The Preparation Of New Type Of Mo Catalysts For The Purification Of Dye Wastewater Performance

This thesis mainly contains two important parts: one is the Na0.5Ce0.5MoO4/MoS2 core-shell structure on properties of mixed dye wastewater in the process of adsorption; the second part is the study on photocatalytic performance of Na0.5Ce0.5MoO4/MoO3 heterojunction for the degradation of wasterwater under visible light irradiation.(1) In this work,the Na0.5Ce0.5MoO4/MoS2 core-shell structure has been synthesized via one-pot hydrothermal method for the first time. It is found that 20%Na0.5Ce0.5MoO4/MoS2 has a significantly improved adsorption capacity for rhodamine B (RhB), but a poor adsorption capacity for MO dye. The measured surface Zeta potential of Na0.5Ce0.5MoO4/MoS2 demonstrates that this difference is mainly resultant from the different electrostatic interactions between Na0.5Ce0.5MoO4/MoS2 and dye molecule. Moreover, the RhB-MO dye mixture is prepared to simulate multi-component wastewater, and we have mainly investigated the adsorption property of RhB-MO dye mixture over 20% Na0.5Ce0.5MoO4/MoS2. It is amazing that over 20% Na0.5Ce0.5MoO4/MoS2, the adsorption equilibrium of RhB can be reached after only 10 min in RhB-MO mixture dye solution; whereas in single RhB dye solution, the adsorption equilibrium can be reached after 180 min. In the RhB-MO solution,the adsorption efficiency of RhB over 20% Na0.5Ce0.5MoO4/MoS2 is 2 times higher than that in the single-component RhB solution,demonstrating that the adsorption of RhB has been greatly promoted by the presence of MO. Besides, we have also investigated the effect of inorganic ion on the adsorption of RhB-MO mixture dye. It is found that the Cr (VI) ion (lOppm) added has significantly decreased the adsorption capacity of RhB; meanwhile, K+ added in RhB-MO mixture dye can slightly promote MO adsorption. The results have been mainly attributed to the interaction among these adsorbates. These findings can help us to develop the efficient adsorption processes for practical wastewaters.(2) In this work,new visible light-responsive Na0.5Ce0.5MoO4/MoO3 is,for the first time,synthesized via a facile method. On one hand,Na0.5Ce0.5MoO4/MoO3 shows greatly improved visible light absorption ability due to the excellent visible light absorbing ability of Na0.5Ce0.5MoO4. Due to a high electrical conductivity, on the other hand, Na0.5Ce0.5MoO4 has greatly promoted the charge transfer. Moreover,because of the matched energy band structures, an intimate heterojunction can form between Na0.5Ce0.5MoO4 and MoO3. Thus the interfacial electric field has significantly refrained the recombination rate of photogenerated carriers. As a result,Na0.5Ce0.5MoO4/MoO3 heterojunctions have greatly higher photocatalytic activities than MoO3 and Na0.5Ce0.5MoO4 for the photodegradation of RhB under visible light irradiation (?> 420 nm). Significantly, the degradation rate of 10%Na0.5Ce0.5MoO4/MoO3 is almost 7 times higher than that of pure MoO3 for the photodegradation of RhB. We could expect that Na0.5Ce0.5MoO4, as a new visible light absorbance and charge transfer medium, could be applied to prepare the other excellent visible light-responsive composite photocatalysts.