Heterogeneous catalytic ozonation by amorphous copper silicate for degradation of p-chloronitrobenzene in water

An amorphous copper silicate catalyst was prepared using Cu(NO3)2 and Na2SiO3 & BULL;9H2O as precur-sors. Characterization of amorphous copper silicate was accomplished by several techniques, includ-ing X-ray diffraction, X-ray photoelectron spectroscopy analysis, scanning electron microscopy, transmission electron microscopy, thermogravimetry-differential thermal curves, Fourier-transform infrared spectroscopy, and nitrogen adsorption-desorption. The results of characterization showed that Cu-Si binary oxide and CuO were formed on the surface of amorphous copper silicate and contained abundant functional groups. The dosages of the catalyst, ozone, and humic acid affected the removal efficiency of p-chloronitrobenzene (p-CNB). A hydroxyl radical (& BULL;OH) scavenger exper-iment, electron spin resonance (ESR) analysis, and pH experiment demonstrated that & BULL;OH was the predominant reactive specie for p-CNB degradation. Catalytic reusability studies demonstrated that amorphous copper silicate maintained its catalytic activity and stability for five consecutive cycles.

Automated summary

An amorphous copper silicate catalyst was prepared and characterized, showing the formation of Cu-Si binary oxide and CuO on its surface with abundant functional groups. The efficiency of p-chloronitrobenzene (p-CNB) removal was affected by the dosage of catalyst, ozone, and humic acid. The dominant reactive species for p-CNB degradation was found to be hydroxyl radical (•OH) based on scavenger experiments, ESR analysis, and pH experiments. The catalyst exhibited good catalytic activity and stability for five consecutive cycles.