2. Preparation of samples
2.1. Preparation of SO42−/TiO2 superacid
Ammonia was added into Ti(SO4)2 solution until pH = 10 at room temperature. This solution was dried at 110 °C for 24 h. The solid was then ground and treated with a solution of 0.5 mol/L H2SO4 for 1 h. The resulting solution was dried at 100 °C, and ground. The solid material was calcinated at 500 °C for 3 h, and ground into powder.
2.2. Preparation of the film-coating solution
Eight percent and 14% polyvinylalcohol (PVA) were prepared by dissolving proper amount of PVA in water at 90–95 °C. After cooling down to 80–85 °C, ethanol, glycol, carboxymethyl cellulose (CMC), ethylenediamine tetraacetic acid (EDTA-2Na) solution and sodium dodecylbenzene sulfonate (DBSNa) solution were added. Then, proper amount of SO42−/TiO2 superacid and 4 g polyaniline were added in batches. At last, 13 mL of white latex was added. The reaction mixture was stirred for 2–3 h, cooled down to 80–85 °C and stirred again for 1 h.
2.3. Preparation of uranium contaminated metal sample
A piece of 5 cm × 5 cm stainless steal sample was dipped into HCl solution, washed with distilled water several times and dried at room temperature. UO2(NO3)2 (1 mg/L) solution was added drop-wise onto the sample surface and dispersed evenly, air-dried and calcinated at 600 °C for 3 h.