Catalytic oxidation of phenol in wastewater — A new application of the amorphous Fe78Si9B13 alloy

The amorphous Fe78Si9B13 alloy was used as a heterogeneous Fenton catalyst in the process of phenol degradation. The influences of main operating parameters such as reaction temperature, catalyst amount, hydrogen peroxide dosage and initial pH of solution on phenol degradation rate were investigated. The maximum mineralization of phenol was achieved at 60°C, 6 g/L Fe78Si9B13, 0.31 mol/L hydrogen peroxide, with an initial pH of 2.5. More than 99% of phenol was completely removed under the optimum conditions within 10 min for a solution containing 1000 mg/L of phenol. Batch experiments for solutions containing phenol concentrations ranging from 50 to 2000 mg/L were investigated under the above conditions and the same excellent degradation rate was obtained. The Fe78Si9B13 showed better catalytic activity than iron powder and Fe2+. Addition of n-butannol (hydroxyl radical scavenger) decreased the degradation rate of phenol, which demonstrates that hydroxyl radicals were mainly responsible for the removal of phenol. We demonstrated that phenol may be degraded by hydroxyl radicals decomposed by hydrogen peroxide on the surface of Fe78Si9B13 and illustrated the reaction mechanism for this process. This amorphous alloy exhibited high stability in recycling experiments and showed excellent reuse performance even after continuous operations of 8 cycles.