| Summary: | P, B and N-doped carbon blacks prepared with H3PO4, urea and H3BO3 were tested as catalysts in the wet peroxide oxidation of a concentrated 4-nitrophenol (4-NP) model solution (C4-NP=5 g·L−1). The highest catalytic activity was found for P-doped carbon black (complete removal of 4-NP after 4 h at 80 °C, Ccat=2.5 g·L−1, CH2O2 17.8 g·L = 1 and initial pH 3, whereas 44-19% removals were reached with the other catalysts). That was ascribed to the strongest acidity (pHPZC=3.5) and hydrophilic character of the catalyst. Initial pH affected the oxidation, allowing to increase strongly the conversion of 4-NP with the P-doped catalyst decreasing the initial pH from 4 to 2 (4-NP removal from 20% to 99% after 8 h of reaction time at 50 °C, Ccat=2.5 g·L−1 andCH2O2 17.8 g·L = 1). An autocatalytic-power-law kinetic model was developed to predict the observed induction period and the dependence on the pH of the 4-NP oxidation, H2O2 consumption and pH evolution (k4- NP=2.2·10−5M−2min−1, kH2O2 4.0·10 M ·min = 6 3 1 and k 5.1·10 M min H + = 3 0.23 1 at 80 °C).
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