Kinetic and mechanistic investigations of the oxidation of organics by near-infrared light driven thermocatalytic activation of peroxydisulfate with Fe3O4

The utilization of renewable solar energy through near-infrared (NIR)-driven photothermal catalysts offers a potential novel strategy for environmental remediation. In this work, we reported an initial demonstration of the peroxydisulfate (PDS) activation in oxidative degradation of organics (represented by bisphenol A (BPA)) via a unique NIR light-to-heat conversion effect using cost-effective and biocompatible nanoparticles (NPs). The systematical investigation of the photothermal experiments found that Fe 3 O 4 magnetic NPs exhibit great photothermal conversion efficiency (65.4%) and have the capability to quickly elevate the system temperature to 61°C. The increased reaction temperature leads to the homolytic fission of the O O bond for producing sulfate radical (SO 4 − ) and the derivative hydroxyl radical ( OH), as confirmed by the radical quenching and electron paramagnetic resonances (EPR) tests, and in turn accelerates the thermocatalytic degradation reaction of BPA. The BPA degradation reaction rate of the NIR/Fe 3 O 4 /PDS system is about 25.8 times and 9.4 times of that in the NIR/PDS and Fe 3 O 4 /PDS systems, respectively. Both photothermal heating and surface valence states conversion of Fe 2+ /Fe 3+ on Fe 3 O 4 under dark conditions make a contribution to the observed oxidation reactions. Moreover, this NIR light-to-heat activation system exhibits efficient photocatalytic degradation of BPA molecules in deep water by virtue of the deep penetration capability of NIR light in water, highlighting NIR-driven photothermal catalysts hold the excellent potential to be applied in practical water restoration through PDS activation.