Development of magnetic graphene oxide adsorbent for the removal and preconcentration of As(III) and As(V) species from environmental water samples
2016
Rashidi Nodeh, Hamid | Wan Ibrahim, Wan Aini | Ali, Imran | Sanagi, Mohd Marsin
New-generation adsorbent, Fe₃O₄@SiO₂/GO, was developed by modification of graphene oxide (GO) with silica-coated (SiO₂) magnetic nanoparticles (Fe₃O₄). The synthesized adsorbent was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. The developed adsorbent was used for the removal and simultaneous preconcentration of As(III) and As(V) from environmental waters prior to ICP-MS analysis. Fe₃O₄@SiO₂/GO provided high adsorption capacities, i.e., 7.51 and 11.46 mg g⁻¹ for As(III) and As(V), respectively, at pH 4.0. Adsorption isotherm, kinetic, and thermodynamic were investigated for As(III) and As(V) adsorption. Preconcentration of As(III) and As(V) were studied using magnetic solid-phase extraction (MSPE) method at pH 9.0 as the adsorbent showed selective adsorption for As(III) only in pH range 7–10. MSPE using Fe₃O₄@SiO₂/GO was developed with good linearities (0.05–2.0 ng mL⁻¹) and high coefficient of determination (R ² = 0.9992 and 0.9985) for As(III) and As(V), respectively. The limits of detection (LODs) (3× SD/m, n = 3) obtained were 7.9 pg mL⁻¹ for As(III) and 28.0 pg mL⁻¹ for As(V). The LOD obtained is 357–1265× lower than the WHO maximum permissible limit of 10.0 ng mL⁻¹. The developed MSPE method showed good relative recoveries (72.55–109.71 %) and good RSDs (0.1–4.3 %, n = 3) for spring water, lake, river, and tap water samples. The new-generation adsorbent can be used for the removal and simultaneous preconcentration of As(III) and As(V) from water samples successfully. The adsorbent removal for As(III) is better than As(V).
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