Dataset Information

Influence of siloxane on the transport of ZnO nanoparticles from different release pathways in saturated sand.

ABSTRACT: The production of nanomaterials (NMs) is expected to grow continuously, yet their transformation, transport, release mechanisms, and interactions with contaminants under environmental conditions remain poorly understood. Few studies have investigated the effects of contaminants on fate and transport of NMs, especially siloxanes that are widely found in products. It is hypothesized that the model contaminant, siloxane (e.g., 1,1,3,3-tetramethyldisiloxane (TMDS)) may influence the mechanisms and transport kinetics of NMs under different release pathways. Sand column experiments were carried out under two different scenarios: the release from a mixed TMDS and nano-ZnO suspension (A) and the release of nano-ZnO from sand contaminated with TMDS (B). Results show that interparticle reactions are dominant in (A) and particle-porous interactions are responsible for blocking effects governing in (B). Insights, especially the kinetics of nano-ZnO from co-transport by a contaminant and from porous media preloaded with a contaminant, and environmental factors affecting the release and retention of nano-ZnO in saturated sand are unveiled. These two dominant transport mechanisms (e.g., interparticle reactions and blocking effects) were derived. This study indicates that the release of ZnO NPs is influenced by the presence of TMDS; the extent of mobility and their transport pathways depend on the pre-existence of TMDS in porous media.

SUBMITTER: Joo SH

PROVIDER: S-EPMC7037544 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Influence of siloxane on the transport of ZnO nanoparticles from different release pathways in saturated sand.

Joo Sung Hee SH Knecht Marc M Su Chunming C Seo Seokju S Lawrence Randy R

RSC advances 20160101 102

The production of nanomaterials (NMs) is expected to grow continuously, yet their transformation, transport, release mechanisms, and interactions with contaminants under environmental conditions remain poorly understood. Few studies have investigated the effects of contaminants on fate and transport of NMs, especially siloxanes that are widely found in products. It is hypothesized that the model contaminant, siloxane (<i>e.g.</i>, 1,1,3,3-tetramethyldisiloxane (TMDS)) may influence the mechanism ...[more]

PMID: 32095232

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Project description:A series of one-dimensional column experiments was conducted to examine the effects of tube length on the transport and deposition of 4-ethoxybenzoic acid functionalized multi-wall carbon nanotubes (MWCNTs) in water-saturated porous media. Aqueous MWCNTs suspensions were prepared to yield three distributions of tube lengths; 0.02-1.3 ?m (short), 0.2-7.5 ?m (medium), and 0.2-21.4 ?m (long). Results of the column studies showed that MWCNT retention increased with increasing tube length. Nevertheless, more than 76% of the MWCNT mass delivered to the columns was detected in effluent samples under all experimental conditions, indicating that the functionalized MWCNTs were readily transported through 40-50 mesh Ottawa sand. Examination of MWCNT length distributions in the effluent samples revealed that nanotubes with lengths greater than 8 ?m were preferentially deposited. In addition, measured retention profiles exhibited the greatest MWCNT deposition near the column inlet, which was most pronounced for the long MWCNTs, and decreased sharply with travel distance. Scanning electron microscope (SEM) images showed that MWCNTs were deposited on sand surfaces over the entire column length, while larger MWCNT bundles were retained at grain intersections and near the column inlet. A mathematical model based on clean bed filtration theory (CBFT) was unable to accurately simulate the measured retention profile data, even after varying the weighting function and incorporating a nonuniform attachment rate coefficient expression. Modification of the mathematical model to account for physical straining greatly improved predictions of MWCNT retention, yielding straining rate coefficients that were four orders-of-magnitude greater than corresponding attachment rate coefficients. Taken in concert, these experimental and modeling results demonstrate the potential importance of, and need to consider, particle straining and tube length distribution when describing MWCNT transport in water-saturated porous media.

Dataset Information

Influence of siloxane on the transport of ZnO nanoparticles from different release pathways in saturated sand.

Publications

Influence of siloxane on the transport of ZnO nanoparticles from different release pathways in saturated sand.

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