Research On Properties Of Lanthanum Oxide-doped Graphene/PTFE Electrode

Electrochemical technology for the organic wastewater pollution control was one of the focus researches for environmental workers. It has shown promising prospect for the destruction of containing biorefractory organic compounds due to its easy applicability, high efficiency, and environmental compatibility. Electrochemical technology shows good prospects in the field of enviroment to treat organic compounds because the reaction condition is mild and the hydroxyl radicals are produced through direct or indirect method by the reaction of a catalytic electrode.Electrochemical technology can be mainly classed as anode oxidation, cathode reduction. However, Electrochemical technology for the organic wastewater was majoring in anode oxidation process, the cathode reduction was paid less attention, and the reserch on cathode reduction still exist some problems. For example, the study of cathode reduction process is limited maining due to the difficulity of the production of cathode materials, H2O2 output and the current efficiency of H₂O₂ production on cathode are not high, the properties of electrode are difficult to achieve ideal. Because of the shortage of cathode materials, a cathode with high production and current efficiency of H₂O₂ was studied in order to degradate organic compounds.The gas diffusion electrode made of graphite and PTFE was used as working electrode, the effects on H₂O₂ output were investigated. The optimized operational parameters were as follows: graphite and PTFE 1:2, oxygen flow rate 0.6 L/min, pH=12, cathodic potential -1.2 V, and N_a2SO₄ concentration 0.5 mol/L. H₂O₂ concentration could reach 1400 mg/L after 4 h at optimized, and the average current efficiency of H₂O₂ production could reach above 55% at the same time.The properties of graphite/PTFE electrodes doped MnO2, CeO2 and La2O3 were studied. And H₂O₂ concentration produced by the three types of electrodes were studied compared with the graphite/PTFE electrode. It Found that three type oxides have catalytic activity of oxygen reduction, the catalytic activity order is: La₂O₃>CeO₂>MnO₂. Compared with the graphite/PTFE electrode, La2O3-doped graphite/PTFE electrode generate H₂O₂ concentration can increased nearly 2-fold.Furthermore, factors influencing cationic red GTL degradation, such as the catalyst loading of La2O3, oxygen flow rate, pH, cathodic potential and N_a2SO₄ concentration were investigated in the system with cathode of La2O3-doped graphite/PTFE electrode. The results show that cationic red GTL degradation rate was 90% in 2 h when the catalyst loading of La2O3 is 25% of graphite weight, oxygen flow rate was 0.3 L/min, pH=2⁵, cathodic potential was -1.2 V and N_a2SO₄ concentration was 0.3 mol/L.Finally, discuss the mechanism of lanthanum oxide-doped graphite/PTFE electrode to produce H₂O₂, intermediate product from cationic red GTL degradation were detected by IC and GC-MS, and a probable degradation pathways of cationic red GTL degradation was put forward. Lanthanum oxide-doped graphite/PTFE electrode having good properties of producing H₂O₂ and degradating organic compounds shows good prospects.