Drastic rate acceleration driven by synergistic effects: Key role of persistent free radicals coupled with ascorbic acid in decomposition of organic contaminants by ferric citrate

摘要

The development of advanced oxidation processes to generate reactive oxygen species (ROS) has been one of the most important and great challenging goals in environmental catalysis field. Herein, a representative of persistent free radicals (PFRs), activated carbon fibers (ACFs), was innovatively employed to construct a novel and outstanding catalytic system, Cit-Fe@ACFs/AA/H2O2, in which PFRs act as an electron sink to release electrons to Cit-Fe ("discharging"), thus accelerating the reaction rate-determining step of Cit-Fe-III to Cit-Fe-II. Meanwhile, ascorbic acid (AA) serves as an electron donor provides electrons to ACFs to supply the consumed PFRs ("charging"). Previously, AA was mainly reported to be a ROS scavenger instead. Remarkably, in our system, the PFRs coupled with AA enabled unblocked electron transfer, strongly improving the generation of ROS ((OH)-O-center dot), allowing for an extreme rate enhancement in oxidative decomposition of organic contaminants by hundreds of times compared with that of the sole Cit-Fe/H2O2 system. (C) 2016 Elsevier B.V. All rights reserved.