Membrane fouling is one of the main drawbacks encountered during the practical application of membrane separation processes. Cleaning of a membrane is important to reduce fouling and improve membrane performance. Accordingly, an effective cleaning method is currently of crucial importance for membrane separation processes in water treatment. To clean the fouling and improve the overall efficiency of membranes, deep research on the cleaning procedures is needed. So far, physical, chemical, or combination techniques have been used for membrane cleaning. In the current work, we critically reviewed the fouling mechanisms affecting factors of fouling such as the size of particle or solute; membrane microstructure; the interactions between membrane, solute, and solvent; and porosity of the membrane and also examined cleaning methods of microfiltration (MF) membranes such as physical cleaning and chemical cleaning. Herein, we mainly focused on the chemical cleaning process. Factors affecting the chemical cleaning performance, including cleaning time, the concentration of chemical cleaning, and temperature of the cleaning process, were discussed in detail. This review is carried out to enable a better understanding of the membrane cleaning process for an effective membrane separation process.

• Klíčová slova
• antifouling, chemical, cleaning, fouling, membrane, microfiltration,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Similar to lipopolysaccharide (LPS), a product of Gram-negative bacteria, the signal macromolecules of Gram-positive bacteria lipoteichoic acid (LTA) and peptidoglycan (PGN) possess multiple biological activities. They may be a source of misinterpretation of experimental findings. We have found that not only LPS but also LTA and PGN can be detected by the Limulus amebocyte lysate (LAL) assay. All of them stimulate the high output in vitro nitric oxide (NO) production of in rat peritoneal cells. The onset of the NO enhancement was observed with 25-100pg/ml of LPS and 25-100ng/ml of PGN and LTA. Polymyxin B (PMX), if applied at concentration 10,000-fold higher than that of LPS, can completely inhibit the NO and LAL binding responses of LPS. The NO-stimulatory and LAL-binding properties of LTA and PGN are not eliminated by PMX. Handling of LPS contamination with PMX may be associated with serious problems because it possesses intrinsic biological activity and becomes cytotoxic at concentration >25μg/ml. The present findings suggest a convenient alternative avoiding these issues. As monitored by the NO and LAL assays, even high amounts of LPS as well as PGN and LTA can be removed by molecular mass cutoff microfiltration. All types of the filters (3kDa to 100kDa) are equally effective. It is suggested that the microfiltration procedure may be considered as a preferable, general and easy method of sample decontamination.

• MeSH
• Bacillus subtilis chemie   izolace a purifikace   MeSH
• buněčné linie MeSH
• centrifugace MeSH
• Escherichia coli chemie   izolace a purifikace   MeSH
• filtrace * MeSH
• krysa rodu Rattus MeSH
• kyseliny teichoové analýza   MeSH
• Limulus test * MeSH
• lipopolysacharidy analýza   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• oxid dusnatý biosyntéza   metabolismus   MeSH
• peptidoglykan analýza   MeSH
• potkani Wistar MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kyseliny teichoové MeSH
• lipopolysacharidy MeSH
• lipoteichoic acid MeSH Prohlížeč
• oxid dusnatý MeSH
• peptidoglykan MeSH

Membrane fouling is one of the most significant issues to overcome in membrane-based technologies as it causes a decrease in the membrane flux and increases operational costs. This study investigates the effect of common chemical cleaning agents on polymeric nanofibrous membranes (PNM) prepared by polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyamide 6 (PA6) nanofibers. Common alkaline and acid membrane cleaners were selected as the chemical cleaning agents. Membrane surface morphology was investigated. The PAN PNM were selected and fouled by engine oil and then cleaned by the different chemical cleaning agents at various ratios. The SEM results indicated that the use of chemical agents had some effects on the surface of the nanofibrous membranes. Moreover, alkaline cleaning of the fouled membrane using the Triton X 100 surfactant showed a two to five times higher flux recovery than without using a surfactant. Among the tested chemical agents, the highest flux recovery rate was obtained by a binary solution of 5% sodium hydroxide + Triton for alkaline cleaning, and an individual solution of 1% citric acid for acidic cleaning. The results presented here provide one of the first investigations into the chemical cleaning of nanofiber membranes.

• Klíčová slova
• PAN, chemical agents, cleaning, membrane, microfiltration, nanofiber,
• Publikační typ
• časopisecké články MeSH

Separation of the ammonium sulfate precipitated protein fraction of mouse ascitic fluid, containing the specific immunoglobulin (pI 6.7-6.8; molecular weight 180000), from ammonium sulfate was investigated by means of non-traditional dialysis, based on the difference in diffusion rates of small and large molecules through porous membranes. The experiments were carried out in spiral membrane modules equipped with a Neosepta (AM-2 or ACS-SB) anion exchange membrane and a microfiltration membrane (Synpore or Sartorius). To enhance the driving force for penetration of ammonium sulfate and low-molecular-weight components from solution of ascitic protein fraction into water, a counterpressure was imposed on the side of microfiltration membrane. The flow rate, counterpressure and the pore sizes of microfiltration membranes had a significant effect on the separation process, as expected. The type of the anion exchange membrane had only a small effect. This process makes it possible to desalt the immunoglobulin fraction with high purity and yield in a few hours instead of 5 days.

• MeSH
• ascitická tekutina imunologie   MeSH
• biotechnologie MeSH
• chlorid sodný izolace a purifikace   MeSH
• dialýza přístrojové vybavení   metody   MeSH
• filtrace přístrojové vybavení   metody   MeSH
• hodnotící studie jako téma MeSH
• imunoglobuliny izolace a purifikace   MeSH
• membrány umělé MeSH
• mikroporézní filtry MeSH
• monoklonální protilátky izolace a purifikace   MeSH
• myši MeSH
• precipitinové testy MeSH
• síran amonný MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorid sodný MeSH
• imunoglobuliny MeSH
• membrány umělé MeSH
• monoklonální protilátky MeSH
• síran amonný MeSH

To date, according to the latest literature inputs, membranes-based technologies (microfiltration, ultrafiltration and nanofiltration) have demonstrated to meet the recovery of biologically active compounds, mainly phenolic compounds and their derivatives, from agro-food products and by-products. The goal of this paper is to provide a critical overview of the on ongoing development works aimed at improving the separation, fractionation and concentration of phenolic compounds and their derivatives from their original sources. The literature data are analyzed and discussed in relation to separation processes, molecule properties, membrane characteristics and key factors affecting the performance of such technologies. Technological advances and improvements over conventional technologies, as well as critical aspects to be further investigated are highlighted and discussed. Finally, a critical outlook about the current status for a large-scale application and the role of these processes from an environmental viewpoint is provided.

• Klíčová slova
• Phenolic compounds, agro-food by-products, foods, nanofiltration, ultrafiltration,
• MeSH
• analýza potravin MeSH
• chemická frakcionace MeSH
• fenoly * izolace a purifikace   MeSH
• membrány umělé * MeSH
• potravinářská technologie * metody   trendy   MeSH
• ultrafiltrace * MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• fenoly * MeSH
• membrány umělé * MeSH

Typically, the various agro-food by-products of the food industry are treated by standard membrane processes, such as microfiltration, ultrafiltration and nanofiltration, in order to prepare them for final disposal. Recently, however, new membrane technologies have been developed. The recovery, separation and fractionation of high-added-value compounds, such as phenolic compounds from food processing waste, are major current research challenges. The goal of this paper is to provide a critical review of the main agro-food by-products treated by membrane technologies for the recovery of nutraceuticals. State-of-the-art of developments in the field are described. Particular attention is paid to experimental results reported for the recovery of polyphenols and their derivatives of different molecular weight. The literature data are analyzed and discussed in relation to separation processes, molecule properties, membrane characteristics and other interesting phenomena that occur during their recovery.

• Klíčová slova
• High added value compounds, Membrane technology, Nutraceuticals, Recovery, Wastes,
• MeSH
• chemická frakcionace MeSH
• fenoly analýza   MeSH
• manipulace s potravinami MeSH
• molekulová hmotnost MeSH
• polyfenoly analýza   MeSH
• potravinářský průmysl MeSH
• potravní doplňky MeSH
• průmyslový odpad analýza   MeSH
• ultrafiltrace MeSH
• zemědělské plodiny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• fenoly MeSH
• polyfenoly MeSH
• průmyslový odpad MeSH

The aim of this study was to investigate the suitability of a novel electrospun polyurethane nanofibre material for water-treatment purposes. Bacterial removal efficiency was tested in the laboratory by filtering artificial water spiked with Escherichia coli through a 0.25 µm nanofibre membrane. The results were compared with those obtained using a commercial microfiltration material (MV020T) with a similar pore size (0.20 µm). Alongside the laboratory experiments, we also determined filtration efficiency with semi-pilot scale experiments using actual wastewater from the secondary sedimentation tank of a wastewater treatment plant. The laboratory experiments indicated very high log10 removal efficiency, ranging from 5.8 to 6.8 CFU (colony-forming units)/ml. These results were better than those of the commercial membrane (3.8-4.6 CFU/ml). The semi-pilot scale experiment confirmed the membrane's suitability for microbial filtration, with both E. coli and total culturable microorganisms (cultured at both 22 and 36 °C) showing a significant decline compared to the non-filtered control (wastewater from the secondary outlet).

• MeSH
• čištění vody přístrojové vybavení   MeSH
• Escherichia coli MeSH
• filtrace přístrojové vybavení   MeSH
• membrány umělé * MeSH
• nanovlákna * MeSH
• pilotní projekty MeSH
• polyurethany chemická syntéza   MeSH
• povidon MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• membrány umělé * MeSH
• polyurethany MeSH
• povidon MeSH

OBJECTIVES: Major medical indications of probiotic bacteria are conditions associated with the gastrointestinal tract. They exhibit not only the local but also systemic effects, the molecular mechanisms of which are poorly understood. We hypothesized that the action at remote sites of the body could be at least partially attributed to substances of the low molecular mass released from digested bacteria and able to cross the intestinal barrier. The aim of the study was the analysis of immunobiological properties of bacterial lysates and characterization of chemical constituents participating on this mode of action. METHODS: Lactobacillus casei probiotic strain DN-114001 was employed. Lysates were prepared by passing bacteria through a French press (1500 psi) followed by lyophilisation. The fractions were prepared by the microfiltration of the crude lysate using the 3-, 10-, 30-, 50-, and 100-kDa cutoff filters (Amicon® Ultra 0.5 ml, Millipore Corp.). This procedure completely removes biologically active bacterial macromolecules such as peptidoglycan (PGN), lipoteichoic acid (LTA) and lipopolysaccharide (LPS). Effects of microfiltrates on the in vitro production of nitric oxide (NO), cytokines, and prostaglandin E2 (PGE2) were investigated in rat peritoneal cells. RESULTS: The original crude lysate (≤10 µg/ml) activated the biosynthesis of NO, PGE2, and secretion of cytokines. The amount of the lysate needed for the preparation of microfiltered fractions exhibiting immunostimulatory effects was 10-fold higher (100 µg/ml). The molecules with the molecular mass ≤3 kDa were responsible for approximately 45% and 83% of the NO- and PGE2-enhancing activities of the crude lysate, respectively. The microfiltered fractions of the lysate also enhanced secretion of interleukin-6 and tumor necrosis factor-α but not that of interleukin-10 and interferon-γ. CONCLUSION: The Lactobacillus casei probiotic strain DN-114001 contains low molecular mass (≤3 kDa) molecules possessing immunostimulatory properties. Their chemical nature remains to be identified.

• MeSH
• bakteriální proteiny chemie   metabolismus   farmakologie   MeSH
• chemická frakcionace MeSH
• cytokiny biosyntéza   metabolismus   MeSH
• dinoproston biosyntéza   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• kyseliny teichoové chemie   metabolismus   farmakologie   MeSH
• Lactobacillus casei metabolismus   MeSH
• lipopolysacharidy chemie   metabolismus   farmakologie   MeSH
• molekulová hmotnost MeSH
• oxid dusnatý biosyntéza   MeSH
• peptidoglykan chemie   metabolismus   farmakologie   MeSH
• peritoneum cytologie   MeSH
• potkani Wistar MeSH
• probiotika farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• cytokiny MeSH
• dinoproston MeSH
• kyseliny teichoové MeSH
• lipopolysacharidy MeSH
• lipoteichoic acid MeSH Prohlížeč
• oxid dusnatý MeSH
• peptidoglykan MeSH

Membrane technology is of great interest in various environmental and industrial applications, where membranes are used to separate different mixtures of gas, solid-gas, liquid-gas, liquid-liquid, or liquid-solid. In this context, nanocellulose (NC) membranes can be produced with predefined properties for specific separation and filtration technologies. This review explains the use of nanocellulose membranes as a direct, effective, and sustainable way to solve environmental and industrial problems. The different types of nanocellulose (i.e., nanoparticles, nanocrystals, nanofibers) and their fabrication methods (i.e., mechanical, physical, chemical, mechanochemical, physicochemical, and biological) are discussed. In particular, the structural properties of nanocellulose membranes (i.e., mechanical strength, interactions with various fluids, biocompatibility, hydrophilicity, and biodegradability) are reviewed in relation to membrane performances. Advanced applications of nanocellulose membranes in reverse osmosis (RO), microfiltration (MF), nanofiltration (NF), and ultrafiltration (UF) are highlighted. The applications of nanocellulose membranes offer significant advantages as a key technology for air purification, gas separation, and water treatment, including suspended or soluble solids removal, desalination, or liquid removal using pervaporation membranes or electrically driven membranes. This review will cover the current state of research, future prospects, and challenges in commercializing nanocellulose membranes with respect to membrane applications.

• Klíčová slova
• Biocompatibility, Commercialization, Mechanical strength, Membrane filtration, Morphology and aspect ratio, Nanocellulose, Water holding capacity,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND: This research paper focuses on removing of arsenic from contaminated water via a nanofibrous polymeric microfiltration membrane, applied in prospective combination with an inorganic sorbent based on iron oxide hydroxide FeO(OH). MATERIALS AND METHODS: Nanofibrous materials were prepared by electrospinning from polyurethane selected by an adsorption test. The chemical composition (FTIR), morphology (SEM, porometry) and hydrophilicity (contact angle) of the prepared nanostructured material were characterized. The process of eliminating arsenic from the contaminated water was monitored by atomic absorption spectroscopy (AAS). The adsorption efficiency of the nanofibrous material and the combination with FeO(OH) was determined, the level of arsenic anchorage on the adsorption filter was assessed by a rinsing test and the selectivity of adsorption in arsenic contaminated mineral water was examined. RESULTS: It was confirmed that the hydrophilic aromatic polyurethane of ester type PU918 is capable of capturing arsenic by complexation on nitrogen in its polymer chains. The maximum As removal efficiency was around 62 %. Arsenic was tightly anchored to the polymeric adsorbent. The adsorption process was sufficiently selective. Furthermore, it was found that the addition of even a small amount of FeO(OH) (0.5 g) to the nanofiber filter would increase the efficiency of As removal by 30 %. CONCLUSIONS: The presented results showed that an adsorption filter based on a polyurethane nanostructured membrane added with an inorganic adsorbent FeO(OH) is a suitable way for the elimination of arsenic from water. However, it is necessary to ensure perfect contact between the surface of the nanostructure and the filtered medium.

• Klíčová slova
• Adsorptive filtration, Arsenic, Iron oxide hydroxide, Polyurethane,
• Publikační typ
• časopisecké články MeSH