One-step self-assembly of Fe-biochar composite for enhanced persulfate activation to phenol degradation: Different active sites-induced radical/non-radical mechanism

Persulfate (PS) activation by nanoscale zerovalent iron (nZVI) is promising for water purification , while is limited due to its easy agglomeration and oxidation. Herein, nZVI encapsuled in carbon matrix shell was synthesized via one-step carbothermal reduction. The core-shell structure effectively inhibited oxidation and agglomeration of nZVI core, and graphitized porous structures facilitated phenol binding with maximal adsorption capacity of 117.10 mg/g achieved by nZVI 0.6 -BC 800 . Both reactive oxygen species ( S O 4 • − $\mathrm{S}{\mathrm{O}}_4^{•-}$ , O • H ${}^{•}\mathrm{O}\mathrm{H}$ , O 2 • − ${\mathrm{O}}_2^{•-}$ and 1 O 2 ) and electron transfer process resulted in phenol decomposition. Owing to diversified active sites, the nZVI 0.6 -BC 800 /PS system could completely degrade phenol degradation within short time, and exhibited great adaptation to extensive pH range (3.0–9.0) and coexisting substances. Additionally, the nZVI 0.6 -BC 800 /PS system could maintain over 85% removal of phenol after three recycles or 50 days of storage, and was highly-efficient to different water environments, thus proposing rational design of iron-carbon catalyst with potential in water treatment.