Preparation Of A Novel Supported Activated Carbon Particle Electrode And Its Degradation Mechanism Of P-aminophenol

P-aminophenol(PAP)is a very important fine chemical intermediate,which is mainly used in the pharmaceutical and dye industries.PAP wastewater has the characteristics,that is,the double toxicity of phenol and aniline,high biochemical degradation difficulty and complex intermediate products,making it a difficult problem in the field of water treatment.At present,there are relatively few research reports about PAP degradation at home and abroad.In this paper,a novel supported activated carbon particle electrode(Ti-Si-Sn-Sb/GAC)was prepared for the first time and applied to degrade PAP by three-dimensional electrocatalytic oxidation technology.The PAP removal rate and degradation mechanism were discussed in depth.The main research contents of this paper are as follows:Ti-Si-Sn-Sb/GAC particle electrode was prepared by a sol-gel method using granular activated carbon(GAC)as the matrix and Ti-Si-Sn-Sb oxide as the catalytic active component.And the preparation parameters of the particle electrode were optimized.The experimental results showed that when the molar ratio of Ti?Si?Sn and Sb was 1:1:0.01:0.001,the calcination temperature was 550 ? and the calcination time was 180 min,the Ti-Si-Sn-Sb/GAC particle electrode had the best electrocatalytic oxidation performance.Then,the surface morphology and crystal structure of GAC before and after loading were characterized by Scanning electron microscope(SEM)?X-ray diffractometer(XRD)?X-ray photoelectron spectrometer(XPS)and Brunauer-Emmett-Teller(BET),confirming that the Ti-Si-Sn-Sb/GAC particle electrode was successfully prepared.The PAP was degraded by three-dimensional electrocatalytic oxidation in which Ti-Si-Sn-Sb/GAC was used as particle electrode.These effects of operating parameters on the PAP removal rate were investigated.The experimental results showed that when the initial p H was 7.0?the cell voltage was 10.0 V ? the aeration flow rate was 50 L/h ? the initial concentration of PAP was 200 mg/L ?the concentration of electrolyte(Na2SO4)was 1.0 g/L?the plate spacing was 30 mm and the filling amount of Ti-Si-Sn-Sb/GAC particle electrode was 50%,the maximum removal rates of PAP and Chemical oxygen demand(COD)were 89.45% and 75.17%,respectively.Based on the experiments results,it was also found that the three-dimensional electrocatalytic oxidation system in which TiSi-Sn-Sb/GAC was used as particle electrode not only produced higher hydroxyl radical(·OH)yield,but also showed obvious advantages in catalytic activity.In addition,after 20 repeated experiments on Ti-Si-SnSb/GAC particle electrode,the removal rate of PAP decreased from 89.45% to 81.37%,and the removal rate of COD decreased from 75.17% to 70.10%,indicating that the Ti-Si-Sn-Sb/GAC particle electrode not only had high catalytic activity,but also had stable catalytic performance.The possible degradation pathway of PAP was analyzed by UVvisible spectrophotometer(UV-Vis)and High performance liquid chromatography(HPLC).Firstly,PAP was oxidized to benzenediol and then to benzoquinone.Next the benzoquinone was transformed into butenedioic acid and oxalic acid with the opening of the benzene ring.Finally,the carboxyl group was further oxidized and mineralized to CO2?H2O and so on.At the same time,the kinetic of PAP degradation process was fitted,and it was found that the degradation process was in accordance with first-order kinetics,which provided a solid theoretical basis for the three-dimensional electro-catalytic oxidation technology in industrial application.