• 文献标题:   Graphene membranes as novel preconcentration platforms for chromium speciation by total reflection X-ray fluorescence
  • 文献类型:   Article
  • 作  者:   ROMERO V, COSTASMORA I, LAVILLA I, BENDICHO C
  • 作者关键词:  
  • 出版物名称:   RSC ADVANCES
  • ISSN:   2046-2069
  • 通讯作者地址:   Univ Vigo
  • 被引频次:   12
  • DOI:   10.1039/c5ra23116g
  • 出版年:   2016

▎ 摘  要

Fabrication of unmodified graphene membranes for their application as selective sorptive platforms of hexavalent chromium [Cr(VI)] is described for the first time. Multilayer graphene membranes are synthesized by drop-casting of graphene oxide (GO) onto a glass substrate followed by mild thermal reduction. As-prepared membranes are formatted to fit the measurement area of total reflection X-ray fluorescence (TXRF). Structural and morphological characterization by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) shows that graphene membranes are 122 nm height and contain non-reduced functional groups resulting in lattice defects. Adsorption isotherm models and characterization by time-of-flight secondary ion mass spectrometry (TOF-SIMS) indicate that adsorption sites on graphene membranes are uniformly distributed and bind Cr(VI) as a monolayer, both by electrostatic interaction and chemisorption. Graphene membranes display high flexibility and become conical-shaped when immersed into stirred liquid samples. When combining graphene membrane preconcentration and TXRF, a detection limit of 0.08 mu g L-1 Cr(VI) is obtained. Repeatability expressed as relative standard deviation is 3% (N = 5). Two certified reference materials, i.e. CASS-4 seawater and NWTM-27.2 lake water, are used for testing accuracy. The proposed method is simple, solvent-free and sensitive, being suitable for Cr speciation in water including high salinity samples.