Facile synthesis of a modified HF-free MIL-101(Cr) nanoadsorbent for extraction nickel in water andwastewater samples

A novel sorbent based on MIL-101(Cr) nanoadsorbent as a MOF structure was used for nickel extraction from water and wastewater samples. In this study, 30 mg of MIL-101(Cr) nanoadsorbent dispersed in 50 mL of water or wastewater samples, after sonication and adjusting pH =8.5, the nickel ions was extracted by carboxyl groups of terephthalic acid (MOF─(C6H4 (COO)2-.... Ni2+) by dispersive suspension-micro solid-phase extraction (DS-μ-SPE). The MOF was separated from liquid phase with filter membrane (0.2 μm), eluted with 0.5 mL of nitric acid as back-extraction solution and finally, the nickel concentration in elution was determined by atom trap-flame atomic absorption spectrometry (AT-FAAS) after dilution with DW up to 1 mL. The LOD, the linear range and preconcentration factor were achieved 1.5 μg L−1, 5-160 μg L−1 and 49.7, respectively. The absorption capacity of MOF for nickel was obtained 136.8 mg g-1. The results of procedure were validated by spiking of samples and ET-AAS analyzer.