Electrochemical Catalytic Degradation Of Tetrabromobisphenol A With Pd-Fe/Ni (CTAB) Electrode As The Cathode

Tetrabromobisphenol A (TBBPA) is a typical brominated flame retardants with the high degradation-resistant properties, it has been treated as an endocrine disrupter in recent years, which needs a high-efficiency technology to deal with it. Considering the special properties of TBBPA, reductive way may be more suitable for its degradation. Electrochemical reduction is a promising way for TBBPA degradation due to its advantages of no additional chemical reagents, versatility, high energy efficiency, environmental compatibility and easily controlled, which has already used in reduction of halogenated organics.However, reduction method only removed the Br atom form TBBPA structure, the reduction products are still macromolecular with the potential of toxic. Hence, it’s necessary to oxide the reduction products completely. Inspired by the above idea, a sequential reduction-oxidation method was proposed in this paper with Pd-Fe bimetal nanoparticls modified Ni foam electrode (Pd-Fe/Ni) as the cathode. The main conclusions as follows:(1) Pd-Fe/Ni electrode was obtained after the process of electrodeposition followed by impregnation deposition. Characterization results show that the surface of Pd-Fe/Ni(CTAB) is smoother with the addition of CTAB in eletrolyte, and the Pd, Fe nanoparticles were well arranged with the addition of CTAB. When CTAB was added into the electrolyte, the surface area of Pd-Fe/Ni electrode is enlarged. The hydrogen evolution reaction is more easily stimulated on Pd-Fe/Ni electrode surface compared with Pd/Ni and Ni electrode. In addition, the addition of Fe nanoparticls can reduce the resistance of Pd-Fe/Ni compared with Pd/Ni, results in the faster transfer of charge on Pd-Fe/Ni electrode, which is beneficial for debromination reaction.(2) The electrocatalytic hydrogenolysis and reduction effect of Fe nanopartiles are concurrence in electrochemical catalytic system with the introduction of Fe nanoparticles on Pd-Fe/Ni electrode, as a result, the debromiantion efficiency is enhanced. The parameters of electrode preparation have a big influence on debromination efficiency, especially for Pd loading amount. The optimized conditions were found to be Fe2+ concentration of 15 mmol/L, deposition current of 10 mA, Pd loading amount of 2.5 mg/cm2 and CTAB concentration of 1 mmol/L.(3) The electrochemical reduction of TBBPA is a process of hydrogen demanded, the optimized reaction conditions were found to be initial pH of 3 and applied current density of 0.83 mA/cm2. Pd-Fe/Ni(CTAB) electrode shows good stability which exhibited great debromination efficiency for TBBPA after four times run.(4) The reaction atmospheric shows big influence on TBBPA electrochemical debromination. At the atmosphere of N2, reduction debromination reaction dominants TBBPA degradation, and the debromiantion is a process of gradually debromiantion. Under air condition, reduction process is suppressed, H2O2 and OH are the main oxidants which play the role of TBBPA oxidation. When at the condition of N2 30 min+air 30 min, sequential reduction-oxidation of TBBPA could realized.(5) Eight products were detected in the electrochemical sequential reduction-oxidation system, the results of product analysis show that the idea of electrochemical sequential reduction-oxidation to deal with TBBPA is feasible.