Preparation\nof Guanidine-Grafted NH<sub>2</sub>‑MIL-101(Fe)/Polyvinylidene\nFluoride Mixed Matrix Membranes for Adsorption of Pb<sup>2+</sup> for\nIsopropanol Purification

Electronic-grade isopropyl alcohol is widely utilized\nin the cleaning\nof semiconductors and microelectronic components. Removing ions like\nPb<sup>2+</sup> is crucial since the presence of impurities may cause\ndegradation of electronics, increased failure rates, and short circuits.\nMembrane materials offer a number of advantages in the field of adsorption\nseparation; however, the lack of adsorption sites results in limited\nadsorption capacity. In the current work, guanidino-grafted NH<sub>2</sub>-MIL-101(Fe) was incorporated into polyvinylidene fluoride\n(PVDF) to prepare MOF/PVDF mixed matrix membranes (NM/PVDF) for the\nremoval of Pb<sup>2+</sup> from isopropanol. Benefiting from the larger\nspecific surface area and more lone electron pairs in the guanidine\ngroup, the Pb<sup>2+</sup> adsorption capacity of the as-prepared\nNM/PVDF membrane was 29.4458 mg/g, which was higher than that of the\nNH<sub>2</sub>-MIL-101(Fe)/PVDF membrane (20.9306 mg/g) and the pure\nPVDF membrane (6.7324 mg/g). The NM/PVDF membrane was able to reduce\nthe concentration of Pb<sup>2+</sup> from 500 to 86.73 ppb. This work\nhighlights the potential of guanidine-grafted Fe-based MOFs/PVDF membranes\nas adsorbents for acquisition of electronic-grade solvents.