Heterogeneous Fenton oxidation of paracetamol using iron oxide (nano)particles

• The advanced oxidation of an emerging water pollutant, paracetamol, is investigated.
• Iron oxides (magnetite and maghemite) are active as Fenton's catalysts.
• The effect of catalyst and oxidant concentrations, and temperature is investigated.
• Nanostructured magnetite exhibits the best activity and recyclability.
• Low iron leaching and low lixiviate activity proved heterogeneous catalysis.

100 mg L−1 paracetamol aqueous solutions were treated by heterogeneous Fenton oxidation at acidic pH (2.6). Three types of iron oxides – nano- and submicro-structured magnetite, nanostructured maghemite – were tested as catalysts for that purpose. For each system, the paracetamol conversion and mineralization yield (Total Organic Carbon removal) were evaluated, as well as the catalyst stability upon recycling.The influence of reaction parameters such as temperature, iron amount, and hydrogen peroxide dosage was also investigated. Paracetamol mineralization was improved by high temperature and low oxidant dosage due to radical scavenging effects. In best conditions (two times the stoichiometric amount of H2O2, a temperature of 60 °C, a catalyst concentration of 6 g L−1), paracetamol was fully degraded after 5 h, but total mineralization was not yet achieved: TOC removal reached about 50% when magnetite powders were used as catalysts. All iron oxides exhibited low iron leaching (<1%) and stable catalytic activity upon first recycling.