Degradation Of Phenol By Bicarbonate-Activated Hydrogen Peroxide With Supported Cobalt Catalysts

Bicarbonate is a common and nontoxic anion in natural water, and can react withhydrogen peroxide to generate peroxymonocarbonate ion （HCO₄^-）, which has a standardreduction potential1.8V （vs NHE）. The decomposition of HCO₄^-can further generateother active oxygen species in situ such as¹O₂·-and O₂^·-by itself or catalyst. So it has beenapplied to the oxidation of organic compounds, such as aliphatic amine, thioether,cysteine and related thiols, methionine, as well as epoxidation of olefins, chemicalwarfare agent decontamination. It has also been applied to the degradation of organicpollutants in wastewater including organic dyes, such as methyl blue, methyl orange,rhodamine B, chlorophenol and so on.The catalysts Co/Support（Support=SiO₂、 TiO₂、 γ-Al₂O₃） and Co/M/γ-Al₂O₃（M=Mg、Zn） in this paper are prepared by wet impregnation method according to thetheory of spontaneous monolayer dispersion. This paper is mainly about the degradationof phenol in objective reaction solution Ⅰ—2and comparative reaction solutionⅡ—2,and catalyst leaching. The conversion of phenol in objective reaction solution Ⅰ—2is10%higher than comparative reaction solutionⅡ—2. This result indicates that addingsodium bicarbonate could promote the degradation of phenol in heterogeneous fentonsystem. To the catalysts Co/Support （Support=SiO₂、TiO₂、γ-Al₂O₃）, the catalytic activitysequence in objective reaction solution Ⅰ—2is Co/γ-Al₂O₃> Co/TiO₂> Co/SiO₂, the bestresult of the conversion of phenol is70%. To the modified catalysts Co/M/γ-Al₂O₃（M=Mg、Zn）, the catalytic activity sequence in objective reaction solution Ⅰ—2isCo/γ-Al₂O₃≈Co/Zn/γ-Al₂O₃> Co/Mg/γ-Al₂O₃, the best result of the conversion ofphenol is70%. After the catalysis reaction goes for5hours between catalysts andobjective reaction solution Ⅰ—2or comparative reaction solutionⅡ—2at45℃,the cobaltleaching of all catalysts is lower than1ppm, the leaching sequence is1ppm>Co/γ-Al₂O₃> Co/SiO₂> Co/TiO₂> Co/Mg/γ-Al₂O₃≈Co/Zn/γ-Al₂O₃≈0.05ppm. This result shows thatthe cobalt leaching of the catalyst is reduced by modification of catalyst.