Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size

Sun, Yuanyuan; Gao, Bin; Bradford, Scott A.; Wu, Lei; Chen, Hao; Shi, Xiaoqing; Wu, Jichun

doi:10.1016/j.watres.2014.09.025

Cited by 192 publications

(88 citation statements)

References 40 publications

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“…The effluent concentrations of GONPs increased gradually and did not reach a steady plateau (with the exception of GONPs at 1 mM NaCl in clean sand column). These results also demonstrated that blocking behavior, i.e., decreasing deposition rates over time [12,41,48,49], occurred as GONPs transport through the packed columns in the absence and presence of biofilm.…”

Section: Influence Of Biofilm and Eps On Gonps Transportmentioning

confidence: 62%

“…To date, several studies have been performed to investigate the influence of environmentally relevant physicochemical factors such as solution chemistry (e.g., pH, ionic strength, and ionic composition) [7][8][9], flow velocity [10], collector properties [11,12] and saturation degree [13] on the transport and deposition kinetics of graphene oxide nanoparticles (GONPs) in laboratory-scale packed column or using a quartz crystal microbalance with dissipation (QCM-D). These published studies have demonstrated that GONPs mobility is strongly influenced by the coupling of these physicochemical factors.…”

mentioning

confidence: 99%

“…These published studies have demonstrated that GONPs mobility is strongly influenced by the coupling of these physicochemical factors. Specifically, the mobility of GONPs generally increased with decreasing ionic strength (IS) and increasing grain size, flow velocity, and moisture content [7][8][9][11][12][13], whereas pH changes (e.g., 5.1-9.0) showed negligible impact on the transport of GONPs [10]. Nonetheless, the roles of biofilm and extracellular polymeric substances (EPS) that occur ubiquitously in aquatic environments, on the transport of GONPs have not yet been examined.…”

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confidence: 99%

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Biofilms and extracellular polymeric substances mediate the transport of graphene oxide nanoparticles in saturated porous media

Wang

et al. 2015

Journal of Hazardous Materials

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Section: Influence Of Biofilm and Eps On Gonps Transportmentioning

confidence: 62%

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confidence: 99%

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confidence: 99%

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Biofilms and extracellular polymeric substances mediate the transport of graphene oxide nanoparticles in saturated porous media

Wang

et al. 2015

Journal of Hazardous Materials

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“…Due to the difficulty in distinguishing soil colloid from sand chipping, soil colloid retention in the sand columns was not measured in this study. However, the values of model fitting was employed to describe soil colloid retention in all columns (Sun et al, 2015b;Wang et al, 2012;Wang et al, 2013). The amount of retained soil colloids sharply decreased with increasing pH.…”

Section: Transport Of Soil Colloidsmentioning

confidence: 99%

Blocking effect of colloids on arsenate adsorption during co-transport through saturated sand columns

Guo

Lei

et al. 2016

Environmental Pollution

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a b s t r a c tTransport of environmental pollutants through porous media is influenced by colloids. Co-transport of As(V) and soil colloids at different pH were systematically investigated by monitoring breakthrough curves (BTCs) in saturated sand columns. A solute transport model was applied to characterize transport and retention sites of As(V) in saturated sand in the presence of soil colloids. A colloid transport model and the DLVO theory were used to reveal the mechanism and hypothesis of soil colloid-promoted As(V) transport in the columns. Results showed that rapid transport of soil colloids, regulated by pH and ionic strength, promoted As(V) transport by blocking As(V) adsorption onto sand, although soil colloids had low adsorption for As(V). The promoted transport was more significant at higher concentrations of soil colloids (between 25 mg L À1 and 150 mg L À1) due to greater blocking effect on As(V) adsorption onto the sand surfaces. The blocking effect of colloids was explained by the decreases in both instantaneous (equilibrium) As adsorption and first-order kinetic As adsorption on the sand surface sites. The discovery of this blocking effect improves our understanding of colloid-promoted As transport in saturated porous media, which provides new insights into role of colloids, especially colloids with low As adsorption capacity, in As transport and mobilization in soil-groundwater systems.

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“…[15] Sun et al demonstrated lower retention of graphene oxides in porous media at high NP concentrations, which was attributed to a blocking effect at high concentrations, where attachment sites are filled more rapidly at the higher NP concentrations. [16] Many other processes such as interaction with buffers, ligands and organic molecules, along with light-induced transformations of NPs are likely to depend on NP concentration, and need in-depth investigation.…”

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confidence: 99%

The concentration-dependent behaviour of nanoparticles

et al. 2016

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Environmental context. Studies of manufactured nanoparticles (NPs) in the environment have been performed almost exclusively at high NP concentrations. These data lead to misunderstandings related to NP fate and effects at relevant environmental concentrations, which are expected to be low. A better understanding of the concentration-dependent behaviour of NPs will improve our understanding of their fate and effects under environmentally realistic conditions.Abstract. This rapid communication highlights the importance of nanoparticle concentration in determining their environmental fate and behaviour. Notably, two fate processes have been considered: dissolution and aggregation. The decrease in nanoparticle concentration results in increased dissolution and decreased aggregate sizes, inferring higher potential for environmental transport of nanoparticles. The behaviour (e.g, dissolution, aggregation, disaggregation) and fate (e.g. mobility, fugacity, non-transient (sink) or transient source) of nanoparticles (NPs) in environmental and toxicological media have been investigated for over a decade, typically at high NP concentrations (e.g. milligram per litre range) which are not relevant to the environment, [1] resulting in some potentially misleading assumptions that (i) NP behaviour is dominated by aggregation and thus their fate is dominated by sedimentation and removal from the water column, or, in porous media, deposition and removal from the aqueous phase [2] ; (ii) NP dissolution is limited for many NPs and rarely are all NPs dissolved fully in environmental and biological media over relevant timescales [1] and (iii) many NPs therefore impart little or no toxic risk to pelagic organisms as a result of limited NP dissolution and NP removal by aggregation and sedimentation. [3] Several NP groups (e.g. Ag NPs, Cu NPs, Cd NPs, ZnO) may undergo dissolution and release ions with well known toxic effects. [4] These various issues complicate NP risk characterisation and are exacerbated by the general use of high NP concentrations in NP fate, behaviour and ecotoxicological studies. [2,5] Use of high NP concentrations has been motivated by poor detection limits of available analytical techniques (e.g. dynamic light scattering, laser Doppler electrophoresis, UV-Vis spectroscopy) together with enhanced likelihood of observing more pronounced changes and effects at high NP concentrations. [6] Furthermore, most published nanoecotoxicological data are acute exposure studies, which also drive the high concentration selection bias in order to generate measurable biological responses. Many NPs tested for toxicity to aquatic organisms have been non-toxic on acute time scales until they reach unrealistically high exposure concentrations. Clear predictive linkages between unrealistic high acute exposures and more realistic low chronic exposures have not been established for aquatic systems, and are likely to be further complicated by differing concentration-dependent behaviours of NPs.Despite these concerns, little attention ha...

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Transport, retention, and size perturbation of graphene oxide in saturated porous media: Effects of input concentration and grain size

Cited by 192 publications

References 40 publications

Biofilms and extracellular polymeric substances mediate the transport of graphene oxide nanoparticles in saturated porous media

Biofilms and extracellular polymeric substances mediate the transport of graphene oxide nanoparticles in saturated porous media

Blocking effect of colloids on arsenate adsorption during co-transport through saturated sand columns

The concentration-dependent behaviour of nanoparticles

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