Multi-scale investigations of carboxymethyl cellulose- coated nanoscale zero valent iron particle transport in porous media
Notice bibliographique
Résumé
Subsurface injection of nano scale zero valent iron (NZVI) particles is an emerging technology for in situ remediation of the sites contaminated by toxic contaminants such as chlorinated organic dense non aqueous phase liquids (DNAPLs) and heavy metals. One of the key challenges in applying NZVI particles for remediation at the field scale is that NZVI particles are not readily transported in subsurface porous media. The overall objective of this research is to address this challenge by conducting a number of column experiments and 2-D pilot scale tank experiments as well as by exploring the deposition mechanics of metal nanoparticles theoretically. Although numerous studies have focused the stability and transport of polymer/polyelectrolyte coated NZVI particles, the comparison of the effect of the same type of polyelectrolyte stabilizer with different molecular weight on the stability and transport of the corresponding coated NZVI particles has not been systematically conducted to date. Varying molecular weights of homologous polyelectrolytes can cause changes in viscosity and rheology in free solution, and alter the extent of colloidal stability when coated on the nanoparticles. Furthermore, most of the studies on NZVI particle transport have been conducted in the vertically placed columns, which are not representative with the actual flow orientation in field, leading to a potential difference of transport performance of NZVI particles between the commonly used vertical flow orientation and the horizontal flow model. In addition, the scale-up effects (from laboratory-scale column to pilot-scale or field-scale demonstrations) on NZVI transport are reported. In this study, a thorough investigation on NZVI transport is conducted in a 2-D pilot-scale tank to shed some light on the transport performance of NZVI particles under conditions that are more close to actual circumstances. Finally, to calculate the deposition rate coefficient of metal nanoparticles during transport, a considerable number of studies on NZVI particles transport employed equations for predicting the single collector contact efficiency that are developed on the basis of the numerical calculations for common colloidal particles such as latex particles, which have smaller densities than those of metal particles. Taking the horizontal flow mode and the density effects for metal nanoparticles into consideration, a new methodology is developed in three dimensions (3-D) to more precisely predict the single collector efficiency of NZVI particles.In the first study, the influence of the molecular weight of the polyelectrolyte grafted on NZVI particle on its stability and transport was investigated. Three carboxymethyl celluloses (CMC) with different molecular weights (90,000 Da, 250,000 Da and 700,000 Da) were used to stabilize NZVI particles. The comparison of the results revealed that the stability and transport of NZVI particles were improved significantly by CMC with high molecular weight, due to its high viscosity property. In the second study, the effects of gravity on NZVI particle during its transport were extensively assessed in vertical and horizontal placed columns under different conditions (mean sand diameters and NZVI concentrations). The results indicated that the gravity forces significantly reduced NZVI particles transport in coarse sand and at high NZVI concentration in horizontally placed columns. To thoroughly study the impact of horizontal orientation flow on the transport of NZVI particles at a larger scale, a series of transport experiments were conducted in a pilot-scale 2-D tank. Furthermore, to address the challenges met in predicting the single collector efficiency in horizontal orientation flow mode, a methodology based on trajectory analysis of particles around a Happel sphere-in-cell model for porous media in 3-D was developed.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».