Mixed Matrix Membranes Based on Fluoropolymers with and -Terphenyl Fragments for Gas Separation Applications.

Novel mixed matrix membranes (MMMs) based on fluoropolymers with - and -terphenyl fragments and NaX zeolites were prepared. The fluoropolymers were synthesized by a one-pot, room-temperature, metal-free superacid-catalyzed stoichiometric and nonstoichiometric step polymerization of 2,2,2-trifluoroacetophenone with two multiring aromatic nonactivated hydrocarbons (-terphenyl and -terphenyl). MMMs were characterized by scanning electron microscopy (SEM) and infrared (Fourier transform infrared (FTIR)) spectroscopy and used in gas permeability tests.

Linear, Single-Strand Heteroaromatic Polymers from Superacid-Catalyzed Step-Growth Polymerization of Ketones with Bisphenols.

Novel, linear, high-molecular-weight single-strand heteroaromatic polymers and copolymers containing 9-xanthene moieties in the backbone were synthesized by metal-free superacid-catalyzed stoichiometric and nonstoichiometric step-growth polymerizations of carbonyl compounds bearing electron-withdrawing substituents with bisphenols. The electrophilic aromatic substitution reactions of ketones with phenol fragments occur exclusively in -positions to the hydroxy phenol group and followed by highly efficient cyclodehydration reaction of hydroxyl-containing intermediates to give corresponding substituted 9-xanthene-2,7-diyl polymers. The polymerizations were performed at room temperature in the Brønsted superacid trifluoromethanesulfonic acid (CFSOH, TFSA) and in a mixture of TFSA with methylene chloride and nitrobenzene.

Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane.

A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180-200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0-1.3 dL/g).

Removal of high phenol concentrations with adapted activated sludge in suspended form and entrapped in calcium alginate /cross-linked poly(N-vinyl pyrrolidone) hydrogels.

The present work evaluates the aerobic removal of 0.25-2 g/L of phenol by adapted activated sludge in batch and continuous reactors, in suspended form and trapped in polymeric hydrogel beads of calcium alginate(1%) and cross-linked poly(N-vinyl pyrrolidone), x-PVP (4%). The mechanical and chemical resistance of the entrapping hydrogel was also evaluated in three different media: (I) rich in phosphate and ammonium ions; (II) using alternate P and N sources, and (III) without nutrients.

Physical characteristics of poly(vinyl alcohol) and calcium alginate hydrogels for the immobilization of activated sludge.

Hydrogels based on poly(vinyl alcohol), PVA, and calcium alginate were prepared by a freezing and thawing cycle process and characterized, in terms of the role of the polymer mixture percentage and the number of treatment cycles, on their weight swelling ratio, WSR, gel fraction, and activated sludge entrapment and immobilization. The results show that the morphology of these hydrogels is highly dependent on the PVA-Ca alginate ratio of 5 wt % total polymer content in the initial aqueous solution and that the number of entrapped microorganisms which survive the freezing-thawing procedure is independent of this ratio. For 80/20 PVA-Ca alginate hydrogels, results also show that for up to three freezing and thawing cycles, the WSR, which is in average 24, is not severely affected by the number of the cycles.