Preparation And Catalytic Property Of Iron-containing Heterogeneous Fenton-like Catalysts

Fenton oxidation process can eliminate organic pollutants from wastewater rapidly and efficiently, but it still exists many questions, such as the strict reaction conditions, low mineralization rate, etc. In view of these weaknesses in the Fenton process, in this dissertation, we synthesized new type of catalysts, Fe^ⅢLysSiW and Wool-Fe/NH₂OH·HCl, for degradation of 4-chlorophenol（4-CP）, and also studied their mineralization ability and mechanism in neutral condition.New type of catalyst, Fe^ⅢLysSi W, was synthesized with FeCl3（Fe^Ⅲ）, lysine（Lys） and silicotungstic acid（SiW）, and its catalytic performance was evaluated with decomposing H₂O₂ to degenerate 4-CP at pH 6.5. The results showed that, Fe^ⅢLysSi W can degradation of 4-CP rapidly: 4-CP was totally disappeared within 15 min under irradiation and 40 min in the dark, separately, and the corresponding TOC removal were high to 98.8% and 71.3% within 3 h, respectively. After the reaction, the concentration of iron leaching was detected as 0.51 ppm under irradiation and 0.48 ppm in the dark, which both were lower than the European Union standard 2 ppm. The repeating tests showed that the catalyst still kept good stability and its catalytic performance was no significant decline.With wool as carrier, the catalysts of Wool-Fe/X（X represents for reagents that were used for modified wool） were synthesized with modifying wool, and their catalytic ability were tested with decomposing H₂O₂ to degenerate 4-CP at pH 6.5. The results showed that, different catalyst showed different catalytic capacity. The initiation time and degradable time of each catalyst under irradiation for 4-CP degradation were: Wool-Fe 120, 180 min;Wool-Fe/CH₂=CHCOOH 70, 130 min; Wool-Fe/NH₂OH·HCl 50, 110 min, respectively. And the corresponding TOC removals were 9.09%, 29.69%, 52.12%, separately. During the process, Wool-Fe/NH₂OH·HCl showed the best catalytic property and leaching the least iron amount, was 0.79 ppm. Since the catalysts leached iron in the treating processes, the catalysts showed worse recycle-ability.4-CP removal declined distinctly with the radical scavenger n-butanol added in both systems of 4-CP oxidation, this means that HO? is the main reactive species to remove 4-CP in the systems. Under irradiation, the relationship of synergetic between Fe^Ⅲ ? FeII and SiW12O404- ? SiW12O405- led to degradation of 4-CP in Fe^ⅢLysSiW/H₂O₂ system; In Wool-Fe/NH₂OH·HCl and H₂O₂ system, 4-CP was removed mainly owing to HO? producd by Fe^Ⅲ ? FeII redox cycle.Both of the two catalysts were used in dealing with wastewater and being compared with catalytic performance, the mineralization rate was also tested with different initial pH and H₂O₂ amount. The results showed that both Fe^ⅢLysSiW and Wool-Fe/NH₂OH·HCl displayed rather week performance at pH 6.5 and H₂O₂ 50 mmol/L, TOC efficiencies were 14.24% and 3.62% within 6 h, respectively, while exhibited comparatively good effects at pH 3.0, those were 43.49% and 18.73%, respectively. Preliminary experiments showed that, both kinds of catalyst in the degradation of sewage showed catalytic activity.