Comparative study on degradation of p-nitrophenol from aqueous solution by catalytic wet peroxide oxidation using pillared bentonite clay catalysts

In order to enhance depuration of organic persistent pollutants from wastewater, the effect of metal loading in pillared clays on the catalytic degradation performance was studied. A local bentonite clay was treated with Al and Cu solutions with different metal loading percentage and the resulting pillared clays were used in the catalytic wet peroxide oxidation of 4-nitrophenol (4-NP). The catalysts were characterized with X-ray diffraction (XRD) analysis, Fourier-transform infrared spectroscopy and inductively coupled plasma atomic emission spectroscopy. Tests were carried out in a batch reactor, following along time the 4-NP degradation. A detailed parametric study was conducted, changing only one experimental variable at a time, while keeping the others constant. The experimental parameters investigated in this work were temperature, catalyst dose, and initial concentration of H2O2 or 4-NP. The optimum conditions were found to be 3 g L-1 catalyst, 10 mM H2O2, 50 degrees C T and 50 mg L-1 4-NP, under which more than 90% of 4-NP, 70% COD and 50% TOC were experimentally removed after 4 h of reaction.