Cryo‐snap: A simple modified freeze‐fracture method for SEM imaging of membrane cross‐sections

Abstract

Cross-sections of thin film polymeric membranes, including reverse osmosis (RO), ultrafiltration (UF), and hollow fiber microfiltration (MF) membranes, are frequently used for both material analysis and for failure and fouling investigation. However, many techniques currently used to prepare cross-sections are far from ideal and result in distortion at cut surfaces. A modified freeze fracture method (Cryo-snap), where the specimen is embedded in ice before cleaving, was developed to minimize the stresses put on the sample during fracturing, thereby reducing the distortion to the cross-section and increasing the resulting detailed resolution. This method was compared to two commonly used sectioning methods, razor sectioning, and direct freeze fracturing. The Cryo-snap method rapidly yielded cross-sections with fewer artifacts than the traditional methods and the sample distortion was extremely low. The method is superior for membrane applications.

Source water quality shaping different fouling scenarios in a full-scale desalination plant at the Red Sea

“…However, a drawback of TEM technique is the unavoidable loss of foulant material during specimen preparation. Due to the anisotropic character of the TFC membranes and delicate structure of the fouling layer, conventional techniques, i.e., razor blade cutting and cryo fracturing (Singh et al, 2011) are also not suitable for obtaining a cross section due to structural deformation (Ferlita et al, 2008). By combining the cross sectioning capability of FIB with the high resolution of the STEM and elemental microanalysis power of EDX, we developed a novel application of these techniques termed as FIB-STEM/EDX line profiling.…”

Surface modification of thin film composite membrane support layers with polydopamine: Enabling use of reverse osmosis membranes in pressure retarded osmosis

“…These samples were prepared using a freeze fracturing technique involving liquid nitrogen [31][32][33] after removal of the PET support layer. This method allows the preparation of clean, straight edges and a preserved internal pore structure for observation.…”

Cellulose multilayer membranes manufacture with ionic liquid

“…Ferlita et ʹʹ al. [36] reported a freeze fracture method for FESEM investigation. The investigated membranes were imaged mostly dry.…”

“…The dense (non porous) areas of the membranes locally obstruct the growth of the interfacial polymerized layer, while the contact between organic and aqueous phase is favored through the pores. Li et al [36] explained that large pores during the interfacial polymerization lead to a rapid transport of amine from the aqueous phase, filling the membrane pores, and the organic phase to react with trimesoyl chloride.…”