## 3 Materials and Methods
### Capillary Flow Porometry (CFP) Method  
The gas liquid and liquid displacement measurements were performed with IFTS fluid porometer (FFP) (model PRM-8710(r), IFTS, Foulayronnes, France) consisted of an automated pressure constant device suitable for working in gas/liquid and liquid/liquid configurations. The device is designed for testing pore sizes down to 4 nm and up to 200 um and uses relatively low pressures from 2 KPa \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Material** & **Manufacturer** & **Pore Range** & \
\begin{tabular}{c} **Nominal** \\ **Pore Size** \\ \end{tabular} & **Type** & **Structure** &
\begin{tabular}{c} **Young-Laplace** \\ **Technique** \\ \end{tabular} \\ \hline Al2O3 & Whatman & UF & 0.02 μm & Disk & Uniform capillary & LLDP \\ \hline PET & Company A & UF & Not available & Flat Sheet & Porous & LLDP \\ \hline CN & Sartorius & MF & 5 μm & Disk & Porous & GLDP/LEP \\ \hline FM & Company B & Particle Filtration & Not available & Flat Sheet & Fiber & GLDP/LEP \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of the four membranes analyzed and porometric technique/s used. Figure 4: SEM images of (**a**) NC 5μm porous structure and (**b**) FM fibers. (minimum) up to a maximum of 1 MPa for the characterization of porous or fiber membranes in the NF to the particle filtration range. The equipment allows for very stable pressure (accuracy \(\pm\)0.1 mbar) to be implemented, which leads to very accurate measurement of the resulting fluxes by using an analytical balance (accuracy of \(\pm\)1 mg) for LLDP characterization or by mass flowmeter (accuracy \(\pm\)1 mL/min) for gas liquid. The included software is able to determine several important parameters related with pore size characterization including mean pore diameter, peak pore size, PSD, fluid permeability, and bubble/droplet point. It also can be adapted to analyze various membrane configurations or modules including hollow fiber, tubular, and flat sheet. Capillary flow porometry (in both versions, gas liquid and liquid-liquid) was performed according to the capillary principle to obtain the PSD of the membranes. The filter media was previously wet in a liquid (wetting phase), then by increasing the pressure of the displacing fluid upstream to the membrane at a predetermined rate, the flow downstream of the membrane is observed, indicating the passage of displacement fluid (gas or liquid) through all the pores in the filter, starting at the maximum diameter filter (bubble point for gas liquid or \"droplet point\" for liquid-liquid) pores until flowing through the smallest ones. Both wetting and displacement fluids are immiscible between them. For the case of UF membranes, LLDP experiments were performed according to the usual procedure [19], and the wetting and displacement liquids used in LLDP analysis were selected according to the membrane hydrophobicity/hydrophilicity, good chemical compatibility with the material matrix active layer, and with the porometer internal parts to avoid corrosion or degradation. Wetting fluid should also exhibit physical properties such as low displacement viscosity and low vapor pressure. A very stable 1:1 (\(\gamma\)/\(v\)) binary mixture composed of water/isobutanol (\(\gamma\) = 1.7 mN/m) was used. This mixture was prepared by pouring proper amounts of Milli-Q(r) grade water and isobutanol (methyl-2-propanol) into a separator funnel and shaking it vigorously during 10 min. After mixing, the two rapidly separating phases are then allowed to stand overnight and then two sharply and clearly separated phases are presented. The higher density phase and water-rich (aqueous) phase is first drained off and used as the displacement liquid, while the alcoholic phase (remaining in the upper part of the funnel due to their lower density) is the wetting one.