Environmental mineralization of caffeine micro-pollutant by Fe-MFI zeolites

Abstract

Environmentally emerging micro-pollutant, caffeine, was mineralized (i.e., full degradation) by the isomorphic incorporation of Fe into silicalite-1 (mordenite framework inverted (MFI) structure zeolite) through a microwave synthesis method. The Fe incorporation conferred mesopore formation that facilitated caffeine access and transport to the MFI zeolite structure. Increasing the Fe content favored the formation of Fe(O)₄ sites within the MFI structure. The catalytic activity for the degradation of caffeine increased as a function of Fe(O)₄ sites via a Fenton-like heterogeneous reaction, otherwise not attainable using Fe-free pure MFI zeolites. Caffeine degradation reached 96% (TOC based) for zeolites containing 2.33% of Fe.