Degradation of organics using LaFeO_(3)as a persulfate activator under low-intensity ultra-violet-light irradiation:Catalytic performance and mechanism

ABO_(3)-type perovskite oxides with abounding defect structures and diverse physical chemistry attributes have been extensively studied in heterogeneous catalysis.Semiconductor LaFeO_(3)perovskites fabricated via the sol-gel method were used as peroxydisulfate(PDS)activators for methylene blue(MB)degradation under low-intensity ultra-violet(UV)-light to evaluate the degradation efficiency of organic pollutants and mechanism.The results indicate that under low-intensity UV irradiation,the developed UV/LaFeO_(3)/PDS system shows excellent degradation ability of organic pollutants in a wide pH range.Electron spin resonance and radical quenching experiments verify that SO_(4)^(·-),·OH,h^(+)and ^(1)O_(2)are generated during the activation process,and ^(1)O_(2)plays a dominant role in MB degradation.Reduction of low oxidation state Fe(Ⅱ)and O_(2)^(2-)/O^(-)on the LaFeO_(3)surface shows that oxygen vacancy,as the electron transfer mediator,enhances the redox cycle efficiency of Fe(Ⅱ)/Fe(Ⅲ).Photogenerated electrons of LaFeO_(3)involved in the cyclic transformation of Fe(Ⅱ)/Fe(Ⅲ)and PDS activation further increase the number of active radicals and thus promote the synergistic effect of photocatalytic coupled with sulfate radicalbased advanced oxidation processes.