Combining chemical oxidation and adsorption is highly desirable but challenging to remove organoarsenic compounds for water purification. Herein, we prepared a Zn-doped CuO (CuZnOx-2) catalyst by incorporating Zn atoms into the CuO lattice, which results in abundant surface oxygen vacancies (OVs) and modulates the electronic structure of Cu-OVs-Zn sites for PMS activation to degrade p-arsanilic acid (p-ASA) and adsorb the secondary arsenic species simultaneously. The elevated d-band centers for Cu upward to the Fermi level can significantly strengthen the adsorption of PMS, p-ASA, and the generated arsenic species. The OVs cause the charge redistribution to form electron-rich centers, which accelerate the electron transfer from Cu-OVs-Zn sites to adsorbed PMS, facilitating the cleavage of peroxide bond to produce SO4•-, •OH. Furthermore, the PMS adsorbed on the local environment of OVs with different configurations can directly decompose to produce 1O2 without undergoing PMS → O2•- → 1O2 or O2 → O2•- → 1O2 processes. The evolution process of the main arsenic species in solution and catalyst surface with oxidation was clarified. The ultimate removal of the total As involves 20 % As(III), 60 % As(V), and 20 % organic arsenic intermediates via forming inner-sphere complexes or electrostatic interaction. This contribution provides a brand-new perspective for the remediation of organoarsenic pollution over designing highly active catalysts.
Keywords: Oxidation-adsorption; Oxygen vacancies; P-arsanilic acid; Persulfate activation; Zn-doped CuO.
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