Synthesis and characterization of Fe3O4@polythionine-Au for the removal and pre-concentration of Cu(II) from marine samples

Abstract

The extraction of Cu(II) ions in marine samples was performed by nanocomposite of magnetic polythionine-Au, as an efficient magnetic extraction phase. For characterization of the prepared materials, different methods including FT-IR, SEM, EDX, TEM and VSM were used. The magnetic polythionine-Au nanocomposite exhibited higher adsorption percentage (98%) than the magnetic polythionine (65%) for uptake of Cu(II) ions. The optimized parameters for magnetic solid-phase extraction procedure were as sample pH of 7, sorption time of 10 min, sorbent dosage of 30 mg, elution solvent (2 mL) of HNO3 (0.3 mol L−1)/thiourea (1% w/v) and breakthrough volume of 300 mL. The adsorption kinetic follows a pseudo-second-order kinetic model and well fitted with the Langmuir isotherm model. The adsorption capacity was 120 mg g−1 for Cu(II). Also, the effect of thermodynamics of adsorption process was discussed. The nanocomposite adsorbent can be used for five cycles without significant decrease in adsorption capacity. The calibration curve was linear in the concentration range of 0.7–50 μg L−1 (R2 = 0.9983). The limits of detection and quantification were achieved as 0.097 and 0.32 μg L−1, respectively. The real samples were a gastropod from the Persian Gulf (Trochus erithreus), and muscle tissues of a fish (Trout) and shrimp. Good relative spiked recoveries (95–105%) were obtained for the real samples.