| Treatment of nonbiodegradable toxic organic pollutants by green chemical process is a very active field in recent years. Some complexes mimicking the oxidative characteristics of iron-containing oxygenase enzymes can effectively employ environmentally friendly oxidants, such as H2O2 and O2, in the treatment of pollutants. These complexes attract more and more attention from chemists and show an attractive potential.In this paper, an efficient catalyst, iron(II)-tetra-(l,4-dithin)-porphyrazine, (abbreviated as FePz(dtn)4), is introduced for first time into an aqueous FePz(dtn)4-resin/O2 system to degrade organic pollutants. The emphasis was placed on the dark-degradation and the photodegradation kinetics, the photodegradation mechanism, the formation of active oxygen radicals and the degraded products. The research provides another approach and catalyst for the effective treatment of organic pollutants in wastewater. It also elucidates the photoreaction mechanism. This constitutes an important contribution to our understanding of reaction mechanism in biomimetic photochemistry. The main results are summarised as follow:(1) The resin to support the catalyst, on the one hand, interacts effectively with the catalyst, to increase the capacity of electron transference so as to improve the effect of the catalyst FePz(dtn)4; on the other hand, for its water absorption and hydrophilic property, making substrates gather around the catalyst, increasing their concentration and probabilities to contact with the catalyst, and promoting the catalyzed degradation of these substrates preferably. Repeatability and stability of the catalyst FePz(dtn)4 were tested in many manners. The catalyst FePz(dtn)4 is stable in the presence of the oxidant. It can be repeatedly used up to 5 cycle runs without loss in activity.(2) The catalyst FePz(dtn)4 is able to activate molecule oxygen as bio-mimetic oxygenase enzyme for oxidative degradation of toxic organic pollutants in aqueous solution. FePz(dtn)4-resin /O2 system shows an excellent oxygenation capability for organic pollutants without light and with light in an extended pH regions in aqueous solution. Rhodamine B (RhB), p-Nitrobenzoic acid (NBA) and p-Aminobenzoic acid (PABA) were taken as examples, we studied their oxidative reaction and degraded products in detail.The experiments indicate that Rhodamine B (RhB) was nearly 52% degraded in alkaline aqueous solution in 7 hours in dark reaction; were about 50%, 66% and 92% degraded, respectively, in acid, neutral and alkaline aqueous solution in 7 hours under visible light illumination (500W halogen lamp); and were all above 90% degraded in aqueous solution at different pH for 15 minutes under UV light illumination (500W mercury lamp). The rate constants of the degradation of Rhodamine (RhB) in FePz(dtn)4/resin/O2 system were measured to be ki,-ght ~2kdark, that is the rate for the light reaction two times than the one for the dark reaction.(3) The intermediates and products formed in the course of the photodegradation or the degradation without light were examined by CODo method and GC-MS. The spectra data of the degraded species demonstrate that the FePz(dtn)4 /Oa system can oxygenate and cleave the aromatic ring of the target molecules to form degraded small molecule species, such as fumaric acid, maleic acid and mineralized products at ambient temperature without and with light. For example, p-nitrobenzoic acid (NBA) was degraded by 85% after 7 hours in the dark reaction. The CODcr value of p-aminobenzoic acid (PABA) was reduced by 19% after 7 hours under visible light illumination.(4) EPR and other experimental results suggest that the oxygenating processes of Rhodamine B (RhB) and p-aminobenzoic acid (PABA) induced by visible light in the presence of FePz(dtn)4 involved formations of active intermediates HO , (V radicals, singlet oxygen '02 and EOa. The photoreaction processes mainly involve the photogeneration and reaction of strong oxidants HO radical and O2~ dominantly produced by the catalyst FePz(dtn)4 und...
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