Synthesis, Characterization Of Mo Series Heteropoly Salt With Keggin Structure And The Catalyzed Oxidation Property On Dye Wastewater

Dye wastewater is a typical industrial wastewater. Since dye wastewater is of dark chroma, large quantum, high organic concentration, complex component, strong toxicity, and biodegradability of poor, it is very difficult to treat it meet to the standards. So,to research and develop the highly efficient treatment method is one of the hotpot of the environmental engineer field at home and abroad. For dye wastewater treatment, the application foundation study of the catalyzed oxidation craft of the heteropoly salt is carried out in this thesis.As a kind of polynuclear inorganic macromolecule compound containing oxobridge, heteopoly acid is the oxygenic ployatomic acid that coordinated with center atom (P?Si?As?Ge etc) and coordinating atom (Mo?V?W etc). There are five species such as Keggin?Dawson?Anderson?Waugh and Silvertong in heteropoly acid assorting by structure of anions. Since the heteropoly acids have such unique cage structures that are similar with liquid phase, catalytic reaction can carry not only on the teeth outwards but also in the body and heteropoly acid have good catalyzed activity and selectivity. The heteropoly acid can be catalysted as acid catalysis and oxidization.The heteropoly salt, Na₅₍₆₎[X(ZrMo₁₁O₃₉)]·nH₂O(X=Fe, Ni, Ce, Mn or Zn)with Keggin structure of the 1:11series, were synthesized by the solution method. Firstly, the mole ratio of the main element of the heteropoly salt was analysed by the Inductively Coupled Plasma-Atmatic Emission Spectrometry(ICP-AES) ; Secondly, the thermostability was analysed by the thermogravimetric analysis/differential thermal analysis(TGA/DTA), and the number of the crystal water could be calculated; Thirdly, the structure was characterized by the fourier transform infrared spectroscopy (FT-IR)?X-ray diffraction(XRD) and ultraviolet spectrum(UV); At last, the crystal form was analysed by the scanning electron microscopy(SEM). The results from the experiment showed that the ratio of the X,Zr and Mo of these heteropoly salt was accorded with the 1:1:11; and had the highly thermostability and the numbers of the crystal water were 19,20,16,19 and 20 respectively; and they had the typical characterisitics of the Keggin structure the heteropoly salt ;and they all had the better crystal structure.The acidic-green B(AGB) was as the objective pollutant to prepare the simulate dye wastewater, and to degrade it with the synthesized heteropoly salt. The catalyzed oxidation degradation effects of the heteropoly salt for the AGB was studied under the condition of the ultraviolet, ultrasonic and the synergistic reaction of both.The benzene rings, naphthalene rings and azo-bond of the AGB were all the functional group which were difficult to degrade, and it was regard as the representative pollutant of the dye wastewater. The results from the experiment showed that :(1) Under the condition of the ultraviolet alone, the photocatalysis degradation rate of Na6[NiZrMo₁₁O₃₉]·20H₂O was reached to 92.64% and was better than others heteropoly salt. It was showed that Ni2+ heteropoly salt possessed good photocatalysis property;(2) Under the condition of ultrasonic alone, the degradation rate of Na₅[FeZrMo₁₁O₃₉]·19H₂O was up to 96.08% and was better than others . It was showed that Fe³⁺ exhibited good ultrasonic degradation characteristic; (3)Except the heteropoly salt Na₆[NiZrMo₁₁O₃₉]·20H₂O, the ultrasonic degradation rate of the four others heteropoly salt was better than their photocatalysis degradation rate;(4)For these five heteropoly salt, the degradation effect of Na₅[CeZrMo₁₁O₃₉]·16H₂O was the poorest because it was not honeycomb structure and Ce located in lanthanide elements;(5)For them, the degradation efficiency of the ultraviolet along with the ultrasonic to the AGB wastewater was obviously superior to the independent condition of them, but the synergistic effect was not very obviously.The study on the reaction kinetics characteristic of the heteropoly salt to degradation AGB dye wastewater was carried out in this thesis under the condition of the ultraviolet or ultrasonic. From the experiments, it was found that each reactor was in accord with the first order dynamics model under these two conditions. The correlation coefficient exceeded 0.99 and showed the better correlation.The reaction rate constant was decreased with the increasing of the concentration of the AGB.In general, the catalysis degradation efficiency of the heteropoly salt with the ultraviolet or with ultrasonic to the AGB dye wastewater was better than the general ultraviolet catalysis and ultrasonic catalysis. These showed that the synthesized heteropoly salt was provided with excellent catalyzed oxidation characteristic, and a kind of newly catalytic agent which could be used widely.