InterPore2026

Time-lapse X-ray microtomography of particle transport and retention in porous media

20 May 2026, 09:20

15m

Oral Presentation (MS02) Environmental Porous Media: Water, Agriculture, and Remediation MS02

Speaker

Muhammad Muqeet Iqbal (CNRS)

Description

Understanding the fate of colloids in porous media, such as rocks and soils, is crucial for environmental applications including groundwater remediation. Colloids spanning nanometre to micrometre length scales can deposit within pore spaces, obstruct flow pathways, and significantly alter permeability. Colloid deposition in porous media may occur through sieving, hydrodynamic bridging, or aggregation driven by physicochemical interactions [1]. Although these mechanisms are well studied in the literature, their relevance and dynamics at the nanoscale are still debated [2]. Recent studies have demonstrated that nanoparticles can significantly modify pore structures [3], that pore geometry and flow velocity influence nanoparticle retention [4], and that deposition processes may be dynamic and partially reversible [5]. However, these investigations have largely relied on pre- and post-injection imaging or bulk-scale measurements, preventing direct observation of transient pore-scale processes. To date, no study has quantified the real-time evolution of nanoparticle concentration within individual pores and throats across a 3D porous network, nor directly linked these changes to porosity and permeability reductions. In particular, real-time pore-scale observations linking particle deposition to permeability-porosity evolution are lacking. This study aims to address this gap by employing time-resolved 3D X-ray micro-computed tomography (micro-CT) to directly visualize nanoparticle transport, retention, and clogging in situ within complex pore networks. We performed a series of controlled flow experiments using time-resolved micro-CT imaging to capture nanoparticle deposition dynamics in 3D porous media (see figure 1). Experiments were conducted using cylindrical porous glass samples (4 mm diameter, 40 mm length) with pore throat sizes ranging from 40 to 100 µm, mounted in a X-ray transparent flow cell. A water–glycerol mixture served as the working fluid, carrying either gadolinium oxide nanoparticles (~50 nm diameter) or silver coated hollow glass sphere (~10 µm diameter) selected for their strong X-ray attenuation. Once fully saturated conditions were established (i.e., using CO2 flushing followed by liquid saturation), nanoparticle suspensions were injected at flow rates between 25 and 250 µL min-1, corresponding to Péclet numbers on the order of 1e5 – 1e6 under a confining pressure of 2 MPa. Quantitative nanoparticle concentration fields were obtained through calibration of X-ray attenuation using nanoparticle-filled glass capillaries. These experiments delivered the first direct, time-resolved visualization of nanoparticle transport and clogging in 3D porous media. They revealed how deposition initiates and propagates within pore networks, alters local hydrodynamics, and drives permeability reduction and flow redistribution. This has important implications for the development of improved predictive models for colloid transport, groundwater remediation, contaminant migration, and subsurface energy storage.