Electrochemical Oxidation Of Refractory Industrial Wastewaters With High Concentration Using Boron-Doped Diamond Electrode

High concentration,large emissions,difficult to handle as well as serious pollution to the environment,which lead refractory industrial wastewater became the hot spot.The traditional method of industrial wastewater treatment can not meet the discharge standards or cost is too high,and the electrochemical method because of it easy to automate,friendly to the environment and present a huge protential.The electrode material is the most important factor in the process of electrochemical oxidation wastewater and the boron-doped diamond(BDD)thin film as a new electrode material has received great attention because its excellent physical and chemical properties.In this paper,we utilized the BDD electrode of electrochemical advance oxidation process to electrolysis the industrial wastewater.With refractory high concentration TNT(2,4,6-trinitrotoluene)red water as research object and the advanced electrochemical oxidation process was investigated by BDD electrode.The influence of several parameters,such as current density(20-100 mA/cm2),NaCl concentration(0-3 g/L)as well as the pH(2.0-10.0)value on the COD removal and the energy consumption were discussed.The results showed that high COD removal and low energy consumption could be realized for the highly NaCl concentration or in the acidic conditions.Although the increase of current density is more beneficial to the COD removal and B/C increase,this process is unfavorable to reduce energy consumption.Most importantly,in anycase,the TNT red water can achieve the biodegradation desire after electrochemical oxidation,which laid a solid foundation for its following biological treatment.With refractory high concentration textile wastewater as research object and the advanced electrochemical oxidation process was investigated by BDD electrode.The influence of several parameters,such as current density(20-100 mA/cm2),NaCl concentration(0-3 g/L)as well as the pH value(2.0-10.0)were investigated on the kinetics of COD oxidation and the energy consumption.From the results of the experience,it can be concluded that the practice well correspond to the kinetic model.The indirect oxidation which mediated by electro-generated strong oxidants could be described by a pseudo-first kinetics constant k.Increased the current density or decreased the pH value,the k would be a linear increase,but an exponential increase when the NaCl concentration increased.It is worth noting that low energy consumption corresponded to high oxidation kinetic,but not fitted to the current density.The process which under the optimum operational conditions could complete removal the COD of the textile wastewater only needed 3 h and the energy consumption as low as to 11.12 kWh·kg-1.The time short and low energy consumption impress that BDD anodes could used to treat textile wastewater through electrochemical oxidation.The service life of BDD electrode is very important.In this article,we researched the microstructure of BDD electrode through the electrochemical treatment.The results show that the BDD electrode surface became smooth and level off due to "polishing" after 30 h electrochemical treatment,but its structure and performances were not affected.The result revealed its good reliability of long-term use.Through the research on electrochemical degradation of TNT red water and textile wastewater by BDD electrodes,it has shown that electrochemical oxidation technology using appropriate electrode materials could realize good treatment effect,high efficiency,strong adaptability,good controllability and reliability,which implies it is worthy of further promotion in practical industrial wastewater treatment.