Study On Electrocatalytic Destruction Of 4-Chlorophenol In Aqueous Solution

The composition of the electrode is the main influence factors on the structure of electro—catalytic electrode,which is important to electro—catalytic characteristics and life time of electrodes.This paper focused on the preparation of palladium-nickel bimetallic composite catalyst deposited on nickel foam(Pd-Ni/Ni foam) and titanium based lead dioxide electrode with an inter—layer of Sb doped tin dioxide (Ti/SnO₂-Sb/PbO₂).Taking 4-Chlorophenol as model substrate, reductive dechlorination and oxidative degradation experiments were investigated with the two electrodes as working electrode,respectively.The Pd-Ni composite particles with a diameter less than 50 nm were finely dispersed on the Ni foam surface.The Pd-Ni/Ni foam electrode exhibited higher dechlorination efficiency than Pd or Ni supported on Ni foam electrodes.High-performance liquid chromatography analysis verified that phenol was the main dechlorination product.For an applied current of 20 mA,a bulk solution temperature of 15℃,and an initial 4—CP concentration of 1 mM,dechlorination efficiency of 82%was observed.Based on electrochemical impedance spectroscopic results and the current efficiency of 4—CP dechlorination at different applied current on various electrodes,we determined the rate—limiting step under various polarization conditions in our experiments.The Ti/SnO₂-Sb/PbO₂ electrode was characterized by X-ray diffraction and scanning electron micrograph.The primary substance on outer layer of the electrodes wasβ—PbO₂,which was compact and symmetrical.The effects of current density,initial concentration and electrolytical concentration were investigated by using this Ti/SnO₂-Sb/PbO₂ electrodes.TOC removal was about 59.8%at a current density of 10 mA cm^-2,an initial 4—CP concentration of 100 mg L^-1 and supporting electrolyte Na₂SO₄ concentration of 0.25 M.The results showed that as the current density increased,the removal of 4—CP and TOC increased.But simultaneously the demanded oxidative electricity per volume solution also increased.With the initial concentration increased,the removal of 4—CP and TOC reduced first,then increased. While with the electrolytical concentration increased,the reverse trend was taken on.Chlorine could transform to hypoclorite or other strong oxidizing substance to accelerate the degradation of 4—CP in this experiment.At last,the rate—determining step and possible reaction mechanism were deduced.