Improvement of a method for the characterization of ultrafiltration membranes by measurements of tracers retention

The aim of this study is to improve protocols for assessing accurate characteristic retention curve and cut-off of membranes, thus enabling the manufacture and performance of the membrane to be monitored. Different data treatments are considered in order to determine membrane retention for fractions of tracer filtered (PEGs in the molar mass range of 1–100 kg mol−1). In the most advanced method of treatment, the observed retention is expressed as a combination of solute transfer coefficients in the boundary layer (kBL) and porous structure (kpore), and the asymptotic retention (Rinf), which is an intrinsic characteristic of the membrane to solute as it is independent of operating conditions. The developed method has proved to be accurate and reproducible in two cases: (i) monitoring of UF membrane integrity during accelerated aging; (ii) for quantification of cut-off change due to UF membrane modification by UV grafting. We propose a simplified procedure that allows a reduction in experimental workload, without loss of sensitivity, for the most advanced method.