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1.
Membranes from polysulfone/N,N-dimethylacetamide/water system : structure and water flux
Vladimir Kaiser, Črtomir Stropnik, 2000, original scientific article

Abstract: Polymeric membranes were prepared by the wet-phase separation method from solutions of different contents of polysulfone in N,N-dimethylacetamide; solutions were cast in different thickness before immersion into the pure water coagulation bath. Two main processes take place during the formation of membranes: nucleation and growth of the polymer lean phase with subsequent solidification of the polymer rich phase, and the formation of channels, macrovoids and mega-macrovoids. By the first process a cellular structure is formed whilst the second process connects the cells by opening the space between them. The degree of interconnectedness is an additional factor that affects the pure water flux. By changing the cast solution compositions and/or their cast thickness the interconnectedness of the cells can be controlled.
Keywords: chemical technology, organic technology, polymer membranes, membrane preparation, wet phase inversion, polymers, polysulphon
Published in DKUM: 18.08.2017; Views: 1125; Downloads: 105
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2.
Enzymatic reactions in high-pressure membrane reactors
Maja Leitgeb, Mateja Primožič, Željko Knez, 2005, original scientific article

Abstract: In the studies on the stability of biocatalysts in a high-pressure batch stirred tank reactor, changes in biocatalyst activity due to pressurizationždepressurization steps were observed. An interesting alternative to overcome this inconvenience is using the high-pressure continuous membrane reactors, where just a single compression and expansion step is necessary. The aim of the research was to carry out the enzyme-catalyzed reactions in high-pressure membrane reactors. At first, high-pressure enzyme-catalyzed hydrolyses of oleyl oleate and sunflower oil were performed in a high-pressure continuous enzymatic flat-shape membrane reactor. Additionally, cellulase from Humicola insolens was covalently immobilized on tubular membrane, and enzyme-catalyzed hydrolysis of carboxy-methyl cellulose was carried out in a high-pressure continuous enzymatic tubular membrane reactor. The membrane-stability tests for flat-shape polysulfon membranes before and after treatment with supercritical CO2 or subcritical propane were done, as well.
Keywords: chemical processing, high pressure technology, membrane reactors, biotechnology
Published in DKUM: 01.06.2012; Views: 1253; Downloads: 67
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3.
Laundry wastewater treatment using coagulation and membrane filtration
Sonja Šostar-Turk, Irena Petrinić, Marjana Simonič, 2005, original scientific article

Abstract: This paper presents the results obtained from laundry wastewater treatment using conventional methods namely precipitation/coagulation and the flocculation process with adsorption on granular-activated carbon (GAC) and an alternative method, membrane filtrations, namely ultrafiltration (UF) and reverse osmosis (RO). Chemical analyses showed that parameter values of untreated wastewater like temperature, pH, sediment substances, total nitrogen and phosphorous, COD, BOD5, and the amount of anion surfactants had been exceeded in regard to Slovenian regulation. These regulations can be used as requirements for wastewater reuse and make treated wastewater an available source for the existing water supply. The study of conventional treatment was based on a flocculation with Al2(SO4)3 18H2O and adsorption on GAC. Membrane filtrations were studied on a pilot wastewater treatment plant: ultrafiltration (UF) and reverse osmosis (RO) units. The membranes used in this experiment were ceramic UF membrane and spiral wounded - polyethersulfone- RO membranes. The quality of the wastewater was improved by both methods and the specifications of a concentration limit for emission into water were confirmed. The disadvantage of GAC is that there is no possibility of any kind of selection, which is essential for recycling and re-use, while permeate coming from RO met the required regulation as well as requirements for reusing in washing process. However, the economical analyses showed that the membrane filtrations are more expensive compared to the GAC treatment process.
Keywords: laundries, washing of textiles, waste waters, advanced oxidation processes, membrane technology, membrane filtration, coagulation
Published in DKUM: 01.06.2012; Views: 2211; Downloads: 109
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