| Heterogeneous Fenton-like catalysis, an environment friendly oxidation technology, hasbecome a research hotspot in the field of wastewater treatment for its significant advantagesand potential applications in the catalytic oxidation of organic compounds. In this research,iron molybdate (Fe2(MoO4)3) was prepared at various conditions and its catalytic performancewas also studied as a heterogeneous Fenton-like catalyst. The main contents are summarizedas follows:(1) Fe2(MoO4)3was prepared by solid state, precipitation and hydrothermal methodrespectively, and their catalytic activity was investigated in degradation of phthalic anhydride.The influence of preparation conditions of percipitation method on Fe2(MoO4)3structure andits catalytic properties was mainly studied. The results showed that the lower agingtemperature, the smaller particle size and the catalyst had the highest catalytic activity in30oC. The particle size decreased with the increasing of pH, and orthorhombic Fe2(MoO4)3particles obtained in acidic (pH=3) and neutral (pH=7) conditions, whereas monoclinicFe2(MoO4)3particles formed in weak acidic conditions, and monoclinic Fe2(MoO4)3had ahigher catalytic activity than orthorhombic structure; When iron or molybdenum content overthe stoichiometric ratio, the Fe2O3and MoO3appeared in the product, resulting the lowercatalytic activity. Calcination temperature and time could affect the particles size andcrystallinity, over the suitable calcination temperature and time, Fe2(MoO4)3particles wouldaggregate and sinter, which decreased the catalytic activity. In summary, the preparationcondition for Fe2(MoO4)3were determined as follows: aging temperature was30oC, pH valuewas6, n(Fe)/n(Mo)=1:1.5, calcination temperature was500oC, and calcination time was2h.(2) The influence of various factors on the removal efficiency of phthalic acid byFe2(MoO4)3/H2O2system and the degradation mechanism were investigated, in addition, thereusability of Fe2(MoO4)3catalyst was also been studied. The results showed that the effectiveutilization rate of H2O2was improved with the increasing phthalic acid initial concentration.Removal efficiency of phthalic acid were positively correlated with catalyst dose, H2O2concentration and reaction temperature, but an excess of H2O2could capture OH, resulting inH2O2utilization rate decreased. Initial pH had great influence on the decomposition of H2O2and the surface properties of Fe2(MoO4)3, strong acidic and neutral conditions were notconducive to the formation of OH. The mechanism of Fe2(MoO4)3/H2O2system could beattributed to the synergistic effect of Fe3+and MoO42-. Fe2(MoO4)3exhibited good catalyticactivity and stability after five recycle times.(3) Immobilized and Ni-doped modifing Fe2(MoO4)3catalysts were prepared by solidstate, precipitation and impregnation method. The results showed that the immobilization ofFe2(MoO4)3on kaolin and silica ash, respectively, had no damage to the Fe2(MoO4)3crystalstructures and surface functional groups, but could improve the catalytic activity and stabilityof Fe2(MoO4)3catalyst. The immobilization of Fe2(MoO4)3on honeycomb ceramic wasadvantageous to the recycling of the catalyst, and had little effect on the catalytic activity ofFe2(MoO4)3. Aluminate cement could inhibit the catalytic activity. Doping Ni might increase the activity of the catalyst, when Ni doping content was10%, the catalyst has the highestcatalytic activity.(4) The catalytic oxidation performance of Fe2(MoO4)3/H2O2system in handling sevenkinds of practical industrial wastewater was studied. The results showed that the catalyticoxidation performance of Fe2(MoO4)3/H2O2system was affected by the property andcomposition of wastewater, and had no direct relationship with initial chemical oxygendemand (COD).The COD removal of esterified wastewater, sebacic acid wastewater, soilrestoration solution, sucralose wastewater, erythromycin thiocyanate biochemical water andEthylmaltol biochemical water were28.8%,21.6%,50.8%,28.6%,10.4%,1.8%and41.0%,respectively. |
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