A novel Fe-containing clinoptilolite for wastewater remediation: degradation of azo-dyes acid orange 7 by H2O2 and ascorbic acid.

A novel 3 wt.% Fe-containing clinoptilolite catalyst was prepared starting from a natural zeolite followed by a ion-exchange synthesis. A Fe-containing ZSM-5 catalyst (commercial zeolite as support) was also prepared for comparison purpose. Both Fe-based catalysts, along with the unexchanged samples, were characterized by complementary techniques (e.g. X-ray powder diffraction (XRD), N2 physisorption at -196°C, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectrometry (EDS) microanalysis). Then, their possible application in wastewater remediation was tested with a solution of azo-dyes acid orange 7 (AO7), as target molecule for azo dyes. As a whole, remarkable results in the AO7 degradation were obtained with the Fe-clinoptilolite in the presence of both ascorbic acid (AA) and H₂O₂. Specifically, AO7 conversion of about 60% was observed over the Fe-clinoptilolite (reaction time = 60 min). Lower performances were achieved in the presence of Fe-ZSM-5 coupled with ascorbic acid and H₂O₂ (AO7 conversion ~ 40%, t = 60 min.), despite the significantly higher SSA of the commercial ZSM-5. Noteworthy, the beneficial role of the ascorbic acid coupled with H2O2 was observed for both Fe-containing catalysts, thus confirming the key role of both oxidant and reductant agents in Fenton-like processes. [ABSTRACT FROM AUTHOR]