The Construction Of Transition Bimetal Oxide Nanocatalysts And The Study Of Microwave-Fenton Performance

Environmental pollution caused by persistent organic matter has caused widespread concern.Microwave-assisted heterogeneous Fenton reaction is a fast and effective method for removing organic pollutants.However,this method still has the disadvantages of low catalyst utilization efficiency and poor recycling performance.In this paper,bimetal nanocatalytic has been constructed in order to overcome these problems.The specific research content is as follows:1.The pine needle-shaped CuCo₂O₄was prepared"for the first time"using the hydrothermal method,and scanning electron microscopy,transmission electron microscopy and X-ray diffractometer were applied to characterize the structure and morphology of the material.The degradation property of antibiotics organic pollutants metatracycline by the prepared catalyst was investigated in microwave-Fenton reaction.The optimized degradation conditions are:500?L H₂O₂,10.0 mg catalyst,50 mg/L metatetracycline,and 90°C reaction temperature.Related kinetic studies show that the activation energy of the microwave Fenton reaction is 17.3 k J/mol,which is much lower than the corresponding heterogeneous Fenton reaction?52.2k J/mol?.Based on the synergistic effect between Cu?II?/Cu?I?and Co?III?/Co?II?,the reaction rate constant of CuCo₂O₄nanoneedle(7.2×10^-1min^-1)was much higher than that of Cu O(1.3×10^-1min^-1),Co₃O₄(2.2×10^-1min^-1)and mixed Cu O/Co₃O₄(1.5×10^-1min^-1).The constructed CuCo₂O₄nanometer needle has high recyclability,and the degradation efficiency remains at 86.4%after 5 cycles.The main active species in the system were studied by electron paramagnetic resonance technique and free radical capture method,and the results showed that·OH played a major role in the degradation process.The possible degradation pathways of metatetracycline were studied by high performance liquid chromatography-mass spectrometry.The results showed that the pollutants were finally degraded to water and carbon after hydroxylation,dealkylation,dehydroxylation,and ring-opening reactions.2.Copper ferrite/reduced graphene oxide aerogel was prepared by a"one-step"hydrothermal method.By characterizing its morphology and structure,it was found that the catalyst presented a composite nanostructure formed by the porous copper ferrite cube loaded on the graphene sheet.It was then used in microwave Fenton to degrade dye organic pollutants in water.Under the optimal conditions?500 W microwave power,600?L H₂O₂,15 mg catalyst,30 mg/L rhodamine B?,the degradation efficiency of the copper ferrite/reduced graphene oxide aerogel is higher than the reference value.The results of thermodynamic studies show that the changes in activation energy,enthalpy change,entropy change,and Gibbs free energy are 0.73k J/mol,-49.5 k J/mol,-0.135 k J/mol·K,and-6.8 k J/mol,respectively.Free radical capture experiments show that·OH,·O₂^-and h⁺all play an important role in the degradation of Rhodamine B.In addition to its high catalytic activity,the copper ferrite/reduced graphene oxide aerogel also exhibits good reusability,with a removal efficiency of 87.4%after 5 cycles.Copper ferrite/reduced graphene oxide aerogel was served as a promising catalyst for wastewater treatment due to its high efficiency,good reusability and simple preparation process.3.A two-dimensional?2D?porous NiCo₂O₄nanosheet was prepared using a sponge as a template.The NiCo₂O₄nanosheet prepared by this method has a higher specific surface area,which is 4.0 times than that of the NiCo₂O₄aggregate prepared without using a sponge as a template.Controlled experiments have shown that the hydrophilic surface and restricted growth of the sponge are critical to shaping the flaky morphology.By controlling the time of the synthesis experiment and the structure and morphology of the step-by-step experiment,we speculated the synthesis mechanism using the template.The catalyst was used in the microwave-Fenton performance test.According to the response surface method,the optimal conditions of the system were optimized:10 mg catalyst,10 mg peroxymonosulfate,300 W microwave power,and 70°C reaction temperature.Under this condition,the degradation rate constant of the pollutants is as high as 0.45 min^-1,which is about 2.0times than that of the NiCo₂O₄aggregates.The results of free radical capture experiment and electron paramagnetic resonance research show that sulfate radical is the main active substance.At the same time,the constructed two-dimensional porous NiCo₂O₄nanometer has good reusability and stability.The leaching of Co³⁺in NiCo₂O₄is only one-third of Co₃O₄,and it can maintain 81.7%degradation even after5 consecutive cycles effectiveness.