Study On Preparation Of Three-Dimensional Electro-Fenton Particle Electrode And Its Treatment Of Coking Wastewater

Coking wastewater is a typical refractory organic industrial wastewater.It will seriously pollute the environment and endanger human health if being treated improperly.Electro-Fenton technology has been widely used in the treatment of refractory organic wastewater due to its advantages such as complete reaction,but it has the disadvantage of high energy consumption.Three-dimensional electro-Fenton system not only continues the advantages of traditional electro-Fenton technology,but also has the advantages of good mass transfer effect,high current utilization rate,reaction efficiency and spatial utilization rate,which has attracted wide attention of domestic and foreign scholars.The experiment used three-dimensional electro-Fenton system to treat coking wastewater and provided a new option for solving the problem of coking wastewater pollution.In this experiment,a kind of iron-loaded needle coke particle electrode was developed independently.The raw coking wastewater was taken as the treatment object,and the COD removal rate was taken as the response index.The effects of preparing conditions including catalyst to binder ratio,Fe²⁺loading,size of particle electrode and calcination temperature on the performance of particle electrode were studied.The optimal preparation conditions of particle electrodes were determined as follows:catalyst to binder ratio was 4:1,Fe²⁺loading was 2.5%,the size of electrode was 5-6mm,and calcination temperature was 400°C.The optimal preparation conditions were determined as follows:catalyst to binder ratio was 4:1,Fe²⁺loading was 2.5%,the size of electrode was 5-6 mm,and calcination temperature was 400°C.The material characterization showed that the iron element was successfully loaded on the surface of needle coke.After the prepared particle electrode was repeatedly used for ten times,the COD removal rate was only reduced from 87.40%to 85.05%.It indicated that the particle electrode had good repeatability and industrial application potential.Three-dimensional electro-Fenton system was constructed with DSA electrode as anode,nickel foam sheet as cathode and self-developed iron-loaded needle coke balls electrode as particle electrodes.The raw and biotreated coking wastewater were treated.The optimal treatment conditions were determined by single-factor and response surface experiments.The COD removal kinetics was studied.The water samples before and after the reaction were analyzed by spectral characterization to explore the pollutant degradation mechanism.Finally,the optimal treatment conditions of raw coking wastewater were determined as follows:electrode spacing was 5 cm,reaction voltage was 11.15 V,initial p H value was 2.62,and particle electrode dosage was 12.23 g/L.Under above conditions,COD,NH₃-N,NO₃-N,TN,and color removal rate could reach 86.20%,100%,72.22%,84.84%,and 95%,respectively.COD removal conformed to the pseudo-second-order kinetics.The optimal treatment conditions for biotreated coking wastewater were determined as follows:the reaction voltage was 11.11 V,the initial p H value was 4.69,and the particle electrode dosage was 11.63 g/L.The COD and color removal rate were85.18%and 99%,respectively.The COD removal conformed to the pseudo-first-order kinetics.The spectral analysis showed that the three-dimensional electro-Fenton system had a good treatment effect on coking wastewater.The macromolecular organic matters were degraded and the rest were mostly olefins and alkanes.Through the determination of UV₂₅₄,it is concluded that UV₂₅₄ of raw coking wastewater was reduced from 0.29 to 0.08,indicating that the biodegradability of coking wastewater was improved after three-dimensional electro-Fenton treatment.The particle electrodes were developed independently with which the three-dimensional electro-Fenton system was constructed to treat coking wastewater in this experiment.The system had good degradation effect on COD,NH₃-N,NO₃-N,TN and chroma.The study can provide theoretical basis for industrial application of three-dimensional electro-Fenton system.