Ca‐Fe mixed metal oxide adsorbent prepared via a novel coprecipitator for efficient fluoride adsorption

The extensive utilization of fluorine industrial products has brought abundant fluorine pollution. The fluorine removal is important. In this study, CaO, as a novel coprecipitator, was conducted to synthesize Ca‐Fe‐SO4 layered double hydroxide (CF) via co‐precipitation of FeSO4. Ca‐Fe mixed metal oxide adsorbent (CCF) was fabricated by calcinating CF for efficient fluoride adsorption. The results showed that CCF adsorbent had an excellent adsorption performance for fluoride. It was attributed to two reasons as follows: On one hand, Ca had a strong affinity for fluoride, improving the adsorption capacity of adsorbent for fluoride. On the other hand, Fe had a strong magnetism, which could promote the recovery of the adsorbed material. The adsorption capacity of CCF for fluorine was analyzed by batch adsorption experiments, the adsorption capacity was 160.66 mg/g at temperature of 298 K and pH of 7. Moreover, the adsorption process of fluorine and the actual adsorption process were in accordance with Langmuir model and the pseudo‐second‐order kinetic model, respectively. According to the analysis of pHzpc, FITR and XPS, the main adsorption mechanisms of CCF for fluoride in water were complexation and electrostatic interactions. Therefore, this study suggested that CaO can be a novel coprecipitator to prepare a new efficient fluorine adsorbent for the treatment of industrial wastewater. A novel Ca‐Fe mixed metal oxide adsorbent had an excellent adsorption performance for fluorine, and the adsorption capacity can reach 160.66 mg/g at temperature of 298 K and pH of 7. The adsorption mechanisms of Ca‐Fe mixed metal oxide adsorbent for fluoride in water was mainly depended on the complexation and electrostatic attraction.