One-step removal of p-arsanilic acid via constructing bifunctional Zr-CuO/α-FeOOH catalyst: Efficient peroxymonosulfate activation, cooperative oxidation and adsorption

Abstract

The simultaneous oxidation and in-situ adsorption of organoarsenic compounds from wastewater remains a formidable challenge due to their structural stability. Herein, we prepared a novel Zr-CuO/α-FeOOH catalyst with dual-active-components to activate peroxymonosulfate (PMS) for p-arsanilic acid (p-ASA) degradation and inorganic arsenic immobilization. By combining the highly efficient PMS activation activity of Zr-CuO with the excellent arsenate adsorption capacity of α-FeOOH, approximately 100 % of p-ASA was degraded and then converted into As(V) to be adsorbed. Comprehensive characterization and theoretical calculations reveal that the introduction of Zr atoms can modulate the electronic structure and increase specific surfaces of CuO simultaneously. The elevated d-band center of Cu results in high chemisorption affinity to PMS. ¹O₂, radicals, and catalyst-mediated electron transfer pathways all contribute to p-ASA oxidation. Additionally, the interaction between the loaded Zr-CuO and the support α-FeOOH also accelerates redox cycles of Cu(I)/Cu(II) and Fe(II)/Fe(III) due to the interface electron rearrangement. The speciation trajectory towards the sequential oxidative transformation of p-ASA via organoarsenic intermediates to As(III) and ultimately As(V) was elucidated. The apparent adsorption kinetics, spectroscopic insights, and bonding chemistry demonstrated that the adsorption of As(V) was mainly chemisorption through surface complexation, and adsorption strength by using as-prepared catalysts follows α-FeOOH > Zr-CuO/α-FeOOH > Zr-CuO. This contribution not only opens a high potential avenue for organic heavy metals treatment but also sheds light on developing advanced catalysts based on the interface mechanism toward PMS activation.