Functionalized magnetic hydrogen-bonded organic framework for preconcentration and rapid detection of lead and copper ions in water

Hydrogen-bonded organic framework (HOF) is a novel and ideal material for preconcentration of heavy metal in water by hydrogen bonding considering simple synthesis and low cost. In this work, magnetic HOF material (Fe 3 O 4 @HOF) was designed and synthesized under simple and mild conditions for preconcentration and detection of lead (Pb) and copper (Cu) in water. This Fe 3 O 4 @HOF exhibits maximum adsorption capacities for 579.81 mg/g Pb 2+ and 146.48 mg/g Cu 2+ , respectively, with an excellent selectivity (>95 % adsorption) for Pb 2+ and Cu 2+ in presence of other ions; as well, shows a favorable recycling performance (>95 % adsorption) after 10 adsorption–desorption cycles based on external magnetic adsorption. The mechanism results proved that the adsorption of Pb 2+ and Cu 2+ might be attributed to chemisorption, electrostatic interactions and ion exchange. Based on the glass fiber membrane filtration, Fe 3 O 4 @HOF can be utilized as enrichment material coupled with X-ray fluorescence spectrometer (XRF) for detection of Pb 2+ and Cu 2+ in water; the limits of detection (LODs) for Pb 2+ and Cu 2+ were 1.5 μg/L and 1.3 μg/L (from 100 mL water to 5 mg Fe 3 O 4 @HOF), respectively. This work presents a green, economical and eco-friendly novel material that can be easily prepared, separated and reused, demonstrating a promising potential for efficient preconcentration and accurate detection of heavy metals in water.