3D porous Ca-modified Mg-Zr mixed metal oxide for fluoride adsorption.

• Ca-modified Mg-Zr MMO was investigated for fluoride treatment. • The maximum adsorption capacity of the CCMZ reached 144.05 mg/g. • Electrostatic attraction and ion exchange are adsorption mechanisms. • The agglomeration of the products was effectively avoided. Fluoride removal is an urgent problem in the field of water treatment. In this study, fluoride adsorption was performed using Ca-Modified Mg-Zr Mixed Metal Oxides (CCMZ), which was successfully prepared by a green hydrothermal process followed by high-temperature calcination. CCMZ was prepared using a lamellar MgO and ZrO 2 Mixed Metal Oxide (MMO). Then, calcium (Ca, a strong fluorophilic metal) was dispersed over the MMO, to form a 3D spongy structure. The obtained microstructural features significantly enhanced the fluoride migration and diffusion, resulting in an adsorption capacity of 144.05 mg/g. The agglomeration of the products was effectively avoided, so CCMZ showed good selectivity and reusability. Batch adsorption experiments and subsequent sample characterization showed that the fluoride adsorption mechanism of CCMZ involved electrostatic attraction and ion exchange mechanism. Therefore, this manuscript provides a rational design and a simple preparation method for a new class of fluoride adsorbents. [ABSTRACT FROM AUTHOR]