Neutral solar photo-Fenton degradation of 4-nitrophenol on iron-enriched hybrid montmorillonite-alginate beads (Fe-MABs)

Abstract

Hybrid montmorillonite-alginate beads (MABs) were prepared by the ion-gelation method from alginate and montmorillonite clay suspension dropped in a calcium chloride solution. Similarly, iron-enriched beads (Fe-MABs) were prepared using iron-exchanged montmorillonite. All beads were characterized by atomic absorption and Fourier-transform infrared spectroscopy. The efficiency of Fe-MABs as catalysts for the solar photo-Fenton performed at initial pH = 7.0 was evaluated by varying the catalyst amount and hydrogen peroxide concentration, and monitoring the removal of 4-nitrophenol (4-NP) at initial concentration of 10 ppm. A kinetic analysis showed that the removal of 4-NP by Fe-MABs followed a pseudo first-order kinetics model (R2 = 0.966). High 4-NP removal (75%) was achieved with 25 Fe-MABs by using 150 ppm of hydrogen peroxide and 40 min of irradiation, while total 4-NP removal was obtained by using 500 ppm of hydrogen peroxide. Moreover, preliminary studies about beads’ recycling showed good removal efficiencies for the first three cycles.