| As a simple, green and low-cost waste water treatment technologies, Fento n and class Fenton Technology had aroused extensive attention in the field of water treatment. In our recent published works, the cobalt-bicarbonate system c an activate H2O2 and produce active free radicals to degrade many organic poll utants in the partial alkaline conditions. In order to overcome the defect of rec overy and toxicity of homogeneous cobalt ion, we utilize the bonding effects o f nitrogen-containing functional groups to load cobalt ions and develop three ki nds of active and stable cobalt-based catalysts. A series of methods, such as ca talytic characterization, catalytic activity, radicals determination, intermediate pro ducts analysis, stability of catalysts and reuse of catalysts, are used to analyze these features and some innovative conclusions are proposed.1) The cobalt-based catalyst of CoxOy-N/GAC is prepared through the pyr olysis method by using granular activated carbon as the carrier and phenanthrol ine as nitrogen source in nitrogen atmosphere. The cobalt-based catalyst mainly exist in metallic phase. But the cobalt which exposed to the air is easy oxidiz ed to form a CoO film. The catalyst has a good catalytic efficiency for the de gradation of Acid Orange 7 (AO7) and the degradation rate is 94.4% in 20 mi n. It also has great stability and The phenomenon of loss of cobalt is almost not found, which may be due to the presence of a strong interaction between t he cobalt and nitrogen. The HO radicals and o2·- ions were produced as the main reactive species. During oxidation, AO7 was attacked by the active specie s and then decomposed to and 1,2-naphthaquinone and p-phenolsulfonic acid. A ferwards, the 1,2-naphthaquinone was further attracted to hydroxylated or polyh ydroxylated derivatives, and finally to carboxylic acids by ring opening.2) the supported cobaltcatalysts of Cts-CoxOy were prepared at different te mperatures by using chitosan as carbon and nitrogen source, it was found thatt he catalytic activity of the catalyst which calcined at 900℃ is the best. The s pecific surface area of the catalyst is 104m2/g. Cobalt catalysts are mainly in t he presence of zero-valent cobalt, but the surface of cobalt is also easy to beo xidized into cobalt oxides. The stability of Cts-CoxOy catalyst is well and thed issolution rate of cobalt ions is only 0.13 mg/L after 20 min reaction. XPS an alysis showed that the interaction between cobalt and nitrogen plays an importa nt role in the stability of the catalyst.3) The cobalt-supported catalyst of Fe3O4@SiO2-NH2-Co is gained by usin g nano magnetic Fe3O4 as shells and coated by SiO2, then utilizing 3-aminopro pyl triethylene silane modified. The catalyst has excellent magnetic properties a nd is easy to be recovered and reused. The catalyst of Fe3O4@SiO2-NH2-Co al so has good catalytic activity. The degradation of 50 uM acid orange 7 can re ach 95% in 40 min under normal temperature. The catalyst also has good stab ility and the loss of cobalt ions is only 0.08mg/L in the reaction processes and the activity is still high during the three times reused. |
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