We report the preparation of centimeter‐scale composite membranes formed by monolayer or bilayer graphene and polydimethylsiloxane (PDMS). Graphene was synthesized on copper foils by chemical vapor deposition (CVD), and two methods for transferring the graphene layers from the Cu to the PDMS were tested. The method based on the use of poly(methyl methacrylate) as a sacrificial support layer was more effective in producing membranes with significant gas‐barrier properties, in which the gas permeability values for CO2 and N2 were reduced by up to 30% as compared to blank PDMS membranes. Raman spectroscopy maps and atomic force microscopy revealed that, on the microscopic scale, graphene is preserved upon transfer, but the presence of extended defects such as folds and tears still limits further increases in the composite barrier properties. The deleterious effect of such defects is reduced by using more than one graphene layer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45521.

This study investigated the behaviour of two intermittently fed vertical flow constructed wetlands (one planted with Tifton 85 and the other unplanted) working in parallel, treating raw municipal sewage in Brazil for a population equivalent around 100 inhabitants. Based on a monitoring programme of over 2 years, the following items were evaluated: influence of batch frequency and the presence of Tifton 85 on the wetlands performance in terms of several physico-chemical and biological constituents. The unit with plants performed better than the one without, indicating a positive influence of the presence of plants. More attachment by total and volatile solids and larger amount of bacteria involved in the nitrogen cycle were observed in the planted filter medium, which can explain its higher nitrification and solids removal. The application of a smaller influent volume with a higher batch frequency improved the performance of both units. No signs of medium clogging have been observed in both units. The system simplicity and the good removal efficiency of organic matter, suspended solids, ammonia and helminth eggs indicate its high applicability in small communities in developing countries such as Brazil.

Some sub-products from the industrial activity are rich in metals, very often being highly toxic to human health and to the environment. Thus, the development of real-time and ultrasensitive techniques for metals detection is relevant. Herein, we report an ion-sensitive field-effect transistor (ISFET) based on l-phenylalanine functionalized graphene that detects Na+, Co2+, and Al3+ at the nanomolar range and Cu2+ at the picomolar range. Our sensor is prepared using a simple functionalization method and is reusable after a standard HCl cleaning process. Altogether, the ISFET is a promising device for real-time detection of metal ions at low concentrations.

Uma das principais aplicações da microfiltração é a clarificação e concentração de sucos de fruta. O objetivo deste trabalho foi estudar a clarificação do suco de melancia usando membranas comerciais de acetato de celulose 0,45 μm. Para avaliar a eficiência do processo, foram determinadas as resistências à transferência de massa e as propriedades do suco. A permeabilidade hidraúlica da membrana foi de 1,5x10-3 m/sPa para a água e de 2,2x10-4 m/sPa para o suco. O permeado foi submetido a análises de cor, transparência, turbidez, pH, densidade, viscosidade, sólidos solúveis totais e acidez. O fluxo permeado do suco variou de 61 a 21 L/m2h durante o experimento. Esta redução esteve associada ao aumento das resistências com o tempo. A resistência da membrana assumiu valores da ordem de 1x106 m2/kg, enquanto a resistência devido a efeitos de polarização de concentração e a formação da torta assumiu valores uma ordem de grandeza maiores. Não houve resistência irreversível detectável.

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