Pollutant Speciation in Water and Related Environmental Treatment Issues

Abstract

Neutron scattering and complementary techniques are extremely useful in the investigation of pollutant speciation in water and aqueous environments, as is shown in this chapter for both heavy metal and organic contaminants. The use of neutron diffraction, in conjunction with isotopic substitution and difference analysis, makes it possible to study the local structure developed around ions and other species in solution and in the pore spaces of minerals such as natural clays. As illustrations, the first-order difference method is applied to the hydration of mercury in aqueous solution, and the second-order difference method is used to determine the solvation of lanthanides in clay minerals. The isotopic substitution of hydrogen for deuterium is a powerful method with which to study both the structure and the dynamics of, for example, organic pollutants. In many cases the combination of neutron and X-ray diffraction is necessary, as shown for the incorporation of arsenic into the structures of minerals such as gypsum and calcite. Finally, some general conclusions and perspectives regarding the application of neutron techniques in environmental issues are drawn.