The Preparation,Characterization Of Ruthenium Oxidation Electrode And Its Application In Wastewater Treatment

Refractory organic wastewater is a kind of wastewater which has strong anti-oxidation capacity,high toxicity and "Three-induced" effect.It mainly includes petrochemical wastewater,pharmaceutical wastewater,landfill leachate,printing and dyeing wastewater,etc.For the wastewater,it is difficult to achieve desired effect treated by traditional treatment methods such as biochemical and physical chemical methods.Electro-catalytic oxidation water treatment technology has attracted much attention because of its advantage of simple equipment,low dependence on the environment and chemical drugs,small area,low sludge production and good operating flexibility.The material selection and preparation of anode is the core of this technology.It has an important influence on the electrochemical reaction rate,reaction activity and energy consumption,and even can directly determine the success or failure of the electrochemical reaction.Ruthenium oxidation electrode is an important kind of industrial electrode.Previous researches of this electrode are mainly focus on chlor-alkali industry,and literture can hardly be found about its application in wastewater treatment.In this paper,SnO₂-Sb₂O₃-RuO₂/Ti and SnO₂-RuO₂-Bi₂O₃-La₂O₃/Ti electrodes were prepared,and SEM,XRD,CV and accelerated life times test were carried out to investigate their characterization and electrochemical performance.Amaranth,which is a refractory azo dye,was selected as the target pollutant for the electro-catalytic oxidation treatment.The main influence factors such as current density,initial Amaranth concentration,initial pH of the solution,electrolyte type and concentration were investigated,and the dynamic equations of the electro-catalytic oxidation were discussed.The specific research concludes were obtained as follows:Firstly,SnO₂-Sb₂O₃-RuO₂/Ti electrode was prepared by thermal decomposition method,and the main influence factors of the preparation were investigated.The optimum preparation conditions are as follows: the calcination temperature is 500?,the coating layer is 6 layers,and n?Sn?: n?Sb?: n?Ru?=10:1:1.Electrochemical characterization shows the electrode is mainly composed of RuO₂,Sb₂O₃ crystals and some other solid states;shallow and narrow range of cracks are distributed on the electrode surface,but large area and high density fragments have not be found;CV curves shows the electrode has a high chloride selectivity;and the accelerated life times is 27 h determined by accelerated life times test.The effects of the current density,solution initial pH and Amaranth initial concentration were investigated on the decolorization efficiency.The results show decolorization efficiency increases with the increasing of current density,and decreases with the increasing of the initial pH;Amaranth initial concentration had no significant effect on the decolorization efficiency,but the decolorization amount increases with its increasing.Under the conditions of current density 20 m A/cm²,initial pH value of 3.02,the decolorization efficiency can reach to 90.51% for 120 min treatment as Na₂SO₄ concentration is 1.02 g/L,and 78.92% for 24 min treatment as Na Cl concentration is 0.12 g/L.Secondly,SnO₂-RuO₂-Bi₂O₃-La₂O₃/Ti electrode was prepared,and it performance was characterized by SEM,XRD,CV and accelerated life times test.The results show as follows: it is mainly composed of RuO₂,SnO₂,Sn Ru Ox,La Bi Oz crystals and solid states;the electrode surface are uniform and smooth,but big bumps and defects appear in some part;it has a high chloride selectivity,and its accelerated life times is 7 h.The effects of the current density,solution initial pH and Amaranth initial concentration were investigated on decolorization efficiency.The results show the decolorization efficiency increases with increasing of the current density and Na Cl concentration.The optimal initial pH is 5.09;and the optimal Na₂SO₄ concentration is 2.03 g/L.Under the conditions of current density 20 m A/cm²,initial pH value of 5.09,the decolorization efficiency can reach to 96.69% for 120 min treatment as Na₂SO₄ concentration is 2.03 g/L,and 100% for 18 min treatment as Na Cl concentration is 0.12 g/L and Na₂SO₄ concentration of 2.03 g/L,the decolorization efficiency can reach to 96.69% for 120 min treatment.The UV-Vis,the normalized absorbance and COD removal rate analysis show Amaranth can be degraded into small organic molecules by ring opening and chain scission reaction,and finally be oxidized into CO₂ and H₂O.Finally,based on the experimental data fitting,the dynamics equations of the electro-catalytic oxidation were investigated.The results show the direct oxidation follows pseudo-first order kinetic equation,and the indirect oxidation follows the binomial equation.