An AFM study of ultrafiltration membranes: Peculiarities of pore size distribution

Abstract

The Mifil ultrafiltration membrane made from aromatic polyamide PA 100 has been studied using a SmartSPM 1000 atomic force microscope (AIST NT, Zelenograd, Russia). Pores on the AFM images have been identified using the Gwyddion software in two ways, by threshold and watershed methods. The pore size data have been subjected to statistical processing and interpretation. Along with the log normal pore size distribution law, a bimodal curve of a special kind has been considered. The accuracy of the approx imation has been assessed using Pearson's goodness of fit test, in which the bimodal distribution has demon strated better agreement with the experimental data. It has been shown that the watershed method provides more detailed information about the pore size distribution of the investigated membrane.

Membrane materials for water purification: design, development, and application

“…As the tip nears the sample surface, deflection of the cantilever is measured by a laser beam reflected from the cantilever onto a photodiode. AFM studies have been applied to various membrane materials (both organic and inorganic) [249][250][251] and processes (from MF to RO). 249,[252][253][254][255][256] Determination of the surface roughness by AFM has become a routine analytical method as it relates to membrane fouling.…”

Correlating polymer structure, dynamics, and function with atomic force microscopy

“…The synthesis of these membranes is beyond the scope of this perspective, but several recent reviews cover this topic, 129–132 as well as many literature examples 133–140 . AFM is commonly utilized to nondestructively characterize membrane topography, including pore size, shape, and size distribution, at a local level, as well as to understand membrane behavior in solvent environments 141–143 . In addition, AFM phase imaging has been used to determine the relative hydrophobicity or hydrophilicity of a membrane sample 144 and to distinguish between new and fouled membranes 145 …”

“…[133][134][135][136][137][138][139][140] AFM is commonly utilized to nondestructively characterize membrane topography, including pore size, shape, and size distribution, at a local level, as well as to understand membrane behavior in solvent environments. [141][142][143] In addition, AFM phase imaging has been used to determine the relative hydrophobicity or hydrophilicity of a membrane sample 144 and to distinguish between new and fouled membranes. 145 Further advances in AFM techniques offer the potential to gain insight into the behavior of membranes in environments that mimic their operating conditions.…”

Influence of Polymer Solvents on the Properties of Halloysite-Modified Polyethersulfone Membranes Prepared by Wet Phase Inversion

“…The average roughness value (R a ) of the membrane surface was determined in the NanoScope Analysis software using at least five AFM images (10 × 10 µm). The size of the membrane pores in the skin layer was calculated based on the AFM images (1 × 1 μm) with the application of the Gwyddion software package using a slightly modified methodology described by Khanukaeva et al [ 54 ]. The images were first flattened to the third order using the NanoScope Analysis software.…”

“…The surface porosity is analyzed based on the position, size, and shape of such created structures which are interpreted as pores. A more detailed description of the method can be found elsewhere [ 54 ].…”