Clay minerals: structure, chemistry and significance in contaminated environments and geological CO2 sequestration

Clay minerals belong to the phyllosilicate family of minerals, which are characterized by their layered structures composed of polymeric sheets of silica tetrahedra attached with octahedral sheets. Research on clay minerals has received considerable attention because of their natural prevalence, reactivity, low cost, nonhazardous nature in handling, etc. Clay minerals have been widely investigated for their significance in various environmental, industrial, and geological settings. In this review, we will discuss the four major groups of clay minerals (kandite, illite, smectite, and vermiculite) as well as some other minerals in this family. This chapter summarizes the types, structural chemistry, and characteristics of various clay minerals; describes their emerging role in the immobilization of hazardous heavy metals and organic contaminants; highlights their significance in natural and engineered environments to reduce and manage mobilization of toxic metals; and partially elucidates the role of clay minerals for the sequestration of carbon dioxide at geological carbon sequestration sites.