Facile pore size tuning and characterization of nanoporous ceramic membranes for the purification of polysaccharide

Developing nanoporous ceramic membranes with tunable pore structure offers a new paradigm to the precise separation and purification of functional polysaccharides. Here, a facile in-situ chemical deposition method was applied to obtain nanoporous ZrO₂ membranes with controllable pore size. A modified rejection curve method based on Poiseuille flow, Ferry's equation, and log-normal distribution was proposed to calculate pore size distribution of membrane. The results showed that with the increase of precursor content from 0 to 20 wt%, the geometric mean diameter of ceramic membranes decreased from 5.9 nm to 3.1 nm, corresponding to a significant decrease of molecular weight cut-off from 15.0 kDa to 3.3 kDa. Still, the pure water permeability was maintained at a high level of about 42 L m⁻² h⁻¹·bar⁻¹. Meanwhile, the geometric standard deviation decreased from 1.20 to 1.16, indicating a narrower pore size distribution. The obtained nanoporous ZrO₂ membrane performed a high rejection of dextran, while the fructose can be effectively and efficiently separated with a separation factor as high as 11.5, therefore enlarging our choices removing fructose from dextran.