Abstract
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•Magnetic ferric modified biochar (MFBC) was used to activate periodate (PI).•Multiple active species (Fe (IV), 1O2, •O2−, and IO3•) existed in MFBC/PI process.•Iron leaching-precipitation and iron redox cycles played important role.•Phosphorus and sulfur atoms on DDA were the main active sites in MFBC/PI systems.
The vital roles of synergetic carbon structure and iron species in periodate (PI)-based oxidation reaction remains unclear. In this study, multiple active species were identified as Fe(IV), 1O2, •O2−, and IO3• in the magnetic ferrite-modified biochar (MFBC)/PI process. The MFBC/PI system maintained stable degradation efficiency under wide pH ranges and the presence of various interfering anions. A unique continuous cycle experiment verifies the contribution of iron leaching-precipitation equilibrium and redox equilibrium to the degradation efficiency of PI/MFBC system. Moreover, except carbonyl functional groups (CO) on biochar could activate PI, the interacted biochar-Fe provides an active site dispersion and fast electron transfer. The attack sites and degradation pathways on DDA were determined with DFT, P and S atoms on diphenylamine dithiophosphoric acid (DDA) were suggested to be the most active sites in MFBC/PI systems. Overall, this work investigated the mechanism of PI activation by the synergistic metal–carbon at the solid–liquid interface of heterogeneous catalysts, would provide a new perspective into the catalytic activation of PI by iron-carbon composites.