Schwertmannite as a new Fenton-like catalyst in the oxidation of phenol by H2O2.

In this study, schwertmannite was prepared through a hydrothermal method and used as a new Fenton-like catalyst in the oxidation of phenol by H2O2. The synthesized iron oxide had a formula of Fe8O8(OH)4.5(SO4)1.75 with a weak crystalline structure as well as a high specific surface area of 325.52 m(2) g(-1). However, schwertmannite has not been used as a Fenton-like catalyst so far, and its catalytic mechanism in the oxidation of phenol is still unknown. This study confirmed that schwertmannite had a good catalytic activity in the oxidation of phenol via a OH radical mechanism. The free radicals could be generated on the schwertmannite surface by ≡ Fe(III) species and in bulk solution by dissolved Fe(III) over a wide pH range. The synthesized schwertmannite also showed a high catalytic ability in the oxidation of phenol in the presence of 0.5M nitrate, chloride or sulfate anions at initial pH 5.0, indicating its potential application in the treatment of high salinity wastewater. In addition, phenol removal percentage could still reach 98% after schwertmannite was successively used for 12 cycles, indicating the good reusability of this catalyst, although a phase transformation of schwertmannite to goethite was observed.