Optimization And Application Of Water Treatment Technology By Boron-doped Diamond Anode

In recent years,the issue of water pollution has become increasingly prominent,which seriously threatens the health of human beings and the stable development of ecology.Therefore,development of emerging and efficient water treatment technologies has become the focus of environmental studies.Electrochemical oxidation technology has attracted the attention of researchers among these water treatment processes because of its unique advantages.Numerous studies have shown that the electrochemical oxidation process is influenced by various factors such as anode material,supported electrolyte,current density,flow rate,initial solution pH,reaction temperature and time,etc.The first three factors are considered to be the most important parameters governing the electrochemical efficiency.Specifically,the choice of anode material will via directly or indirectly routes affect the degradation efficiency and energy consumption.Boron-doped diamond(BDD),as a new type of electrode material,has become a promising electrocatalytic electrode in the field of water treatment due to its excellent electrochemical properties.This dissertation mainly deals with the water treatment technologies concerning BDD anode,and the works conducted include two parts:In the first part,the effects of electrode material,electrolyte and current density on anodization are investigated by factor design methodology(FDM).Acid Orange II is chosen as a pollutant model,as well as three anode materials and two supporting electrolytes are used to form six different reaction systems(BDD/Na2SO4,BDD/NaCl,MMO/Na2SO4,MMO/NaCl,Pt/Na2SO4 and Pt/NaCl).The reaction rates are monitored by changing supporting electrolyte concentration,applied current density,flow rate and reaction time.The results show that BDD/NaCl system is the best combination in the case of lower electrolyte concentration.Electrolyte concentration and current density are key parameters in dictating the degradation performance.Current density has always shown a strong and positive impact.However,electrolyte concentration shows completely different degradation effects in these reaction systems:Positive effects are observed in BDD/NaCl and MMO/NaCl system,while negative effects are observed in BDD/Na2SO4,MMO/Na2SO4,Pt/Na2SO4 and Pt/NaCl systems.The second part deals with the treatment of human metabolic wastewater by BDD technology.Central composite designs(CCDs)and Doehlert design(DM)are employed to optimize the experimental conditions for the degradation of creatinine and uric acid,respectively.The influences of four operating parameters including electrolyte properties,concentration,current density and flow rate on the removal of pollutants are investigated.The results show that two different experimental designs result in a similar order of main effect(initial NaCl concentration>current density>flow rate>initial Na2SO4(NaHCO3)concentration).All of them are positive effects,and the first three are also statistically significant.In addition,the main intermediates were determined by LC/MS analysis,and the possible degradation mechanism and pathway are also proposed.