Post-modification synthesis of functionalized Zr-based metal-organic framework/alginate aerogel for sensitive fluorescence sensing and efficient adsorption removal of Cu(II) and Cr(VI) in apple juice

Achieving the integration of detection and removal for Cu(II) and Cr(VI). • Cr(VI) is captured by amino groups of MDS and partially reduced to Cr(III). • Pyridine and amino of aerogel provided coordination sites to capture Cu(II). • Biocompatible aerogel has low cytotoxicity for L929 cells. • Detection and removal have no obvious effect on the quality of apple juice. Heavy metal pollution in food, particularly Cu(II) and Cr(VI), poses a significant threat to human health. A bifunctional composite aerogel (MDS) is successfully synthesized, immobilizing a 5,5′-diamino-2,2′-bipyridine (dabpy) post-modified MOF-808 within a sodium alginate (SA) aerogel for sensitive detection and efficient removal of heavy metal ions in apple juice. Mechanism studies reveal that pyridinic N and NH 2 in MDS display a high affinity for Cu(II), while Cr(VI) exhibits an electrostatic attraction to the protonated NH 2 . The interaction process triggers electron transfer, which leads to fluorescence quenching. MDS aerogel shows detection of Cu(II) and Cr(VI) with low limits of detection, and adsorption capacities of 354.91 mg/g for Cu(II) and 258.62 mg/g for Cr(VI). The MDS aerogel removal efficiency exceeded 94% in apple juice. In vitro cytotoxicity assays indicate low cytotoxicity of MDS. This work offers a potential bifunctional platform for heavy-metal sensing and removal in food matrices. Download: Download high-res image (135KB) Download: Download full-size image