Ligand competition strategy-induced metal-organic gel MOG-808 for the detection and removal of Cr(VI) from celery juice.

Hexavalent chromium (Cr(VI)) contamination of vegetables significantly threatens food safety due to its carcinogenicity, toxicity, and bioaccumulation properties. This work synthesizes metal-organic gel MOG-808 by employing a ligand competition method for the detection and removal of Cr(VI) in celery juice. Introducing bipyridine to compete with the ligand of MOF-808 induced transformation into amorphous MOG-808 with low coordination active sites to specifically recognize Cr(VI). MOG-808 demonstrates excellent fluorescence detection and adsorption capabilities for Cr(VI) with a limit of detection of 0.042 μmol/L and a maximum adsorption capacity of 353.47 mg/g. MOG-808 achieves a removal rate of 98.4 % for Cr(VI) at an initial concentration of 1.0 mg/L in celery juice with minimal impact on the juice's quality. The MOG-808 in the form of gel exhibits excellent anti-interference and reusability. This study successfully develops a multifunctional MOG-based absorbent, providing a potential strategy for detecting and removing Cr(VI) contamination in food matrices.