Preparation Of Adsorption-catalysis Dual Function Electrocatalysts And Their Application Of U(?) Removal From Groundwater And Dehalogenation

Heavy metals and halogenated antibiotics widely exist in ground and surface water,causing serious damage to the ecosystem.Electro-reduction,applying a potential to the cathode and anode for driving the transformation of the pollutant is highly efficient,which has been wildly used in the heavy metal removal and dehalogenation due to its environmental friendly and easy operation,achieving efficient control of heavy metals and the organic pollutants.However,recent works show that the high energy consumption,high cost of electrode and large energy loss limit the application of the electro-reduction,in which high treatment efficiency can not be achieved in the condition of limited energy allocation.At present,the design of catalysts,electron transfer mechanism and pollutant molecule migration as well as transformation on the interface of the cathode are the current works,decreasing the energy consumption and improving the reaction efficiency.The main studies are summarized as follows:1.The methods of electrochemical reduction and oxidation recovery of U(?)in groundwater were established for the first time,solving the problem of secondary pollution caused by bio-recommendation.With the applied potential of-0.6 V,U(?)was electro-reduced to U(IV)O₂covering the whole area of working electrode and the removal efficiency can achieve at 99.9%in 11 hours.The U(IV)O₂can be oxidatively recovered by dilute HNO₃.The electro-reduction of U(?)was improved with the accumulation of the UO₂on the surface of Ti electrode.This phenomenon may be contributed to the adsorption of U(?)by U(IV)O₂,causing over 60.0%of U(?)removal efficiency under the open circuit.The DFT calculation indicates that the adsorption of U(?)provides a strong interaction against the electrostatic repulsion between U(?)-CO₃species and cathode.2.The electro-reductive removal of U(?)mainly relies on the accumulation of UO₂on the electrode surface,causing the removal performance unsatisfied when the initial U(?)concentration was very low(<10?M).Using A-TNTs can improve the U(?)electro-reductive removal performance,in which over 99.0%of the U(?)was removed in 30 minutes with 10?M of the initial U(?)concentration.A-TNTs provides a high efficiency of U(?)diffuse and electron transfer making A-TNTs an excellent U(?)electro-reductive removal performance.The U(?)removal efficiency can remain over 95.0%with 21 times of U(?)addition under-0.4 V,however,the removal efficiency was lower than 50.0%after 3 times of U(?)addition with an open circuit,showing the advantage of electro-reduction method.3.To improve the U(?)removal efficiency by A-TNTs,the electro-oxidative synthesis of TNTs and the annealing process was controlled to change the surface morphology(I-TNTs)and the facet exposing(001-TNTs).Immediately rising temperature makes irregular crack on the surface of TNTs providing a pluralistic U(?)diffusing and large electro-reductive active area.Decreasing the water addition during the electro-oxidative synthesis of TNTs can expose more 001 facet of Ti O₂.The U(?)electro-reductive removal performance by I-TNTs and 001-TNTs was 1.75 and 4.90 times higher than that by A-TNTs,improving the activity of cathode.4.Based on the electrochemical reductive dehalogenation of halogenated organic pollutants,the method of simultaneous improvement of adsorption and electron transfer enhanced the efficiency of electrochemical reduction reaction.The Co-O/P cathode was synthesized by a one-step electro-deposition on the surface of Ti plate improving the electro-reductive dehalogenation performance of CAPs.The FLO removal efficiency was improved by 6 and 2 times compared with Ti and Pd/C electrode,respectively.The high FLO dehalogenation performance was attributed to the improvement of trapping FLO through the surface complex forming by Co-O and the reduction of FLO through atomic H produced by Co-P.