Study on the coordination properties of [CeFx]4−x and [BFy]3−y in sulfuric acid medium by complexometric potentiometric titration

•Coordination properties of CeFx4−x and BFy3−y were investigated by complexometric potentiometric titration.•The fluorine was recovered as KBF4 before extractive separation of rare earths.•Fluorine can be separated from cerium from fluorine-bearing rare earth sulfate solution.

Complexometric titration experiments were carried out in three systems of F–Ce, F–B and F–Ce–B to investigate the coordination properties of CeFx4−x and BFy3−y with ion-selective electrode as indicator. The structure of the complex was characterized by Raman spectrometer. The results show that in sulfuric acid medium, F− coordinates with Ce4+ to form CeF22+ complex, and B(OH)3 can take the F− from CeF22+ to form BF4−. The BFy3−y is more stable than CeFx4−x. The KBF4 product was prepared and confirmed by XRD. The results indicate that it is feasible to separate fluorine from cerium with B(OH)3 and recover fluorine as KBF4 before extraction from fluorine-bearing rare earth sulfate solution.

Graphical abstractThe graphical abstract shows the complex reaction of F− and H3BO3 in F–Ce mixed solution under acidic condition.Figure optionsDownload full-size imageDownload as PowerPoint slide