Abstract. Polysulfone (PSF) based ultrafiltration (UF) membranes are considered to be one of the most important materials to be used for separation processes with large benefits due to their hydrolytic stability, chemical resistance, high strength, creep resistance, etc. For these reasons, they can be employed in several diversified applications. Among the most important 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: different kinds of polymeric membranes are used to separate several contaminants from feeding water with a good efficiency. The drawbacks for membranes are represented from their hydrophobicity and low fouling resistance that decreases 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 work, that represents the description of the activity second year of a project of joint lab Italia-Mexico, a state of the art was realised on the topic and a series (11) of new PSF flat asymmetric membranes were synthesised through the phase inversion method by non-solvent coagulation bath technique investigating a series of experimental parameters determining the transversal and surface morphology and, hence, the process final efficiency. The preparation method was further optimised as well as the experimental operative parameters. In particular, the investigated parameters were: time (1, 2hrs.) and temperature (80, 120°C) of polymer solubilisation, the polymeric solution viscosity to be stratified in order to improve the stiffness of the membrane final samples, the de-mixing time (Dt=10, 20, 40s) into the non-solvent (distilled water) bath for the membrane formation, the stratification step by Doctor-Blade casting technique using 3 different initial thicknesses on micrometric knife, the surfactant concentration (1, 10, 30 and 50wt.%) used. The surfactant, already used during the first year of the project activity, is the three-block copolymer Pluronic p-123 and was employed to realise asymmetric films with a suitable finger-like macro-voids morphology, The membranes were characterised in terms of water retention (at rT), dimensional analysis (length, width, thickness variations), swelling, percentage qualitative porosity evaluation, X-Ray diffraction measurements (XRD), dynamo-mechanical analysis (DMA), Contact Angle measurements, cross-section SEM in order to define the correlation between the used parameters and the properties of the final membrane prototypes. The main results obtained were: a good level of membrane preparation procedure standardisation: definition of experimental parameters, demixing time to obtain finger-like morphology along the membrane section, surfactant concentration and The ratio between the doctor-blade knife thickness and that of final membrane; more, the reproducibility was verified and fourteen new membrane membranes were realised. Some of them were identified as good prototypes to be further optimized during the third year of the project activity, in particular PSF2-20 (pure PSF), PSF2-16 (50wt. % of p-123), PSF2-22BIS (1wt% of p-123), PSF2-23 (10wt.% of p-123), PSF2-24 (30wt% of p-123).
Joint laboratory on green separation processes for the wastewaters treatment and recovery of contaminating species". Laboratori Congiunti Bilaterali Internazionali del CNR (II call 2016) - tematico ICT (triennio 2017- 2019)". Proto. N. 0082227. 24 months Progress External Report N. 12/2019
A Saccà;R Pedicini;A Carbone;A Patti;I Gatto;
2019
Abstract
Abstract. Polysulfone (PSF) based ultrafiltration (UF) membranes are considered to be one of the most important materials to be used for separation processes with large benefits due to their hydrolytic stability, chemical resistance, high strength, creep resistance, etc. For these reasons, they can be employed in several diversified applications. Among the most important 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: different kinds of polymeric membranes are used to separate several contaminants from feeding water with a good efficiency. The drawbacks for membranes are represented from their hydrophobicity and low fouling resistance that decreases 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 work, that represents the description of the activity second year of a project of joint lab Italia-Mexico, a state of the art was realised on the topic and a series (11) of new PSF flat asymmetric membranes were synthesised through the phase inversion method by non-solvent coagulation bath technique investigating a series of experimental parameters determining the transversal and surface morphology and, hence, the process final efficiency. The preparation method was further optimised as well as the experimental operative parameters. In particular, the investigated parameters were: time (1, 2hrs.) and temperature (80, 120°C) of polymer solubilisation, the polymeric solution viscosity to be stratified in order to improve the stiffness of the membrane final samples, the de-mixing time (Dt=10, 20, 40s) into the non-solvent (distilled water) bath for the membrane formation, the stratification step by Doctor-Blade casting technique using 3 different initial thicknesses on micrometric knife, the surfactant concentration (1, 10, 30 and 50wt.%) used. The surfactant, already used during the first year of the project activity, is the three-block copolymer Pluronic p-123 and was employed to realise asymmetric films with a suitable finger-like macro-voids morphology, The membranes were characterised in terms of water retention (at rT), dimensional analysis (length, width, thickness variations), swelling, percentage qualitative porosity evaluation, X-Ray diffraction measurements (XRD), dynamo-mechanical analysis (DMA), Contact Angle measurements, cross-section SEM in order to define the correlation between the used parameters and the properties of the final membrane prototypes. The main results obtained were: a good level of membrane preparation procedure standardisation: definition of experimental parameters, demixing time to obtain finger-like morphology along the membrane section, surfactant concentration and The ratio between the doctor-blade knife thickness and that of final membrane; more, the reproducibility was verified and fourteen new membrane membranes were realised. Some of them were identified as good prototypes to be further optimized during the third year of the project activity, in particular PSF2-20 (pure PSF), PSF2-16 (50wt. % of p-123), PSF2-22BIS (1wt% of p-123), PSF2-23 (10wt.% of p-123), PSF2-24 (30wt% of p-123).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
