engleski

Phenol oxydation by PP-CWAO treatment with Cu/13X

Water pollution is characterized mainly by the volume of waste to be treated and by the nature, concentration and toxicity of pollutants that form it. These parameters are all factors that have to be taken into account when choosing the treatment method to use. WAO (Wet Air Oxidation) is a phenol oxidation treatment method based on oxidation with air or oxygen, and is conducted at elevated temperatures (373-573 K) and pressures (1 - 20 MPa). With addition of homogeneous or heterogeneous catalysts, WO processes can be carried out at lower pressures and temperatures. If these processes use hydrogen peroxide as oxidizing agent, the process is called CWPO (Catalytic Wet Peroxide Oxidation), in which treatment is carried out at atmospheric pressure and temperatures below 373 K. To take advantages of the CWPO & CWAO process, and maximize the effectiveness of treatment, in this work, mixture of both oxidants (oxygen and hydrogen peroxide) was used. Activity of synthesized and calcined Cu/13X catalyst was tested in the PP-CWAO (Peroxide Promoted Catalytic Wet Air Oxidation) reaction using batch reactor. The catalysts were characterized by different methods (XRD, AAS, BET surface area). The catalytic tests were carried out in a stainless steel Parr reactor in batch operation mode at the constant catalyst mass (0.1 g / 200 cm-3), different temperatures (333 - 353K) and air pressures (2 - 20 bar). The initial concentration of phenol was 0.01 mol dm-3 while the concentration of hydrogen peroxide varied from 0.01 mol dm-3 to 0.14 mol dm-3 . Based on the results it has been concluded that the PP-CWAO process leads to higher pollutant removal conversions than the CWAO and CWPO processes. The results were influenced by the Ph: H2O2 : air molar ratio. A synergistic effect was found when H2O2 is combined with air which leads to higher mineralization of the phenol. The stability measurements showed that thermal treatment stabilizes the Cu/13X catalyst from leaching.

Catalytic oxidation; CWAO; CWPO; PP-CWAO; phenol

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