Effect of salt on electrocatalytic performance and mechanism
To understand the effect of salt on the performance and mechanism of electrocatalytic degradation,the performance test of electrocatalytic oxidation of an industrial wastewater was carried out.The effect of salt on the electrocatalytic oxidation was analyzed by investigating the COD(chemical oxygen demand)removal efficiency under different salt contents(0.1％-2.0％),current densities(5-20mA/cm2),plate spacing(0.5-1.5cm)and pH(4-10).The production of active species in different salt-containing systems was analyzed by electron paramagnetic resonance(EPR/ESR)technique.In addition,the service life of the electrode was evaluated by a rapid test method.The results showed that the maximum COD removal efficiency of the electrocatalytic system without salt and with the addition of NaCl and Na2SO4 were 58.4％,84.7％and 63.3％,respectively,and the corresponding current efficiencies were 15.4％,19.6％and 16.7％.A quadruple peak intensity of 1∶2:2∶1 was found in the original electrocatalytic system,which was consistent with the characteristic peak of OH.The characteristic peaks of·OH、1O2和·O2 werefound in the electrocatalytic system with Na2SO4,while similar characteristic peak of chlorine-containing free radicals were additionally found in the electrocatalytic system with NaCl.Under the enhanced test conditions,the electrode lifetime was 11460s.NaCl was beneficial to increasing the maximum COD removal rate with high current efficiency and enriching the types of active species.
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