Understanding The Effect of Organic and Inorganic Matrices On The Mechanisms Controlling Nanoparticle Transport in Porous Media

**Understanding the effect of organic and inorganic matrices on the mechanisms controlling nanoparticle transport in porous media**:

- Réf **ABG-128507**
- Sujet de Thèse
- 12/02/2025
- Contrat doctoral
- Université Gustave Eiffel
- Lieu de travail- Nantes - Pays de la Loire - France
- Intitulé du sujet- Understanding the effect of organic and inorganic matrices on the mechanisms controlling nanoparticle transport in porous media
- Champs scientifiques- Ecologie, environnement

**Description du sujet**:
Due to the complexity of soils (minerals, organic matter, microorganisms) and the technical issues to measure soil contamination in situ, many powerful environmental models predicting the fate and transport of contaminants in soils are being developed (5-7). However, there are still limitations with respect to comprehensive predictions of contaminant fate in soils. For instance, the transport mechanisms are inferred from particle breakthrough curves (BTCs) measured in the column effluents, which interpretation is likely to be non-unique (8).

Originality of the project:
To better analyze BTCs data, we have used during recent years Magnetic Resonance Imaging (MRI) to obtain images inside the studied samples to observe both dynamic and static phenomena of NPs during transport experiments (9-13). However, this has been done in model systems (mineral part of soils) without taking into account the interactions with soil organic matter (SOM). In this project, we will include the study of the interactions between NPs and SOM in systems of different complexity in order to be able to better modeling the transport of NPs in soils.

Scientific methodology:
The experimental conditions will be designed to mimic the interactions of NPs (neutral, negatively charged and positively charged) in soils of increasing complexity. NPs will be prepared and characterized in terms of size and surface properties (e.g zeta potential, single particle inductively coupled plasma mass spectrometry (spICP-MS)). The suspensions will be injected in model soils prepared in the laboratory and packed in laboratory columns. Moreover, NPs with different functional groups will be used to investigate the consequence of adsorption of contaminants into the well characterized porous surface. Finally, under different saturation conditions will be used (60-100%). The hydrodynamic parameters of the laboratory columns will be determined before the suspensions are injected. Then, the eluates leaving the columns will be characterized to follow the evolution of the NPs' major element concentrations (e.g. Ti, Fe....) in a conventional way (BTC), but also of the eluted particles' properties by spICP-MS and DLS (particle size). MRI experiments will allow the observation of pulse front and adsorption of NPs inside the columns. The overall aim is to determine the processes responsible for migration and retention using non-invasive MRI to elucidate the non-uniqueness of BTCs.

This PhD project will focus on three main actions:
1) Transport experiments in sand packings, clay
- or/and LHA-coated sand.

2) MRI monitoring of selected transport experiments.

3) MRI monitoring under different saturation conditions.

References

(1) Hagens, W. I.; Oomen, A. G.; de Jong, W. H.; Cassee, F. R.; Sips, A. J. A. M. What Do We (Need to) Know about the Kinetic Properties of Nanoparticles in the Body? Regulatory Toxicology and Pharmacology 2007, 49 (3), 217-229.

(2) Nemmar, A.; Hoet, P. H. M.; Vanquickenborne, B.; Dinsdale, D.; Thomeer, M.; Hoylaerts, M. F.; Vanbilloen, H.; Mortelmans, L.;Nemery, B. Passage of Inhaled Particles Into the Blood Circulation in Humans. Circulation 2002, 105 (4), 411-414.

(6) McGinley, P. M.; Katz, L. E.; Weber, W. J. A Distributed Reactivity Model for Sorption by Soils and Sediments. 2.Multicomponent Systems and Competitive Effects. Environmental Science & Technology 1993, 27 (8), 1524-1531.

(7) Lafolie, F.; Hayot, C.; Schweich, D. Experiments on Solute Transport in Aggregated Porous Media: Are Diffusions Within Aggregates and Hydrodynamic Dispersion Independent? Transport in Porous Media 1997, 29 (3), 281-307.

(10) Lehoux, A. P.; Faure, P.; Michel, E.; Courtier-Murias, D.; Rodts, S.; Coussot, P. Transport and Adsorption of Nano-Colloids in Porous Media Observed by Magnetic Resonance Imaging. Transport in Porous Media 2017, 119 (2), 403-423.

(13) Raimbault, J., Peyneau, P.E., Courtier-Murias, D., Bigot, T., Gil Roca, J., Béchet, B., Lassabatère, L. Investigating the impact of exit effects on solute transport in macroporous media. Hydrology and Earth System Sciences, 2021, 25(2), 671-683.

**Nature du financement**:

- Contrat doctoral

**Précisions sur le financement**:

- ANR COMMON (2025-2029)

**Présentation établissement et labo d'accueil**:

- Université Gustave Eiffel

Université Gustave Eiffel campus de Nantes