Mapping absorbency in cellulosic fibres with iron tracers.

Area of Science:

• Materials Science
• Chemical Engineering
• Biotechnology

Background:

• Assessing paper's water absorbency is complex due to simultaneous fiber swelling and deformation during liquid imbibition.
• Traditional gravimetric tests offer limited insight into the spatial and temporal distribution of liquid within paper structures.

Purpose of the Study:

• To develop a novel method for mapping liquid imbibition in paper using in situ precipitated iron oxide nanoparticles.
• To investigate the two-phase nature of liquid absorption in cellulosic materials.

Main Methods:

• In situ precipitation of iron oxide nanoparticles at the wetting front during liquid absorption.
• Mapping iron distribution in 3D using X-ray micro-computed tomography (μCT).
• Mapping iron distribution in 2D using energy-dispersive X-ray spectroscopy (EDS).

Main Results:

• Iron oxide tracers demonstrated robust attachment to cellulosic fibers.
• Tracer distribution analysis revealed distinct patterns between the wetting front and saturated regions.
• Evidence suggests a two-phase imbibition process: initial cell wall percolation followed by external pore filling.

Conclusions:

• Iron tracers provide enhanced contrast for μCT imaging of fiber networks.
• The developed method allows for new imaging modalities to study liquid transport in porous materials.
• The study elucidates a two-phase mechanism governing liquid absorption in paper-like substrates.