Articoli di riviste: "Protein fouling"

1

Peiris, R. H., H. Budman, R. L. Legge e C. Moresoli. "Assessing irreversible fouling behavior of membrane foulants in the ultrafiltration of natural water using principal component analysis of fluorescence excitation-emission matrices". Water Supply 11, n. 2 (1 aprile 2011): 179–85. http://dx.doi.org/10.2166/ws.2011.025.

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Natural river water is comprised of different foulant components such as natural organic matter and colloidal/particulate matter. Both individual and combined contributions of these foulant components results in different fouling behaviour. The ability to characterize these contributions that lead to reversible and irreversible membrane fouling would be beneficial for the implementation of fouling monitoring and control strategies for membrane-based drinking water treatment operations. A fluorescence excitation-emission matrix and principal component analysis-based approach was able to qualitatively estimate the accumulation of humic substances (HS)-, protein- and colloidal/particulate matter-like foulant components in membranes during the ultrafiltration (UF) of natural river water. A bench-scale flat sheet UF cross-flow set-up and successive permeation and membrane backwashing cycles were used. Analysis of the accumulation of these foulant components revealed that the increased levels of colloidal/particulate matter accumulation in the membranes appeared to have increased the extent of irreversible fouling by HS-like matter whereas lower irreversible fouling by protein-like matter was observed with increased colloidal/particulate matter accumulation. The results also indicate that the combined contributions by these foulants are important in the fouling of membranes during the UF of river water.

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Yan, Linlin, Ruixue Li, Yu Song, Yanping Jia, Zheng Li, Lianfa Song e Haifeng Zhang. "Characterization of the Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Evolution of the Foulants’ Composition and Aggregation Ability". Membranes 9, n. 7 (16 luglio 2019): 85. http://dx.doi.org/10.3390/membranes9070085.

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In this study, the characteristics of membrane foulants were analyzed with regard to morphology, composition, and aggregation ability during the three stages of transmembrane pressure (TMP) development (fast–slow–fast rise in TMP) in a steady operational membrane bioreactor (MBR). The results obtained show that the fouling layer at the slow TMP-increase stage possessed a higher average roughness (71.27 nm) and increased fractal dimension (2.33), which resulted in a low membrane fouling rate (0.87 kPa/d). A higher extracellular DNA (eDNA) proportion (26.12%) in the extracellular polymeric substances (EPS) resulted in both higher zeta potential (-23.3 mV) and higher hydrophobicity (82.3%) for initial foulants, which induced and increased the protein proportion in the subsequent fouling layer (74.11%). Furthermore, the main composition of the EPS shifted from protein toward polysaccharide dominance in the final fouling layer. The aggregation test confirmed that eDNA was essential for foulant aggregation in the initial fouling layer, whereas ion interaction significantly affected foulant aggregation in the final fouling layer.

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Chen, Yian, Montserrat Rovira-Bru, Francesc Giralt e Yoram Cohen. "Hydraulic Resistance and Protein Fouling Resistance of a Zirconia Membrane with a Tethered PVP Layer". Water 13, n. 7 (31 marzo 2021): 951. http://dx.doi.org/10.3390/w13070951.

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The influence of surface modification of zirconia (ZrO2) membrane with tethered poly(vinyl pyrrolidone) (PVP) chains was evaluated with respect to the impact of pH and ionic strength on hydraulic resistance and fouling resistance in the filtration of bovine serum albumin (BSA) and lysozyme (Lys) as model protein foulants. The tethered PVP surface layer led to membrane permeability and fouling propensity that were responsive to both pH and ionic strength. The PVP-modified membrane (PVP-ZrO2) hydraulic resistance increased by up to ~48% over a pH range of 6–11, but with no discernible impact at lower pH. Membrane hydraulic resistance was virtually unaffected by ionic strength over the 0.001–1 M range. However, reversible foulant cake resistance in BSA and Lys solution filtration increased with elevated ionic strength, owing in part to the weakening of protein–protein repulsion. Irreversible BSA and Lys fouling was affected by the operational pH relative to the protein isoelectric point (IEP) and reduced under conditions of chain swelling. Irreversible membrane fouling resistance for both proteins was significantly lower, by ~11–49% and 18–74%, respectively, for the PVP-ZrO2 membrane relative to the unmodified ZrO2 membrane. The present results suggest the merit of further exploration of fouling reduction and improvement of membrane cleaning effectiveness via tuning pH and ionic strength triggered conformational responsiveness of the tethered target polymer layer.

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Sun, Chunyi, Na Zhang, Fazhan Li, Guoyi Ke, Lianfa Song, Xiaoqian Liu e Shuang Liang. "Quantitative Analysis of Membrane Fouling Mechanisms Involved in Microfiltration of Humic Acid–Protein Mixtures at Different Solution Conditions". Water 10, n. 10 (22 settembre 2018): 1306. http://dx.doi.org/10.3390/w10101306.

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A systematical quantitative understanding of different mechanisms, though of fundamental importance for better fouling control, is still unavailable for the microfiltration (MF) of humic acid (HA) and protein mixtures. Based on extended Derjaguin–Landau–Verwey–Overbeek (xDLVO) theory, the major fouling mechanisms, i.e., Lifshitz–van der Waals (LW), electrostatic (EL), and acid–base (AB) interactions, were for the first time quantitatively analyzed for model HA–bovine serum albumin (BSA) mixtures at different solution conditions. Results indicated that the pH, ionic strength, and calcium ion concentration of the solution significantly affected the physicochemical properties and the interaction energy between the polyethersulfone (PES) membrane and HA–BSA mixtures. The free energy of cohesion of the HA–BSA mixtures was minimum at pH = 3.0, ionic strength = 100 mM, and c(Ca2+) = 1.0 mM. The AB interaction energy was a key contributor to the total interaction energy when the separation distance between the membrane surface and HA–BSA mixtures was less than 3 nm, while the influence of EL interaction energy was of less importance to the total interaction energy. The attractive interaction energies of membrane–foulant and foulant–foulant increased at low pH, high ionic strength, and calcium ion concentration, thus aggravating membrane fouling, which was supported by the fouling experimental results. The obtained findings would provide valuable insights for the quantitative understanding of membrane fouling mechanisms of mixed organics during MF.

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Miyoshi, Taro, Yuhei Nagai, Tomoyasu Aizawa, Katsuki Kimura e Yoshimasa Watanabe. "Proteins causing membrane fouling in membrane bioreactors". Water Science and Technology 72, n. 6 (2 giugno 2015): 844–49. http://dx.doi.org/10.2166/wst.2015.282.

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In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

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Scudeller, Luisa A., Pascal Blanpain-Avet, Thierry Six, Séverine Bellayer, Maude Jimenez, Thomas Croguennec, Christophe André e Guillaume Delaplace. "Calcium Chelation by Phosphate Ions and Its Influence on Fouling Mechanisms of Whey Protein Solutions in a Plate Heat Exchanger". Foods 10, n. 2 (27 gennaio 2021): 259. http://dx.doi.org/10.3390/foods10020259.

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Fouling of plate heat exchangers (PHEs) is a recurring problem when pasteurizing whey protein solutions. As Ca2+ is involved in denaturation/aggregation mechanisms of whey proteins, the use of calcium chelators seems to be a way to reduce the fouling of PHEs. Unfortunately, in depth studies investigating the changes of the whey protein fouling mechanism in the presence of calcium chelators are scarce. To improve our knowledge, reconstituted whey protein isolate (WPI) solutions were prepared with increasing amounts of phosphate, expressed in phosphorus (P). The fouling experiments were performed on a pilot-scale PHE, while monitoring the evolution of the pressure drop and heat transfer coefficient. The final deposit mass distribution and structure of the fouling layers were investigated, as well as the whey protein denaturation kinetics. Results suggest the existence of two different fouling mechanisms taking place, depending on the added P concentration in WPI solutions. For added P concentrations lower or equal to 20 mg/L, a spongy fouling layer consists of unfolded protein strands bound by available Ca2+. When the added P concentration is higher than 20 mg/L, a heterogeneously distributed fouling layer formed of calcium phosphate clusters covered by proteins in an arborescence structure is observed.

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Buchori, Luqman, Heru Susanto e Budiyono Budiyono. "SINTESIS MEMBRAN ULTRAFILTRASI NON FOULING UNTUK APLIKASI PEMPROSESAN BAHAN PANGAN". Reaktor 13, n. 1 (3 febbraio 2010): 10. http://dx.doi.org/10.14710/reaktor.13.1.10-15.

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Membran ultrafiltrasi (UF) telah terbukti sebagai proses yang menjanjikan untuk aplikasi di bidang pemprosesan bahan pangan. Namun, peristiwa fouling dapat menurunkan kinerja membran secara signifikan. Meskipun banyak metode pengendalian fouling telah diusulkan, dalam banyak kasus kinerja proses sangat dipengaruhi oleh membran sebagai jantung dari proses. Dalam makalah ini pengendalian fouling dilakukan dengan memodifikasi permukaan membran dengan teknik kopolimerisasi foto-grafting. Acrylic acid (AA), acrylamido methylpropane sulfonic acid (AMPS), poly(ethylene glycol) methacrylate (PEGMA), dan N,N-dimethyl-N-(2-methacryloyloxyethyl-N-(3sulfopropyl)ammonium betaine sebagai senyawa zwitterion (ZI) digunakan sebagai monomer fungsional. Pengaruh waktu iradiasi terhadap efektifitas modifikasi telah diamati. Kinerja membran hasil modifikasi kemudian diuji dengan menggunakan berbagai model larutan foulant yang meliputi larutan protein, larutan polisakarida dan larutan polifenol. Hasil penelitian menunjukkan bahwa sifat non fouling membran sangat jelas dapat ditingkatkan baik dengan PEGMA maupun dengan ZI. Secara umum, modifikasi menggunakan PEGMA menunjukkan kinerja yang lebih baik. Larutan polifenol menunjukkan karakter foulant yang paling kuat diantara model foulant.

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Berg, Thilo H. A., Jes C. Knudsen, Richard Ipsen, Frans van den Berg, Hans H. Holst e Alexander Tolkach. "Investigation of Consecutive Fouling and Cleaning Cycles of Ultrafiltration Membranes Used for Whey Processing". International Journal of Food Engineering 10, n. 3 (1 settembre 2014): 367–81. http://dx.doi.org/10.1515/ijfe-2014-0028.

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Abstract Development of resistance during multiple foulings and three-step Cleaning-In-Place (CIP) operations, simulating an industrial cleaning regime of polysulfone ultrafiltration membranes, was investigated. The study explored how trans-membrane pressure (150 and 300 kPa) and feed protein concentration (0.9 and 10%) influenced resistance reduction during filtration and flux recovery by the cleaning procedures. New membranes, pre-cleaned with a full CIP cycle, were used for each experiment. Subsequent fouling (simulating production) and CIP were done three times in a row and the development of fouling layer resistance was monitored and evaluated. Results show that filtration performance decreased during the first days of usage, possibly related to build-up of internal fouling. Cleaning success based on flux recovery was negatively influenced by a high protein concentration in the feed, but independent of the trans-membrane pressure during filtration.

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Peiris, R. H., M. Jaklewicz, H. Budman, R. L. Legge e C. Moresoli. "Characterization of hydraulically reversible and irreversible fouling species in ultrafiltration drinking water treatment systems using fluorescence EEM and LC–OCD measurements". Water Supply 13, n. 5 (1 settembre 2013): 1220–27. http://dx.doi.org/10.2166/ws.2013.130.

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The application of the fluorescence excitation-emission matrix (EEM) approach and liquid chromatography–organic carbon detection (LC–OCD) analysis for the characterization of hydraulically reversible and irreversible fouling species, extracted from hollow fiber ultrafiltration (UF) membranes used in drinking water treatment, was demonstrated. Hydraulically reversible and irreversible fouling species were extracted from two pilot UF membrane systems operated in parallel with lake water as the feed. Two membrane cleaning protocols, hydraulic- and chemical-based (NaOCl and citric acid) cleaning, were considered. Colloidal/particulate matter together with protein-like and metal species in water appeared to contribute to the formation of a hydraulically removable fouling layer on the membranes. Hydraulically irreversible fouling, in contrast, was impacted considerably by humic substances (HS) and protein-like matter. The formation of an irreversible fouling layer was also likely influenced by interactions between the colloidal/particulate matter and metal species together with HS and protein-like matter. LC–OCD analysis revealed the presence of predominant levels of lower molecular weight HS-like matter – compared to the HS-like matter commonly present in lake water – in the citric acid extracted foulant fraction. The permeability loss due to hydraulically irreversible UF fouling was considerably greater than the permeability loss due to hydraulically reversible UF fouling. A permanent permeability loss (∼25–35% of the initial permeability) was present even after the application of considerably strong chemical cleaning protocols on both pilot systems. This study indicated that the fluorescence EEM approach can be applied for monitoring and characterization of membrane cleaning procedures and as a potential diagnostic tool for assessing the effectiveness of hydraulic- and chemical-based cleaning protocols employed in UF drinking water treatment operations using rapid off-line measurements. On the other hand, since the LC–OCD analysis technique is a comparatively time consuming method, it may be used for verification of the fluorescence EEM-based results of the foulant fractions.

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Chaipetch, Wiparat, Arisa Jaiyu, Panitan Jutaporn, Marc Heran e Watsa Khongnakorn. "Fouling Behavior in a High-Rate Anaerobic Submerged Membrane Bioreactor (AnMBR) for Palm Oil Mill Effluent (POME) Treatment". Membranes 11, n. 9 (25 agosto 2021): 649. http://dx.doi.org/10.3390/membranes11090649.

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The characteristics of foulant in the cake layer and bulk suspended solids of a 10 L submerged anaerobic membrane bioreactor (AnMBR) used for treatment of palm oil mill effluent (POME) were investigated in this study. Three different organic loading rates (OLRs) were applied with prolonged sludge retention time throughout a long operation time (270 days). The organic foulant was characterized by biomass concentration and concentration of extracellular polymeric substances (EPS). The thicknesses of the cake layer and foulant were analyzed by confocal laser scanning microscopy and Fourier transform infrared spectroscopy. The membrane morphology and inorganic elements were analyzed by field emission scanning electron microscope coupled with energy dispersive X-ray spectrometer. Roughness of membrane was analyzed by atomic force microscopy. The results showed that the formation and accumulation of protein EPS in the cake layer was the key contributor to most of the fouling. The transmembrane pressure evolution showed that attachment, adsorption, and entrapment of protein EPS occurred in the membrane pores. In addition, the hydrophilic charge of proteins and polysaccharides influenced the adsorption mechanism. The composition of the feed (including hydroxyl group and fatty acid compounds) and microbial metabolic products (protein) significantly affected membrane fouling in the high-rate operation.

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Daufin, Georges, Françoise Michel, Jean-Pierre Labbé, Auguste Quemebais e André Grangeon. "Ultrafiltration of defatted whey: improving performance by limiting membrane fouling". Journal of Dairy Research 60, n. 1 (febbraio 1993): 79–88. http://dx.doi.org/10.1017/s0022029900027369.

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SummaryDefatted whey was obtained by aggregating residual fat to calcium phosphate precipitates and separating the precipitate by membrane microfiltration (pore diameter 0·2 μm). When ultrafiltering this defatted whey the performance of an inorganic membrane (molecular mass cut-off, 10 kDa) was limited by the large concentration of Ca and phosphates. Consequently, the influence of the aggregation pH (either decreasing or constant) on membrane fouling has been studied for ultrafiltration (UF) of defatted sweet whey and defatted whey UF retentates (protein content up to 30g l–1). In all experiments protein rejection was 100%. When pH was kept constant during the pretreatment, membrane fouling was significantly lowered. Hydraulic resistances ascribed to irreversible fouling were in good agreement with fouled membrane analyses performed by i.r. and X-ray photoelectron spectroscopies. They showed that provided a low Ca and phosphate content was maintained in the microfiltrate, which was achieved at constant pH, no apatite was detected within the membrane, and proteins were less fouling. On the other hand, the amount of fouling material depended on the transmembrane pressure gradient along the hydraulic path. On the membrane surface, the higher the pressure, the higher the fouling. In the membrane bulk, the fouling heterogeneity depended on the ability of the defatted whey to precipitate apatite. If it did, the higher the pressure, the higher the calcium phosphate and the protein fouling. With other phosphate structures, the bulk fouling depended on the barrier formed by surface fouling layers and the protein concentration polarization layer, which were more resistant to solute and solvent transfer under higher pressure, where they were thicker.

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Nichka, Vladlen S., Thibaud R. Geoffroy, Victor Nikonenko e Laurent Bazinet. "Impacts of Flow Rate and Pulsed Electric Field Current Mode on Protein Fouling Formation during Bipolar Membrane Electroacidification of Skim Milk". Membranes 10, n. 9 (26 agosto 2020): 200. http://dx.doi.org/10.3390/membranes10090200.

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Fouling is one of the major problems in electrodialysis. The aim of the present work was to investigate the effect of five different solution flow rates (corresponding to Reynolds numbers of 162, 242, 323, 404 and 485) combined with the use of pulsed electric field (PEF) current mode on protein fouling of bipolar membrane (BPM) during electrodialysis with bipolar membranes (EDBM) of skim milk. The application of PEF prevented the fouling formation by proteins on the cationic interface of the BPM almost completely, regardless of the flow rate or Reynolds number. Indeed, under PEF mode of current the weight of protein fouling was negligible in comparison with CC current mode (0.07 ± 0.08 mg/cm2 versus 5.56 ± 2.40 mg/cm2). When a continuous current (CC) mode was applied, Reynolds number equals or higher than 323 corresponded to a minimal value of protein fouling of BPM. This positive effect of both increasing the flow rate and using PEF is due to the facts that during pauses, the solution flow flushes the accumulated protein from the membrane while in the same time there is a decrease in concentration polarization (CP) and consequently decrease in H+ generation at the cationic interface of the BPM, minimizing fouling formation and accumulation.

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13

Xu, Hao, Kang Xiao, Jinlan Yu, Bin Huang, Xiaomao Wang, Shuai Liang, Chunhai Wei, Xianghua Wen e Xia Huang. "A Simple Method to Identify the Dominant Fouling Mechanisms during Membrane Filtration Based on Piecewise Multiple Linear Regression". Membranes 10, n. 8 (29 luglio 2020): 171. http://dx.doi.org/10.3390/membranes10080171.

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Membrane fouling is a complicated issue in microfiltration and ultrafiltration. Clearly identifying the dominant fouling mechanisms during the filtration process is of great significance for the phased and targeted control of fouling. To this end, we propose a semi-empirical multiple linear regression model to describe flux decline, incorporating the five fouling mechanisms (the first and second kinds of standard blocking, complete blocking, intermediate blocking, and cake filtration) based on the additivity of the permeate volume contributed by different coexisting mechanisms. A piecewise fitting protocol was established to distinguish the fouling stages and find the significant mechanisms in each stage. This approach was applied to a case study of a microfiltration membrane filtering a model foulant solution composed of polysaccharide, protein, and humic substances, and the model fitting unequivocally revealed that the dominant fouling mechanism evolved in the sequence of initial adaptation, fast adsorption followed by slow adsorption inside the membrane pores, and the gradual growth of a cake/gel layer on the membrane surface. The results were in good agreement with the permeate properties (total organic carbon, ultraviolet absorbance, and fluorescence) during the filtration process. This modeling approach proves to be simple and reliable for identifying the main fouling mechanisms during membrane filtration with statistical confidence.

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Pelegrine, D. H. G., M. T. M. S. Gomes e Carlos Alberto Gasparetto. "Temperature effect on whey protein fouling". Publicaciones e Investigación 2, n. 1 (15 giugno 2008): 15. http://dx.doi.org/10.22490/25394088.1134.

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<p align="left">El presente trabajo es un estudio del fenómeno de incrustación de la proteína del suero de leche al interior de un intercambiador de calor por donde fuye agua caliente por entre los dos tubos. La cinética de incrustación depende de los efectos de la transferencia de masa, que es una función de la solubilidad de las proteínas. Para describir la cinética de incrustación de las proteínas se desarrolló un algoritmo de cálculo dependiente de la solubilidad. La solubilidad de la proteína fue determinada en una investigación por separado. Los resultados mostraron que el tiempo necesario para que el tubo de radio interior disminuyera en un 30% de la radio original fue menor para altas temperaturas. Además, la deposición de las proteínas de suero de leche fue más intensa en la entrada que en la salida. Por lo tanto, la tasa de reducción de radio fue más rápido en esa zona. El experimento para comprobar el algoritmo se llevó a cabo en una planta piloto.</p>

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Suki, A., A. G. Fane e C. J. D. Fell. "Modeling fouling mechanisms in protein ultrafiltration". Journal of Membrane Science 27, n. 2 (giugno 1986): 181–93. http://dx.doi.org/10.1016/s0376-7388(00)82055-4.

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Sioutopoulos, Dimitrios, Anastasios Karabelas e Vasileios Mappas. "Membrane Fouling Due to Protein—Polysaccharide Mixtures in Dead-End Ultrafiltration; the Effect of Permeation Flux on Fouling Resistance". Membranes 9, n. 2 (1 febbraio 2019): 21. http://dx.doi.org/10.3390/membranes9020021.

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Significant gaps exist in our knowledge of ultrafiltration (UF) membrane fouling, due to mixtures of poly-saccharides and proteins, despite a fair amount of related research. To get new insights into fouling layer characteristics, experiments were performed under constant-flux, within the range of practical interest (15–90 L/m2h), with typical polysaccharides (sodium alginate, SA), proteins (bovine serum albumin, BSA) as well as their mixtures in various proportions (1:3, 1:1, 3:1), and total organic matter concentration of 30 mg/L. The feed-water salinity and calcium ion concentration were 2000 mg/L NaCl and 2 mM, respectively. The temporal evolution of such fouling layers on flat-sheet membranes was monitored by recording the trans-membrane pressure variation. The results show that the specific fouling resistance α is strongly affected by flux, and the fouling propensity of polysaccharide-protein mixtures is significantly enhanced compared to single foulants, i.e., when BSA and SA are alone. The fouling layers are compressible and their resistance α tends to increase with the mass ratio of alginate in the mixture, particularly at high fluxes. To quantify these effects, correlations are presented of the initial fouling resistance αi with permeate flux J and of the evolution of α. R&D priorities are suggested on this topic of mixed foulants.

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Li, Juan, Liming Zhao, Yaosong Wang, Chaoqin Chen, Jiachun Zhou, Yongjun Qiu e Hailong Du. "Analysis of membrane fouling by proteins during nanofiltration of chitin alkali wastewater". Journal of Water Reuse and Desalination 4, n. 4 (22 aprile 2014): 253–62. http://dx.doi.org/10.2166/wrd.2014.005.

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The membrane fouling mechanism used during the nanofiltration (NF) of chitin alkali effluent was investigated. Tests were carried out in three large-scale chitin-processing plants with three kinds of wastewater. An alkali resistant NF membrane with molecular weight cut-off of 250 Da was employed. The reflection coefficient (σ) and diffusion coefficient (Ps) of total proteins were deduced, assuming that the proteins were single entities in the feed. Viscosity and osmosis pressure were measured to evaluate their influences on the permeate flux. Furthermore, the fraction of the protein fouling was extracted and qualitatively analyzed by mass spectrometry. Results showed that the NF permeate flux of alkali wastewater with the highest protein concentration (4.00%) was the lowest, and that σ and penetration Ps decreased with protein content growth. Over 60% of the peptides in the permeate were hydrophobic, whereas 70% of the peptides in the adsorption cake were hydrophilic. Irreversible resistance was the predominant resistance during NF processing, and the fouling behaviour of hydrophilic fractions was dominant.

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Kelly, Sean T., e Andrew L. Zydney. "Protein fouling during microfiltration: Comparative behavior of different model proteins". Biotechnology and Bioengineering 55, n. 1 (5 luglio 1997): 91–100. http://dx.doi.org/10.1002/(sici)1097-0290(19970705)55:1<91::aid-bit11>3.0.co;2-6.

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Oymaci, Pelin, Pauline E. Offeringa, Zandrie Borneman e Kitty Nijmeijer. "Effect of Osmotic Pressure on Whey Protein Concentration in Forward Osmosis". Membranes 11, n. 8 (29 luglio 2021): 573. http://dx.doi.org/10.3390/membranes11080573.

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Forward osmosis (FO) is an emerging process to dewater whey streams energy efficiently. The driving force for the process is the concentration gradient between the feed (FS) and the concentrated draw (DS) solution. Here we investigate not only the effect of the DS concentration on the performance, but also that of the FS is varied to maintain equal driving force at different absolute concentrations. Experiments with clean water as feed reveal a flux increase at higher osmotic pressure. When high product purities and thus low reverse salt fluxes are required, operation at lower DS concentrations is preferred. Whey as FS induces severe initial flux decline due to instantaneous protein fouling of the membrane. This is mostly due to reversible fouling, and to a smaller extent to irreversible fouling. Concentration factors in the range of 1.2–1.3 are obtained. When 0.5 M NaCl is added to whey as FS, clearly lower fluxes are obtained due to more severe concentration polarization. Multiple runs over longer times show though that irreversible fouling is fully suppressed due to salting in/out effects and flux decline is the result of reversible fouling only.

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Simonič, Marjana, e Zorka Novak Pintarič. "Study of Acid Whey Fouling after Protein Isolation Using Nanofiltration". Membranes 11, n. 7 (30 giugno 2021): 492. http://dx.doi.org/10.3390/membranes11070492.

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In this paper, nanofiltration (NF) of acid whey after isolation of proteins was studied. Two membranes were tested: NF-99 (Alfa Laval) and DL (Osmonic Desal). Based on previous measurements that determined the highest efficiency in separating lactic acid and lactose whey, the pH was adjusted to 3. First, the most appropriate transmembrane pressure (TMP) was determined based on the highest flux measured. The TMP range was 5–25 bar for the DL membrane and 10–30 bar for the NF-99 membrane. The temperature was kept at 4 °C using a thermostat. The mechanisms of membrane fouling were investigated. The Hermia models and the modified Tansel model were applied to study the fouling mechanism and to determine which membrane would foul earlier and more severely, respectively. The most suitable TMP was determined at 20 bar. Despite the 1.4 times higher flux of the sample at DL, the fouling rate was higher when NF-99 was used. The results showed that the Tansel model is suitable for predicting the fouling time of protein-isolated whey by nanofiltration.

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Malakian, Anna, e Scott M. Husson. "Evaluating Protein Fouling on Membranes Patterned by Woven Mesh Fabrics". Membranes 11, n. 10 (25 settembre 2021): 730. http://dx.doi.org/10.3390/membranes11100730.

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Membrane surface patterning is one approach used to mitigate fouling. This study used a combination of flux decline measurements and visualization experiments to evaluate the effectiveness of a microscale herringbone pattern for reducing protein fouling on polyvinylidene fluoride (PVDF) ultrafiltration membranes. Thermal embossing with woven mesh stamps was used for the first time to pattern membranes. Embossing process parameters were studied to identify conditions replicating the mesh patterns with high fidelity and to determine their effect on membrane permeability. Permeability increased or remained constant when patterning at low pressure (≤4.4 MPa) as a result of increased effective surface area; whereas permeability decreased at higher pressures due to surface pore-sealing of the membrane active layer upon compression. Flux decline measurements with dilute protein solutions showed monotonic decreases over time, with lower rates for patterned membranes than as-received membranes. These data were analyzed by the Hermia model to follow the transient nature of fouling. Confocal laser scanning microscopy (CLSM) provided complementary, quantitative, spatiotemporal information about protein deposition on as-received and patterned membrane surfaces. CLSM provided a greater level of detail for the early (pre-monolayer) stage of fouling than could be deduced from flux decline measurements. Images show that the protein immediately started to accumulate rapidly on the membranes, likely due to favorable hydrophobic interactions between the PVDF and protein, followed by decreasing rates of fouling with time as protein accumulated on the membrane surface. The knowledge generated in this study can be used to design membranes that inhibit fouling or otherwise direct foulants to deposit selectively in regions that minimize loss of flux.

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22

Ran, De Qin, Lin Guo Lu, Li Na Cao, Yong Shang e Wei Dian Zhao. "Assessing Membrane-Protein Interactions Using Fourier Transform Infrared Spectroscopy Technique". Advanced Materials Research 955-959 (giugno 2014): 1496–99. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1496.

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Protein fouling has been reported to be one of the main obstacles for the membrane processes applied in water treatment, pharmaceutical industry, and biotechnology, etc. The extent and nature of membrane fouling are by the interfacial interactions between membranes and protein, however, have not been fully understood. In recent years, a Fourier transform infrared (FTIR) spectroscopic method has been developed to quantify and analyze membrane fouling in various conditions and good results have been achieved. The scope of the current paper was to review literature on membrane–protein interactions using FTIR in the membrane systems. It will be conducive to further application of the membrane systems in the future.

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23

Paone, F., F. Bisignano, G. De Luca e S. Curcio. "Multiscale Modelling of Protein Fouling in Ultrafiltration". Procedia Engineering 44 (2012): 338–40. http://dx.doi.org/10.1016/j.proeng.2012.08.408.

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24

Hedayati, Mohammadhasan, Matt J. Kipper e Diego Krapf. "Anomalous protein kinetics on low-fouling surfaces". Physical Chemistry Chemical Physics 22, n. 9 (2020): 5264–71. http://dx.doi.org/10.1039/d0cp00326c.

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Abstract (sommario):

Single-molecule tracking reveals the protein bovine serum albumin exhibits anomalous kinetics with a heavy-tailed dwell time distribution on PEG surfaces. This effect is shown to be caused by the ability of the protein to oligomerize in solution.

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25

Collier, Nicolas, Dorothée Callens, Pierre Campistron, Bertrand Nongaillard, Maude Jimenez, Ghassan Alogaili, Pascal Debreyne e Guillaume Delaplace. "Ultrasonic Adhesion Measurement of Whey Protein Fouling". Heat Transfer Engineering 36, n. 7-8 (14 novembre 2014): 771–79. http://dx.doi.org/10.1080/01457632.2015.954963.

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26

Jim, K. J., A. G. Fane, C. J. D. Fell e D. C. Joy. "]Fouling mechanisms of membranes during protein ultrafiltration". Journal of Membrane Science 68, n. 1-2 (aprile 1992): 79–91. http://dx.doi.org/10.1016/0376-7388(92)80151-9.

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27

Güell, Carme, e Robert H. Davis. "Membrane fouling during microfiltration of protein mixtures". Journal of Membrane Science 119, n. 2 (ottobre 1996): 269–84. http://dx.doi.org/10.1016/0376-7388(96)80001-j.

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28

Sousa, Mayko Rannany S., Jaime Lora-García, María-Fernanda López-Pérez e Marc Heran. "Identification of Foulants on Polyethersulfone Membranes Used to Remove Colloids and Dissolved Matter from Paper Mill Treated Effluent". Water 12, n. 2 (29 gennaio 2020): 365. http://dx.doi.org/10.3390/w12020365.

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Abstract (sommario):

In this study, membrane fouling caused by paperboard mill treated effluent (PMTE) was investigated based on a dead-end ultrafiltration (UF) pilot-scale study. The membranes employed were commercial hydrophobic UF membranes made of polyethersulfone (PES) with a molecular weight cut-off of 10 kDa, 50 kDa, and 100 kDa. Membrane fouling mechanism during dead-end filtration, chemical analysis, field emission scanning electron microscopy (FESEM), energy-dispersive spectrophotometry (EDS), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and 3D fluorescence excitation–emission matrix (3DEEM) analysis were applied to understand which fraction of the dissolved and colloidal substances (DCS) caused the membrane fouling. The results indicated that the phenomenon controlling fouling mechanism tended to be cake layer formation (R2 ≥ 0.98) for all membranes tested. The 3DEEM results indicate that the majority of the organic foulants with fluorescence characteristics on the membrane were colloidal proteins (protein-like substances I+II) and macromolecular proteins (soluble microbial products, SMP-like substances). In addition, polysaccharide (cellulosic species), fatty and resin acid substances were identified on the fouled membrane by the ATR–FTIR analysis and play an important role in membrane fouling. In addition, the FESEM and EDS analyses indicate that the presence of inorganic foulants on the membrane surfaces, such as metal ions and especially Ca2+, can accelerate membrane fouling, whereas Mg and Si are linked to reversible fouling.

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29

Wang, Shengli, Xin Lu, Lanhe Zhang, Jingbo Guo e Haifeng Zhang. "Characterization of the Initial Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Effects of Permeation Drag". Membranes 9, n. 9 (17 settembre 2019): 121. http://dx.doi.org/10.3390/membranes9090121.

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In this study, the properties of the initial fouling layer on the membrane surface of a bioreactor were investigated under different operating modes (with or without permeate flux) to improve the understanding of the effect of permeation drag on the formation of the initial fouling layer. It was found that protein was the major component in the two types of initial fouling layers, and that the permeation drag enhanced the tryptophan protein-like substances. The attraction of the initial foulants to the polyvinylidene fluoride (PVDF) membrane was ascribed to the high zeta potential and electron donor component (γ−) of the membrane. Thermodynamic analyses showed that the permeation drag-induced fouling layer possessed high hydrophobicity and low γ−. Due to permeation drag, a portion of the foulants overcame an energy barrier before they contacted the membrane surface, which itself possessed a higher fouling propensity. A declining trend of the cohesive strength among the foulants was found with the increasing development of both fouling layers.

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30

Lin, Zhifeng, Yuhong Ma, Changwen Zhao, Ruichao Chen, Xing Zhu, Lihua Zhang, Xu Yan e Wantai Yang. "An extremely simple method for fabricating 3D protein microarrays with an anti-fouling background and high protein capacity". Lab Chip 14, n. 14 (2014): 2505–14. http://dx.doi.org/10.1039/c4lc00223g.

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31

Nguyen, S. T., F. A. Roddick e J. L. Harris. "Membrane foulants and fouling mechanisms in microfiltration and ultrafiltration of an activated sludge effluent". Water Science and Technology 62, n. 9 (1 novembre 2010): 1975–83. http://dx.doi.org/10.2166/wst.2010.505.

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Membrane fouling in microfiltration (MF) and ultrafiltration (UF) of an activated sludge (AS) effluent was investigated. It was found that the major membrane foulants were polysaccharides, proteins, polysaccharide-like and protein-like materials and humic substances. MF fouling by the raw effluent was governed by pore adsorption of particles smaller than the pores during the first 30 minutes of filtration and then followed the cake filtration model. UF fouling could be described by the cake filtration model throughout the course of filtration. Coagulation with alum and (poly)aluminium chlorohydrate (ACH) altered the MF fouling mechanism to follow the cake filtration model from the beginning of filtration. The MF and UF flux improvement by coagulation was due to the removal of some of the foulants in the raw AS effluent by the coagulants. The MF flux improvement was greater for alum than for ACH whereas the two coagulants performed equally well in UF. Coagulation also reduced hydraulically irreversible fouling on the membranes and this effect was more prominent in MF than in UF. The unified membrane fouling index (UMFI) was used to quantitatively evaluate the effectiveness of coagulation on membrane flux enhancement.

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32

Belmar-Beiny, M. Teresa, e Peter J. Fryer. "Preliminary stages of fouling from whey protein solutions". Journal of Dairy Research 60, n. 4 (novembre 1993): 467–83. http://dx.doi.org/10.1017/s0022029900027837.

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Abstract (sommario):

SummaryFouling from milk fluids is a severe industrial problem which reduces the efficiency of process plant. The chemistry of fouling has been thoroughly investigated but the sequence of events that occur is not yet clear. Deposit contains both protein and minerals. Experiments have been carried out to determine the sequence of events in the fouling of stainless steel surfaces at 96 °C from turbulent flows of whey. Contact times between 4 and 210 s have been studied, and surface analysis techniques used to detect the distribution of elements. The first layer of deposit, formed after 4 s of contact between the fluid and the surface (fluid temperature 68 and 73 °C), consisted mainly of protein and was identified by X-ray photoelectron spectroscopy analysis. There was a lag phase of up to 150 s for a fluid temperature of 73 °C before deposit aggregates were observed to adsorb on to the surface. These aggregates were identified as protein and Ca by X-ray elemental mapping. No P was found in any experiments for this exposure. After 60 min contact time, however, both Ca and P were found at the interface between deposit and the stainless steel surface, irrespective of the Ca and P content of the test fluid.

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33

Ho, Chia-Chi, e Andrew L. Zydney. "Protein Fouling of Asymmetric and Composite Microfiltration Membranes". Industrial & Engineering Chemistry Research 40, n. 5 (marzo 2001): 1412–21. http://dx.doi.org/10.1021/ie000810j.

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34

Gillham, C. R., P. J. Fryer, A. P. M. Hasting e D. I. Wilson. "Cleaning-in-Place of Whey Protein Fouling Deposits". Food and Bioproducts Processing 77, n. 2 (giugno 1999): 127–36. http://dx.doi.org/10.1205/096030899532420.

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35

Cutler, H. E., S. M. Husson e S. R. Wickramasinghe. "Prefiltration to suppress protein fouling of microfiltration membranes". Separation and Purification Technology 89 (marzo 2012): 329–36. http://dx.doi.org/10.1016/j.seppur.2012.01.048.

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36

Nilsson, Jan L. "Protein fouling of uf membranes: Causes and consequences". Journal of Membrane Science 52, n. 2 (settembre 1990): 121–42. http://dx.doi.org/10.1016/s0376-7388(00)80481-0.

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37

Clark, W. M., A. Bansal, M. Sontakke e Y. H. Ma. "Protein adsorption and fouling in ceramic ultrafiltration membranes". Journal of Membrane Science 55, n. 1-2 (gennaio 1991): 21–38. http://dx.doi.org/10.1016/s0376-7388(00)82325-x.

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38

Tracey, Eve M., e Robert H. Davis. "Protein Fouling of Track-Etched Polycarbonate Microfiltration Membranes". Journal of Colloid and Interface Science 167, n. 1 (ottobre 1994): 104–16. http://dx.doi.org/10.1006/jcis.1994.1338.

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39

Bode, Katharina, Rowan J. Hooper, William R. Paterson, D. Ian Wilson, Wolfgang Augustin e Stephan Scholl. "Pulsed Flow Cleaning of Whey Protein Fouling Layers". Heat Transfer Engineering 28, n. 3 (marzo 2007): 202–9. http://dx.doi.org/10.1080/01457630601064611.

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40

Lim, Y. P., e A. W. Mohammad. "High Concentration Protein Ultrafiltration: a Comparative Fouling Assessment". IOP Conference Series: Materials Science and Engineering 358 (maggio 2018): 012056. http://dx.doi.org/10.1088/1757-899x/358/1/012056.

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41

Cole, M. A., N. H. Voelcker e H. Thissen. "Electro-induced protein deposition on low-fouling surfaces". Smart Materials and Structures 16, n. 6 (9 ottobre 2007): 2222–28. http://dx.doi.org/10.1088/0964-1726/16/6/025.

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42

Yao, Meng, Kaisong Zhang e Li Cui. "Characterization of protein–polysaccharide ratios on membrane fouling". Desalination 259, n. 1-3 (settembre 2010): 11–16. http://dx.doi.org/10.1016/j.desal.2010.04.049.

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43

Mueller, J. "Protein fouling of surface-modified polymeric microfiltration membranes". Journal of Membrane Science 116, n. 1 (24 luglio 1996): 47–60. http://dx.doi.org/10.1016/0376-7388(96)00017-8.

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44

Molena, Elena, Caterina Credi, Carmela De Marco, Marinella Levi, Stefano Turri e Giovanni Simeone. "Protein antifouling and fouling-release in perfluoropolyether surfaces". Applied Surface Science 309 (agosto 2014): 160–67. http://dx.doi.org/10.1016/j.apsusc.2014.04.211.

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45

Ayadi, M. A., J. C. Leuliet, F. Chopard, M. Berthou e M. Lebouché. "Continuous ohmic heating unit under whey protein fouling". Innovative Food Science & Emerging Technologies 5, n. 4 (dicembre 2004): 465–73. http://dx.doi.org/10.1016/j.ifset.2004.08.001.

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46

Fukuda, Makoto, Hiroki Yoshimoto, Hitoshi Saomoto e Kiyotaka Sakai. "Validity of Three-Dimensional Tortuous Pore Structure and Fouling of Hemoconcentration Capillary Membrane Using the Tortuous Pore Diffusion Model and Scanning Probe Microscopy". Membranes 10, n. 11 (29 ottobre 2020): 315. http://dx.doi.org/10.3390/membranes10110315.

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Abstract (sommario):

Hemoconcentration membranes used in cardiopulmonary bypass require a pore structure design with high pure water permeability, which does not allow excessive protein adsorption and useful protein loss. However, studies on hemoconcentration membranes have not been conducted yet. The purpose of this study was to analyze three-dimensional pore structures and protein fouling before and after blood contact with capillary membranes using the tortuous pore diffusion model and a scanning probe microscope system. We examined two commercially available capillary membranes of similar polymer composition that are successfully used in hemoconcentration clinically. Assuming the conditions of actual use in cardiopulmonary bypass, bovine blood was perfused inside the lumens of these membranes. Pure water permeability before and after bovine blood perfusion was measured using dead-end filtration. The scanning probe microscopy system was used for analysis. High-resolution three-dimensional pore structures on the inner surface of the membranes were observed before blood contact. On the other hand, many pore structures after blood contact could not be observed due to protein fouling. The pore diameters calculated by the tortuous pore diffusion model and scanning probe microscopy were mostly similar and could be validated reciprocally. Achievable pure water permeabilities showed no difference, despite protein fouling on the pore inlets (membrane surface). In addition, low values of albumin sieving coefficient are attributable to protein fouling that occurs on the membrane surface. Therefore, it is essential to design the membrane structure that provides the appropriate control of fouling. The characteristics of the hemoconcentration membranes examined in this study are suitable for clinical use.

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47

Ayadi, M. A., T. Benezech, F. Chopard e M. Berthou. "Thermal performance of a flat ohmic cell under non-fouling and whey protein fouling conditions". LWT - Food Science and Technology 41, n. 6 (luglio 2008): 1073–81. http://dx.doi.org/10.1016/j.lwt.2007.06.022.

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48

Jensen, Jannie K., Niels Ottosen, Søren B. Engelsen e Frans van den Berg. "Investigation of UF and MF Membrane Residual Fouling in Full-Scale Dairy Production Using FT-IR to Quantify Protein and Fat". International Journal of Food Engineering 11, n. 1 (1 febbraio 2015): 1–15. http://dx.doi.org/10.1515/ijfe-2014-0254.

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Abstract This study investigates the distribution of residual fouling in used spiral wound ultrafiltration (UF) and microfiltration (MF) membrane cartridges. Residual fouling on four full-scale production UF membrane cartridges and two full-scale MF membrane cartridges were investigated with infrared spectroscopy inspecting fat and protein deposits. A non-homogenous distribution of residual fouling was observed with concentrations highest at the center tube decreasing away from the feed side. Analysis of variance was used to evaluate significant factors affecting the model. The observed tendencies can be explained by flow and pressure differences caused by design aspects of spirally wound membrane cartridge and the steel housing. Variations between individual sheets from the same cartridges were observed, suggesting a role from manufacturing variability in residual fouling after cleaning-in-place. This paper describes a new method for mapping fouling proposing a semi-quantifiable description. This description might guide membrane developers and users to optimize cleaning methods in the future.

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Piluharto, Bambang, Achmad Sjaifullah, Istiqomah Rahmawati e Maryanto Maryanto. "Polysulfone Membrane with UV-Photografting Technique and it Application at Soya Milk Filtration Processing". Jurnal ILMU DASAR 14, n. 1 (8 gennaio 2013): 39. http://dx.doi.org/10.19184/jid.v14i1.480.

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Abstract (sommario):

In the separation process of solution containing protein, interaction between membrane surface and protein can cause fouling irreversibely. So, efficiency of filtration process will decline. In this research, to improve the effeciency of filtration was done by modification of membrane using UV-photografting technique. Acrylic acid had been introduced topolysulphone membrane via this technique. The hydrophylic membrane was obtained. The membrane performance was evaluated in soymilk fouling test. The first step of research had obtained PSF membrane optimation about PSF 18%. In second step, the research was focused on the modification and characterization of PSF membrane by UV-Fotografting tehchnique. In this technique, monomer concentration and radiation time was used as variable. As the result, PSF membrane had been modificated succesfully by UV- photografting tehchnique with optimum condition in 15 minutes time radiation and concentration of acrylic acid 5%. Performance of modified membranes (flux and permselectivity) were better than unmodified membranes. The fouling test showed that the modified membranes have reduced fouling degree significantly. Keywords : Ultrafiltration membrane, UV-photografting, flux and permselectivity, fouling

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50

Ma, Wen, Md Saifur Rahaman e Heloise Therien-Aubin. "Controlling biofouling of reverse osmosis membranes through surface modification via grafting patterned polymer brushes". Journal of Water Reuse and Desalination 5, n. 3 (19 marzo 2015): 326–34. http://dx.doi.org/10.2166/wrd.2015.114.

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Abstract (sommario):

Thin film composite (TFC) polyamide membranes are extensively used as selective barriers in reverse osmosis processes. The major challenge faced with TFC membranes is significant fouling on the surface, which restricts the overall purification performance. To address the fouling problem, we developed novel fouling-resistant surface coatings via polyelectrolyte [poly(allylamine hydrochloride)/poly(styrene sulfonate)] layer-by-layer self-assembly, functionalized with patterned antimicrobial and antifouling/fouling-release polymer brushes. Two types of different polymer brushes, among antimicrobial poly(quaternary ammonium), antifouling poly(sulfobetaine) and fouling-release poly(dimethylsiloxane) (PDMS), were selected and grafted in a checkerboard pattern, with a square feature of 2 µm. The successful patterning and incorporation of different polymer brushes on the membrane was confirmed through X-ray photoelectron spectroscopy analysis. Grafting with sulfobetaine and PDMS significantly increased the hydrophilicity and lowered the surface energy of the membrane, respectively. The fouling-resistant property of the modified membrane was evaluated via static protein (bovine serum albumin) deposition and bacterial (Escherichia coli) cell adhesion tests. Surface modifications proved to diminish protein adhesion and exhibited 70–93% reduction in bacterial cell attachment. This observation suggests that the modified membranes have strong antifouling properties that inhibit the irreversible adhesion of organic and bio-foulants on the membrane surface.

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