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

Zhang, Miaoyue; Bradford, Scott A.; Šimůnek, Jirka; Vereecken, Harry; Klumpp, Erwin

doi:10.1021/acs.est.6b03285

Cited by 49 publications

(25 citation statements)

References 73 publications

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“…Similar to the NaCl experiments (Fig. 2), this indicates that GO was interacting in the presence of a shallow primary minimum and/or the significant influence of lever arms on GO retention (Torkzaban and Bradford, 2016;Zhang et al, 2016).…”

Section: Cation Type and Exchangesupporting

confidence: 75%

“…2 during Phase II. This observation indicates that most of the retained GO following IS reduction were associated with a shallow primary minimum on a rough sand surface (Tables S4 and S5), and that level arms from microscopic roughness and grain-grain contacts played an important role in the GO retention (Torkzaban and Bradford, 2016;Zhang et al, 2016); e.g., the lever arms are constant during Phases I and II, whereas they randomly vary during determination of the RP. An additional experiment was conducted to further demonstrate the role of pore structure on the GO retention.…”

Section: Tablementioning

confidence: 89%

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Mechanisms of graphene oxide aggregation, retention, and release in quartz sand

Liang

Bradford

Šimůnek

et al. 2019

Science of The Total Environment

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Section: Cation Type and Exchangesupporting

confidence: 75%

Section: Tablementioning

confidence: 89%

Mechanisms of graphene oxide aggregation, retention, and release in quartz sand

Liang

Bradford

Šimůnek

et al. 2019

Science of The Total Environment

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“…However, MWCNTs retention still resulted in a hyper-exponential shape even under low IS conditions (1 mM KCl) that should minimize the contribution of colloid aggregation and chemical heterogeneity. Results for theoretical calculations that consider forces and torques that act on colloids near heterogeneous surfaces, and comparison of retention in batch and column studies indicate that retention of MWCNTs is controlled by surface straining near macroscopic roughness locations and grain-grain contacts under low IS conditions (Bradford and Torkzaban, 2015;Zhang et al, 2016). Similarly, other studies have concluded that straining played a dominant role in the retention of MWCNTs (Jaisi et al, 2008;Kasel et al, 2013aKasel et al, , 2013bWang et al, 2012).…”

Section: Transport and Retention Of Mwcntsmentioning

confidence: 85%

Roles of cation valance and exchange on the retention and colloid-facilitated transport of functionalized multi-walled carbon nanotubes in a natural soil

et al. 2017

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a b s t r a c tSaturated soil column experiments were conducted to investigate the transport, retention, and release behavior of a low concentration (1 mg L À1 ) of functionalized 14 C-labeled multi-walled carbon nanotubes (MWCNTs) in a natural soil under various solution chemistries. Breakthrough curves (BTCs) for MWCNTS exhibited greater amounts of retardation and retention with increasing solution ionic strength (IS) or in the presence of Ca 2þ in comparison to K þ , and retention profiles (RPs) for MWCNTs were hyperexponential in shape. These BTCs and RPs were well described using the advection-dispersion equation with a term for time-and depth-dependent retention. Fitted values of the retention rate coefficient and the maximum retained concentration of MWCNTs were higher with increasing IS and in the presence of Ca 2þ in comparison to K þ . Significant amounts of MWCNT and soil colloid release was observed with a reduction of IS due to expansion of the electrical double layer, especially following cation exchange (when K þ displaced Ca 2þ ) that reduced the zeta potential of MWCNTs and the soil. Analysis of MWCNT concentrations in different soil size fractions revealed that >23.6% of the retained MWCNT mass was associated with water-dispersible colloids (WDCs), even though this fraction was only a minor portion of the total soil mass (2.38%). More MWCNTs were retained on the WDC fraction in the presence of Ca 2þ than K þ . These findings indicated that some of the released MWCNTs by IS reduction and cation exchange were associated with the released clay fraction, and suggests the potential for facilitated transport of MWCNT by WDCs.

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“…22 Some interacting colloids are therefore susceptible to diffusive and/or hydrodynamic removal on rough surfaces, 24 even under electrostatically favorable conditions. 25 When both NR and CH are considered on the SWI, results indicate that NR tends to control the interaction energy profile shape, as well as colloid retention and release. 16,22,24 To date, no published studies have considered the influence of NR and CH on both the SWI and the colloid.…”

Section: ■ Introductionmentioning

confidence: 98%

Contributions of Nanoscale Roughness to Anomalous Colloid Retention and Stability Behavior

et al. 2017

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All natural surfaces exhibit nanoscale roughness (NR) and chemical heterogeneity (CH) to some extent. Expressions were developed to determine the mean interaction energy between a colloid and a solid-water interface, as well as for colloid-colloid interactions, when both surfaces contain binary NR and CH. The influence of heterogeneity type, roughness parameters, solution ionic strength (IS), mean zeta potential, and colloid size on predicted interaction energy profiles was then investigated. The role of CH was enhanced on smooth surfaces with larger amounts of CH, especially for smaller colloids and higher IS. However, predicted interaction energy profiles were mainly dominated by NR, which tended to lower the energy barrier height and the magnitudes of both the secondary and primary minima, especially when the roughness fraction was small. This dramatically increased the relative importance of primary to secondary minima interactions on net electrostatically unfavorable surfaces, especially when roughness occurred on both surfaces and for conditions that produced small energy barriers (e.g., higher IS, lower pH, lower magnitudes in the zeta potential, and for smaller colloid sizes) on smooth surfaces. The combined influence of roughness and Born repulsion frequently produced a shallow primary minimum that was susceptible to diffusive removal by random variations in kinetic energy, even under electrostatically favorable conditions. Calculations using measured zeta potentials and hypothetical roughness properties demonstrated that roughness provided a viable alternative explanation for many experimental deviations that have previously been attributed to electrosteric repulsion (e.g., a decrease in colloid retention with an increase in solution IS; reversible colloid retention under favorable conditions; and diminished colloid retention and enhanced colloid stability due to adsorbed surfactants, polymers, and/or humic materials).

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

Cited by 49 publications

References 73 publications

Mechanisms of graphene oxide aggregation, retention, and release in quartz sand

Mechanisms of graphene oxide aggregation, retention, and release in quartz sand

Roles of cation valance and exchange on the retention and colloid-facilitated transport of functionalized multi-walled carbon nanotubes in a natural soil

Contributions of Nanoscale Roughness to Anomalous Colloid Retention and Stability Behavior

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