Modified Titanium Based PbO₂ Dimensionally Stable Anode For Electrocatalytic Degradation Of Pharmaceutical Wastewater

The development of medical has greatly enhanced and improved the quality of human life.However,with the mass output and use of pharmaceutical products,pharmaceutical wastewater with complex ingredients and poor biodegradability has also been accumulated,which caused great pressure on the ecosystem.Several technologies have been developed for the removal of ACE wastewater,including electrocatalysis,physical adsorption,biochemical method,etc.Among them,electrocatalytic oxidation technology with high efficiency,simple operation and good environmental compatibility becomes one of the effective methods for the removal of pharmaceutical wastewater.Electrode materials are the core components of the electrocatalytic system.Therefore,exploring a high performance electrode with low cost,high efficiency,excellent stability and high catalytic activity is a valuable strategy for improving the efficiency of electrocatalytic degradation.In this thesis,carbon nanotubes/graphite carbon nitride（GCN/CNT）,Mn doped graphite carbon nitride（MnCN）,and Ni/S modified Ti/PbO₂ electrodes are prepared by a simple one-step electrodeposition method using titanium sheet as the substrate.As-prepared electrodes are further used for electrocatalytic degradation of acetaminophen,nitrofurazone,and ibuprofen pharmaceutical wastewater,respectively.The main research contents are as follows:（1）GCN/CNT modified Ti/PbO₂ electrode is prepared by one-step electrodeposition and used for high-efficiency electrochemical degradation of acetaminophen pharmaceutical wastewater.The introduction of GCN/CNT enhanced the oxygen evolution potential,charge transfer resistance,stability and electrocatalytic activity of Ti/PbO₂ electrode.The degradation of acetaminophen on Ti/PbO₂-GCN-CNT electrode consumes low energy.Under the condition of current density 15 m A cm^-2,initial p H 7,6.0 g L^-1 Na₂SO₄ and 25℃,the acetaminophen and COD removal efficiencies reached up to 83.22%and 76.32%,respectively,after 3 h degradation.Mechanism analysis shows that the degradation process of acetaminophen follows quasi-first order kinetics.?OH radicals play a major role in the indirect oxidation of acetaminophen.The possible pathways of acetaminophen degradation is elaborated based on the intermediates determined by LC-MS.（2）MnCN modified Ti/PbO₂ electrode is fabricated by simple electrodeposition for the degradation of nitrofurazone wastewater.Ti/PbO₂-MnCN electrode obtained by adding0.020 g MnCN in electrodeposition solution has a smaller and more compact pyramid stacking surface.Furthermore,the introduction of MnCN enhanced the oxygen evolution potential,charge transfer resistance,stability and electrocatalytic activity of Ti/PbO₂electrode.The degradation of nitrofurazone on Ti/PbO₂-MnCN electrode requires low energy.Under the condition of current density 25 m A cm^-2,initial p H 5,6.0 g L^-1 Na₂SO₄and 30℃),the nitrofurazone removal efficiency and COD removal efficiency reach up to100%and 93.67%,respectively,after 60 min continuous electrolysis.Mechanism analysis demonstrates that the degradation process of nitrofurazone abides by quasi-first order kinetics.?OH radicals are the mian active substance in nitrofurazone degradation.The possible mechanism of nitrofurazone degradation is proposed based on the intermediates identified by LC-MS analysis.（3）Ti/PbO₂-Ni-S electrode with high oxygen evolution potential,low impedance,satisfactory stability and excellent electrocatalytic activity is successfully synthesized by one-step electrodeposition for electrocatalytic degradation of ibuprofen wastewater.The degradation process of ibuprofen on Ti/PbO₂-Ni-S electrode requires low energy.Under the experimental parameters of current density 16 m A cm^-2,initial p H 3,6.0 g L^-1 Na₂SO₄and 25°C,the ibuprofen efficiency and COD removal efficiency reach up to 94.65%and88.51%,respectively.Mechanism analysis indicates that the degradation process of ibuprofen conforms to the quasi-first order kinetic model and?OH radicals play a leading role in the electrocatalytic degradation of ibuprofen.The possible pathways for the degradation of ibuprofen wastewater is proposed based on the intermediates measured by LC-MS.In summary,the researches above show that Ti/PbO₂-GCN-CNT,Ti/PbO₂-MnCN-2 and Ti/PbO₂-Ni-S electrodes have a promising application prospect in the treatment of pharmaceutical wastewater.