Antioil Ag 3 PO 4 Nanoparticle/Polydopamine/Al 2 O 3 Sandwich Structure for Complex Wastewater Treatment: Dynamic Catalysis under Natural Light

We have successfully fabricated sandwich structural Ag 3 PO 4 nanoparticle/polydopamine/Al 2 O 3 porous small balls (APPAOs) by a facile homogeneous precipitation method, which exhibit a natural light catalysis capacity to degrade different kinds of water pollutants including industrial dyes and agricultural pesticides. The porous Al 2 O 3 provides the substrate to form the Ag 3 PO 4 /Al 2 O 3 heterojunction, as well as increases the specific surface area (SSA) of the Ag 3 PO 4 nanoparticle, thus greatly enhancing the photocatalytic capacity. Polydopamine (PDA) plays the role of adhesive between Al 2 O 3 substrate and Ag 3 PO 4 nanoparticle, aiming to stabilize the synthesized APPAO catalyst. A part of Ag 3 PO 4 is reduced by PDA and transformed into a Ag nanosphere, which further increases SSA and enhances the catalytic ability of the material by the plasmonic effect. Further study shows that there is a dynamic process between catalysis and adsorption/desorption equilibrium; i.e., with the catalysis going ahead, the adsorption/desorption equilibrium accordingly shifts thus thoroughly treating the pollutants. In addition, the superhydrophilic surface provides the APPAO with an excellent antioil property, which greatly reduces secondary pollution, and the small ball structure makes the material easy to use and recycle. Because of its excellent reusability, mild catalytic conditions, and ease of use, the APPAO has great potential to be used in the field of low-cost practical wastewater treatment.