Mechanisms of TiO2 nanoparticle transport in porous media: Role of solution chemistry, nanoparticle concentration, and flowrate

Chowdhury, Indranil; Hong, Yongsuk; Honda, Ryan J.; Walker, Sharon L.

doi:10.1016/j.jcis.2011.04.111

Cited by 213 publications

(172 citation statements)

References 37 publications

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“…dispersion vs. agglomeration, of manufactured nanoparticles and the agglomerates they can form will depend on the physicochemical properties of the medium. Indeed, pH, ionic strength, temperature and the presence of natural organic matter (NOM) [6][7][8][9] will control transport and toxicity towards living organisms. 10,11 As a result, to achieve a better understanding of the fate, transport and impact of manufactured NPs once released into an aquatic system, their interaction and potential transformation in the presence of NOM have to be investigated for risk evaluation.…”

Section: Introductionmentioning

confidence: 99%

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

Loosli

Coustumer

Stoll

2014

Environ. Sci.: Nano

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One major concern in the fate of nanomaterials in aquatic systems is the lack of data on nanomaterial transformations under relevant environmental conditions. The disagglomeration of aggregates composed of manufactured anatase titanium dioxide nanoparticles is investigated here in the presence of alginate and Suwannee River humic acids at varying concentrations using dynamic light scattering and electrophoretic measurements. Stability of TiO 2 nanoparticle agglomerates at typical environmental concentrations of natural organic matter is discussed at a pH value corresponding to the point of zero charge of TiO 2 nanoparticles. In this scenario, the surface charge of TiO 2 is neutralized, allowing the nanoparticles to form large agglomerates. Alginate and Suwannee River humic acids exhibit a negative structural charge under this pH condition and adsorption of both natural polyelectrolytes on the surface of nanoparticle agglomerates leads to disagglomeration and significant redispersion of TiO 2 nanoparticles into fragments. Results indicate that both electrostatic forces and steric interactions play key roles during the disagglomeration process and that the physicochemical properties of natural organic matter are found to influence the kinetics and importance of fragmentation in the disagglomeration process. Most importantly, our data indicate that the presence of natural organic matter at typical environmental concentrations induces significant disagglomeration of large submicron nanoparticle agglomerates. Such a result constitutes an important outcome with regards to the risk associated with manufactured nanoparticles by including the possible transformations of the micron size range structures they can form. Nano impactOne of the main problems in the ecological risk assessment of nanomaterials is the lack of important information on their environmental (bio)physicochemical transformations. The disagglomeration of manufactured titanium dioxide nanoparticles is investigated here in the presence of alginate and Suwannee River humic acids at realistic environmental concentrations. Under such concentration conditions, the adsorption of these compounds is found to induce disagglomeration and significant redispersion of TiO 2 nanoparticles into fragments. Such a result constitutes an important outcome with regards to the risk associated with manufactured nanoparticles by considering one important life-cycle transformation of micron size range structures composed of nanoparticles in aquatic systems.

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Section: Introductionmentioning

confidence: 99%

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

Loosli

Coustumer

Stoll

2014

Environ. Sci.: Nano

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“…Fang et al (2013) found that favorable attachment condition at pH 2.6 resulted in complete retention of TiO 2 NPs in both saturated and unsaturated porous columns. However, Chowdhury et al (2011) demonstrated that a significant portion of TiO 2 NPs could be eluted from porous columns at pH 5.0, which might be attributed to the observed smaller aggregate size and blocking effect even with electrostatically favorable interaction between collector and TiO 2 NPs.…”

Section: Introductionmentioning

confidence: 92%

“…S9). Negative charge of both quartz sand and TiO 2 NPs resulting from the coating of HS on the surface indicated that the existence of electrostatic repulsive forces led to unfavorable conditions for deposition of TiO 2 NPs onto the collector (Chowdhury et al 2011). The elution of TiO 2 NPs from the columns was dramatically enhanced with increase of HS, and the maximum C/C 0 observed increased from 0.20 to 0.88 with a change in HS concentration from 0.5 mg L -1 to 10 mg L -1 (Table 1).…”

Section: Transport Of Tio 2 Nps In Porous Media Under Acidic Conditionsmentioning

confidence: 99%

“…A substantial amount of work on transport and deposition behaviors of TiO 2 NPs has been conducted in various aqueous environmental conditions using well-controlled porous media packing columns. These investigations have provided insights into the influence of environmental conditions, such as pH, ionic strength, natural organic matter, and surfactants on the stability and mobility of TiO 2 NPs (Chen et al 2011(Chen et al , 2012Chowdhury et al 2011;Fang et al 2013;Shih et al 2012;Solovitch et al 2010;Wang et al 2012). pH is a key factor affecting the electrokinetic properties and transport of TiO 2 NPs in porous media.…”

Section: Introductionmentioning

confidence: 99%

“…The point of zero charge (PZC) of TiO 2 NPs usually falls within the range 4.4-6.2 (Chen et al 2012;Dietrich et al 2012;Loosli et al 2013;Petosa et al 2012), and the mobility of uncoated TiO 2 NPs would therefore be enhanced in alkaline conditions because of the unfavorable electrostatic repulsion between the particles and negatively charged collector (Fang et al 2013;Solovitch et al 2010;Wang et al 2012). In contrast, when pH approached to the PZC, the concurrence of aggregation and limited mobility of bare TiO 2 NPs was observed in the porous media (Chowdhury et al 2011;Godinez and Darnault 2011;Solovitch et al 2010). pH of surface water and subsurface water is generally in the range of 5.0-9.0; however, some of environmental media in vast tropical and subtropical areas exist in acidic conditions.…”

Section: Introductionmentioning

confidence: 99%

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Facilitated transport of titanium dioxide nanoparticles by humic substances in saturated porous media under acidic conditions

Zhang

et al. 2015

J Nanopart Res

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The transport behavior of titanium dioxide nanoparticles (TiO 2 NPs, 30 nm in diameter) was studied in well-defined porous media composed of clean quartz sand over a range of solution chemistry under acidic conditions. Transport of TiO 2 NPs was dramatically enhanced by humic substances (HS) at acidic pH (4.0, 5.0 and 6.0), even at a low HS concentration of 0.5 mg L -1 . Facilitated transport of TiO 2 NPs was likely attributable to the increased stability of TiO 2 NPs and repulsive interaction between TiO 2 NPs and quartz sands due to the adsorbed HS. The mobility of TiO 2 NPs was also increased with increasing pH from 4.0 to 6.0. Although transport of TiO 2 NPs was insensitive to low ionic strength, it was significantly inhibited by high concentrations of NaCl and CaCl 2 . In addition, calculated Derjaguin-LandauVerwey-Overbeek (DLVO) interaction energy indicated that high energy barriers were responsible for the high mobility of TiO 2 NPs, while the secondary energy minimum could play an important role in the retention of TiO 2 NPs at 100 mmol L -1 NaCl. Straining and gravitational settlement of larger TiO 2 NPs aggregates at 1 mg L -1 HS, pH 5.0, and 2 mmol L -1 CaCl 2 could be responsible for the significant retention even in the presence of high energy barriers. Moreover, more favorable interaction between approaching TiO 2 NPs and TiO 2 NPs that had been already deposited on the collector resulted in a ripening-shape breakthrough curve at 2 mmol L -1 CaCl 2 . Overall, a combination of mechanisms including DLVO-type force, straining, and physical filtration was involved in the retention of TiO 2 NPs over the range of solution chemistry examined in this study.

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Predicting colloid transport through saturated porous media: A critical review

et al. 2015

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Understanding and predicting colloid transport and retention in water‐saturated porous media is important for the protection of human and ecological health. Early applications of colloid transport research before the 1990s included the removal of pathogens in granular drinking water filters. Since then, interest has expanded significantly to include such areas as source zone protection of drinking water systems and injection of nanometals for contaminated site remediation. This review summarizes predictive tools for colloid transport from the pore to field scales. First, we review experimental breakthrough and retention of colloids under favorable and unfavorable colloid/collector interactions (i.e., no significant and significant colloid‐surface repulsion, respectively). Second, we review the continuum‐scale modeling strategies used to describe observed transport behavior. Third, we review the following two components of colloid filtration theory: (i) mechanistic force/torque balance models of pore‐scale colloid trajectories and (ii) approximating correlation equations used to predict colloid retention. The successes and limitations of these approaches for favorable conditions are summarized, as are recent developments to predict colloid retention under the unfavorable conditions particularly relevant to environmental applications. Fourth, we summarize the influences of physical and chemical heterogeneities on colloid transport and avenues for their prediction. Fifth, we review the upscaling of mechanistic model results to rate constants for use in continuum models of colloid behavior at the column and field scales. Overall, this paper clarifies the foundation for existing knowledge of colloid transport and retention, features recent advances in the field, critically assesses where existing approaches are successful and the limits of their application, and highlights outstanding challenges and future research opportunities. These challenges and opportunities include improving mechanistic descriptions, and subsequent correlation equations, for nanoparticle (i.e., Brownian particle) transport through soil, developing mechanistic descriptions of colloid retention in so‐called “unfavorable” conditions via methods such as the “discrete heterogeneity” approach, and employing imaging techniques such as X‐ray tomography to develop realistic expressions for grain topology and mineral distribution that can aid the development of these mechanistic approaches.

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Mechanisms of TiO2 nanoparticle transport in porous media: Role of solution chemistry, nanoparticle concentration, and flowrate

Cited by 213 publications

References 37 publications

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

Effect of natural organic matter on the disagglomeration of manufactured TiO2 nanoparticles

Facilitated transport of titanium dioxide nanoparticles by humic substances in saturated porous media under acidic conditions

Predicting colloid transport through saturated porous media: A critical review

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