Surface modification of zeolites for environmental applications

In recent years natural and surface-modified zeolites (SMZs) have been developed as potential materials for environmental applications. The surface modification with quaternary ammonium salts (i.e., surfactants), induces an inversion of the surface charge of the zeolites making them simultaneously cationic and anionic exchangers, but also adsorbents of organic molecules. In this chapter an overview of SMZ applications, obtained by interaction with cationic surfactants, is given alongside the methods used for their characterization. Different modified zeolites were tested for sorption of several anions (mainly arsenate and chromate), as well as benzene, toluene, ethylbenzene, and xylene and polycyclic aromatic hydrocarbons. Results show the good potential of SMZs in removing harmful elements and, thanks to their proven chemical and biological stability, pave the way for their possible industrial use for the simultaneous removal of toxic species from wastewater of several origins, as well as in the realization of more complex systems such as permeable barriers.