5377/6/2/23 |
work_keys_str_mv | AT alokgoel relevanceofcolloidinherentsaltestimatedbysurfacecomplexationmodelingofsurfacechargedensitiesfordifferentsilicacolloids AT johanneslutzenkirchen relevanceofcolloidinherentsaltestimatedbysurfacecomplexationmodelingofsurfacechargedensitiesfordifferentsilicacolloids |