Zn-MOFs/CNTs Composites: Fast and Effective Heavy Metal Ion Removal from Wastewater

The subsistence of heavy metal ions, including Cu²⁺ and Pb²⁺, raises substantial concerns due to their potential toxicity to both the environment and human health. In this study, a novel adsorbent, the Metal-organic framework based on zinc (Zn-MOFs), incorporated with carbon nanotubes (CNTs), denoted as Zn-MOFs/CNTs, were synthesized using a room-temperature precipitation method for the efficient removal of heavy metals. The Zn-MOFs/CNTs composites were meticulously characterized using a range of analytical techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). The effectiveness of Zn-MOFs/CNTs in removing Cu²⁺ and Pb²⁺ ions from water was assessed, considering adsorption time and initial ion concentration as key parameters. The results demonstrated the remarkable performance of Zn-MOFs/CNTs, achieving removal efficiencies exceeding 98% for Pb²⁺ and 93% for Cu²⁺ within a 12-minute timeframe. The maximum adsorption capacities determined (qm) by Langmuir isotherms were 1620 mg/g for Cu²⁺ and 1480 mg/g for Pb²⁺ at 303 K. The study concludes by providing recommendations and suggesting future directions for enhancing the application of MOFs-functionalized/CNTs in water treatment and reuse.