Preparation Of MnO₂/carbon Matrix Composite Electrode And Study On Electrocatalytic Degradation Of Phenol

Phenol is a typical representative of refractory organic pollutants.Due to its strong toxicity and disbiodegradability,phenol will have serious effects on water body.Electrocatalytic oxidation is a kind of environment-friendly advanced oxidation process and gets more and more attention of researchers in recent years because of its high efficiency,easy to manage,no secondary pollution,etc.Electrode materials play a pivotal role in electrocatalytic oxidation and exploitation of high active,low cost and reusable electrode is the key of electrocatalytic water treatment processes.MnO2/Carbon matrix composite electrode materials were prepared with cheap graphite materials.MnO2-PVA/GB and MnO2-CMC/GP electrodes were prepared by coating method,and MnO2/GP electrode by electrodeposition.The morphology,topography and electrocatalytic properties of the electrodes were characterized by FT-IR,XRD,SEM,cyclic voltammetry,Tafel curve and polarization curve.FT-IR showed that the structure of Mn-OH was found in all three electrodes,which was beneficial to the rapid generation of high price manganese oxide(Mn Ox+1).XRD showed that the MnO2 in coated electrode is orthorhombic and ? type,and the MnO2 in electrodeposition electrode is amorphous.The SEM of MnO2-PVA/GB electrode showed a small number of MnO2 exposed on the electrode surface,and MnO2 in MnO2-CMC/GP and MnO2/GP electrode are extensively distributed on the surface.By electrocatalytic characterization,the CV curve of MnO2/GP electrode has the highest potential of oxidation of phenol,which was 1.33 V.The Tafel curve shows that the MnO2/GP electrode was least prone to corrosion,and the corrosion rate of MnO2-CMC/GP electrode was the slowest.The polarization curve showed that the over potential for oxygen evolution of the MnO2/GP electrode was the highest,which was 1.89 V,and the performance of the MnO2/GP electrode was better than that of the other two electrodes.The performance of the three kinds of MnO2/graphite electrodes on electrocatalytic oxidation of phenol was investigated.Process conditions include MnO2 content,temperature,p H,current density,concentration of electrolyte,concentration of phenol,etc.were compared to investigate the effects of operation conditions on the phenol degradation rate.The experimental results showed that the 3 h phenol degradation rate on MnO2-PVA/GB,MnO2-CMC/GP and MnO2/GP electrodes was 82.5%,97.4% and 97.3%,respectively.Isopropyl alcohol(IPA)of 3 m L reduced the degradation rate of phenol by 50% to 75%,indicating it's hydroxyl radical(·OH)that achieving the oxidation of phenol.Under the optimal conditions,the coulomb efficiency of electrocatalytic oxidation of phenol on MnO2-PVA/GB,MnO2-CMC/GP and MnO2/GP electrodes was 5.58%,7.80% and 7.83%,respectively.Electrocatalytic oxidation of phenol on the three electrodes conforms to the first order kinetic model,and the rate constant k is 1.036×10-2,2.015×10-2 and 2.090×10-2 min-1,respectively.Cheap and efficient electrocatalytic oxidation electrodes were studied and prepared for fast degradation of phenol pollutants.This study will provide reference for industrial application of electrocatalytic oxidation water treatment process.