Application of Nanofiltration to the Treatment of Acid mine Drainage Waters

This study investigated the separation of uranium and other elements in high concentrations from acid mine waters at Caldas Uranium Mining, in the southeast of Brazil, using nanofiltration membranes. Nanofiltrarion is widely used in water treatment due to the lower energy requirements and higher yields than reverse osmosis. Separation characteristics are dependent on both the molecular size and charge of the dissolved species in the feed solution as well as membrane properties. In this investigation the potential of nanofiltration to removed dissolved species like uranium from acid mine water drainage was measured. Two composite aromatic polyamide commercially membranes of FilmTec/Dow were tested and it found that uranium rejections of greater than 90% and also showed potential for the separation of aluminum and manganese

Stability of a nanofiltration membrane after contact with a low-level liquid radioactive waste

This study investigated the treatment of a liquid radioactive waste containing uranium (235U + 238U) using nanofiltration membranes. The membranes were immersed in the waste for 24-5000 h, and their transport properties were evaluated before and after the immersion. Surface of the membranes changed after immersion in the waste. The SW5000 h specimen lost its coating layer of polyvinyl alcohol, and its rejection of sulfate ions and uranium decreased by about 35% and 30%, respectively. After immersion in the waste, the polyamide selective layer of the membranes became less thermally stable than that before immersion

Preparação e caracterização de membranas poliméricas sulfonadas e avaliação do potencial de utilização como membranas ion-seletivas

Este trabalho visa a preparação e caracterização de membranas planas poliméricas de ultrafiltração com alta permeabilidade e seletividade a cátions para serem aplicadas no tratamento de rejeitos radioativos. Para obtenção de membranas de ultrafiltração é necessário obter características morfológicas específicas, tais como estrutura assimétrica e distribuição estreita de tamanho de poros na superfície. Estas características são determinadas pelas condições de preparação das membranas e para isto foi utilizado o método de inversão de fase por imersão/precipitação que permite obter membranas com características adequadas para cada aplicação. Para este estudo foram preparadas membranas de ultrafiltração a partir de soluções poliméricas contendo poli (éter-sulfona) (PES), polisulfona sulfonada (PSS) e polivinilpirrolidona (PVP) solubilizadas em N,N-dimetilacetamida. A polisulfona sulfonada foi adicionada à composição das membranas com o objetivo de conferir o caráter protônico às membranas. Neste trabalho os seguintes parâmetros foram investigados: presença ou não da PSS, tempo de exposição e composição do banho de imersão (água pura e soluções de N,N-dimetilacetamida/água). As membranas foram caracterizadas por Microscopia Eletrônica de Varredura (MEV) e experimentos de permeação. Para comparação foi utilizada membrana comercial de ultrafiltração à base de poli(éter-sulfona), 30 K, da Milipore

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved