title: Spherical silica particles decorated with graphene oxide nanosheets as a new sorbent in inorganic trace analysis.
abstract: 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 13.6 mg g(-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 0.27 ng mL(-1) for Cu(II) and Pb(II), respectively).
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland. Electronic address: rafal.sitko@us.edu.pl.
authors.forename: Rafal
authors.initials: R
authors.lastname: Sitko
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Zawisza
authors.affiliation: University of Silesia, Institute of Physics, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Talik
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland.
authors.forename: Paulina
authors.initials: P
authors.lastname: Janik
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Osoba
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Feist
authors.affiliation: University of Silesia, Institute of Chemistry, ul. Szkolna 9, 40-006 Katowice, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Malicka
keywords: Flame atomic absorption spectrometry; Graphene; Nanomaterial; Preconcentration; Solid sorbent; Solid-phase extraction