Modified carbide-derived carbons used in the catalytic wet peroxide oxidation of oily wastewaters
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Modified carbide-derived carbon (CDC) materials, prepared
from TiC, were tested as catalysts in the decomposition of H2O2
and in the catalytic wet peroxide oxidation (CWPO) of
4-nitrophenol (4-NP), either in aqueous phase or in biphasic
medium. The reactive extraction of Ti from the metal carbide
(2 μm) was carried out to prepare the CDC materials, as
described elsewhere [1]. Briefly, 0.03 m s−1 Cl2 gas was used
(1.5 mol m−3 in He) as extraction agent during 5 h at 800, 1000
and 1200 ºC. Afterwards, H2 was used for 0.5 h at the extraction
temperature to remove residual chlorine, resulting in CDC-800,
CDC-1000 and CDC-1200 materials, respectively. Additionally,
CDC-800 was treated with a mixture of 98% H2SO4 and
30% w/v H2O2 (3:1) at room temperature for 3 h by two
methods: (1) wetting the material in the oxidative solution and
(2) oxidizing the material partially encapsulated with WAX
paraffin, resulting in CDC-800-Ox and CDC-800-Wax,
respectively. Firstly, the materials were tested in the
decomposition of H2O2 and, then, in the adsorption and CWPO
of 4-NP, adapting the experimental procedure described in
previous works [2-3] at the following operating conditions:
25-50 ºC, pH0 = 3.0, and concentrations of solid material, 4-NP
and H2O2 of 2.5 g/L, 5.0 g/L and 17.8 g/L, respectively.
Cyclohexane, c-C6 (O/W volume ratio = 1:5) was used to
simulate oily wastewater and study the influence of the oil phase
presence in the medium.
