Preparation of SiO₂@TiO₂:Eu³⁺@TiO₂ core double-shell microspheres for photodegradation of polyacrylamide

Recently, polyacrylamide (PAM) has been widely used in polymer flooding technology to enhance oil recovery and oil production. However, the difficulty in removing hydrolysed PAM (HPAM) from wastewater still seriously blocks the further application of polymer flooding in the oilfields. Herein, we demonstrate the preparation of SiO₂@TiO₂:Eu³⁺@TiO₂ core double-shell microspheres (STT) through a two-step solvothermal and sol-gel coating strategy. The as-prepared STT exhibits an ideal photocatalytic activity for the photodegradation of HPAM. More importantly, by using STT as the model, the correlation between fluorescence intensity and photocatalytic activity of the photocatalysts is investigated. The results suggest their oppositional relationship. Since many kinds of photocatalysts are utilized in the degradation of organic pollutants, it is believed that our work will not only promote the development of photocatalysis in the field of oil extraction, but also offer a convenient method for evaluating the photocatalytic activity of the photocatalysts.