Synergic photocatalytic effect between TiO2 and a fluorinated transparent ionomeric material in the oxidation of hydrosoluble pollutants in turbid suspensions

The crystal violet (CV) dye has been chosen to study the photooxidation activity of titanium dioxide immobilized into a transparent fluoropolymeric matrix toward organic pollutants. The photoactive matrix was directly coated on the UV source by applying a TiO2 containing fluorinated ionomeric dispersion and a perfluorinated transparent amorphous polymer in an appropriate sequence. The photocatalytic activity of the multilayered coating towards the hydrosoluble organic CV dye was evaluated in transparent solution and in highly turbid suspension. The turbidity was obtained by dispersing insoluble microparticles of calcium sulfate in the polluted aqueous solution. The photoabatement rates obtained in transparent and in turbid conditions were 0.0918 min-1 and 0.0300 min-1, respectively. The TiO2 nanoparticle dispersed in the fluorinated matrix revealed a higher photocatalytic activity than simple dispersed TiO2 in both transparent as well as turbid conditions. The immobilization of the catalyst in a stable fluorinated matrix avoided the TiO2 separation and prevented catalyst losses. The synergism in the activity between the TiO2-based photocatalyst and the fluorinated matrix was particularly evident at low pollutant concentrations

Comparison of Branched and Linear Perfluoropolyether Chains Functionalization on Hydrophobic, Morphological and Conductive Properties of Multi-Walled Carbon Nanotubes

The functionalization of multi-walled carbon nanotubes (MW-CNTs) was obtained by generating reactive perfluoropolyether (PFPE) radicals that can covalently bond to MW-CNTs’ surface. Branched and linear PFPE peroxides with equivalent molecular weights of 1275 and 1200 amu, respectively, have been thermally decomposed for the production of PFPE radicals. The functionalization with PFPE chains has changed the wettability of MW-CNTs, which switched their behavior from hydrophilic to super-hydrophobic. The low surface energy properties of PFPEs have been transferred to MW-CNTs surface and branched units with trifluoromethyl groups, CF3, have conferred higher hydrophobicity than linear units. Porosimetry discriminated the effects of PFPE functionalization on meso-porosity and macro-porosity. It has been observed that reactive sites located in MW-CNTs mesopores have been intensively functionalized by branched PFPE peroxide due to its low average molecular weight. Conductivity measurements at different applied pressures have showed that the covalent linkage of PFPE chains, branched as well as linear, weakly modified the electrical conductivity of MW-CNTs. The decomposed portions of PFPE residues, the PFPE chains bonded on carbon nanotubes, and the PFPE fluids obtained by homo-coupling side-reactions were evaluated by mass balances. PFPE-modified MW-CNTs have been characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), static contact angle (SCA), surface area, and porosity measurement

Absorption and photocatalytic degradation of VOCs by perfluorinated ionomeric coating with TiO2 nanopowders for air purification

In this work, we propose a transparent multilayered perfluoropolymeric coating as immobilization method for TiO2 nanoparticles, and evaluate its suitability in the gas phase photocatalytic degradation of six different volatile organic compounds. The coating was made of a layer of TiO2-containing perfluorosulfonic acid polymer on a layer of perfluorinated amorphous polymer. The chemical stability of perfluoropolymeric materials to UV radiation and UV-activated TiO2 overcomes the possible degradation of the polymeric immobilization system which is typical of more traditional polymeric coatings. Moreover, the TiO2-containing ionomeric perfluorosulfonic layer worked as selective membrane for pollutants absorption and catalyst preservation, depending on the interactions between the superacidic polar heads of the ionomer and the pollutants, in particular those capable of hydrogen bonding. Gas-phase photocatalytic degradation tests were performed using pentane, methanol, 2-propanol, toluene, dichloromethane and pyridine as reference volatile organic pollutants, thus ranging on different polarity properties. Results indicate performances comparable to other approaches reported in the literature and show a strong influence of both atmospheric conditions (namely, humidity) and pollutant nature – polarity, proticity – on the actual kinetics of photodegradation, also depending on the interactions regulating the affinity between the ionomeric layer of the coating and pollutants. The high potential of the coating in the photodegradation was confirmed by the observed values of the photoabatement rates: all approximatively above 10−5 s−1 and maximum for alcohols (1.4 × 10−4 and 1.7 × 10−4 s−1 in dry and humid conditions, respectively)

Method of making fluoro vinyl ethers and polymers obtainable therefrom

none1Fluorovinyl ethers having the formula CFX-CXOCF2OR, wherein R is a C2-C6 linear, branched or C5-C6 cyclic (per)fluoroalkyl group, or a C2-C6 linear, branched (per)fluoro oxyalkyl group containing from one to three oxygen atoms; when R is fluoroalkyl or fluorooxyalkyl group as above defined, it can contain from 1 to 2 atoms, equal or different, selected from the following: H, Cl, Br, I; X-F, H; and homopolymers or polymers obtainable polymerizing said Fluorovinyl ethers with at least another polymerizable monomer.W. NavarriniNavarrini, WALTER MAURIZI

Fluorovinylethers and polymers obtainable therefrom

reserved1The present invention relates to Fluorovinyl ethers, the process for preparing them and the polymers obtainable therefrom. Furthermore the need was felt to have available amorphous or crystalline copolymers having a low content of C(O)F end groups. A lower content of C(O)F end groups leads to obtain polymers having a higher thermal stability. A lower Tg allows to have elastomeric polymers which can be used at lower temperatures and therefore to have available elastomers with a wider use range.W. NavarriniNavarrini, WALTER MAURIZI

“Bis(fluoroxy)difluoromethane CF2(OF)2: a useful reagent in the preparation of new perfluorovinylether monomers.”

14th European Symposium on Fluorine Chemistry, Poland (2004)