| With the rapid development of global industrialization,waste gas,waste water containing heavy metals are discharged into the environment,resulting in water pollution and serious harm to human and nature.Therefore,it is very important for human health and environmental protection to find efficient,clean and energy-saving methods to treat heavy metal polluted water.Among the heavy metal hazards,cadmium pollution is the most serious.Traditional methods of cadmium removal:chemical precipitation,ion exchange,membrane separation,etc.Although the technology is widely used,these methods have the disadvantages of high energy consumption,high investment and secondary pollution.In recent years,a new type of desalination technology:flow electrode capacitive deionization technology has attracted more and more attention due to its advantages of cleanness,low energy consumption,continuous desalination and energy recovery.In recent years,a new desalination technology:flow electrode capacitive deionization（FCDI）has attracted more and more attention due to its advantages of cleanness,low energy consumption,continuous desalination and energy recovery.In this paper,using commercial activated carbon as electrode material,the removal efficiency of cadmium ion by FCDI technology with short circuit closed operation mode was studied.First of all,FCDI optimization experiments were carried out from the operation conditions of FCDI（applied voltage,flow rate of electrode and influent solution）,composition of electrode materials,and concentration of activated carbon in electrode solution to improve the performance of FCDI.Then,the removal performance of FCDI under different operation conditions（applied voltage,initial ion concentration of solution,p H value of solution）and the continuity and cycle stability of FCDI system were studied.In addition,the amount of ions remaining in the activated carbon after desalination was used to explore the process of adsorption and desorption of ions in the experimental process.Firstly,the desalting performance of FCDI under different operating conditions was studied.The results show that the applied voltage has a great influence on the desalting performance of FCDI,and the desalting rate and desalting rate increase by 59.10%and 6.60 mg/min respectively with the increase of applied voltage;The desalting rate and desalting rate increased by 16.13%and1.51 mg/min respectively with the increase of electrode flow rate.The desalting rate of FCDI increased by 19.22%and the desalting rate increased by 2.14 mg/min with the increase of flow rate in the range of 5 ml/min～27 ml/min;With the increase of activated carbon concentration in the electrode,the desalting rate and desalting rate increased by 70%and 8 mg/min,respectively.The growth rate of desalting rate and desalting rate decreased significantly at 25ωt%;After adding carbon black,the desalination rate of the electrode increased by 20%,14%and 19%,and the desalination rate increased by 2.32 mg/min,1.50 mg/min and 2 mg/min,respectively.Then the removal efficiency of FCDI for cadmium ion was studied.The results showed that the initial ion concentration had a significant effect on the removal of cadmium ion by FCDI.When the concentration of cadmium ion was 10 mg/L,the maximum removal rate was 50%,and then decreased significantly with the increase of concentration.When p H=3,the removal rate of cadmium ion is 54%.With the increase of applied voltage,the removal rate of Cd2+increased from0 to 46.60%;FCDI can remove cadmium ions continuously and stably.The results show that Cd（OH）2precipitation is found on the anion exchange membrane;The FTIR spectra of activated carbon before and after the experiment showed that the types of functional groups on the surface of activated carbon after adsorption of cadmium ions did not change.In this paper,the desalting performance of FCDI under different operating conditions and the removal efficiency of FCDI for cadmium ion were systematically studied to provide some practical experience for the treatment of heavy metal cadmium by FCDI. |
