Role of Electrostatic Interactions in the Retention of Pharmaceutically Active Contaminants by a Loose Nanofiltration Membrane
نویسندگان
چکیده
The role of electrostatic interactions in the separation of pharmaceuticals by a loose nanofiltration (NF) membrane was examined. While retention of the non-ionizable pharmaceutical carbamazepine was relatively independent of the solution chemistry, retention of the ionizable pharmaceuticals sulfamethoxazole and ibuprofen was strongly influenced by the solution pH and ionic strength. This finding is consistent with previous results investigating the effects of solution pH and ionic strength on the retention of proteins and organic acids. Pharmaceutical retention increases dramatically as the compound transforms from a neutral to a negatively charged species when the solution pH increases above its pKa value. In contrast, solution ionic strength suppresses the double layer or the Debye screening length and therefore reduces the effectiveness of electrostatic interaction as a major retention mechanism by the loose NF. However, because of the formation of a hydrated layer around the charged functional groups of the pharmaceuticals and the fact that at a sufficiently high ionic strength the Debye length approaches a relatively constant value, this reduction in retention is relatively small. As a result, even at comparatively elevated ionic strengths, retention of the negatively charged sulfamethoxazole and ibuprofen by the loose NF membrane is considerably high.
منابع مشابه
Nanofiltration of Hormone Mimicking Trace Organic Contaminants
The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore sizes were used in laboratory-scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound—nonylphenol, tertbutylphenol, or bisphenol A. Retention of the compounds was determined at various solution chemi...
متن کاملProtein and Lactose Separation by Modified Ultrafiltration Membrane using Layer by Layer Technique
Layer-by-Layer (LbL) is a method which can be used for nanoscale coating and surface functionalization of a material. LbL technique mainly uses the electrostatic attracting between charged materials (polyelectrolytes, nanoparticles, etc.) and an oppositely charged surface. In this study, protein separation (BSA) from lactose solution was carried out using the LbL self-assembly method, which was...
متن کاملEffects of organic and colloidal fouling on the rejection of two pharmaceutically active compounds (PhACs) by nanofiltration processes: role of membrane foulants
متن کامل
Pharmaceutical retention mechanisms by nanofiltration membranes.
This study investigates the retention mechanisms of three pharmaceuticals-sulfamethoxazole, carbamazepine, and ibuprofen-by nanofiltration (NF) membranes. Laboratory-scale experiments were carried out with two well-characterized NF membranes, with the goal of relating pharmaceutical retention behavior to membrane characteristics, physicochemical properties of the pharmaceutical molecules, and s...
متن کاملfaImpact of Organic Matrix Compounds on the Retention of Steroid Hormone Estrone by a ‘Loose’ Nanofiltration Membrane
The impact of solute-solute interactions on retention and membrane adsorption of the micropollutant estrone was determined in the presence of surfactant sodium dodecyl sulphate (SDS), natural organic matter (NOM) and cellulose. A five cycle stirred cell protocol was used to study progressing saturation of a loose nanofiltration membrane with estrone. Adsorption was absent at high pH when the es...
متن کامل