Removing organic compounds from aqueous medium via wet peroxidation by gold catalysts

A new heterogeneous Fenton-like system, consisting of supported Au catalysts and hydrogen peroxide, was proved to be effective in removing low level organic compounds (ca. 100 ppm) such as phenol, ethanol, formaldehyde, and acetone in aqueous solution. Among all gold catalysts the Au/hydroxyapatite (Au/HAp) exhibits the highest activity, and even better than the conventional iron ions exchanged zeolite (Fe/ZSM-5) catalyst. In particular, unlike the limited operational pH range (pH: 2-5) for the other heterogeneous Fenton catalysts such as Fe/ZSM-5, Au/HAp shows higher stability even in strong acid solution (pH ∼ 2), due to almost no leaching of active metal from supports into solution. It can be potentially applied in treating the industrial wastewaters with strong acidity and purifying drinking water. In addition, in the case of complete oxidation of phenol, a plausible route was suggested for deep understanding of this process.