NOVEL CYCLIC PROCESS MEDIATED BY COPPER OXIDES ACTIVE IN THE DEGRADATION OF NITROPHENOLS - IMPLICATIONS FOR THE NATURAL CYCLE

Direct photolysis was not found to be effective in the degradation of nitrophenols Biological degradation is known to be slow (a few days) a nd not to proceed at all in the case of dinitropenols. These later com pounds are not biocompatible toward common biological degradation. Dif ferent copper oxides were used in the present study in thermal and lig ht-induced reactions to degrade a variety of nitrophenols in the prese nce of oxygen. The highest rate of degradation was observed with a lar ge surface area CuO aerogel (20 m(2)/g). The aim of this study was thr eefold: (1) to report the details of the reaction leading to nitrophen ols degradation by different copper oxides or Cu salts, (2) to use dio xygen as the oxidant instead of the more costly peroxides currently us ed, and (3) to explore the effect of the number and position of the su bstituent groups on the rate of degradation. The results obtained indi cate that up to 10 consecutive catalytical degradation cycles for 2-ni trophenol were successfully mediated by CuO aerogel under light. The o xidant used was air (O-2) at PH 2.5. The oxidation potential for the c ouple Cu+/Cu2+ in the CuO aerogel, was found to be different from the standard values reported in solution. Photodegradation of dinitropheno ls were observed via the CuO aerogel, but the mineralization was not c ompleted over 24 h. The degradation and photodegradation via the Cu ca talyst used led to partial mineralization of the substrate with the fo rmation of CO2, H-2 (relatively small amounts), nitrite, nitrate, ammo nia, and insoluble polymer.