Reconstruction and analysis of pore blockage fouling in ceramic ultrafiltration membranes through FIB-SEM

Abstract

Pore blockage fouling significantly impairs ultrafiltration (UF) efficiency. Recent advances in volume electron microscopy have enabled nanoscale investigations of its mechanisms. Here, we developed a focused ion beam-scanning electron microscopy (FIB-SEM) tomography strategy that enables accurate 3D reconstruction of organic foulant accumulation within ceramic membrane pores. FIB-SEM achieves a voxel resolution of 2 × 2 × 5 nm3. The high-resolution imaging clearly reveals the trilayer structure of ceramic UF membranes, and captures the dynamic evolution of pore blockage fouling. The interface between the top and intermediate layers emerges as the primary site for initial membrane fouling. This localized channel constriction decreases the theoretical water permeability by 76.5%, directly explaining the rapid initial flux decline. Lattice Boltzmann simulations reveal that multilayer membrane structures create flow stagnation zones. Near-zero velocities trigger foulant accumulation, clarifying pore blockage mechanisms. 3D reconstruction and pressure distribution analysis revealed that pore blockage fouling is effectively removed during physical backwash, but could rapidly accumulate again at the initial stage of the next operation cycle. This study provides key insights into pore blockage fouling in trilayer ceramic UF membranes, and offers a theoretical basis for guiding the design of anti-fouling membranes.