In this study, caged calcium alginate-caged multiwalled carbon nanotubes dispersive microsolid phase extraction was described for the first time for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatographic analysis. Fluorene, phenanthrene and fluoranthene were selected as model compounds. The caged calcium alginate-caged multiwalled carbon nanotubes was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and thermal gravimetry analyses. The effective parameters namely desorption solvent, solvent volume, extraction time, desorption time, the mass of adsorbent and sample volume were optimized. Under the optimum extraction conditions, the developed method showed good linearity in the range of 0.5-50 ng mL-1 (R2 ≥ 0.996), low limits of detection and quantification (0.42-0.22 ng mL-1) (0.73-1.38 ng mL-1) respectively, good relative recoveries (71.2-104.2%) and reproducibility (RSD 1.8-12.4%, n = 3) for the studied PAHs in water sample. With high enrichment factor (1,000), short extraction time (<30 min), low amounts of adsorbent (100 mg) and low amounts of solvent (0.1 mol) have proven that the microsolid phase extraction method based on calcium alginate-caged multiwalled carbon nanotubes are environmentally friendly and convenient extraction method to use as an alternative adsorbent in the simultaneous preconcentration of PAHs from environmental water samples.

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In this study, the Met-GO@Alg as a novel adsorbent was composed of metformin (Met), graphene oxide (GO), alginate beads (Alg) for removal of lead ions from aqueous media. The adsorbent material was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) techniques. The effect of solution pH)5(, adsorbent dosage)20 mg(, contact time)90 min(, temperature and co-existing ions were studied and optimized. The Pb 2+ adsorption nature and mechanism were adopted with various isotherms, kinetics, and thermodynamic models. Hence, the adsorption kinetic process fits with the pseudo-second-order model (R 2 > 0.97) with 95% removal efficiency at 90 min. The adsorption isotherm is well fit to the Freundlich model (R 2 > 0.99) with the maximum adsorption capacity of 370 mg. g À1 .Overall, Met-GO@Alg nanocomposite revealed good efficiency, applicability, and five times reusability.