Review of the dielectric properties of nanofiltration membranes and verification of the single oriented layer approximation

Effect of temperature on ion transport in nanofiltration membranes: Diffusion, convection and electromigration

“…The range of temperature studied by Amar et al [10] (22 -50 o C) is practically relevant because the lower limit represents the temperature at which several labscale experiments are conducted ( [21], [24]) and at which membrane specifications from the manufacturer are provided. The upper limit of 50 o C is slightly lower than the upper limit of the temperature tolerance of the experimental setup used in reference [10] and represents the typical temperature of geothermal brackish water which is often used as NF feed [10].…”

“…As inputs to this model, the membrane is characterized by certain structural parameters (pore radius and effective active layer thickness) and electrical parameters (membrane charge and pore dielectric constant) [21] [23]. These nanofiltration membrane properties are affected by experimental conditions such as feed composition, pH, concentration and temperature [24] [25] [10]. An understanding of how membrane properties affect the modes of solute exclusion and solute transport for different solutes is important in order to gain intuition about nanofiltration.…”

“…In the previous sections of this work, the effect of dielectric exclusion was not considered, since our approach is to examine the impact of membrane parameters individually. In the model used for this work, dielectric exclusion governed only by the Born effect is considered, which accounts for the solvation energy barrier for the ion to enter the pore, resulting in a decreased dielectric constant of the solvent within the pore [14] [21] [24]. Thus, the Born effect accounts for the energy penalty for an ion to shed its hydration shell when moving from a fully solvated state in bulk solution to the constricted passage within the pore, where there isn't enough 'space' for all of the ion's hydration shells.…”

Recovery of Organic Acids from Fermentation Broth Using Nanofiltration Technologies: A Review

“…The dielectric exclusion mechanism is usually used to describe the rejection mechanism of non-symmetrical electrolyte mixture containing ions of different charges. The detail interactions has been reviewed by Oatley et al 26 Meanwhile, for hydration mechanism, only limited description was reported. Yaroshchuk 25 has described the rejection performance of NF membrane based on hydration mechanism from the loss of water dissolving ability of the NF membrane.…”

“…23,25 It is believed that every NF membranes may have different dominant rejection mechanism for combinations of several rejection mechanisms, depending on the micro-hydrodynamic and interfacial events occurring at the membrane surface and within the membrane nanopores. 23,26 26 Donnan exclusion is a classical known rejection mechanism in NF separation, which is usually used to describe the high rejection of divalent ions and low rejection of monovalent ions in organic acids separation. 6,10 It describes the membrane potential interaction between charge species and the fixed electrical charges attached to the membrane matrix.…”