In situ liquid SEM imaging analysis revealing particle dispersity in aqueous solutions.

A quantitative description on dispersity of boehmite (γ-AlOOH) particles, a key component for waste slurry at Hanford sites, can provide useful knowledge for understanding various physicochemical nature of the waste. In situ liquid scanning electron microscopy (SEM) was used to evaluate the dispersity of particles in aqueous conditions using a microfluidic sample holder, System for Analysis at Liquid Vacuum Interface (SALVI). Secondary electron (SE) images and image analyses were performed to determine particle centroid locations and the distance to the nearest neighbour particle centroid, providing reliable rescaled interparticle distances as a function of ionic strength in acidic and basic conditions. Our finding of the particle dispersity is consistent with physical insights from corresponding particle interactions under physicochemical conditions, demonstrating delicate changes in dispersity of boehmite particles based on novel in situ liquid SEM imaging and analysis. LAY DESCRIPTION: In situ liquid scanning electron microscopy (SEM) was used to determine the interparticle distance of boehmite (γ-AlOOH) particles, a key component for waste slurry at Hanford sites. This type of quantitative measurement is important to understand various physicochemical nature of the radiological waste containing boehmite. In situ liquid SEM was enabled by a unique vacuum compatible microfluidic cell, System for Analysis at Liquid Vacuum Interface (SALVI). We collected secondary electron (SE) images and performed image analyses to determine particle centroid locations and the distance to the nearest neighbour particle centroid to arrive at the interparticle distances in acidic and basic conditions. Our results show that delicate changes occur among boehmite particles under different pH conditions using novel in situ SEM imaging.