Molybdenum-based Composites Catalyzed Air Oxidation To Degrade Dye Wastewater At Room Temperature And Pressure

Wet catalytic oxidation（CWAO）technology is limited in the application process of organic wastewater degradation due to the demanding conditions of high temperature and high pressure.Therefore,this paper has successfully prepared the molybdenum/water-talc catalytic materials and Mo/graphene molybdenum based composites.By using the free radicals with strong oxidation properties generated in the process,the performance of the molybdenum based composites catalytic air oxidation degradation dye wastewater at room temperature and pressure was investigated.The research results are as follows:（1）.A novel-structured Mo-Cu-Fe-O composite was successfully prepared by co-precipitation and impregnation method.The properties of the as-prepared samples were determined using X-ray diffraction,temperature programmed reduction by H₂,cyclic voltammetry,and temperature programmed desorption by O₂.The results showed that Mo⁶⁺ diffused into the Cu-Fe-O crystal lattice and then formed a new crystalline phase of CuMoO₄.The Mo-Cu-Fe-O catalyst had redox properties,and its surface contained active sites for oxygen adsorption.In addition,the catalytic activity of the Mo-Cu-Fe-O composite was evaluated by the degradation of Cationic red GTL,Crystal Violet,and Acid Red in catalytic wet air oxidation（CWAO）at ambient temperature and pressure.The Mo-Cu-Fe-O catalyst showed excellent activity at basic conditions for the degradation of Cationic Red GTL.High removal efficiencies of 91.5%and 92.8% were achieved for Cationic red GTL and Crystal violet,respectively,in wastewater,and the efficiency remained high after seven cycles.However,almost no degradation of acid red occurred in the CWAO process.Furthermore,hydroxyl radicals were formed in the CWAO process,which induced the decomposition of the two cationic dyes in wastewater,and the toxicity of their effluents was decreased after degradation.The results indicate that the Mo-Cu-Fe-O composite shows excellent catalytic activity for the treatment of wastewater contaminated with cationic dyes.（2）.The graphene-like materials were prepared using the waste LDHs adsorbent as the carrier,the transition metal Mo as the active component,and the Mo/graphene-like composites were prepared by impregnation method.The optimal preparation conditions of catalysts for:the kind of graphene as a carrier,ammonium molybdate solution for pickling liquid,in the impregnation concentration is 2 mol/L,calcination temperature is 400℃,roasting time for 3 h.Under the optimal preparation conditions,the catalyst was synthesized by wet catalytic oxidation to degrade the rhodamine B dye wastewater of 20 mg/L,and the catalyst dosage was 0.25 g/L.After20 min of reaction,the dye decolorization rate reached 85.0%.By controlling different reaction conditions,this paper discussed the degradation effect of Mo/graphene composite materials on organic wastewater under different reaction conditions,studied the effect of dye concentration on treatment effect,the effect of catalyst dosage on treatment effect,and the effect of aeration on treatment effect.As the initial concentration of Rhodamine B increased,the decolorization rate decreased and the reaction rate decreased.With the increase of catalyst dosage,the decolorization rate of Rhodamine B increased.When the catalyst dosage was 0.25 g/L,the reaction rate reached its maximum.The aeration rate of Rhodamine B affected the catalytic oxidation effect of Rhodamine B to some extent.When the aeration rate was 13.5 L/min,the decolorization rate of Rhodamine B was the highest.Under acidic conditions,catalytic degradation is more favorable.Reaction temperature 45℃,the catalyst has high catalytic activity and reaction 30 min,dye decolorization rate can reach 85.5%.Under atmospheric pressure in the process of wet catalytic oxidation,the optimal processing conditions as follows:reaction temperature 45℃,the simulated dye wastewater pH value of 3,catalyst dosing quantity is 0.25 g/L,air is 13.5 L/min,under this condition,Rhodamine B decoloring rate reached 100%.