Capacitive Deionization Process And Mechanism In Treatment High-salinity Wastewater Produced In Ferrovanadium Magnetite Extraction

In the western region of Liao Ning,in the roasting process of ferrovanadium magnetite extraction,large amounts of waste water with high salinity and ammonia nitrogen is produced.At present,conventional technologies possess the drawback of high cost,poor performance and high energy comsumption.This study focuses the desalination of capacitive deionization?CDI?in treating ferrovanadium magnetite extraction.In this study,the foamed copper/activated carbon electrode applied in CDI was fabricated by the method of preparation supercapacitor electrode and the low price of activated carbon with excellent performance was used as the main electrode material.The CDI module was constructed with the prepared electrodes and then the experimental system was constituted.The different factors such as voltage,flow rate,initial concentration ware investigated and the effects of factors on electro-adsorption experiment were studied.The most optimal processing parameters of CDI in this study are charging voltage of 1.4 V,flow rate of 10 m L/min,space between polar plates of 4mm.Besides,operating condition was optimized to realize the good capability of desalination.The kinetics analysis demonstrated that the electrosorption of NaCl on electrodes during dealing different operating voltages followed pseudo-first-order model.The ion electrosorption on the electrodes can be represented by the Langmuir equation.This phenomenon indicating that the monolayer adsorption was primary during the electrosorption process.The experiment of adsorption-desorption in desalination process presented a better reversibility of activated carbon.The activated carbon was modified by the HNO₃ to improve the physical structure characteristics and surface chemical properties,respectively.Modified activated carbon was prepared HNO₃-AC electrodes and then the CDI system was consisted for the experiment.Moreover,the effects of the operating conditions have been studied to optimize the electro-adsorption test results.The consecutive electro-adsorption/electro-desorption cycle figure clearly indicates that AC,HNO₃-AC electrodes have the good properties of regeneration and the HNO₃-AC electrodes have a shorter cycle times than the AC electrode's.This study has concluded that the activated carbon modified by HNO₃ has increased the surface functional groups and enhanced the hydrophilicity on the surface of the electrode.The results also suggest that the charge efficiency and the electro-adsorption capacity are improved.So the HNO₃ modification method has heightened the physical structure characteristics and surface chemical properties of the activated carbon electrode,which is applicable to CDI.The electricity consumption analysis of treating Vanadium titanium magnetite wastewater by capacitive deionization indicate that:the HNO₃-AC electrode and AC electrode could treat experimental wastewater well.At the same time,the consumption of electrode material and the processing time also can be reduced by modification.