Partitioning of organic solutes between water and polyamide layer of RO and NF membranes: Correlation to rejection

Determination of concentration-dependent transport coefficients in nanofiltration: Defining an optimal set of coefficients

“…This omission may be justified for membranes with large pores, such as UF membranes, where non-steric exclusion is often negligible thereby K ∼ 1, if the solute size is not too close to the pore size [4]. It is however an unacceptable oversimplification in NF, where non-steric molecular interactions with the membrane material may change K by orders of magnitude [20][21][22] and lead to erroneous conclusions regarding molecular frictions.…”

Ion transport in the polyamide layer of RO membranes: Composite membranes and free-standing films

“…This leads to mathematical complexities, for which many routinely used simplifying concepts, such as well-defined double electric layer, hydration shells of ions, etc., become fuzzy. Additionally, experimental analysis is complicated by the fact that the active layer is inherently very thin (15-200 nm) [5,[7][8][9][10][11][12][13] and morphologically and compositionally non-uniform. Its bulk and surface properties are then not necessarily identical and results of surface or averaged bulk measurements are not simply related to transport characteristics of its dense selective part buried inside the selective layer [14,15].…”

“…It was demonstrated recently that, apparently, due its high cross-linking and stability in organic solvents, the genuine polyamide active layer may be separated from commercial membranes by dissolving away the porous support and mounting the free polyamide film on a suitable solid substrate [7,8,11,16,21,22]. In this way a number of characteristics of interest, such as overall dry and wet thickness, swelling extent, sorption of organics, permeability of the polyamide layer to different ions, fine morphological features, etc.…”

Modeling of Aniline Removal by Reverse Osmosis Using Different Membranes

“…Aniline rejection percentages of 20 % and 63 % were obtained with polyamide NF and RO membranes [25]. Polyacrylic acid composite membranes were found to be suitable RO membranes for the separation of low-molecular-weight organic aqueous solutions, achieving 90.4 % aniline rejection [26].…”