Photoelectrochemical degradation of Reactive Brilliant Red X-3B on three different anodes

Photochemical, electrochemical and photoelectrochemical degradation of Reactive Brilliant Red X-3B were studied by using (TiO2Ti)-Ti-/, SnxSb1-O2/Ti and RuxPd1-xO2/Ti as anodes, respectively. The results showed that the decoloration over the three anodes in the photoelectrochemical process could be more than 97% within 60 min. The photoelectric synergic effect was observed over all the three anodes including semiconductor anode of TiO2/Ti and conductor anodes of SnxSb1-xO2/Ti and RuxPd1-xO2/Ti. Two different processes were performed using SnxSb1-xO2/Ti as anode in NaCl solution. In an EP process the system is first electrochemically treated for 20 min followed by photochemical treatment for 20 min, while in a PE process the turn of electrochemical and photochemical treatment was reversed. It was found that the intermediate produced by electrochemical treatment in the EP process exhibited significant activity in the following photochemical treatment, the decoloration. rate increased from 17 % to 75 % after illumination for 3 min. No such increase in the decoloration rate was observed in the PE process. In another independent photochemical process, photodecoloration is carried out directly using NaClO as an additive and the light irradiation for this system caused similar sudden increase in decoloration rate as in the EP process. These facts suggested that in the EP process, HOCl and CIO- generated from the hydrolyzation of Cl-2 by electrolysis was immediately photolyzed to HO center dot, O- and Cl center dot, which could decolorize the X-3B dye very efficiently.