C. Algieri

Permeation properties of a thin silicalite-1 (MFI) membrane

Abstract A thin MFI zeolite membrane was synthesised on a porous α-Al 2 O 3 tubular support by in situ nucleation and secondary growth. Single gas permeances (CH 4 , H 2 , N 2 , CO, CO 2 ) were measured through the MFI membrane according to the pressure drop method, from room temperature to 280xa0°C, with pressure differences between 0.1 and 0.4xa0bar. The membrane combines high permeances (1.6–8.0xa0μmolxa0m −2 xa0s −1 xa0Pa −1 ) and also good separation properties (the H 2 /SF 6 permselectivity value is equal to 24 at room temperature). The membrane has been tested also in the pervaporation of an ethanol/water mixture, showing high fluxes (2.1xa0kgxa0m −2 xa0h −1 ) and low selectivity.

Bio-mimetic sensors based on molecularly imprinted membranes.

An important challenge for scientific research is the production of artificial systems able to mimic the recognition mechanisms occurring at the molecular level in living systems. A valid contribution in this direction resulted from the development of molecular imprinting. By means of this technology, selective molecular recognition sites are introduced in a polymer, thus conferring it bio-mimetic properties. The potential applications of these systems include affinity separations, medical diagnostics, drug delivery, catalysis, etc. Recently, bio-sensing systems using molecularly imprinted membranes, a special form of imprinted polymers, have received the attention of scientists in various fields. In these systems imprinted membranes are used as bio-mimetic recognition elements which are integrated with a transducer component. The direct and rapid determination of an interaction between the recognition element and the target analyte (template) was an encouraging factor for the development of such systems as alternatives to traditional bio-assay methods. Due to their high stability, sensitivity and specificity, bio-mimetic sensors-based membranes are used for environmental, food, and clinical uses. This review deals with the development of molecularly imprinted polymers and their different preparation methods. Referring to the last decades, the application of these membranes as bio-mimetic sensor devices will be also reported.

Tyrosinase immobilized on a hydrophobic membrane

Polyvinylidene fluoride (PVDF) membrane surfaces were ad hoc functionalized chemically to make them suitable for enzymatic immobilization. The process was performed by grafting the membrane surface with 1,4‐diaminobutane and subsequently by activating it with glutarhaldehyde. The chemico‐physical properties of the original PVDF membrane and of the modified membranes were studied by infrared spectroscopy, scanning electron microscopy, and static contact angle measurements. The activated membranes were used as a support for covalent immobilization of tyrosinase. The activity of free and immobilized enzyme was studied and compared. The experimental data showing the specific activity of the immobilized enzyme are similar to the value obtained with the free one. This means that the immobilization procedure did not alter the catalytic properties of the tyrosinase. In addition, the surface modification of the PVDF made it a promising material to use in enzyme or biomolecule immobilization processes.

Organic-template-free synthesis of nanosized NaY crystals induced by a FAU membrane

Zeolite NaY nanocrystals with uniform particle size distribution have been prepared with high yield in a short duration, organic-template-free, hydrothermal synthesis by using FAU membranes as structure directing agents.

Emerging Tools for Recognition and/or Removal of Dyes from Polluted Sites: Molecularly Imprinted Membranes

Dyes are used in different industries as textile, paper, food processing, cosmetic, leather tanning, rubber, printing and so on. These chemical substances have negative effect on the quality of the water and food, causing human diseases and environmental problems. In view of these aspects, colorant have attracted the interest of the scientists in developing efficient routes for their detection and/or removal from the polluted sites. Although traditional technologies used for removal of dyes are efficient, there is the necessity of developing innovative systems both more cheaply and of easy performance. In this scenario, the integration of the membrane science with the molecular imprinting technology is an alternative way that present many advantages such us the removal or detection of a specific dye or a class of dyes and cost reduction processes. In fact, exploiting the benefits of these two technologies it is possible to develop molecularly imprinted membranes able to recognize a dye of interest in specific mode. This potential is promising for combatting the illegal use of dyes in food, drinks and aquaculture as well as for their removal. The main positive aspects of the imprinted membranes are their chemical stability, reusability, as well as the resistance to the pH and temperature. In addition, their preparation requires short operation time and it is not expensive. All these properties have an encouraging impact in dealing with the problem of dyes contamination. This short review offers a description of the concept of molecular imprinting, starting from the approach of the synthesis of imprinted polymers until the description of the preparation of imprinted membranes. The application of imprinted polymers and membranes for the detection and/or removal of dyes from polluted sites will be also discussed.