Hydrogen adsorption in zeolites A, X, Y and RHO

We have investigated the use of zeolites as potential hydrogen storage materials. The zeolites A, X, Y and RHO, which encompass a range of different pore geometries and compositions, were synthesised by hydrothermal methods, and different cation-exchanged forms were prepared through ion-exchange from aqueous metal nitrate solutions. The phase composition and crystallinity of samples were interrogated by powder X-ray diffraction. Scanning electron microscopy revealed cubic crystals of zeolites both before and after ion-exchange. Hydrogen adsorption capacities were measured using a constant pressure Thermogravimetric Analyser; data were obtained over a range of pressures from 0 to 15 bar and isothermally at temperatures from -196 to 300 °C. The results showed that hydrogen uptake in zeolites is strongly dependent upon temperature, and also on framework and cation type. Surface area measurements were also carried out on these materials and the results used to interpret the hydrogen adsorption data. © 2003 Elsevier B.V. All rights reserved

Urban geochemistry: research strategies to assist risk assessment and remediation of brownfield sites in urban areas

Urban geochemical maps of Wolverhampton and Nottingham, based on multielement analysis of surface soils, have shown distribution patterns of “total” metals concentrations relating to past and present industrial and domestic land use and transport systems. Several methods have been used to estimate the solubility and potential bioavailability of metals, their mineral forms and potential risks to urban population groups. These include sequential chemical extraction, soil pore water extraction and analysis, mineralogical analysis by scanning electron microscopy, source apportionment by lead isotope analysis and the development of models to predict metal uptake by homegrown vegetables to provide an estimate of risk from metal consumption and exposure. The results from these research strategies have been integrated with a geographical information system (GIS) to provide data for future land-use planning