An explanation for differences in the process of colloid adsorption in batch and column studies

Treumann, Svantje; Torkzaban, Saeed; Bradford, Scott A.; Visalakshan, Rahul Madathiparambil; Page, Declan

doi:10.1016/j.jconhyd.2014.06.007

Cited by 86 publications

(65 citation statements)

References 61 publications

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“…Ideally, both colloids would have the same surface properties. However, the literature indicates that even the surface properties of CML colloids vary with size Treumann et al, 2014). Trends for D21g retention, release, and surface properties have been observed to be generally consistent with 1 μm CML colloids .…”

Section: Column Experimentsmentioning

confidence: 89%

“…These discrepancies can be explained by factors that are not considered in these DLVO calculations. For example, the combined influence of Born repulsion and nanoscale surface roughness has been demonstrated to produce a finite depth of the primary minimum that changes with solution IS in a similar manner to the secondary minimum Shen et al, 2012), and some of the colloids in a primary minimum may therefore be susceptible to hydrodynamic removal (Treumann et al, 2014). Colloid release from a primary minimum during physicochemical perturbations has also been attributed to chemical heterogeneity and steric forces (Pazmino et al, 2014).…”

Section: Amount Of Transient Colloid Releasementioning

confidence: 99%

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Equilibrium and kinetic models for colloid release under transient solution chemistry conditions

Bradford

Torkzaban

Leij

et al. 2015

Journal of Contaminant Hydrology

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We present continuum models to describe colloid release in the subsurface during transient physicochemical conditions. Our modeling approach relates the amount of colloid release to changes in the fraction of the solid surface area that contributes to retention. Equilibrium, kinetic, equilibrium and kinetic, and two-site kinetic models were developed to describe various rates of colloid release. These models were subsequently applied to experimental colloid release datasets to investigate the influence of variations in ionic strength (IS), pH, cation exchange, colloid size, and water velocity on release. Various combinations of equilibrium and/or kinetic release models were needed to describe the experimental data depending on the transient conditions and colloid type. Release of Escherichia coli D21g was promoted by a decrease in solution IS and an increase in pH, similar to expected trends for a reduction in the secondary minimum and nanoscale chemical heterogeneity. The retention and release of 20 nm carboxyl modified latex nanoparticles (NPs) were demonstrated to be more sensitive to the presence of Ca 2+ than D21g. Specifically, retention of NPs was greater than D21g in the presence of 2 mM CaCl 2 solution, and release of NPs only occurred after exchange of Ca 2+ by Na + and then a reduction in the solution IS. These findings highlight the limitations of conventional interaction energy calculations to describe colloid retention and release, and point to the need to consider other interactions (e.g., Born, steric, and/ or hydration forces) and/or nanoscale heterogeneity. Temporal changes in the water velocity did not have a large influence on the release of D21g for the examined conditions. This insensitivity was likely due to factors that reduce the applied hydrodynamic torque and/or increase the resisting adhesive torque; e.g., macroscopic roughness and grain-grain contacts. Our analysis and models improve our understanding and ability to describe the amounts and rates of colloid release and indicate that episodic colloid transport is expected under transient physicochemical conditions. Published by Elsevier B.V.

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Section: Column Experimentsmentioning

confidence: 89%

Section: Amount Of Transient Colloid Releasementioning

confidence: 99%

Equilibrium and kinetic models for colloid release under transient solution chemistry conditions

Bradford

Torkzaban

Leij

et al. 2015

Journal of Contaminant Hydrology

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“…In brief, the amount of retention in batch and column experiments depends on the forces and torques that act on MWCNTs near the porous medium surface. 29,32 The torque balance between applied hydrodynamic (T H ) and resisting adhesive (T A ) torques is not continuously satisfied in a well-mixed batch system because changes in the flow direction alter the lever arms. Conversely, the torque balance in the column system is constantly satisfied (T H ≤ T A ) at microscopic roughness locations ( Figure S1) and grain− grain contacts that reduce the lever arm for T H and increase the lever arm for T A .…”

Section: 12mentioning

confidence: 99%

“…However, distinct differences in the amount of colloid retention on clean quartz sand have been reported for various sized colloids and solution chemistries. 32 In particular, much greater amounts of colloid retention occur in packed column than batch systems, especially for larger colloids and lower ionic strength (IS) conditions, due to differences in lever arms associated with applied hydrodynamic and resisting adhesive torques at microscopic roughness locations and grain−grain contacts; 32 for example, lever arms are constant in column systems whereas they continuously change in mixed batch systems. It is still unclear whether differences in colloid retention in batch and column systems will decrease under electrostatically favorable conditions that occur on iron oxide-coated surfaces.…”

Section: ■ Introductionmentioning

confidence: 99%

Do Goethite Surfaces Really Control the Transport and Retention of Multi-Walled Carbon Nanotubes in Chemically Heterogeneous Porous Media?

Zhang

Bradford

Šimůnek

et al. 2016

Environ. Sci. Technol.

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Transport and retention behavior of multi-walled carbon nanotubes (MWCNTs) was studied in mixtures of negatively charged quartz sand (QS) and positively charged goethite-coated sand (GQS) to assess the role of chemical heterogeneity. The linear equilibrium sorption model provided a good description of batch results, and the distribution coefficients (K D ) drastically increased with the GQS fraction that was electrostatically favorable for retention. Similarly, retention of MWCNTs increased with the GQS fraction in packed column experiments. However, calculated values of K D on GQS were around 2 orders of magnitude smaller in batch than packed column experiments due to differences in lever arms associated with hydrodynamic and adhesive torques at microscopic roughness locations. Furthermore, the fraction of the sand surface area that was favorable for retention (S f ) was much smaller than the GQS fraction because nanoscale roughness produced shallow interactions that were susceptible to removal. These observations indicate that only a minor fraction of the GQS was favorable for MWCNT retention. These same observations held for several different sand sizes. Column breakthrough curves were always well described using an advective-dispersive transport model that included retention and blocking. However, depth-dependent retention also needed to be included to accurately describe the retention profile when the GQS fraction was small. Results from this research indicate that roughness primarily controlled the retention of MWCNTs, although goethite surfaces played an important secondary role.

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“…They consider various equilibrium and kinetic models such as the firstorder sorption of contaminants to soil, the first-order kinetic attachment of colloids (Jin et al, 1997;Treumann et al, 2014), irreversible nonlinear kinetic attachment of colloids , and competitive Langmuir kinetic sorption of contaminants on colloids (van de Weerd and Leijnse, 1997). In this study, additional processes are considered in the numerical analysis of the experimental data, including blocking and depth-dependent retention of MWCNTs during transport (Kasel et al, 2013a) and a non-simultaneous release of MWCNTs and contaminants (Pang and Sim unek, 2006;Sim unek et al, 2006).…”

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confidence: 99%

Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils

Zhang

Engelhardt

Šimůnek

et al. 2017

Environmental Pollution

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a b s t r a c tBatch and saturated soil column experiments were conducted to investigate sorption and mobility of two 14 C-labeled contaminants, the hydrophobic chlordecone (CLD) and the sulfadiazine (SDZ), in the absence or presence of functionalized multi-walled carbon nanotubes (MWCNTs). The transport behaviors of CLD, SDZ, and MWCNTs were studied at environmentally relevant concentrations (0.1e10 mg L À1 ) and they were applied in the column studies at different times. The breakthrough curves and retention profiles were simulated using a numerical model that accounted for the advective-dispersive transport of all compounds, attachment/detachment of MWCNTs, equilibrium and kinetic sorption of contaminants, and co-transport of contaminants with MWCNTs. The experimental results indicated that the presence of mobile MWCNTs facilitated remobilization of previously deposited CLD and its co-transport into deeper soil layers, while retained MWCNTs enhanced SDZ deposition in the topsoil layers due to the increased adsorption capacity of the soil. The modeling results then demonstrated that the mobility of engineered nanoparticles (ENPs) in the environment and the high affinity and entrapment of contaminants to ENPs were the main reasons for ENP-facilitated contaminant transport. On the other hand, immobile MWCNTs had a less significant impact on the contaminant transport, even though they were still able to enhance the adsorption capacity of the soil.

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An explanation for differences in the process of colloid adsorption in batch and column studies

Cited by 86 publications

References 61 publications

Equilibrium and kinetic models for colloid release under transient solution chemistry conditions

Equilibrium and kinetic models for colloid release under transient solution chemistry conditions

Do Goethite Surfaces Really Control the Transport and Retention of Multi-Walled Carbon Nanotubes in Chemically Heterogeneous Porous Media?

Co-transport of chlordecone and sulfadiazine in the presence of functionalized multi-walled carbon nanotubes in soils

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