Enrica Fontananova

Potential of brackish water and brine for energy generation by salinity gradient power-reverse electrodialysis (SGP-RE)

In the present work, a salinity gradient power-reverse electrodialysis (SGP-RE) unit was tested for the production of electrical energy by exploiting the chemical potential of real brackish water and exhaust brine from a solar pond. A cross-flow SGP-RE module (REDstack B.V.), equipped with AEM-80045 and CEM-80050 membranes specifically developed by Fujifilm Manufacturing Europe B.V. within the EU-funded project REAPOWER (“Reverse Electrodialysis Alternative Power Production”), was able to generate a maximum power density (expressed in W m−2 membrane pair – MP) of 3.04 W m−2 MP when operated with pure NaCl aqueous solutions (0.1 M in low concentration compartment – LCC, 5 M in high concentration compartment – HCC) at 20 °C and at a recirculation rate of 20 L h−1. However, a drastic reduction to 1.13 W m−2 (−63%) was observed when feeding the SGP-RE unit with artificial multi-ion solutions mimicking real brackish water and exhaust brine. Further experimental activity allowed to identify Mg2+ ion as responsible for the significant increase in stack resistance and consequent depletion in SGP-RE performance. Therefore, specific softening treatments of the real solutions should be considered in order to maintain the process efficiency at practical level.

Energetics of protein nucleation on rough polymeric surfaces.

Metropolis Monte Carlo (MC) algorithm of the two-dimensional Ising model is used to study the heterogeneous nucleation of protein crystals on rough polymeric surfaces. The theoretical findings are compared to those obtained from classical nucleation theory (CNT), and to experimental data from protein model hen egg white lysozyme (HEWL) crystallized on poly(vinylidene fluoride) or PVDF, poly(dimethylsiloxane) or PDMS and Hyflon homemade membranes. The reduction of the activation energy for the nucleation process on polymeric membranes, predicted to occur at increasing surface roughness, results in a nucleation kinetics that is many orders of magnitude faster than in homogeneous phase. In general, MC stochastic dynamics offers the unique opportunity to investigate the effects of collective molecular aggregation at site level on the nucleation rate and, consequently, allows to identify optimal morphological and structural properties of polymeric membranes for a fine control of the crystallization kinetics.

Membrane Materials for Addressing Energy and Environmental Challenges

Our modern society must solve various severe problems to maintain and increase our quality of life: from water stress to global warming, to fossil fuel depletion, to environmental pollution. The process intensification (PI) strategy is expected to contribute to overcoming many of these issues by facilitating the transition from a resource-intensive to a knowledge-intensive industrial system that will guarantee sustainable growth. Membrane operations, which respond efficiently to the requirements of the PI strategy, have the potential to replace conventional energy-intensive separation techniques, which will boost the efficiency and reduce the environmental impact of separations as well as conversion processes. This work critically reviews the current status and emerging applications of (integrated) membrane operations with a special focus on energy and environmental applications.

From hydrophobic to hydrophilic polyvinylidenefluoride (PVDF) membranes by gaining new insight into material's properties

This work provides an easy and versatile strategy to manufacture novel polyvinylidenefluoride (PVDF) membranes by solution casting and phase separation techniques displaying tailored physicochemical and microstructural features depending on the opportune combination of functionalization by blending chemical additives (multiwalled carbon nanotubes, MWCNTs) and manufacturing procedure. The systematic study of the effect of (i) polymer concentration, (ii) use of pore forming additives (LiCl), and (iii) type and concentration of MWCNTs, on the PVDF crystalline composition and membrane microstructure, highlights the strong relationships of these parameters with the wettability, fouling and transport attributes of the formed membranes. The results provide the key to discriminate membrane preparation conditions favoring hydrophilic, low fouling, and highly selective PVDF–MWCNTs membranes, for water-treatment applications in pressure-driven membrane operations, from conditions favoring the formation of hydrophobic and waterproof membranes, to be used in the membrane contactors field. Also, they open exciting perspectives for a more effective development of PVDF-based nanostructured membranes for advanced separations based on a comprehensive investigation and understanding of materials properties.

Solvent-free, heterogeneous photooxygenation of hydrocarbons by Hyflon® membranes embedding a fluorous-tagged decatungstate

Hybrid fluoropolymeric membranes with 25% loading of the fluorous-tagged (RfN)4W10O32 effect the solvent-free photooxygenation of benzylic C-H bonds with up to 6100 TONs in 4 hours.

Catalytic Membranes and Membrane Reactors: An Integrated Approach to Catalytic Process with a High Efficiency and a Low Environmental Impact

Abstract The design of new heterogeneous photooxygenation systems able to employ visible light, oxygen, mild temperatures, and solvent with a low environmental impact has been investigated. In particular, the heterogenization of decatungstate (W 10 O 32 4− ), a polyoxometalate with photocatalytic activity in oxidation reactions, has been carried out in polymeric membranes of polyvinylidenefluoride. The polymeric catalytic membranes prepared by phase inversion technique have been successfully applied in the aerobic mineralization of phenol in water, which was used as an example of organic pollutant. In order to evaluate the effect of the polymeric environment on the overall catalyst behavior, we have also heterogenized the decatungstate (opportunely functionalized) in perfluorinated membrane made of Hyflon. The photocatalytic composite membranes are characterized by different and tuneable properties depending on the nature of the polymeric micro-environment, in which the catalyst is confined. Moreover, the selective separation function of the membrane results in enhanced performance in comparison with homogeneous reactions.

Membrane technologies for seawater desalination and brackish water treatment

Abstract Membrane technology currently dominates the industry of desalination and brackish water treatment. Seawater reverse osmosis (SWRO) systems account for more than 50% of the global capacity (about 70xa0million m 3 /day) of desalination plants. This success history began almost 50xa0years ago with the discovery of asymmetric cellulose acetate RO membranes by Loeb and Sourajan; more recently, the impressive development in membrane materials, modules, and process design has resulted in overall energy consumption of 3–5xa0kWh/m 3 of desalted water, much less than the energy required by conventional thermal processes (10–15xa0kWh/m 3 ). This chapter aims to provide a general overview of membrane operations currently in use in seawater and brackish water desalination for potable water production. After introducing the problem of water shortage and providing a general classification of main desalination technologies, the chapter focuses on the principles of RO, polymeric materials and modules in use, plant design strategies including the pretreatment step, energy input and related recovery devices, potentialities offered by novel salinity gradient power technologies (with an emphasis on pressure-retarded osmosis and reverse electrodialysis), environmental problems related to brine disposal, membrane distillation as a viable option in the logic of zero liquid discharge, and the economics of membrane desalination.

CO2 conversion in a photocatalytic continuous membrane reactor

The reduction of CO2 with water by using photocatalysts is one of the most promising new methods for achieving CO2 conversion to valuable hydrocarbons such as methanol (MeOH). In this work, prepared TiO2–Nafion™-based membranes were used in a photocatalytic membrane reactor, operated in continuous mode, for converting CO2 to methanol. By using the membrane with the best TiO2 distribution, a MeOH flow rate/TiO2 weight of 45 μmol (gcatalyst h)−1 was measured when operating at 2 bar of feed pressure. This value is higher than those reported in most of the literature data to date. Moreover, methanol production is considered as a relevant advance over the existing literature results which mostly propose CH4 as the reaction product.

Bioinspired Synthesis of CaCO3 Superstructures through a Novel Hydrogel Composite Membranes Mineralization Platform: A Comprehensive View

Hydrogel composite membranes (HCMs) are used as novel mineralization platforms for the bioinspired synthesis of CaCO3 superstructures. A comprehensive statistical analysis of the experimental results reveals quantitative relationships between crystallization conditions and crystal texture and a strong selectivity toward complex morphologies when monomers bearing carboxyl and hydroxyl groups are used together in the hydrogel layer synthesis in HCMs.

Polyvinylidenefluoride/carbon nanotubes mixed matrix membranes with tailored properties

Membrane operations are promising tools for efficient and environmentally friendly separations. However, the development of advanced membranes with tailored properties is a key issue to be addressed in order to better exploit the potentialities of membrane-based separations. An important approach toward this aim is the development of mixed matrix membranes in which an organic and an inorganic phase coexist in order to have synergic effects on membrane properties. The peculiar properties of carbon nanotubes (CNTs) such as high electrical and thermal conductivity, high strength and unique transport properties, has motivated a considerable effort to produce CNT-polymer composites in order to engineer membrane properties. In this work the roughness, wettability, morphology, crystalline phase and pore size of polyvinylidenefluoride (PVDF) membranes were tailored working on the membrane preparation conditions, as well as, by blending the polymer with multiwalled carbon nanotubes (MWCNTs). A study on the effect ...