Karakterizacija polimernih nanofiltracijskih membrana

As membrane processes are increasingly used in industrial applications, there is a growing interest in methods of membrane characterization. Traditional membrane characteristics, such as cut-off value and pore size distribution, are being supplemented by membrane surface characteristics, such as charge density or zeta potential and hydrophobicity. This study, therefore, characterizes the three different polymeric membranes used (NFT-50, DL and DK). The molecular mass cut-off (MMCO) value was determined using a set of reference solutes within the molecular range 150-600 Da, whereas streaming potential measurements enabled quantification of the surface charge characteristics. Hydrophobicity was studied using contact angle measurements. The results indicated that even though all three membranes had very similar layer compositions which consisted of poly(piperazneamide), as top layers they showed different values of measured quantitive. The NFT-50 membrane had the lowest MMCO value and the most hydrophilic membrane surface, followed by DK and DL. Membrane fouling as measured by flux reduction was determined by streaming potential measurements and accompanied by a positive change in zeta potential.Znanstvena istraživanja metoda za karakterizaciju membrana za pročišćavanje otpadnih voda u stalnom su porastu. Tradicionalne metode karakterizacije veličinom i raspodijelom pora dopunjuju se metodama karakterizacije određivanjem zeta-potencijala i hidrofilno/hidrofobnih svojstva. Stoga su u ovom radu karakterizirane tri različite polimerne nanofiltracijske membrane NFT-50, DL i DK karakterizirane veličinom MMCO odabirom tri referentne otopine molekulske mase 150-600 Da. Elektrokinetičke karakteristike tih membrana vrednovane su pomoću potencijala strujanja a hidrofobnost pomoću kontaktnog kuta. Rezultati istraživanja ukazuju na to da su, unatoč gotovo jednakom gornjem sloju kompozitnih membrana, mjerne veličine različite. Najnižu MMCO vrijednost i najvišu hidrofilnost ima NFT-50 membrana kojoj slijede DK i DL. Smanjivanje protoka permeata ukazuje na začepljivanje membrana, koje je izmjereno pomoću potencijala strujanja te rezultiralo smanjivanjem zeta-potencijala

Biomimetic aquaporin membranes coming of age

Membrane processes have been widely used for water purification because of their high stability, efficiency, low energy requirement and ease of operation. Traditional desalting membranes are mostly dense polymeric films with a "trade off" effect between permeability and selectivity. Biological membranes, on the other hand, can perform transport in some cases with exceptional flux and rejection properties. In particular the discovery of selective water channel proteins - aquaporins - has prompted interest in using these proteins as building blocks for new types of membranes. The major challenge in developing an aquaporin-based membrane technology stems from the fact that the aquaporin protein spans a membrane only a few nanometers thick. Such ultrathin membranes will not be able to withstand any substantial pressures, nor being industrially scalable without supporting structures. Incorporating aquaporin proteins into compatible materials, while ensuring membrane performance, scalability, and cost-effective production, is crucial for a successful technology development. Since the first suggestions for using aquaporins in membrane technology appeared around ten years ago, two main approaches have been suggested based on planar membranes and vesicles respectively. Here we summarize the essentials of aquaporin protein function and review the latest progress in this fascinating area of membrane research and development

Analityczna ocena rozkładu termicznego dzianin bawełniano-modakrylowych

Fabric flammability is affected by various factors such as the fibre composition, fabric construction, FR (flame retardant) finish, oxygen concentration and environmental conditions (moisture content, heat.). Inherently FR fabrics are synthetics which have been changed at the molecular level to make the fabrics thermally stable and able to pass FR tests.The thermal properties of knitted fabrics produced from cotton, modacryl and their blends were investigated in this paper. The design of FR knitted fabrics and an optimal blend ratio were evaluated by different thermoanalytical methods: the flame behaviour and thermal stability with the limited oxygen index (LOI), thermal gravimetric analysis (TGA),coupled thermal gravimetry - Fourier transform infrared technique (TG-FTIR) and microscale combustion calorimetry (MCC). Surface characterisation of the knitted fabrics designed was evaluated by the streaming potential method. Knitted fabric in the blend ratio C50:M50 proved to possess the most favourable FR characteristics, additionally confirmed by optimal hydrophilic properties evaluated through zeta potential measurement.Na palność wyrobu mają wpływ różne czynniki, takie jak skład włókien, budowa wyrobu, wykończenie nadające mniejszą palność, stężenie tlenu i warunki środowiskowe (zawartość wilgoci, ciepło). Wyroby o zmniejszonej palności są syntetykami, które zostały zmodyfikowane na poziomie molekularnym, tak aby uczynić z nich wyroby stabilne termicznie, które mogą pomyślnie przejść testy palności. W pracy badano właściwości cieplne dzianin wytwarzanych z bawełny, modakrylu i ich mieszanek. Optymalny stosunek mieszanki oceniono różnymi metodami termoanalitycznymi tj.: zachowanie płomienia i stabilność termiczna z ograniczonym wskaźnikiem tlenu (LOI), termiczna analiza grawimetryczna (TGA), sprzężona grawimetria cieplna - technika podczerwieni z transformatą Fouriera (TG -FTIR) i mikroskopowa kalorymetrii spalania (MCC). Charakterystykę powierzchni dzianin oceniono metodą potencjału strumieniowego. Dzianiny o stosunku mieszania C50:M50 okazały się posiadać najbardziej korzystne cechy zmniejszonej palności, dodatkowo potwierdzone optymalnymi właściwościami hydrofilowymi ocenianymi za pomocą pomiaru potencjału zeta