Spherical silica particles decorated with graphene oxide nanosheets as a new sorbent in inorganic trace analysis

• Published in: Analytica chimica acta 2014-06, Vol.834, p.22-29
• Main Authors: Sitko, Rafal, Zawisza, Beata, Talik, Ewa, Janik, Paulina, Osoba, Grzegorz, Feist, Barbara, Malicka, Ewa
• Format: Article
• Language: English
• Subjects: Adsorptivity; Covalence; Flame atomic absorption spectrometry; Graphene; Metal ions; Nanomaterial; Nanostructure; Oxides; Preconcentration; Solid sorbent; Solid-phase extraction; Sorbents; Surface chemistry
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2014.05.014

[Display omitted] •Graphene oxide (GO) covalently bonded to the spherical silica.•Very stable sorbent for SPE of metal ions.•Excellent contact with solution due to the softness and flexibility of GO nanosheets.•Several adsorption–elution cycles without any loss of adsorptive properties.•High adsorption capacity due to the wrinkled structure of GO nanosheets. Graphene oxide (GO) is a novel material with excellent adsorptive properties. However, the very small particles of GO can cause serious problems is solid-phase extraction (SPE) such as the high pressure in SPE system and the adsorbent loss through pores of frit. These problems can be overcome by covalently binding GO nanosheets to a support. In this paper, GO was covalently bonded to spherical silica by coupling the amino groups of spherical aminosilica and the carboxyl groups of GO (GO@SiO2). The successful immobilization of GO nanosheets on the aminosilica was confirmed by scanning electron microscopy and X-ray photoelectron spectroscopy. The spherical particle covered by GO with crumpled silk wave-like carbon sheets are an ideal sorbent for SPE of metal ions. The wrinkled structure of the coating results in large surface area and a high extractive capacity. The adsorption bath experiment shows that Cu(II) and Pb(II) can be quantitatively adsorbed at pH 5.5 with maximum adsorption capacity of 6.0 and 13.6mgg−1, respectively. Such features of GO nanosheets as softness and flexibility allow achieving excellent contact with analyzed solution in flow-rate conditions. In consequence, the metal ions can be quantitatively preconcentrated from high volume of aqueous samples with excellent flow-rate. SPE column is very stable and several adsorption–elution cycles can be performed without any loss of adsorptive properties. The GO@SiO2 was used for analysis of various water samples by flame atomic absorption spectrometry with excellent enrichment factors (200–250) and detection limits (0.084 and 0.27ngmL−1 for Cu(II) and Pb(II), respectively).