Synthesis of Sodium Alginate graphene oxide-silver thin film for mercury detection

In this study, sodium alginate graphene oxide silver (GO-Ag) thin film composite with different amount of GO-Ag solution were synthesized using solvent casting method for the detection of mercury ions (Hg2+) by using spectrophotometry. Due to the harmful effect of Hg2+, it is crucial to have an option in detection and identification the level of Hg2+. The GO-Ag composite are chosen as an assay for optical determination of Hg2+. GO is an effective host material for the silver particle growth for the presence of surface functional groups and it also has excellent properties which is high specific surface area. Reduced graphene oxide (rGO) uniformly decorated with silver particles was synthesized through the microwave irradiation of an aqueous solution containing a silver ammonia complex (Ag (NH3) 2OH) and GO. The presence of GO, on the other hand, prevents the agglomeration of the AgNPs and enhances the stability of the composite material in solution. The thin film composites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-visible absorption spectra. The thin film undergoes a significant reduction in intensity of absorption on the surface plasmon resonance (SPR) band of the Ag particles upon the every addition 10 μM of concentration of Hg2+, and this effect is based on the disappearance of the localized SPR absorption of the Ag particles due to the formation of silver-mercury amalgam. The FTIR analysis results showed a decrease in the intensity of the adsorption bands of the oxygenated functional groups for the sodium alginate GO-Ag thin film samples. While, for the XRD analysis of the thin film shows the existence of Ag particles on the layer of sodium alginate GO-Ag thin film with the diffraction pattern of silver crystal structure. However, the chemical structure of the alginate in the composite films barely changes with the increasing content of graphene oxide, indicating that there were mainly physical interaction but scarcely chemical reaction between alginate and graphene oxide.