The Performance And Mechanism In The Electrocatalytic Reduction Of Tetrabromobisphenol A With Nano-palladium Modified Electrode

Tetrabromobisphenol A is the most widely used brominated flame retardant.It has a large demand and a large amount of use,but it has adverse effects on endocrine,reproduction and behavior,and has attracted extensive attention from relevant scholars.Electrochemical reduction dehalogenation technology is considered to be one of the most promising water treatment strategies because it does not cause secondary pollution and has high degradation efficiency.In this paper,nano-palladium was used as the electrode modification material,and the physicochemical properties of the prepared electrode were clarified by various characterization methods.The effect of different influencing factors on the electrocatalytic reduction and debromination efficiency of tetrabromobisphenol A was studied.Finally,the reaction mechanism of electrocatalytic reduction debromination reaction was explored.In this paper,the required working electrode is prepared by chemical reduction.Then,scanning electron microscope,X-ray diffractometer,X-ray photoelectron spectroscopy,electrochemical impedance spectroscopy and cyclic voltammetry were used to show that the surface of the prepared Pd/Ni-foam electrode was adhered with high content of zero-valent nano-palladium.The Pd/rGO/CC electrode is loaded with spherical nano-palladium particles of zero valence state on the graphene structure.Moreover,the performance of electron transfer and electrochemical surface activity of the palladium-loaded electrode is improved compared to the electrode without palladium.Subsequently,tetrabromobisphenol A was used as the target pollutant.The effects of working electrode,cathode potential,electrolyte,initial concentration and palladium loading on the reductive debromination efficiency were studied.The experimental results show that the debromination efficiency of tetrabromobisphenol A is the highest when Pd/Ni-foam is used as the electrode.When the cathode potential is-0.4 V^-1.2 V,the debromination efficiency increases with the decrease of the cathode potential.However,when the cathode potential is lower than-1.2 V,the debromination efficiency decreases as the cathode potential continues to decrease.The debromination efficiency when using Na₂SO₄ as electrolyte is higher than that when using PBS as electrolyte.With the increase of the initial concentration of tetrabromobisphenol A and the loading of palladium,the debromination efficiency showed a trend of increasing first and then decreasing.The debromination efficiency of tetrabromobisphenol A and tribromophenol can reach 100%when electrocatalytic reduction debromination experiments are carried out on four widely used brominated flame retardants under suitable experimental conditions.However,due to the high degree of bromination of HBCD and decabromodiphenyl ether,the reaction system has limited processing capacity,resulting in low debromination efficiency of 50.7%and 13.3%,respectively.Since hydrogen is produced by the combination of active hydrogen atoms,the amount of hydrogen generated can reflect the amount of active hydrogen atoms generated from the side.Based on this,it is indirectly proved by the hydrogen microelectrode that the reduction of the cathode potential is beneficial to the generation of active hydrogen atoms;the buffered saline solution PBS can generate more active hydrogen atoms than the Na₂SO₄ solution;the Pd/Ni-foam electrode is more favorable for the reaction than the Pd/rGO/CC electrode.In addition,the important role of the active hydrogen atom in the electrochemical reduction debromination reaction was confirmed by t-butanol,but in the absence of active hydrogen atoms,the direct reduction of electrons can also be subjected to electrocatalytic reduction debromination.In this paper,a combination of various analytical methods to clarify the reduction and debromination efficiency of electrocatalytic brominated flame retardants and clarify the debromination mechanism,which provides an effective method for the efficient treatment of halogenated pollutants.