Polyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and f-potential. The nanoparticles were tested against E. coli (10 6 CFU/ ml) in aqueous solution, showing a synergic activity of the heteropolyacid H 5 PMo 10 V 2 O 40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture.

Polyvinylidene difluoride (PVDF) mixed matrix membranes loaded with inorganic TiO2 nanoparticles have received increasing attention in the last few years as self-cleaning membranes for possible application in wastewater treatment and seawater filtration. These novel membranes show increased hydrophilicity, stability and catalytic activity under UV-A irradiation. In this work, PVDF-TiO2 hollow fibers were prepared by employing new strategies for enhancing the stability of the TiO2 dispersion, reducing particle agglomeration and improving their distribution. The spinning conditions for producing ultrafiltration hollow fiber membranes from PVDF material and nano-TiO2 were investigated. Finally, the optimized fibers have been characterized and tested for methylene blue (MB) degradation in water and salty seawater, revealing good permeability, long-term stability under UV-A irradiation, and photo-catalytic activity in both test solutions.

Polyvinylidenefluoride (PVDF) hollow fiber membranes prepared in laboratory through the inversion phase method were characterized and used to clarify an aqueous extract from red wine lees. Steady-state permeate fluxes of 53 kg/m2h were obtained in the treatment of the aqueous extract in selected operating conditions. Suspended solids were completely retained by the hollow fiber membranes while bioactive compounds, including polyphenols, anthocyanins, and resveratrol were recovered in the permeate stream. The clarified stream was then fractionated by nanofiltration (NF). Three different commercial membranes, in flat-sheet configuration (NP010 and NP030 from Microdyn-Nadir, MPF36 from Koch Membrane Systems), were selected and tested for their productivity and selectivity towards sugars and bioactive compounds, including phenolic compounds, anthocyanins, and resveratrol. All selected membranes showed high retention towards anthocyanins (higher than 93%). Therefore, they were considered suitable to concentrate anthocyanins from clarified wine lees extracts at low temperature. On the other hand, NF permeate streams resulted enriched in phenolic compounds and resveratrol. Among the selected membranes, the MPF36 exhibited the lowest retention towards resveratrol (10%) and polyphenols (26.3%) and the best separation factor between these compounds and anthocyanins.

A novel stimuli-responsive strategy against the irreversible fouling of porous materials and surfaces is presented herein. This is based on the molecular design of catalytic pore walls that foster a chemo-mechanical, self-cleaning behavior under neutral pH and mild conditions of pressure and temperature. This approach builds on bioinspired remediation mechanisms involving natural catalase enzymes for H2O2 dismutation and endogenous oxygen production. It is thus demonstrated that a very efficient antifouling activity is observed when the material pores are armed with oxygen evolving catalysts that are known to liberate nascent oxygen gas when exposed to H2O2 as chemical trigger. To this aim, the catalase-like behavior of the tetra-ruthenium substituted polyoxometalate (Ru4(SiW10)2), has been exploited for in-pore oxygen evolution so to induce an active fluid mixing and the displacement of foulant particles. The present study includes the fabrication of hybrid polymeric films with porous architecture embedding Ru4(SiW10)2 as artificial catalase to guarantee the material self-defense against pore occlusion and oxidative damage with aqueous H2O2 as mild chemical effector. The self-catalytic “in-pore” remediation is readily applied to various materials/interfaces with porous texture and high surface area with the aim to provide long-lasting functional performance