Fullerol modification ferrihydrite for the degradation of acid red 18 under simulated sunlight irradiation

Fullerol (polyhydroxyfullerene, PHF) has shown favorable electron accepting properties in semiconductor photocatalytic systems, but little is known about the possibility of electron transfer mediation of PHF in heterogeneous photo-Fenton processes. This work intends to investigate the effect of PHF on the heterogeneous photo-Fenton activity of ferrihydrite (Fh). PHF/ferrihydrite (PHF/Fh) composites were prepared and their photo-Fenton activities in the degradation of acid red 18 under simulated sunlight irradiation were examined. The structural characteristics of the as-synthesized samples were studied using XRD, SEM-EDS, SPM, DRS, and N-2 adsorption-desorption. The results showed that PHF/Fh had much higher catalytic activities than Fh, and appropriate contents of PHF on PHF/Fh could enhance the stability of Fh. In addition, the presence of PHF on PHF/Fh could enhance the production of O-1(2) and (OH)-O-center dot as compared with pure Fh. We propose that the excited state PHF could efficiently sensitize the ground state O-2 to generate O-1(2), and at the same time could transfer electrons to the Fe3+ on Fh, leading to an accelerated reduction of Fe3+ to Fe2+. As a result, the decomposition of H2O2 (by Fe2+) into (OH)-O-center dot could be promoted as well. On the other hand, based on the results of GAMESS calculation and GC-MS analysis, the degradation pathway of AR18 was further proposed. (C) 2016 Elsevier B.V. All rights reserved.