Concurrent destruction strategy: NaNO2-catalyzed, trichlorophenol-coupled degradation of p-nitrophenol using molecular oxygen

Oxidative degradation of p-nitrophenol (PNP) was investigated with NaNO2 as the catalyst and dioxygen as the oxidizing agent in the presence of trichlorophenol (TCP). Although degradation of PNP alone was proved to be inefficient toward the NaNO2-mediated oxidative degradation system, when PNP in combination with TCP was used as the substrate, NaNO2 showed relatively high catalytic activity for eradicating both PNP and TCP with molecular oxygen. Reaction conditions to the degradation system, e.g., temperatures, reaction time, pH, NaNO2 and TCP concentrations were optimized. PNP could be highly efficiently degraded in the NaNO2/TCP/O-2 system (more than 99% removal for PNP) and the TOC removal of the mixture of PNP and TCP could reach 71% at 150 degrees C, 0.5 MPa oxygen pressure. Degradation products were determined, and 93% carbon atom was clarified. A plausible overall mechanism for the formation of active species is described, in which peroxylnitrite was believed to be a dominating active intermediate being responsible for destroying the substrates, PNP and TCP. The novel NaNO2-based concurrent oxidation system for PNP and TCP provides a potential application in treatment of multi-component industrial effluents. (c) 2009 Elsevier Ltd. All rights reserved