| Iron-based compounds active H2O2/O2 process is so-called Fenton/Fenton-like reactions, which possess lot of advantages such as high catalytic efficiency, strong oxidation ability and non-toxicity. This is one of the most promising technologies for organic wastewater treatment. Fenton/Fenton-like reagents can activate H2O2/O2, which indicates that these processes possess potential applications for H2O2/O2 detection. Although the classic Fenton system is of high efficiency, it requires to operate at pH< 3.0 to prevent the precipitation of iron. Usually, a large excess of Fe2+/Fe3+ in traditional Fenton systems cannot be recycled, producing large amounts of iron sludge. To overcome these drawbacks, heterogeneous Fenton-like catalysts have been widely used to broaden the range of pH for applications. However, many of them do not show favorable catalytic activity. Thus, to develop high catalytic activity heterogeneous Fenton-like catalyst is a currently hot research field of environmental catalysis. The aim of this dissertation is to investigate the Fenton reagent, nano-BiFeO3 and EDTA modified nano-BiFeO3 heterogeneous Fenton-like catalyst for determination of H2O2 and removal of organic pollutants. The major contents are described as follows:(1) A spectrophotometric method for determination of H2O2 was developed with the aid of oxidation decolorization of methyl orange (MO) by using Fenton reaction. This new method is based on the formation of·OH radicals in Fenton reaction as the strongly oxidizing species to oxidize MO, and the extent of decolorization of MO solution is proportion to the concentration of H2O2. The major operational parameters include reaction time, solution pH, initial MO concentration, and initial Fe2+ concentration were further investigated. Under the optimized conditions, the linear range for H2O2 concentration was from 5.0×10-7 to 1.0×10-4 mol L-1 with a detection limit of 2.0×10-7 mol L-1. The proposed method has been applied for the determination of H2O2 in rainwater, and the results are in good agreement with the standard HRP-DPD method. F-test results indicate that there are no significant differences between the two methods.(2) A fluometric method for determination of dissolved oxygen based on the catalytic activation of oxygen by Fe2+ chelates was established. The mechanism of the O2 activation by Fe2+ chelates involves the formation of a complex between the Fe2+ chelates and O2, then an electron in 3d orbit of Fe2+ transfer to O2 and form O2-·species, which are further reacted under acid catalysis to produce H2O2, leading to the generation of·OH radicals. The·OH radicals react with coumarin to produce highly fluorescent product, 7-hydroxycoumarin. Furthermore, the fluorescence intensity of 7-hydroxycoumarin is proportion to the concentration of dissolved oxygen. The major operational parameters include ligands, reaction time, solution pH, initial coumarin concentration, and initial Fe2+ chelates concentration were further investigated. Under the optimized conditions, the linear range for dissolved oxygen concentration was from 0.96 to 9.22 mg L"1 with a detection limit of 0.35 mg L-1. The proposed method has been applied for determination of dissolved oxygen in East Lake and Han River samples, and the results are in good agreement with the standard iodometric method.(3) Nano-BiFeO3 as a heterogenous Fenton-like catalyst for the degradation kinetics of organic pollutants such as rhodamine B (RhB), methylene blue (MB) and phenol was investigated. Furthermore, a series of characterization tests were performed to investigate the total organic carbon (TOC) removal of pollutants, activation energy, catalyst lifetime and catalyst stability. Electron spin resonance spin-trapping (ESR) and flurosence probing techniques proved that·OH radicals were the main reactive species. Furthermore, a series of Density Functional Theory (DFT) calculations were conducted to preliminary study the mechanism of H2O2 activation.(4) A fluometric method for determination of H2O2 and glucose was established. This method was based on the catalytic activation of H2O2 by nano-BiFeO3 to produce·OH radicals, which in turn oxidize the weakly fluorescent benzoic acid (BA) to a strongly fluorescent hydroxylated benzoic acid product (OHBA), and the fluorescence intensity of OHBA is proportion to the concentration of H2O2. By coupling the oxidation of glucose catalyzed by glucose oxidase (GOx) with the BA oxidation catalyzed by nano-BiFeO3, a fluorometric method was further developed for quantitative analysis of glucose. The major operational parameters include reaction time, solution pH, initial BA concentration, and initial BiFeO3 concentration were further investigated. Under the optimized conditions, the linear range for H2O2 concentration was from 2.0×10-8 to 2.0×10-5 mol L-with a detection limit of 4.5×10-9 mol L-1, and for glucose concentration was from 1.0×10-6 to 1.0×10-4 mol L-1 with a detection limit of 5.0×10-7 mol L-1. The proposed method has been applied for determination of H2O2 in rainwater and glucose in human serum samples, and the results are in good agreement with the standard HRP-DPD method and the data provided by the glucometer.(5) The effect of chelating agents on nano-BiFeO3 catalytic activity of H2O2 was investigated. The results showed that EDTA and NTA modification can significantly improve the catalytic activity of nano-BiFeO3, nevertheless, decrease by using F" and C2O42-. ATR-FTIR and Zeta potential characterization resluts proved that the surface complexation exists between nano-BiFeO3 and ligands. ESR and flurosence probing techniques proveed that the surface complexation can enhance or inhibit the activation of H2O2 to generate·OH. The EDTA modification of BiFeO3-H2O2 system can be further used as a new practical technique for treating contaminated water.
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