High-gravity-assisted rapid and controlled synthesis of hollow zirconia nanoparticles for dye and phosphate adsorption

Nanosized zirconia with hollow structure combines the advantages of nanosized zirconia and hollow materials, is promising for a broad range of applications. Herein, we propose an approach for efficiently synthesizing hollow zirconia nanoparticles (HZNs) based on CaCO 3 templating by a high-gravity-assisted precipitation approach in a rotating packed bed (RPB) reactor. The as-prepared HZNs has an average hollow size of about 100 nm and the highest reported BET surface area of 398.9 m 2 /g. Compared to conventional stirred tank reactor, the RPB significantly shortens the coating reaction time from 30 min to 1 s to form core–shell structures. And the crystal form, shell thickness, hollow size and morphology can be readily controlled. Furthermore, the HZNs exhibit superior Congo red adsorption capacity of 1106.1 mg/g, which is increased by 50 % compared to the highest capacity reported in allied zirconia systems. Importantly, the HZNs also realize efficient adsorption of other azo dyes and phosphate.