Exploration and removal of multiple metal ions using mixed-linker-architected Zn-MOF in aqueous media

A Zn-based 3D MOF, [Zn2(H3L1)(L2)].H2O named PUC-5 was synthesized using trimesic acid (H3L1) and 1-(3-aminopropyl)Imidazole (L2) by solvothermal method. PUC-5 has been characterized using SCXRD, PXRD, FT-IR, SEM, XPS, TGA, BET and Zeta potential techniques. The PUC-5 exhibited extremely high water and pH stability. We explored the utility of PUC-5 as a sensitive probe for the detection and removal of multiple heavy metal ions (Fe2+, Pb2+ and V5+) from water. The detection limits calculated in the case of Fe2+, Pb2+ and V5+ were 0.129 µM, 0.113 µM and 0.246 µM which were found to be lower than the limits established by the world health organisation (WHO) for drinking water. The detection ability of PUC-5 towards targeted metal ions was further confirmed by Zeta potential, FTIR and XPS techniques. Moreover, the adsorption potential of PUC-5 towards Fe2+, Pb2+ and V5+ was studied by the ICP-MS method. Different kinetic and isotherm models were used to assess the effects of time, temperature, adsorbent content and initial metal ions concentration on PUC-5′s ability to adsorb Fe2+, Pb2+, and V5+. The adsorption process of metal ions could be well depicted by Pseudo-second-order kinetics and Langmuir isotherm models suggesting monolayer chemisorption with maximum adsorption capacities of 208.7, 192.6 and 203.6 mg g−1 for Fe2+, Pb2+ and V5+ respectively. Furthermore, the thermodynamic parameters support the spontaneous behaviour and exothermic nature of the adsorption process. Interestingly, PUC-5 is a recyclable material and can be reused with high adsorption efficiency suggesting a high potential of adsorbent towards Fe2+, Pb2+ and V5+.