| With the development of dye industry, the dye wastewater has become one of the important fields in the enrironmental problems. In order to make the dye wastewater have higher degradation and supply an effective treatment method, the Fenton reaction on the degradation of dye wastewater was studied. The Fenton reaction whicn can decompose most organics was an important advaced oxidation technology in water treatment. However, it still has many shortcomings. In order to improve the efficiency of Fenton reaction, improvement was studied on the degradation of malachite green and rhodamine B. The optimum condition and the mechanism of [Fe(Ⅲ)-salen]Cl complex Fenton reaction and the graphite tailing Fenton reaction were investigated.The different treatment on malachite green and rhodamine B was compared. The decolorization order of the methods was [Fe(Ⅲ)-salen]Cl complex Fenton reaction> Fe3+/H2O2system> H2O2alone>[Fe(Ⅲ)-salen]Cl complex alone.The optimum condition of malachite green degradation in [Fe(Ⅲ)-salen]Cl complex Fenton reaction was that:the concentration of the [Fe(Ⅲ)-salen]Cl complex was35μmol/L, the concentration of H2O2was10mmol/L, the molar ratio of Fe(Ⅲ) to salen ligand was1:10, the initial concentration of malachite green was100mg/L and the reaction temperature was20℃. The decolorization of malachite green under the optimum condition was97.95%. The optimum condition of rhodamine B degradation in [Fe(Ⅲ)-salen]Cl complex Fenton reaction was that:the concentration of the [Fe(Ⅲ)-salen]Cl complex was40μmol/L,the concentration of H2O2was15mmol/L, the molar ratio of Fe(Ⅲ) to salen ligand was1:10, the initial concentration of rhodamine B was100mg/L and the reaction temperature was20℃. The decolorization of rhodamine B under the optimum condition was97.95%.The pseudo-first order reaction kinetics in different treatment was compared and they all obeyed pseudo-first order equation. The hydroxyl radical and the Fe(Ⅳ) species were the active oxidation species. The TOC removal rate of malachite grren and rhodamine B in [Fe(Ⅲ)-salen]Cl complex Fenton reaction was54.35%and58.39%. According to the GC-MS analyse, the possible degradation intermediates of malachite green were dimethylform amide, glutaraldehyde,3-(hydroxymethyl) pentanedial,3-(diphenylmethylene) pentanedial,3-(hydroxydiphenylmethyl) pentanedial, formic acid and (2)-pent-2-enedioic acid. The possible degradation intermediates of rhodamine B were ethanediamine, glutaraldehyde,3-(hydroxymethyl) pentanedial,3-(diphenylmethylene) pentanedial,3-(hydroxydiphenylmethyl) pentanedial, formic acid and (2)-pent-2-enedioic acid. The pseudo-activated energy of malachite green and rhodamine B was calculated by the related kinetic constants.The GT used in this study was characterized by X-ray diffraction (XRD), Energy dispersive spectrometry (EDS) and Brunauer-Emmett-Teller (BET) method. The mesoporous structure of the GT made it as an absorbent and the encapsulated Fe2O3in GT was able to initiate the Fenton reaction.The decolorization in graphite taling Fenton-like reaction was much higher than in graphite tailing adsorption and the hydroxyl peroxide alone. The optimum condition of malachite green degradation in graphite taling Fenton-like reaction was that:the initial concentration of malachite green was100mg/L, the concentration of H2O2and graphite tailing was4g/L and5g/L. The decolorization of malachite green under the optimum condition was99.51%. The optimum condition of rhodamine B degradation in graphite taling Fenton-like reaction was that:the initial concentration of rhodamine B was100mg/L, the concentration of H2O2and graphite tailing was10g/L and50g/L. The decolorization of malachite green under the optimum condition was93.39%.According to the mechanism of degradation of malachite green and rhodamine B in graphite tailing Fenton-like process, the graphite has the adsoption and Fenton reaction. The reaction solution has the active oxidation speciey-hydroxyl radical. The TOC remevol rate of Malachite Green and Rhodamine B was60.38%and49.02%. The malachite green and rhodamine B molecules were not mineralized completely and they were oxidized to low melocule organics.After the degradation of malachite green and rhodamine B in the graphite tailing Fenton-like process, the iron ion leaching was detected. Depending on the results of Atomic Absorption Spectrophotometer, the concentration of the iron ions in malachite geen and rhodamine B solution was about0.2309mg/L and0.4824mg/L and the release of the iron ions from GT to the solution could be ignored. So it can be concluded that the Fenton oxidation process is mainly due to the heterogeneous effect of the catalyst and not to the leaching of iron ions.The leached iron ions in the solution can be discharged accodingto the standard of the watswater discharge in our country. The possible degradation process was that the encapsulated Fe2O3in GT was the Fenton reaction site of the catalyst. And the heterogeneous Fenton reaction process may be that the malachite green and rhodamine B molecules in the solution contacted with encapsulated Fe2O3in GT, were oxidized first by H2O2. With the movement of malachite green and rhodamine B molecules, other molecules touched the catalysis center again and they are degraded at the first.
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