Fabrication of magnetic core–shell Fe3O4@SiO2@Bi2O2CO3–sepiolite microspheres for the high-efficiency visible light catalytic degradation of antibiotic wastewater

A novel magnetic core–shell architecture Fe 3 O 4 @Sio 2 @Bi 2 O 2 CO 3 –sepiolite composite was successfully fabricated by coating a layer of Bi 2 O 2 CO 3 –sepiolite mixture onto Fe 3 O 4 @Sio 2 cores through a facile hydrothermal method. The photodegradation rates of ciprofloxacin (CIP) and tetracycline hydrochloride (TC-H) were 92.1% and 100%, respectively. A suitable amount of sepiolite in Fe 3 O 4 @Sio 2 @Bi 2 O 2 CO 3 –sepiolite can enlarge the specific surface area, promote the formation of an excellent photocatalyst structure, and generate a strong interfaces effect between the sepiolite and Fe 3 O 4 @Sio 2 @Bi 2 O 2 CO 3 . This condition endowed the as-prepared photocatalyst with high light harvesting capability and abundant active reaction sites. It also boosted the separation of photogenic e − /h + pairs. Moreover, this condition inhibited the recombination of e − /h + pairs and decreased the energy band gap, thereby enhancing the visible light catalytic degradation of antibiotics. The active species produced during photocatalysis included h + and •O 2 − , with h + as the dominant active species. The as-prepared photocatalyst exhibited excellent photocatalytic degradation activity, magnetic separation performance, recyclability , and stability.