Co<sub>4</sub>(PW<sub>9</sub>O<sub>34</sub>)<sub>2</sub> Polyoxmetalate Cluster Intercalated\nin Layered Double Hydroxides\nas Catalyst for the Oxidation of <i>p</i>‑Arsanilic\nAcid and Subs

The ecological risk associated with the hidden release\nof inorganic\narsenic from <i>p</i>-arsanilic acid (<i>p</i>-ASA) due to microbial activities and sunlight irradiation underscores\nthe urgent need for an effective <i>p</i>-ASA control strategy.\nHerein, polyoxometalate cluster intercalated layered double hydroxides\n(LDH-CoPW) were synthesized to activate peroxymonosulfate (PMS) for\nthe rapid degradation of <i>p</i>-ASA while simultaneously\nimmobilizing inorganic arsenic. CoPW was loaded into the nanolayer\nof LDH through a simple ion exchange method, LDH-CoPW with a confined\nstructure possessed independent adsorption and catalytic sites, and\nthe confined CoPW acted as the activator for PMS activation while\nthe LDH layer was responsible for the adsorption of inorganic arsenic.\nNoninterfering operation of the active sites endowed LDH-CoPW with\ndistinguished performance. Satisfactory removal of <i>p</i>-ASA and TOC by the LDH-CoPW/PMS system was attributed to the long-acting\noxidation capacity of Co(IV)O. By calculating the second-order\nreaction rate constants of Co(IV)O with probes for the first\ntime, we determined the striking contribution of Co(IV)O to\nthe <i>p</i>-ASA degradation via the probe-based kinetic\nmodel and revealed the underlying mechanism of PMS activation. This\nwork lies in providing a catalyst synthesis strategy that mitigates\nthe antagonism between active sites and elucidating the activation\nmechanism of PMS by LDH-CoPW synthesized using this strategy.