Preparation Of MOF Derived Non-metallic Nitrogen Doped Carbon And Its Application In Catalytic Ozonation And Electrooxidation Systems

The characteristics of MOFs materials,such as high specific surface area,large porosity,and flexible and controllable structure and function,make them widely studied in catalysis,adsorption,and sensing,but there are still many challenges in practical applications.Currently,a large amount of research has been devoted to the development and application of low-cost MOFs,and the international chemical giant BSAF has achieved industrialized mass production and sales of some MOFs.Due to their high specific surface area,high porosity,and diverse active centers,MOFs have demonstrated excellent adsorption and separation capabilities in practical application scenarios such as water purification,gas separation,and volatile organic compounds（VOCs）adsorption.However,there are few literature reports on how to effectively treat waste MOFs adsorbents generated after adsorption saturation.According to previous literature research,MOFs can be used as self sacrificial templates to obtain derived carbon,nitrogen doped carbon,metal oxide/carbon hybrid materials through high-temperature calcination,which provides important enlightenment for further realizing the high value resource utilization of waste MOFs in this study.In this study,it is proposed to conduct pyrolysis of simulated waste MOF adsorbents to obtain derived nitrogen doped carbon materials,and further expand their application to the study of ozone catalytic oxidation and electrocatalytic oxidation systems for the treatment of organic wastewater,optimize experimental parameters,elaborate the internal mechanism,and evaluate the ability to treat actual wastewater,with a view to truly realizing the harmless and resourceful disposal and utilization of waste MOF adsorbents.The main research contents and conclusions are as follows:（1）Using the failed MOFs adsorbents saturated with tetracycline hydrochloride（TCH）as sacrificial templates,resource conversion was achieved in the laboratory stage to prepare metal free MOF derived nitrogen doped carbon materials（Dr-CN）.SEM,XRD,FTIR,XPS,Raman and other series of characterization analysis showed that the N element came from the saturated adsorption of TCH pollutants.The successful introduction of N element significantly affected the physical and chemical properties of Dr-CN.Graphite nitrogen was the main active site,and the number of surface hydroxyl and oxygen vacancies increased.These composition changes may have an impact on the improvement of the catalytic activity of Dr-CN materials.（2）A Dr-CN/O₃ system was constructed.When the O₃ concentration was 32 mg/L,the input rate was 50 m L/min,and the catalyst dosage was 0.1 g/L,the complete degradation of oxalic acid（OA）at 100 mg/L was achieved within 20 minutes.The degradation rate constant was 0.109±0.008 min^-1,and the mineralization rate reached 81.4%,both higher than the two commercially available activated carbon materials and metal free MOF derived carbon materials（Dr-C）,showing excellent catalytic activity.Research shows,·OH plays a key role in the removal and mineralization of OA.The yield of·OH of Dr-CN/O₃ is about 1.3 times higher than that of Dr-C/O₃;The Dr-CN/O₃ system exhibits good treatment potential for different types of actual organic wastewater.After 60 minutes of treatment,the treatment results for the selected three types of actual organic wastewater can reach the corresponding COD emission indicators,indicating that the Dr-CN/O₃ system has a certain application potential.（3）The mixed doping of Magnéli phase titanium suboxide（Ti₄O₇）and Dr-CN has successfully produced a Dr-CN/Ti₄O₇ composite electrode.Through electrode characterization analysis,the doping of Dr-CN reduces the interfacial transfer resistance of the electrode,increases the active area,but also reduces the oxygen evolution potential.The experimental results showed that at a current density of 10 m A/cm²,the degradation rate of0.5%Dr-CN/Ti₄O₇ composite electrode for tetracycline hydrochloride at 50 mg/L reached94.5%at 60 min,which was higher than that of pure Ti₄O₇ electrode（59.8%）and other doped Ti₄O₇ composite electrodes;Dr-CN doping significantly enhances the direct electron transfer ability of the electrode·OH production.（4）Doping with Dr-CN can reduce the service life of the electrode,but after cycling for20 times,the performance of the 0.5%Dr-CN/Ti₄O₇ composite electrode only decreases to a relatively low level（TCH removal rate decreased from 94.5%to 86.8%）.The industrial service life is about 14.8 years,and the energy consumption is lower than that of other doping ratios and pure Ti₄O₇ electrodes.At a current density of 20 m A/cm² and p H=3,it exhibits a good COD removal rate for actual organic wastewater.A small amount of（0.5%）Dr-CN doping can improve the oxidation ability of the electrode and reduce energy consumption,which has great potential in the application of advanced treatment of actual organic wastewater.This study provides a practical method for the treatment and reuse of discarded and ineffective MOFs adsorbents.The nitrogen doped carbon materials obtained exhibit excellent catalytic activity and potential application value in both ozone catalytic oxidation and electrocatalytic oxidation systems.