Study On Treatment Of Cyanide Wastewater By Three-dimensional Electrode

In this paper,the self-made coal-based electrode materials were optimized by nitric acid and potassium hydroxide activation as the cathode and anode,the activated carbon was the particle electrode,and the cyanide wastewater was treated with the three-dimensional electrode.The properties of the plates and particle electrodes were analyzed by scanning electron microscopy?SEM?and energy dispersive spectroscopy?SEM-EDS?,low temperature N2 adsorption method,infrared spectroscopy?FT-IR?,cyclic voltammetry and AC impedance.The removal regularities and reaction mechanism of total cyanide,copper,zinc,free cyanide and thiocyanine in wastewater were studied emphatically.The results show that the coal-based electrode material is more suitable for the cathode than the stainless steel,and the effect of the three-dimensional electrode is better than that of the two-dimensional electrode.The removal rates of CNT,Cu,Zn,SCN-and CN-in waste water were 93.94%,95.22% and 97.23% respectively when the voltage was 4V,the time was 4h,the dosage of particles was 2g and the particle size was 1mm.99.38% and 94.93% respectively.The applied voltage has a direct effect on the removal mechanism of each ion in the three-dimensional electrode system.When the applied voltage is 0V,the removal of each ion is mainly due to the adsorption of the coal-based electrode material and the particle electrode.When the voltage is 1 2V,The anodic electrodeposition is mainly composed of anions,and the enrichment of ions is supplemented.After the voltage exceeds 3 4V,the cathodic electrodeposition of metal ions is mainly composed of anodic oxidation of SCN-and CN-.The kinetic studies show that the process of total cyanide and zinc ions in the cyanide wastewater treated with the three-dimensional electrode system is in accordance with the first order kinetic model with a rate constant of 1.07×10-2 g·mg-1·min-1 and 1.51×10-2 g·mg-1·min-1.Potassium hydroxide and nitric acid can effectively improve the surface structure,composition and electrochemical properties of coal-based electrode materials.The results show that with the increase of potassium hydroxide,the specific surface area of coal-based electrode material increases,the porosity increases and the electrochemical performance is improved.When the amount of potassium hydroxide is 15%,when the nitric acid concentration is 40%,the iodine adsorption value of coal-based electrode material can reach 820mg/g.The specific surface area of 530 m²·g^-1,the total pore volume of 0.299 cm3·g-1,the porosity of 74.25%.The removal rates of CNT,Cu,Zn and CN-were 72.63%,78.34%,67.23% and 77.16%,respectively,when the voltage was 2V.