Preparation of Ag@Ag2O/AgCl composite photocatalytic material and degradation performance for SD I under sunlight

Abstract

The photocatalytic material Ag@Ag₂O/AgCl was successfully prepared using GO and CA gel as carriers, through chemical coupling, in situ deposition, and photo-induced reduction. The performance of the composite photocatalytic material, its photodegradation performance, mechanism, and pathways of Sudan I (SD I) in APG aqueous solution were explored. The results showed that the prepared composite photocatalytic material was loaded with a large amount of irregular nano-Ag₂O, AgCl, and silver nanoparticles (AgNPs). In the material, the mass fraction of Ag element is the highest (36.41 wt%). The photocatalytic material showed a significant broad absorption in both the UV and visible light regions, and under visible light irradiation, it can generate a stable and reversible photocurrent, with a small resistance to photogenerated electron transfer, exhibiting good photocatalytic performance. SD I exhibits good solubility in APG (7 mL/1000 mL) aqueous solution after ultrasonic and heating (100 ℃) treatment for 30 min. At a certain concentration of SD I, acidic solution and lower temperature are conducive to the photocatalytic degradation of SD I, and the catalytic degradation process conforms to the pseudo-first-order reaction kinetic relationship. Through five cycles of experiments, the stability of the material was demonstrated to be good. Superoxide radicals (·O₂⁻) and holes (h⁺) generated during the photocatalytic degradation are the main active species responsible for degrading SD I. SD I molecules were decolorized by N=N and C-N bond cleavage, and the benzene and naphthalene ring were opened under the action of active substances (h⁺, ·O₂⁻) and finally mineralized into CO₂, H₂O and inorganic ions.