EDTA-Modified magnetic graphite oxide for preconcentrating Hg2+ from water for XRF analysis


by: Sherwin L. Escayo, Erwin P. Enriquez


The performance of EDTA-modified magnetic graphite oxide (EDTA-mGO) as a potential preconcentration agent for XRF analysis of Hg2+ from water was investigated in this study. First, EDTA-mGO was prepared following a stepwise reaction: 1) graphite was oxidized using modified Hummer’s method to produce graphite oxide (GO), 2) co-precipitating Fe3O4 nanoparticles onto synthesized GO and 3) Fe3O4–GO was reacted with EDTA in acetic acid solution. The synthesized EDTA-mGO was characterized using FTIR, XRD, DLS and SEM. Next, 25 mg of EDTA-mGO was used to preconcentrate 250.0 mL Hg2+ aqueous solution (0.0, 0.1, 0.3, 0.5, 0.7, 1.0 and 1.5 ppm) at pH 7.5 for 10 min. Results of XRF analysis of water samples containing Hg2+ showed that the characteristic Hg X-ray lines (Lα1=9.989 keV; Lβ1=11.824keV) were enhanced using the EDTA-mGO as preconcentration agent. In addition, the sensitivity of the XRF analysis of Hg2+ from water was amplified ~1500 times. LOD and LOQ of the XRF analysis with preconcentration were much lower than the XRF analysis without preconcentration and were calculated to be 0.246 ppm and 0.747 ppm, respectively. The improved detection and quantification of Hg2+ from water is attributed to the strong association between Hg2+ and EDTA-mGO. Overall, EDTA-mGO was shown to be a potential preconcentration agent for the XRF analysis of Hg2+ from water.

Keywords: modified graphite oxide, EDTA, Fe3O4, preconcentration agent, XRF, mercury (II) ion