Investigation of the behavior and mechanism for defluoridation by modified mayenite (Ca12Al14O33) in sodium aluminate solution

Removal of fluorine in sodium aluminate solution facilitates the purity of aluminum products and reduces the corrosiveness of equipment. Hence, a modified synthetic method was used to prepare mayenite (Ca12Al14O33) adsorbent with the enhanced fluorine adsorption capacity in sodium aluminate solution. The adsorption process conformed to a pseudo-second-order kinetic model (R2 = 0.99) and Langmuir adsorption isotherm (R2 = 0.98) indicating that the adsorption of fluorine by Ca12Al14O33 is chemisorption. According to X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT − IR), X-ray fluorescence (XRF), and X-ray photoelectron (XPS) analysis, the mechanism of fluorine adsorption by Ca12Al14O33 was the ligand exchange with − OH and the formation of F − Al bond. Therefore, Ca12Al14O33 could be used as a potential adsorbent for fluorine in sodium aluminate solution.