| Traditional homogeneous Fenton oxidation system has a strict requirement of low pH, and produce large amounts of iron sludge. These shortcomings hinder Fenton technology the further application and development. Heterogeneous Fenton and heterogeneous photo-Fenton can overcome these shortcomings of homogeneous Fenton, therefore they were attentioned by researchers.In this paper, we prepared catalyst LiFe(WO4)2 by solid-mixed method, and investigated heterogeneous Fenton and heterogeneous photo-Fenton that LiFe(WO4)2 catalyzed, then took the dynamic analysis. The final results of our study could provide theoretical and operational guidance for turning experiment to practical applications.We established heterogeneous Fenton reaction system. For heterogeneous Fenton formed of catalyst and H2O2, decolorization rate of methylene blue was 97.8% at 120min, and it was higher than the two simple sum of only the catalyst and only hydrogen peroxide. Through experimental study, the best catalyst preparation conditions were as follows: sintering temperature was 700℃, the sintering time was 7h. We investigated the influencing factors in the heterogeneous Fenton reaction, the results showed that when the catalyst dosage was 10g/L, the amount of hydrogen peroxide used was 200 mM, the initial pH was 3, the reaction temperature was 50℃, the decolorization of methylene blue was the best, the reaction decolorization rate reached 99.9% at 120min. Investigation results about pH showed that pH range of reaction was expanded. UV-Vis spectra and IR spectra showed that methylene blue is degraded in the reaction. Free radical inhibitors inhibitted the heterogeneous Fenton reaction, indicating that free radical theory was reasonable.We established heterogeneous photo-Fenton reaction system, and the results showed that there was synergy among UV,catalyst and hydrogen peroxide. We researched the factors that affectted heterogeneous photo-Fenton reaction. The results showed that when the catalyst dosage was 1g/L, the amount of hydrogen peroxide was 10mM, the initial pH was 5, the light intensity was 0.5mw/cm2, the initial concentration of methylene blue was 100ppm, decolorization rate of the reaction reached 93.3% at 60min. Investigation results about pH showed that pH range of reaction was expanded. In each repeated run, heterogeneous Fenton ran 120min, heterogeneous photo- Fenton ran 60min, decolorization rate could reach more than 90%, indicating the catalyst was still active in the reaction process. And the dissolution of iron was only below 0.7% of total iron, showing the catalyst had good stability during the reaction, and the reaction would not produce large amounts of iron sludge.We established dynamic model of heterogeneous Fenton and heterogeneous photo-Fenton affected by catalyst amount and the amount of hydrogen peroxide. The results showed that heterogeneous Fenton and heterogeneous photo-Fenton reaction rate increased positively with increasing catalyst light dosage and hydrogen peroxide, and the amount of catalyst had greater impact on the reaction rate. |
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