Effects of Ionic Environments on Bovine Serum Albumin Fouling in a Cross-Flow Ultrafiltration System (original) (raw)
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Electrostatic repulsion as a mechanism in fouling of ultrafiltration membranes
Water science and technology : a journal of the International Association on Water Pollution Research, 2008
Studies of electrostatic repulsion in ultrafiltration membranes are limited to applications of different organic compounds carrying a set of unique characteristics, or to changes of general water parameters such as ionic strength and pH. The proposed method of deliberate alteration of surface charge of organic molecule by succinylation or by guanidination provides an opportunity to selectively investigate the electrostatic mechanism without changing size or hydrophobic properties of investigated molecule. The approach was successfully implemented on BSA protein, and new inside into the mechanism of electrostatic mechanism was obtained. The electrostatic repulsion becomes important when zeta potential of the protein exceeded 20 mV, when before the threshold the interactions were mainly governed by size exclusion.
Journal of Membrane Science, 2000
It was studied how protein-protein and protein-membrane interactions influence the filtration performance during the ultrafiltration of protein solutions over polymeric membranes. This was done by measuring flux, streaming potential, and protein transmission during filtration of bovine serum albumin (BSA) solutions at various pH values using various membranes with different cut-off values.
Analysis of Initial Protein Surface Coverage on Fouled Ultrafiltration Membranes
Journal of Colloid and Interface Science, 1996
brane material for both partially and totally retained mem-Internal surface coverage of protein in membranes during the branes for long-term ultrafiltration (10). Generally it has initial phase of ultrafiltration was analyzed. Bovine serum albumin been found that protein deposition, on the order of 0.5 to (BSA), in solutions of pH 5 and 7 with 0.05 and 0.15 M NaCl, 200 mg/cm 2 , can adsorb on the membrane over a long time were ultrafiltered with 100,000-MWCO polysulfone membranes. (approximately 24 h) (8). This large discrepancy may be Mass uptake of the membranes was determined using electron due to assumptions of nominal surface area being equivalent paramagnetic resonance spectroscopy for separate membranes for to the adsorption area and to error in protein measurement. fractions of an hour for up to 4 h. The resulting data were com-An extensive study that considered the entire membrane area pared with models for surface coverage. The results showed a indicated that near-monolayer adsorption (0.5 mg/cm 2) was significant amount of protein loading exists in a very short time of exposure during ultrafiltration. The amount of material found obtained for bovine serum albumin (BSA) on polyether sulin this period was not a function of solution properties; however, fone membranes during long-term static adsorption (8). solution properties did affect the resistance per mass for adsorbed While studies have concentrated on long-term protein adspecies when the pH was near the isoelectric point of BSA. The sorption studies, only limited research has considered initial modeling comparison implied that the entrained solute from pH adsorption behavior (9-11). Initial studies and understand-7 appeared to behave as though it was lodged in the ultrathin skin ing the dependency of the solute interactions as a function area of the membrane. Solute in the membrane at pH 5 and low of solution properties can provide information on the initial ionic strength appeared to be lodged and adsorbed throughout the steps in the fouling process. However, difficulties in measurmembrane substructure.
Chemical Engineering Journal, 2010
The potential use of ultrafiltration (UF) in food industry has been well established. However there have been very few in-depth studies in understanding the fouling phenomena during the UF of food proteins, especially the random-coil type. In this study, the influence of solution chemistry on the extent of fouling and the associate fouling mechanism during UF has been investigated using concentrated gelatin with a hydrophilic regenerated cellulose acetate membrane (30 kDa MWCO). It was found that there was insignificant fouling under static condition, but severe fouling was observed during the dynamic filtration. The maximum flux decline rate was obtained at the isoelectric point (IEP) of gelatin, suggesting complementary electrostatically driven fouling. Addition of salt increased flux at pH values near the IEP but had a negative effect at pH above or below the IEP. The experimental data showed that both protein-protein and protein-membrane interactions influenced the gelatin ultrafiltration performance. The experimental data were fitted well into the fouling models thereby demonstrating that the solution chemistry influenced the fouling mechanism in gelatin ultrafiltration.
Analysis of Protein Separation Mechanism in Charged Ultrafiltration Membrane
Journal of Engineering and Technological Sciences, 2018
The separation mechanism of proteins on a charged ultrafiltration membrane was analyzed using the extended Nernst-Planck (N-P) model. The model was solved numerically based on experimental data during ultrafiltration of bovine serum albumin/BSA and hemoglobin at various pH (between 5 and 8) to obtain the flux parameter (J v). The flux parameter was used to determine the effective charge of the membrane () and the actual membrane porosity (A k). These two parameters were then used to predict the transport mechanism of proteins through the charged membrane. Higher flux was obtained during the ultrafiltration of BSA compared to hemoglobin. The most effective separation of mixed proteins occurred at pH 5 ( albumin = 5). In addition, the mobility of a single protein was lower than when it was mixed with other proteins that had different charges. The effective charges of the membranes were varied between 0.99996 to 1.0000, which means that the fixed charge on the membrane structure was higher than the concentration of proteins, thus the effective charge of the membrane was not influenced by the presence of protein charge at various pH. On the contrary, the value of A k was influenced by the type and charge of the proteins. A decrease of negative charge along with an increase of solution pH increased the porosity of the membrane, thus reducing the rejection of proteins.
Ion-exchange membrane fouling by peptides: A phenomenon governed by electrostatic interactions
Journal of Membrane Science, 2011
The aim of this work was to study the impact of acidification and basification pre-treatment on the integrity and the susceptibility of anion- (AEM) and cation- (CEM) exchange membranes to fouling by peptides. The acidification and basification of ion-exchange membrane interfaces appear during electrodialysis when the limiting current density is reached. At this point, the mass transport of ions is
Quantifying the effect of ionic strength on colloidal fouling potential in membrane filtration
Journal of Colloid and Interface Science, 2005
Ultrafiltration experiments were conducted to study the fouling potential of colloidal suspensions under different ionic strengths and colloid concentrations. A linear relationship was found relating the colloidal fouling potential to the logarithm of the Debye-Hückel parameter, a characteristic for electrical double layers of colloids. This finding provided a useful quantitative linkage between the colloidal fouling potential and the water chemistry. Considering the linear dependence of colloidal fouling potential on the colloid concentration, a bilinear model was proposed to explain the coupling effects of colloid concentration and ionic strength of the suspension on the fouling potential. The model predictions of fouling potential were found to fit accurately with experimentally determined fouling potential values. Further analysis of the model showed that ionic strength can significantly affect colloidal fouling, for example, a 10-fold increase in ionic strength from 0.001 to 0.01 M for a given feed concentration has the same membrane fouling effect as doubling the feed concentration. The model allows for a quick and reliable assessment of fouling potential without even performing any experiments. This could then be used to design the membrane process or pretreatment stages required to mitigate membrane fouling. 2004 Elsevier Inc. All rights reserved.
Separation and Purification Technology, 2015
Protein fractionation by membrane technology has many advantages for separations, in comparison with conventional methods. In this paper, the influence of different type and concentration of two electrolytes: NaCl and MgCl 2 on buffer capacity and hydrodynamic radius of bovine plasma proteins were analyzed as a way to improve protein separation by cross-flow ultrafiltration. A tubular ceramic membrane with 0.2 lm pore size was used. The evolution of permeate flux and BSA transmission was determined at 25°C and transmembrane pressure range of 0.2-1.4 bar. The membrane fouling was evaluated through the resistance model application, identifying the operational conditions of the highest BSA transmission through the membrane. In this regard, it was demonstrated that the effective radius of the protein and its buffering capacity were affected by the use of MgCl 2 at 0.006 (w/v), which caused conformation changes in the protein structure resulting in a less resistance to transport.
Pulsed-electric-field crossflow ultrafiltration of bovine serum albumin
Journal of Membrane Science, 1993
A conventional crossflow ultrafiltration (CUF) apparatus was modified by the mcluslon of electrodes which permitted a pulsed electric field to be produced across the ultrafiltration membrane (PEF-UF process) Using this apparatus, a dlscontmuous electrophoretlc velocity was unposed upon the protems bemg concentrated, opposing their convectwe movement toward the CUF membrane This resulted m a lower concentration of reJected solute protein in the fluid boundary layer adJacent to the hqh-pressure side of the membrane and, hence, in a lower solute-related filtration resistance than m the case of conventional ultrafiltration (zero electric field) Studies of the PEF-UF process with bovme serum albumm (BSA) m the range of 0.5-5% w/v demonstrated a 25-40% decrease in the solute-related resistance to the permeate flux compared to the case of a zero electric field Accordmgly, higher permeate fluxes and, therefore, higher rates of concentration of the protein solution were obtamed than for conventional crossflow ultrafiltration When the electnc field was reimposed following a penod of operation under conventional CUF con&tlons, the permeate flux could be restored to nearly the same higher value observed u&ally for the PEF-UF process
Journal of Membrane Science, 2006
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 pK a 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 membranes. 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.