Transport of citrate-coated silver nanoparticles in unsaturated sand

Kumahor, Samuel K.; Hron, Pavel; Metreveli, George; Schaumann, Gabriele E.; Vogel, Hans‐Jörg

doi:10.1016/j.scitotenv.2015.03.023

Cited by 36 publications

(25 citation statements)

References 53 publications

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“…2b and 3b). The similar retardation-type behavior of engineered NPs has been previously reported (Torkzaban et al, 2010;Liang et al, 2013a;Kumahor et al, 2015). Torkzaban et al (2010) reported delays in the breakthrough of quantum dot NPs (QDNPs) due to high initial rates of particle deposition.…”

Section: Transport and Retention Of Agnps Through Saturated And Unsatsupporting

confidence: 80%

“…3) for both soil and sand columns. Although other authors such as Kasel et al (2013a) and Kumahor et al (2015) also observed such fluctuations, no acceptable explanation has been suggested so far. Fig.…”

Section: Transport and Retention Of Agnps Through Saturated And Unsatmentioning

confidence: 87%

“…They suggested that a high diffusive mass transfer rate of QDNPs from the bulk solution to the sand surfaces and the QDNPs mass transfer to the unfavorable regions of the sand surfaces can explain this behavior. Also, coatings of the natural organic material (NOM) may result in more hydrophobic AgNPs in soil (Kumahor et al, 2015). Hence, a reversible attachment process would occur and the BTCs would be observed with retardation.…”

Section: Transport and Retention Of Agnps Through Saturated And Unsatmentioning

confidence: 99%

“…Colloid retention under unsaturated flow conditions is more complicated due to the presence of air in the soil system and due to water flow being constrained to smaller pores. Colloid retention in unsaturated porous media under electrostatically unfavorable deposition conditions has been attributed to attachment to the solid-water interface (SWI), attachment to the air-water interface (AWI), deposition on solid surfaces, retention at the solid-air-water triple point and, straining in thin water films (Chen and Flury, 2005;Bradford and Torkzaban, 2008;Torkzaban et al, 2008;Fang et al, 2013;Kumahor et al, 2015). Under unsaturated conditions, colloid transport may increase due to moving AWI (McCarthy and McKay, 2004) or decrease due to greater colloid attachment to stationary AWI (Chen et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Bradford et al (2002) reported that the retention of colloids under unsaturated flow conditions was controlled by the spatial distribution of water saturation and may increase due to limited preferential flow and a greater contact time between the media matrix and the colloids. Kumahor et al (2015) also investigated the transport of citrate-coated AgNPs in unsaturated sand columns. They suggested that a non-equilibrium interaction occurred at the SWI, while an equilibrium sorption to the AWI led to retardation of AgNPs.…”

Section: Introductionmentioning

confidence: 99%

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Transport of silver nanoparticles in intact columns of calcareous soils: The role of flow conditions and soil texture

et al. 2018

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A B S T R A C TGrowing production of manufactured nanomaterials has increased the possibility of contamination of groundwater resources and soils by nanoparticles (NPs). It is crucial to study the fate of NPs in subsurface porous media in order to evaluate and control their risks to ecosystems and human health. Hence, this study was conducted to investigate the transport and retention of polyvinylpyrrolidone (PVP) stabilized silver nanoparticles (AgNPs, a diameter of 40 nm) under saturated and unsaturated conditions in intact columns of two calcareous sandy loam (TR) and loam (ZR) soils. Furthermore, similar experiments were conducted using sand quartz as a reference medium. A pulse of the AgNP suspension with an input concentration (C 0 ) of 50 mg L −1 was injected into the columns for 3 pore volumes. The transport of bromide (Br), as a non-reactive inert tracer, was also examined. High mobility of AgNPs was observed through the sand columns due to unfavorable conditions for AgNP deposition on the quartz sand surfaces. Nearly all AgNPs introduced into the columns of both soils were retained in the soil. Percentages of AgNPs leached out of the columns were < 1% of the total injected mass in both soils. Hyperexponential retention profiles (RPs) were observed in both soils and maximum concentrations of 100-130 mg kg −1 were determined near the columns' inlet. However, slightly stronger retention of AgNPs and greater maximum retained concentrations on the solid phase (S max ) in the ZR soil compared with the TR soil may be attributed to smaller grain sizes of the ZR soil. Hydrodynamic forces adjacent to the solid surfaces near the column inlet can provide a viable explanation for the hyperexponential shape of RPs. The one-site kinetic attachment model in HYDRUS-1D, which accounted for time-and depth-dependent retention, was successfully used to analyze the retention of AgNPs. The results showed that the degree of saturation had little effect on the mobility of AgNPs through undisturbed soil columns. Our results suggested the limited transport of AgNPs in neutral/alkaline calcareous soils under both saturated and unsaturated conditions.

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