Preparation of Prussian Blue Analogue Modified Porous Ceramic Balls and Its Application in As Adsorption

Porous ceramic ball with the size of 3 similar to 5 mm was prepared by powder sintering and space-holder method at 1573 K for 1 h. A desilication process was adopted to decrease the Si/Al molar ratio of porous ceramic ball surface. After being alkaline treated in 1 mol/L NaOH solution for 10 h, Si/Al molar ratio of porous ceramic ball surface was decreased from 4.5 to 1.76. Surface topography of the desilicated and undesilicated porous ceramic balls were investigated by scanning electron microscopy (SEM). In the SEM images of desilicated porous ceramic ball, plenty of nanoparticles about 30 nm were observed. The reveal of the 30 nm nanoparticles means that the amorphous phase which was generated in the sintering process was greatly dissolved into the NaOH solution. A Prussian blue analogue was synthesized on the surface of the desilicated porous ceramic balls by the reaction between desilicated porous ceramic balls and potassium ferrocyanide solution. The Prussian blue analogue on the surface of desilicated porous ceramic ball was characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared absorption spectrum (IR), which showed that a kind of Al-Fe Prussian blue analogue was fabricated on the surface of the desilicated porous ceramic balls. The mechanism of the formation of Al-Fe Prussian blue analogue on the surface of desilicated porous ceramic ball was also investigated, which showed that the desilication process plays an important role in the formation of Al-Fe Prussian blue analogue. By the desilication process, the Si/Al molar ratio of porous ceramic ball surface was greatly decreased, which means more Al-activity sites were generated. With the mixture of desilicated porous ceramic balls and potassium ferrocyanide solution, the Fe(CN)(6)(4-) was bonding to the Al atoms on the surface of desilicated porous ceramic ball and the Al-Fe Prussian blue analogue was generated. The As adsorption capacity of Prussian blue analogue modified porous ceramic ball was also investigated with NaH2AsO4 as arsenic source.