| Chlorophenols (CPs) are a kind of typical hardly-degradable organic pollutants. Its have strong bactericidal activity, biotoxicity, carcinogenicity, mutagenicity, and teratogen effect. In addition, CPs cause potential hazardous effects on human health and environment because of their high degree of bioaccumulation. Therefore, CPs listed as priority pollutants in many countries. Because of the high degree of biotoxicity and hardly degradable, CPs are hardly effectively degraded by physicochemical or biochemical techniques alone. Recently, Advanced Oxidation Technology (AOPs) has been highlighted in refractory organic wastewater treatment. AOPs has advantages of strong oxidation, rapid reaction, good selectivity, wide application and little secondary pollution etc. However, photocatalysis and Fenton technologies have been the most widely researched. This paper studied the technology of combining photocatalysis and Fenton (Heterogeneous UV-Fenton technology) for chlorophenol wastewater treatment. The theoretical basis and practical experience for the industrial application of technology were provided. Based on the adsorption phase reactor technology, nano-heterogeneouscatalysts were successfully prepared. The influence of various factors to the morphology and performance of products were gained. Then, catalysts were analyzed the characterized. Nano-heterogeneous Fe-Cu catalysts were composed of α- Fe2O3,γ- Fe2O3and CuO. The particle size of the catalysts was less than 10nm. Moreover, the results showed that the catalysts were uniform, good dispersion, stability, good photosensitivity and high catalytic activity. Si, Fe, Cu molecular weight ratio of catalysts was about 80.4:12:7.6.Multi-influent factors of 2,4-DCP degradation, such as pH value, H2O2 dosage, catalyst dosage, reaction time, and reaction temperature were investigated in the Heterogeneous UV-Fenton system. The results showed that the heterogeneous catalysts had good stability, high activity in the wide pH scale ranges, and kept in good catalytic ability after used repeatedly. As oxidant, a certain amount of H2O2 can increase system removal efficiency. On the other hand, as scavenger of ·OH, H2O2 overdose not only consumed generated-OH, also catalyze the decomposition of H2O2. Therefore, utilization of H2O2 was reduced, and the oxidation efficiency of system was decreased. In addition, temperature has less affected on the Heterogeneous UV-Fenton reaction, but high temperature would catalyze the decomposition of H2O2.Effects of heterogeneous UV-Fenton system, compared with homogenous Fenton system, treatment on phenol-containing wastewater in paper gray water were studied. The results showed both technologies can effectively decompose the refractory organics in wastewater. When dosage of H2O2 was 0.5Qth, the indexes of effluent could meet the requirements of the national emission standard (GB3544-2008). Heterogeneous catalysis, compared with homogeneous catalysis, can significantly broaden the applicable pH range and greatly reduce the amount of iron clay. Considered the organic pollutants characteristics and molecular weight in wastewater, paper compared the removal effects of organics treatment of these two processes. The homogeneous Fenton treatment effect of the organic pollutants with molecular weight higher than 10,000 was better, because of the function in coagulation. However, heterogeneous UV-Fenton reaction was equally effective at removing all kinds of organic material. The degradation rate of UV254 for both two processes was higher than the CODcr method. This indicated that these two processes were preferentially oxidized the substances which were absorbed in 254nm. After treatment, most hydrophobic substances in wastewater were converted to hydrophilic substances and high weight molecular degraded to small weight molecular.Investigated the removal of the 2,4-DCP and CODCr in different simulated wastewater systems, there was synergistic effect of UV- Fenton reaction and heterogeneous Fenton reaction, and the removal effect much better than connecting two processes directly. Research showed that generated ·OH maintained at a high level in the reaction, and the rate of formation followed zero-order kinetics equation (K.OH= 0.059). Organic acids were generated during the chemical reaction by measured pH values.2,4-DCP degradation pathways in the heterogeneous UV-Fenton reaction were obtained by analyzing the chlorine ions and other intermediate products measured by GC-MS and HPLC.According to the Free Radical theory, the dynamic models of H2O2 consumption and 2,4-DCP degradation were established by investigating the degradation of 2,4-DCP in heterogeneous UV-Fenton reaction. Then, the applicability of kinetic model was verified by using the actual experimental data. The results indicated that the experimental data agreed well with the kinetic model. Therefore, the Free Radical theory is the reaction mechanism of Heterogeneous UV-Fenton reaction for the kinetic model. In this paper, the dynamic models of H2O2 consumption and 2,4-DCP degradation were showed as follows:66.27×ln[H2O2]0/[H2O2]+([H2O2]0-[H2O2])=1.22t92×ln[2,4-DCP]0/[2,4-DCP]+2.12×([2,4-DCP]0-[2,4-DCP])=[H2O2]0-[H2O2]... |
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