Tesi di Dottorato
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Item Functionalized polymeric membranes for development of biohybrid systems(2016-02-26) Vitola, Giuseppe; Giorno, Lidietta; Drioli, Enrico; Molinari, RaffaeleLe proprietà di superficie di una membrana sono di grande importanza per la sua funzione. Mediante tecniche di funzionalizzazione chimica è possibile ottenere membrane con gruppi funzionali in grado di adempiere nuove e diverse funzioni che rendono la membrana funzionalizzata un dispositivo in grado di svolgere funzioni multiple trovando applicazione in vari impieghi. Le membrane funzionalizzate, infatti, trovano impiego nei processi di separazione, nei settori che richiedono l’uso di membrane biocompatibili, e nell’immobilizzazione di biomolecole che a sua volta trova applicazione nella preparazione di biosensori e bioreattori a membrana. Questi ultimi sono particolarmente interessanti poiché sfruttano l’alta superficie specifica della membrana e permettono di integrare il processo di separazione con quello catalitico. Il presente lavoro di tesi ha riguardato lo sviluppo di membrane polimeriche biofunzionalizzate per la decontaminazione di acque da sostanze tossiche quali i pesticidi organofosfati. Il lavoro è stato focalizzato sullo studio di diverse tecniche per l’ingegnerizzazione di membrane polimeriche aventi differenti caratteristiche chimico-fisiche. L’impatto dei diversi tipi di funzionalizzazione è stato valutato considerando il grado di legame e le proprietà catalitiche di biomolecole immobilizzate sulle membrane funzionalizzate. I polimeri utilizzati per l’immobilizzazione delle biomolecole sono stati il fluoruro di polivinilidene (PVDF) e il polietersulfone (PES), materiali ampiamente usati in sistemi di filtrazione. La proteina sieroalbumina bovina (BSA) e l’enzima lipasi da candida rugosa (LCR) sono state selezionate quali biomolecole modello per lo studio della capacità di legame e le proprietà catalitiche delle membrane ingegnerizzate. Le condizioni ottimali di funzionalizzazione e immobilizzazione sono state poi impiegate per lo sviluppo di sistemi bioibridi contenenti l’enzima fosfotriesterasi (PTE), un enzima in grado di operare la detossificazione di organofosfati. Al fine di migliorare le performance degli enzimi immobilizzati sul PVDF è stato sviluppato un nuovo approccio di ingegnerizzazione. Esso ha riguardato la sintesi di nanoparticelle colloidali a base di poliacrilammide e il loro utilizzo, dopo opportuna funzionalizzazione, come vettori per l’immobilizzazione covalente di enzimi sul PVDF. La nuova strategia di immobilizzazione ha permesso di mantenere il microambiente idrofilo a livello dell’enzima immobilizzato migliorandone di conseguenza le proprietà catalitiche. La strategia allo stesso tempo ha consentito di preservare l’idrofobicità della membrana. Tale proprietà è necessaria per lo sviluppo di sistemi operanti nella decontaminazione di aria. I risultati hanno mostrato che l’enzima fosfotriesterasi immobilizzato sul PES mantiene un’attività residua maggiore rispetto a quella dell’enzima immobilizzato sul PVDF. La membrana biocatalitica in PES è risultata idonea per la decontaminazione di organofosfati in fare acquosa.Item Evaluation of thermal polarization and membrane characteristics for membrane distillation(2014-11-11) Alì, Aamer; Drioli, Enrico; Aimar, Pierre; Bouzek, Karel; Fila, Vlastimil; Molinari, RaffaeleThe current PhD work emphasizes on various aspects of membrane distillation for approaching zero liquid discharge in seawater desalination. In broader sense, two themes have been discussed in detail: (i) correlation between membrane features and their performance in MD (ii) understanding and control of thermal polarization in MD. Introduction and state-of-the-art studies of MD including progress in membrane development, understanding the transport phenomenon, recent developments in module fabrication, fouling and related phenomenon and innovative applications have been discussed in introductory part of the thesis. The effect of operating conditions and dope compositions on membrane characteristics and correlation between membrane features and their performance has been discussed in subsequent section. It has been established that membrane morphology plays a crucial role in performance of the membrane for real applications. Furthermore, it has been demonstrated that the effect of membrane morphology is different for direct contact and vacuum configurations. Theoretical and experimental aspects of thermal polarization in direct contact membrane distillation have also been investigated. Thermal polarization phenomenon in a flat sheet membrane has been studied by using a specifically designed cell. The effect of operating conditions and solution concentration on thermal polarization has been explored experimentally. It has been observed that increased solution concentration favors the thermal polarization due to resulting poor hydrodynamic at the membrane surface and increase in diffusion resistance to the water vapors migrating from bulk feed phase to the membrane surface. Some active and passive techniques to decrease thermal polarization and possible fouling in membrane distillation have also been discussed in the current study. Thermal polarization can be greatly reduced by inducing secondary flows in the fluid flowing inside the fiber. The induction of secondary flows in the current study has been realized by using the fibers twisted in helical and wavy configurations. Due to improvement of thermal polarization coefficient on up and downstream, the undulating fiber geometries provide high flux and superior performance ratio. Application of intermittent and pulsatile flow to control thermal polarization in MD has also been discussed. It has been inferred that these flows have positive impact on performance ratio and volume based enhancement factors without compromising on packing density of the system. The application of MD for treatment of produced water has also been studied. The effect of membrane features on their performance for the treatment of this complex solution has been discussed. The desirable membrane features for successful application of MD for such treatment have been distinguished. It has been inferred that MD possesses the capability to produce a distillate of excellent quality and is an interesting candidate to recover the minerals present in the produced water. The fouling tendency of the membranes with different characteristics towards different types of feed solutions has also been discussed in this study. It has been shown that the porosity enhanced through the introduction of macrovoids in non-solvent induced phase separation technique creates problems related with wetting and pore scaling during practical application of such membranes. The fouling related issues are less severe in the membranes with sponge like microstructure but the overall porosity of such membranes is relatively less. Thus it has been concluded that there should be an optimum between the high throughput and stable performance of the membranes synthesized through phase inversion techniques. Conclusions of the study and future perspectives have been discussed in the last section of the study.Item Biodegradable polymeric membrane systems for tissue engineering applications(2013-11-12) Messina, Antonietta; De Bartolo, Loredana; Curcio, Efrem; Molinari, RaffaeleItem Graphene and titanium based semiconductors in photocatalytic hydrogen and oxygen generation and hydrogenation of organics also in membrane reactors(2013-11-12) Lavorato, Cristina; Molinari, Raffaele; Argurio, Pietro; Garcia, HermenegildoThe development of graphene (G)-based materials as photocatalysts has become in the last years of high interest due to their sustainability and flexibility in the modification and design, particularly in the field of photocatalytic generation of hydrogen. Carbon based materials are sustainable when they are derived from renewable biomass feedstocks. G is a versatile material allowing different modification strategies to improve its activity. Thus, the present thesis reports that inserting heteroatoms, adding semiconductors or changing the layers size, the activity of the materials prepared can be improved for different applications. Sun light is one of major renewable energy resource. The use of light as driving force for chemical reactions has attracted much attention of organic chemists. Heterogeneous photocatalysis is a discipline which includes a large variety of reactions, in particular hydrogen (considered the perfect renewable energy source in the future) and oxygen generation from water and hydrogenation of multiple bonds are the target of this PhD thesis. Photocatalytic reductions represent an alternative to conventional catalytic hydrogenation and it represent a more sustainable method to synthesize organic compounds under mild conditions in the presence of affordable photocatalysts. Photocatalytic processes in membrane reactors represent a technology of great scientific interest because it allows chemical reactions and separation processes to be accomplished in one step, which in turn results in lower processing cost and minimum environmental impact. The preparation and characterization of G-based semiconductors has been carried out in the first part of the Thesis and their photocatalytic activity for hydrogen and oxygen generation from water was determined in the second part. Graphite was oxidized to graphene oxide (GO) and its photocatalytic activity for hydrogen generation from water/methanol mixtures with visible or solar light was enhanced by the presence of dyes, in the absence of any noble metal. The most efficient tested photocatalyst was the one containing a tris(2,2-bipyridyl) ruthenium(II) complex incorporated in the interlayer spaces of a few layers of GO platelets with a moderate degree of oxidation. This photocatalyst was two orders of magnitude more efficient than a titania based photocatalyst containing Au, when the reaction is performed under 532 nm laser as excitation light. Doping G with nitrogen by pyrolysis of chitosan leads to a material that behaves as a semiconductor and exhibits high efficiency for the photocatalytic generation of hydrogen from water-methanol mixtures with similar efficiency using UV or visible light. This similar photocatalytic activity wis due to the fact that, in contrast to GO, N-doped G exhibits an almost “neutral” absorption spectrum. The main parameter controlling the residual amount of nitrogen and the resulting photocatalytic activity is the pyrolysis temperature that produces an optimal material when the thermal treatment is carried out at 900 °C. Furthermore, N-doped G was able to generate hydrogen also upon illumination of simulated sunlight. The use of G as co-catalyst of metal oxides semiconductors to enhance their photocatalytic activity has been extensively reported. Using alginate, a natural polysaccharide from algae, simultaneously as G precursor and as ceria nanoparticles template agent, a series of materials consisting of highly crystalline ceria nanoparticles embedded on a few layers G matrix has been prepared. Varying the weight percentage of ceria/alginate and the pyrolysis temperature, it was possible to prepare a ceria/G photocatalyst that exhibits about three times higher photocatalytic activity for water oxidation to oxygen than commercial ceria. Pyrolysis at 900 °C under inert atmosphere of alginate renders a graphitic carbon that upon ablation by exposure to a pulsed 532 nm laser (7 ns, 50 mJ pulse−1) in acetonitrile, water, and other solvents leads to the formation of multilayer graphitic quantum dots. The dimensions and the number of layers of these graphitic nanoparticles decrease along the number of laser pulses leading to G quantum dots (GQDs). Accordingly, the emission intensity of these GQDs increases along the number of laser shots, the maximum emission intensity appearing at about 500 nm in the visible region increasing in intensity along the reduction of the particle size. Transient absorption spectroscopy has allowed detection of a transient signal decaying in the microsecond time scale that has been attributed to the charge separation state. During the second part of the present thesis the photocatalytic hydrogenation of acetophenone by using titanium based semiconductors in batch and membrane reactors under UV and visible light has been studied. Different photocatalytic tests have been performed using ethanol or water and formic acid in a batch reactor in order to optimize the reaction parameters before to be applied in membrane reactors with different substrate addition mode. The use of a membrane reactor system for the photocatalytic hydrogenation of acetophenone in water solution with formic acid as hydrogen and electron donor was found to improve the efficiency of the photocatalytic system with respect to the use of batch reactor. The most efficient system for photocatalytic hydrogenation of acetophenone in terms of productivity, amount of phenylethanol produced and extraction of desired product was found to be the membrane reactor in which acetophenone was used as both organic phase and substrate. The presence of palladium enhances the visible light photocatalytic activity of TiO2 photocatalyst, that is not active alone. The productivity by using Pd/TiO2 photocatalyst under visible light increases five times more than using TiO2 under UV lightItem Development of membrane bioreactor (MBR) process applying novel low fouling membranes(2013-11-12) Deowan, Shamim Ahmed; Drioli, Enrico; Molinari, Raffaele; Figoli, Alberto; Hoinkis, JanWater is a part and parcel of human life. Water contaminated from industry and agriculture with heavy metal ions, pesticides, organic compounds, endocrine disruptive compounds, nutrients (phosphates, nitrates, nitrites) has to be effi-ciently treated to protect humans from being intoxicated with these compounds or with bacteria. Clean water as basis for health and good living conditions is too far out of reach for the majority of the population in the world (Bionexgen, 2013). Water recycling is now widely accepted as a sustainable option to re-spond to the general increase of the fresh water demand, water shortages and for environmental protection. Water recycling is commonly seen as one of the main options to provide remedy for water shortage caused by the increase of the water demand and draughts as well as a response to some economical and environmental drivers. The main options for wastewater recycling are industri-al, irrigation, aquifer recharge and urban reuse (Pidou, M., 2006). Among the industrial wastewaters, the textile industry is long regarded as a water intensive sector, due to its high demand of water for all parts of its pro-cedures. Accordingly, textile wastewater includes quite a large variety of con-tents, chemicals, additives and different kinds of dyestuffs. The main environ-mental concern with this waste water is about the quantity and quality of the water discharged and the chemical load it carries. To illustrate, for each ton of fabric products, 20 – 350 m3 of water are consumed, which differs from the color and procedure used. The quality of the textile wastewater depends much on the employed coloring matters, dyestuffs, accompanying chemicals, as well as the process itself (Brik et al., 2006). MBR technology is recognised as a promising technology to provide water with reliable quality for reuse. It provides safely reuse water for non-potable use. But the treated textile wastewater by MBR technology alone can’t comply with the reuse or discharge standard in many countries due to its colouring matters and dyestuffs remained in the effluent, if otherwise, MBR is associated with other technology like NF, RO, other processes or the applied membrane is modified or a novel MBR is applied. Fouling is another limiting factor for worldwide application of MBR technology especially in high-strength industri-al wastewater like textile wastewater. Moreover, membrane fouling is regarded as the most important bottleneck for further development of MBR technology. It is the main limitation for faster development of this process, particularly when it leads to flux losses that cleaning cannot restore (Howell et al. 2004). In this thesis work, a novel membrane bioreactor (MBR) process was devel-oped by modifying a applied commercial PES UF membrane in MBR module by nano-structured novel coating through polymerisable bicontinuous micro-emulsion (PBM) process with the purpose of having higher hydrophilicity and low fouling propensity. Before starting the MBR experiments, some characteri-sation tests such as SEM, AFM images analysis, roughness measurements, pore geometry, contact angel, standard salt rejections, model textile dye rejec-tions were performed. In addition, fouling tests using two laboratory cross flow testing units were conducted as well. To reach the ultimate goal of research, 6 sheets of novel coated membranes with size of 30 cm × 30 cm were prepared and these were used to prepare a three-envelope MBR module of 25 cm × 25 cm in size (total membrane area 0.33 m2) similar to that of a commercially available three-envelope PES UF MBR module. This novel MBR module was tested in a submerged lab-scale MBR pilot plant (tank volume ca. 60 L) for about 6 months using model textile dye wastewater (MTDW) as test media for all experiments with the aim of having uniform compositions with respect to time. The tests were done based on carefully selected operation conditions. Prior to testing of the novel membrane module MBR, experiments were carried out with a commercial PES UF MBR module using the same pilot plant set up and the same selected operating conditions for about 10 months. After comple-tion of trials with the novel coated MBR module, similar experiments were carried out again with a commercial PES UF MBR module to check the simi-larity of the biological sludge conditions and other operation conditions as well. In short, the sequences of the experiments were as follows: Commercial PES UF MBR (10 months) →novel membrane coated MBR (6 months)→PES UF MBR (1.5 months) The ultimate goal of the experiments was to compare the results between the commercial MBR and novel coated MBR module in order to demonstrate im-provement regarding fouling propensity and permeate water quality. The performance analysis shows that the novel coated MBR module compared to the commercial MBR module has 7% points higher COD removal efficien-cy, 20% points higher blue dye removal efficiency, high antifoul-ing/antimicrobial properties, resulting in a very low-fluctuating and highly ro-bust MBR process which looks promising with regard to economic viability. Since the newly developed MBR module worked excellent on laboratory scale it consequently should be deployed at an industrial site to be tested with real ii wastewater. Therefore, this novel three-envelope MBR module is on the way to be tested with real wastewater in a textile factory in Tunisia. The findings of these on-site pilot trials will serve as a basis for further improvement and even-tually pilot trails with larger membrane area will be addressedItem Total and parial oxidation reactions in photocatalytic membrane reactors(2008-11-11) Caruso, Angela; Molinari, RaffaeleItem Modelling of PD-Based membranes and PD-Based Membrane reactors for hydrogen purification and production by methane steam reforming(2008-11-17) Caravella, Alessio; Molinari, Raffaele; Di Maio, Francesco Paolo; Di Renzo, AlbertoItem Membrane Emulsification to develop biohybrid microstructured and multifunctional systems(2009-11-13) Piacentini, Emma; Drioli, Enrico; Molinari, Raffaele; Giorno, LidiettaItem Process innovation and process intensification by membrane systems in the treatment of gas industrial streams(2014-06-10) Chiappetta, Giovanni; Drioli, Enrico; Barbieri, Giuseppe; Molinari, RaffaeleItem Studio teorico di membrane bicompatibili per applicazioni farmaceutiche(2014-05-29) Cairo, Patrizia; Tocci, Elena; Curcio, Efrem; Molinari, RaffaeleTo design advanced dosage forms, suitable carrier materials are used to overcome the undesirable properties of drug molecules. Hence various kinds of high-performance biomaterials are being constantly developed. From the viewpoint of the optimization of pharmacotherapy, drug release should be controlled in accordance with the therapeutic purpose and pharmacological properties of active substances. The main objective of the present thesis was to characterize the interactions between drugs and drug carriers by using combined molecular dynamics, molecular mechanics, and docking computational techniques. These simulations are likely to benefit the study of materials by increasing our understanding of their chemical and physical properties at a molecular level and by assisting us in the design of new materials and predicting their properties. Simulations are usually considerably cheaper and faster than experiments. Molecular simulations also offer a unique perspective on the molecular level processes controlling structural, physical, optical, chemical, mechanical, and transport properties. In particular the attention was put on cyclodextrinic carriers supported on membrane and molecularly imprinted polymers. Thus, structural information, such as the geometries of the cyclodextrinic complexes, and thermodynamic data, i.e. the variation of the enthalpy, were considered to draw a complete picture of the βCD-drug interactions. The results were in good agreement with the experimental data found in the measurement of stability constants. Finally the molecular dynamics on the polymeric system formed by adding on the surface of PEEK-WC the βCD-drug complex showed the release of the included drug in a water solution. The docking and molecular mechanics techniques provided also informations on the geometry and the energy of complexation of a β-cyclodextrin derivative with naringin showing that the driving force for the host-guest complexation is due to the van der Waals interaction. Moreover the molecular dynamics calculations provided details on the complexation of naringin on the PEEK-WC surface containing the β-cyclodextrin derivative. The binding affinity and selectivity of MIP towards drug template were calculated from the interaction energy between the ligand and the monomers and from docking simulations, respectively, as also the number of hydrogen bonds was determined. Our computational results shown a higher interaction energy between the drug template and monomers and justified the experimental data of selective recognition and rebinding of the template in terms of MIP performance confirming the reliability of our computational method. Moreover the diffusion coefficient of 5-FU into a PMAA matrix on the release step was determined.Thus, atomistic modelling of material structure was a tool for understanding the mechanisms of physical processes on atomic and molecular levels, gaining insights into the molecular origins of behaviour of bulk polymers.