EFFECT OF SnO_2 ADDITION ON THE SERVICE LIFE AND ELECTROCHEMICAL PROPERTIES OF Ti/IrO_2,+Ta_2O_5 ANODES IN PHENOLSULFONIC ACID SOLUTION
EFFECT OF SnO_2 ADDITION ON THE SERVICE LIFE AND ELECTROCHEMICAL PROPERTIES OF Ti/IrO_2, Ta_2O_5 ANODES IN PHENOLSULFONIC ACID SOLUTION

Service life of two different oxide anodes in phenolsulfonic acid (PSA) solution was investigated by accelerated electrolysis. The durability of Ti/IrO_2 Ta_2 O_5 anode increased by the addition of SnO_2 in the mixed oxides. The degradation mechanisms of Ti/IrO_2 Ta_2 O_5 and Ti/IrO_2 Ta_2 O_5 SnO 2 anodes were different. It was shown from the observation of scanning electron microscopy (SEM) and the electrochcmical measurement that, the deactivation of Ti/IrO_2 Ta_2 O_5 anode was due to the build-up of an organic film on surface. The growth of the covered film on surface was restricted by addition of SnO_2, which resulted in increasing of the service life of anodes. The over-potential for oxygen evolution on Ti/IrO_2 Ta_2 O_5 electrode increased after doping SnO_2, and the intermediate products of PSA building-up on the surface was much more rapidly oxidized. Meanwhile, a certain part of the surface oxide deposit entered into the solution leading to loss of oxides, which resulted in degradation of Ti/IroO_2 Ta_2 O_5 anode containing SnO_2 component.