Abstract. Polysulfone (PSF) based ultrafiltration (UF) membranes are considered to be one of the most important materials to be used for separation/filtration processes with large benefits due to their hydrolytic stability, chemical resistance, high strength, creep resistance, etc. For this, they are employed in several diversified applications: the wastewaters purification represents one of the most interesting aims in the context of a sustainable economy. The membranes processes are the most exploitable for this aim and different kinds of polymeric membranes are used to separate contaminants from feeding water with a good efficiency. The main drawbacks for membranes are represented from their hydrophobicity and low fouling resistance that decrease the water permeability, molecular selectivity and membrane lifetime. In order to have more hydrophilic polysulfone (PSF) membranes with antifouling properties, different strategies are applied. In the present activity, reporting the partial results obtained during the stage @CNR-ITAE from student Sofia Galilea Quiroz Yebra, at first, a state of the art was realised on the topic and a series of new PSF flat asymmetric membranes (13) were synthesised through the phase inversion method by non-solvent coagulation bath technique, investigating the experimental parameters determining the transversal and surface morphology of the membranes obtained and, hence, their properties. The preparation method was further optimised if compared to the that previously used as well as the experimental operative parameters. In-fact, starting from previous results (see Int. Report 5/2018), the firstly investigated factor was the reliability of the synthesis parameters: time (1, 2hrs.) and temperature (80, 120°C) for PSF polymer solubilisation, de-mixing time (Dt=20'') in the non-solvent bath for membrane formation, surfactant concentration (10wt.%). The surfactant selected during the project is three-block copolymer Pluronic p123? and it was employed to cast asymmetric films with a suitable finger-like macro-voids morphology. Moreover, the knife's light of the stratification device (Doctor-Blade) for membranes was further studied and two different thicknesses were used (300 and 500 ?m). The introduction of ionic liquid -IL (selected IL: Cyphos-104) was employed in order to trigger a mechanism of charges repulsion inside the polymer matrix and to avoid the passage of the contaminant metal ions. Another set of PSF membranes was cast in order to investigate the influence of the coagulation bath temperature and three different temperature (10, 20, 30°C) were studied. The membranes were usually characterised in terms of water retention (at rT), dimensional analysis (length, width, thickness variations), swelling, percentage porosity, TG-DSC, XRD, dynamo-mechanical analysis (DMA), Contact Angle measurements for wettability, surface area (BET), surface and cross-section SEM in order to define the correlation between the used parameters and the properties of the final membrane prototypes, IR, AFM and permeability. A cross-flow filtration cell (Sterlitech) connected to a suitable system able to recirculate a specified feeding setting the desired operative conditions (T, P, t) had to be used for final filtration tests. In this particular case, only some of these characterisations, usually jointly performed from ITAE and UGto., were performed. The tests were only partially completed and will be here reported in a raw form. The present work has to be intended as a simple report of the done activity from student. In any case, the main results obtained were: a good level of standardisation of solid flat asymmetric PSF membranes preparation procedure, definition of some important experimental parameters (Dt, p123 concentration, ratio between initial and final thickness on membrane, solubilisation t and T, Cyphos-104 concentration). At the end, the reliability was verified casting different membrane with the same parameters and analysing them by Cross-section SEM. Thirteen new membranes were, however, realised. Some of them were identified as good prototypes to be further optimized, in particular PSF2-28 (10 wt.% of p123 and 1wt.% of Cyphos-104).
Solid polymer membranes for purification of industrial grade wastewaters with recovery of contaminant species.
Ada Saccà
2020
Abstract
Abstract. Polysulfone (PSF) based ultrafiltration (UF) membranes are considered to be one of the most important materials to be used for separation/filtration processes with large benefits due to their hydrolytic stability, chemical resistance, high strength, creep resistance, etc. For this, they are employed in several diversified applications: the wastewaters purification represents one of the most interesting aims in the context of a sustainable economy. The membranes processes are the most exploitable for this aim and different kinds of polymeric membranes are used to separate contaminants from feeding water with a good efficiency. The main drawbacks for membranes are represented from their hydrophobicity and low fouling resistance that decrease the water permeability, molecular selectivity and membrane lifetime. In order to have more hydrophilic polysulfone (PSF) membranes with antifouling properties, different strategies are applied. In the present activity, reporting the partial results obtained during the stage @CNR-ITAE from student Sofia Galilea Quiroz Yebra, at first, a state of the art was realised on the topic and a series of new PSF flat asymmetric membranes (13) were synthesised through the phase inversion method by non-solvent coagulation bath technique, investigating the experimental parameters determining the transversal and surface morphology of the membranes obtained and, hence, their properties. The preparation method was further optimised if compared to the that previously used as well as the experimental operative parameters. In-fact, starting from previous results (see Int. Report 5/2018), the firstly investigated factor was the reliability of the synthesis parameters: time (1, 2hrs.) and temperature (80, 120°C) for PSF polymer solubilisation, de-mixing time (Dt=20'') in the non-solvent bath for membrane formation, surfactant concentration (10wt.%). The surfactant selected during the project is three-block copolymer Pluronic p123? and it was employed to cast asymmetric films with a suitable finger-like macro-voids morphology. Moreover, the knife's light of the stratification device (Doctor-Blade) for membranes was further studied and two different thicknesses were used (300 and 500 ?m). The introduction of ionic liquid -IL (selected IL: Cyphos-104) was employed in order to trigger a mechanism of charges repulsion inside the polymer matrix and to avoid the passage of the contaminant metal ions. Another set of PSF membranes was cast in order to investigate the influence of the coagulation bath temperature and three different temperature (10, 20, 30°C) were studied. The membranes were usually characterised in terms of water retention (at rT), dimensional analysis (length, width, thickness variations), swelling, percentage porosity, TG-DSC, XRD, dynamo-mechanical analysis (DMA), Contact Angle measurements for wettability, surface area (BET), surface and cross-section SEM in order to define the correlation between the used parameters and the properties of the final membrane prototypes, IR, AFM and permeability. A cross-flow filtration cell (Sterlitech) connected to a suitable system able to recirculate a specified feeding setting the desired operative conditions (T, P, t) had to be used for final filtration tests. In this particular case, only some of these characterisations, usually jointly performed from ITAE and UGto., were performed. The tests were only partially completed and will be here reported in a raw form. The present work has to be intended as a simple report of the done activity from student. In any case, the main results obtained were: a good level of standardisation of solid flat asymmetric PSF membranes preparation procedure, definition of some important experimental parameters (Dt, p123 concentration, ratio between initial and final thickness on membrane, solubilisation t and T, Cyphos-104 concentration). At the end, the reliability was verified casting different membrane with the same parameters and analysing them by Cross-section SEM. Thirteen new membranes were, however, realised. Some of them were identified as good prototypes to be further optimized, in particular PSF2-28 (10 wt.% of p123 and 1wt.% of Cyphos-104).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
