Microwave Solvothermal Fabrication of Zirconia Hollow Microspheres with Different Morphologies Using Pollen Templates and Their Dye Adsorption Removal

Both porous and scale-like wall zirconia (ZrO 2 ) hollow microspheres were successfully prepared through a facile and mild microwave solvothermal method using the rape pollen as biotemplates. The formation mechanisms were discussed for both ZrO 2 hollow microspheres fabricated using pollen biotemplate with different pollen treatments. The porous ZrO 2 hollow microspheres had a specific surface area of 40.92 m 2 ·g –1, significantly higher than scale-like wall ZrO 2 hollow microspheres (24.79 m 2 ·g –1 ) and ZrO 2 particles (27.99 m 2 ·g –1 ). The adsorption test results showed that porous ZrO 2 hollow microspheres had a higher adsorption capability (96.98 g·mg –1 ) than scale-like wall ZrO 2 hollow microspheres (38.55 g·mg –1 ) and ZrO 2 particles (32.03 g·mg –1 ) for Congo red. The adsorption followed pseudo-second-order kinetics, and the adsorption process was homogeneous adsorption of monolayer.