A novel UIO-66-NH2@TA adsorbent for effective solid-phase extraction of Pb (II) from environmental water and juices

In this study, a new metal-organic framework adsorbent (UIO-66-NH2@TA) which can efficiently and selectively capture lead ions was developed by functionalizing UIO-66-NH2 with tannic acid (TA) by Michael addition re -action. The structural and morphological properties of the produced adsorbent, as well as its adsorption mechanism for Pb (II) were discussed. The maximum adsorption capacity of Pb (II) was 475.78 mg/g at pH 5.0, which was significantly higher than the adsorption capacity of many adsorbents reported in the literature. In addition, the adsorption isotherms and kinetics conformed to the Langmuir model and pseudo-second-order kinetic model, respectively. The results indicated that the adsorptive behavior of the adsorbent mainly depen-ded on the active sites on the surface of the adsorbents. The UIO-66-NH2@TA showed favorable selectivity to-ward Pb (II) against the interference of coexisting metal ions. It was found that the excellent Pb (II) removal performance of UIO-66-NH2@TA was mainly attributed to the synergistic effect of physical adsorption and chemisorption. Moreover, the UIO-66-NH2@TA showed extraction efficiencies of 88.01%, 82.44%, 80.20% and 74.99% for Pb (II) with initial concentration of 100 mg/L in river water, sea water, peach juice drink, and grape juice, respectively. This work proved that the UIO-66-NH2@TA had a wide application prospect in the field of Pb (II) treatment.

Automated summary

In this study, a novel metal-organic framework adsorbent (UIO-66-NH2@TA) was successfully synthesized by functionalizing UIO-66-NH2 with tannic acid (TA) through Michael addition reaction. The adsorbent exhibited a high adsorption capacity for lead ions and showed selectivity towards Pb (II) in the presence of coexisting metal ions. The adsorption isotherms and kinetics followed the Langmuir model and pseudo-second-order kinetic model, respectively. Furthermore, the UIO-66-NH2@TA demonstrated efficient extraction of Pb (II) from various aqueous samples. These findings suggest that UIO-66-NH2@TA holds great potential for the treatment of Pb (II) contamination.