Research Of Treatment On Cyanide Absorption And Recovery Of CO₂ By New Ionic MembraneDevice

Emission of cyanide contained waste gases, especially in the carbon fiber industry, is focused more and more attention due to its toxicity. The traditional chemical absorption method has many problems which are difficult to be resolved completely. The electrodialysis and electrodeionization new technology could produce alkali liquid and oxidant, and make ion migrate. These functions not only can concentrate carbonate ions, but also are able to oxidize cyanide. It is obvious valuable to explore the new principle of acidic waste gas processing method.Multi chamber ionic membrane device adding a certain amount of sodium chloride was applied to produce alkaline solution and oxidant hypochlorite which were used to absorb cyanide contained waste gases and oxidize cyanide respectively in the experiments. Carbonate obtained by absorbing carbon dioxide at the same time could be concentrated and recovery as CO2. According to the purpose of oxidative removal of cyanide, a new type of ionic membrane device was applied to electrooxidation of cyanide, and cyanide could not be detected after migration and oxidation. The device was tested to be good at producing alkali solution and has a wide range of capacity to oxidize cyanide. The co-exist carbon dioxide gas is absorbed by alkaline solution at the same time, which could be migrated and enriched to available chemical products.Results of the research show that this method can effectively remove cyanide. The higher initial concentration of cyanide solution, the lower energy consumption per unit quality of cyanide required. When the concentration of cyanide is 80 mg/L, the energy consumption is 2.099 MJ/g-CN-. Compared with the traditional chemical absorption method, only electricity is consumed during the operation. The absorbent can be recycled, and it does not produce waste water in the whole process. Dealing with co-exist carbonate, under the optimal condition, the carbon dioxide recovery rate can reach to 33.5 mmol/h, current efficiency is 61.3%, and the energy consumption is 3.37 MJ/kg-CO2 correspondingly. As it is environmentally friendly, this technology is a new method for disposing industrial carbon dioxide waste gas.During the disposing process of acid waste gas containing cyanide, the oxidation of cyanide and the absorbing liquid regeneration will complete in the same device at the same time, and there is no need to add any other oxidant solutions or gases except sodium chloride, and no waste water produced, which has a great advantage compared with traditional treatments. Electrodeionization is commonly used in the preparation of pure water and ions'concentration. This method uses the electrolytic oxidation reduction effect, thus EDI is developed new applications.