Research On Boron-doped Diamond Thin Film Electrodes And Application To Wasterwater Treament

Diamond thin film is a perspective material to be used in electrochemistry and electrochemical engineering due to its excellent electrochemical performance. Potential application of wastewater treatment has been proposed and is being actively pursued now. In this dissertation, the physical and electrochemical behaviors of the boron-doped diamond film electrode prepared by chemical vapor deposition technique were studied. And investigation of the oxidation of 4-nitrophenol on diamond electrode was also carried out with the goal of developing application in the electrochemical oxidation of refractory organics in superhigh COD for wastewater treatment.The electrochemical oxidation of 4-nitrophenol has been studied on boron-doped diamond electrodes on acid medium by cyclic voltammetry and HPLC . The results showed that in the potential region where the supporting electrolyte is stable, reactions occur, resulting in the loss of activity due to electrode fouling. Galvanostatic electrolyses cause complex oxidation reactions that lead to incineration of 4-nitrophenol. Phenol, benzoquinone, maleic, and oxalic acid have been detected as soluble products during the electrolysis of TNP. These results suggest that the electro-oxidation of 4-nitrophenol begin by the release of nitro groups from the aromatic ring to form non-nitrogenated phenolic compounds. These compounds are transformed into carboxylic acids which end to be oxidized to CO2. The complete removal of organic compounds contained in the waste has been obtained in sulfuric medium.A new equipment for wastewater treatment was developed, which was suitable for BDD thin film electrodes mentioned above. The electrochemical oxidation of wastewater in the second factory of Tian jin reagent, containing phosphorus, was carried out using our equipment. In particular, the effects of operating factors on current efficiency and pollutant removal were studied, such as time of electrolyte , voltage, space between anode and cathode. Examination results show that removal rate of COD is near 100% and current efficiency is over 0.8.