Iron catalysts by chemical activation of sewage sludge with FeCl3 for CWPO

•Iron carbon catalysts obtained by chemical activation of dry biosolids with FeCl3.•Those catalysts proved to be active in CWPO of antipyrine.•The main feature of the catalysts was a high stability.•Complete conversion of antipyrine and 70% TOC removal were achieved.

Highly stable iron on activated carbon catalysts were prepared by chemical activation of dry sewage sludge with iron chloride at different mass ratios (MR = mass of activating agent per unit mass of precursor). The iron content of the resulting catalysts varied between 5.2% and 7.3%. They showed a well-developed porosity, with BET surface areas above 800 m2/g, despite the high amount of inorganic matter of the sewage sludge used as precursor. TEM images confirmed the presence of iron nanoparticles sized between 3 and 11 nm fairly well dispersed. The catalysts were tested batchwise in the CWPO of antipyrine, a recognized emergent pollutant. Working with 500 mg·L−1 of the catalyst prepared with MR = 3 complete conversion of antipyrine (20 mg·L−1) and almost 70% of TOC reduction were achieved in 1 h with the stoichiometric theoretical amount of H2O2, at pH = 3 and 50 °C. This catalyst showed a high stability, in long-term (80 h on stream) continuous experiments where almost negligible iron leaching was observed.

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