| Low rank coal in Northern Shaanxi of yulin and direct coal liquefaction residue were adopted as the raw materials for preparation of the electrode material by carbonization and activated process by HNO3, it was used in the electric adsorption process of the leaching gold tail solution, explore the law and reaction mechanism of the total cyanide, thiocyanate, copper ion removal for the process of electric adsorption further.In the performance experiments for the coal-based electrode material, the effects of the carbonization end temperature, carbonization time, concentration of HNO3,activation time, activation temperature factors for the specific capacitance and the adsorption capacity of electrode material were mainly investigated. The coal-based electrode materials was analysis and characterization by N2 stripping, cyclic voltammograms and AC impedance test. The results showed that with the carbonization temperature of 800 ℃, carbonization time of 90 min, concentration of nitric acid of 40%,modification time of 8 h, modification temperature of 25 ℃, the specific surface area of the coal base electrode materials was 325 m2/g, total pore volume was 0.162 cm3/g, the average aperture was 1.899 nm, impedance was 3.67 ?, quality of specific capacitance was 120.576 F/g, respectively. Under the voltage of 2.0 V with 5 h, the electric adsorption removal rate of after precipitation solution for total cyanide, copper, zinc and thiocyanate were 75.17%, 88.48%, 29.51% and 75.17% respectively.The electric adsorption experiment of cyanide wastewater in-depth exploded the influence of the applied voltage and pH of process and the result for the treatment.Studies have shown that the applied voltage has greater influence for the process ofelectrical adsorption, with the higher applied voltage, the removal rate of ions increase gradually. Without electricity, only had adsorption reaction; with voltage below 0.4 V,reacted the electric adsorption processes; with voltage of 0.5 V to 2.0 V, process was occured the electric adsorption and enrichment precipitation; the ions in the solution were enrichment precipitation and electrodeposition with the voltage was higher than2.0 V. With different pH, the process of electric adsorption was generated in different sediment. Control the pH above 8.96 of the solution at the initial stage of the electric adsorption, generation the precipitate of Cu2[Fe（CN）6] and Zn（OH）2, then the pH below8.5, it was generated in large amounts of CuSCN in the solution, the thiocyanate and copper ions concentration in the wastewater were reduced greatly. The kinetics studies shows that the electric adsorption behavior of total cyanide and the total copper in the solution were accorded to the secondary kinetic model and the equilibrium adsorption capacity were 13.73 mg/g and 2.45mg/g, respectively, the rate constant K were9.71×10-5 g·mg-1·min-1 and 2.10×105 g·mg-1·min-1, respectively, indicated the adsorption rate was slow. Thermodynamic results indicated that the electric adsorption process of total copper and total cyanide conformed to the isothermal model of Freundlich. The electric adsorption thermodynamic parameters ΔGo<0, ΔHo<0, ΔSo<0showed that the liquid process from the disordered state to ordered state transition with exothermic and spontaneous. |
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