Studying absorbance properties and mercury remediation capabilities of gold–graphene oxide–iron oxide (Au–GO–Fe3O4) nanoparticle systems

Abstract

Mercury pollution is a rampant problem in many economically significant Philippine freshwater ecosystems. Communities dependent on these freshwater sources are therefore at risk for exposure to harmful levels of mercury. Various formulations of a novel gold–graphene oxide–iron oxide (Au–GO–Fe3O4) hybrid nanoparticle system were created and subjected to UV–Vis spectroscopy to determine optimal formulations that would best serve as potential substrates for Surface-Enhanced Raman Spectroscopy (SERS) detection of mercury. Optimal formulations of Au–GO–Fe3O4 were also introduced into mercury-polluted environments to evaluate its ability to remove mercury from both water and biological tissues. Spectroscopic analysis revealed that Fe3O4-rich formulations of Au–GO–Fe3O4 had the greatest potential to boost Raman signal intensities of mercury due to red shifting of absorbance peaks and overall increased absorbance across visible wavelengths resulting in the inclusion of greater areas underneath absorbance peaks. Mercury remediation experiments likewise demonstrated Au–GO–Fe3O4 to significantly reduce average concentrations of mercury from 1.67 to 0.82 ppm in polluted water samples – corresponding to a mercury removal efficiency of 50.9% and a mercury adsorption capacity of 5.89 mg/g. The results highlight the viability of Au–GO–Fe3O4 to function as both substrate for SERS detection of mercury and as effective adsorbent for mercury remediation.