Improved materials for environmental application: Surfactant-modified zeolites

The surface properties of zeolites A, X, Y and natural zeolite clinoptilolite (CLI) functionalized by cationic surfactants were investigated. The quaternary ammonium type surfactants, such as hexadecyltrimethylammonium (HDTMA) chloride, stearildimethylbenzylammonium (SDMBA) chloride and distearildimethylammonium (DSDMA) chloride, replaced inorganic cations like Na+ and Ca2+ on the external surface of zeolites. The adsorption capacities of all organic cations followed the order of CLI > CaY > CaX > CaA > NaY > NaX > NaA and increased with the increase of Si/Al molar ratio in zeolite structure. This modification resulted in an alteration in the surface property of zeolites - it changed from hydrophilic to hydrophobic. The adsorption of selected pesticides with different hydrophobicity on surfactant-modified zeolites was studied. It is shown that surfactant-modified zeolites can be used for removal of pesticides from the environment. The increase in hydrophobicity of pesticides resulted in an increase in pesticide adsorption on SDMBA and DSDMA modified zeolites.