Efficient Naphthalene Degradation in Fes2-Activated Nano Calcium Peroxide System: Performance and Mechanisms

FeS2 was applied as an activator and reductant in nano calcium peroxide (nCP) based Fenton-like system to degrade naphthalene (NAP). The results indicated that 96.9% of NAP was removed within 180 min at optimal dosages in the nCP/FeS2 system and the NAP degradation efficiency was influenced by the initial solution pH and dissolved oxygen (DO) concentration. nCP/FeS2 system could degrade NAP efficiently (> 96%) at a wide pH range of 3.0~9.0 which was ascribed to the pH buffer-like property of FeS2 . FeS2 reacted with Fe(III) to accelerate the Fe(II)/Fe(III) cycle and the oxygen-releasing property of nCP increased the applicability of nCP/FeS2 system in different DO concentration conditions. The X-ray photoelectron spectroscopy (XPS) spectra of FeS2 indicated the changes in the elemental valence and content of Fe and S on the FeS2 surface. HO• was demonstrated to be the dominant oxidizing species in the nCP/FeS2 system. In addition, the NAP degradation intermediates were analyzed to reveal the degradation process. The good performance of nCP/FeS2 system in different solution matrixes and actual groundwater strongly indicated that the potential applicability of nCP/FeS2 system in remediating NAP-contaminated groundwater. Finally, the efficient degradation of other pollutants demonstrated the broad-spectrum reactivity of nCP/FeS2 system.