MOF-based devices for detection and removal of environmental pollutants

Abstract This chapter is dedicated to devices for environmental applications using metal–organic frameworks (MOFs) as active sorbents. The discussion involves the current status and the progress in the fabrication of these devices and their performances toward different kinds of substrates, in gaseous or vapor form, or dissolved in aqueous solutions. Two areas are discussed, the first regards the sensing of chemical species, the second deals with their removal . Section 12.2 classifies the different methods used for analyte detection and quantification in MOF-based sensing devices, in particular focusing on variations of: mechanochemical properties , with emphasis on quartz crystal microbalances and surface acoustic wave systems; optical properties , such as adsorption, fluorescence, and refractive index; electrochemical properties , like conductivity and impedance. Section 12.3 presents several examples of sensing devices, with MOFs as the sensitive matrix, for the detection of three common categories of pollutants: gases, such as carbon dioxide, nitric oxides, and hydrogen sulfide; volatile organic compounds; organic and inorganic species dissolved in water. Section 12.4 examines removal devices. Three major types of systems are discussed: preconcentrators for solid-phase extraction, filtration devices using MOFs as active sorbents, and fluidic devices able to work in a continuous way. In most cases, the devices are used for the decontamination of gaseous mixtures, the sequestration of organic or inorganic pollutants from aquatic sources, or their extraction from liquid and solid substrates, with examples of real case studies. The chapter shows that this field of research, although still in development, is nevertheless providing interesting ideas and useful knowledge in the fabrication of systems suitable for environmental applications.