Degradation of Rhodamine B Dye by Cactus Polysaccharide-Synthesized Silver Nanoparticles Monitored by Fluorescence Excitation-Emission Matrix (FEEM) Spectroscopy

The degradation of Rhodamine B dye (RhB) by polysaccharide-synthesized silver nanoparticles (PE-AgNPs) has been studied by fluorescence excitation (λex) and emission (λem) matrices (FEEM) spectroscopy. This study reports the behavior of RhB under the influence of PE-AgNPs using the FEEM technique. The observed 3D excitation and emission maps reveal that, at λex (400 nm)/λem (580 nm), fluorescence quenching occurs. The 3D maps/peaks show that this type of quenching occurs in the presence of PE-AgNPs and is indicated by the decrease in the intensity of spectral peaks. At pH 8, the maximum quenching of these peaks occurrs. Further investigations show that temperature and contact time influence RhB quenching significantly. The trends observed shows that higher temperatures leads to reduction of RhB fluorescence intensity increases with increase in temperature and decrease with time. This study suggests that the fluorescence quenching of RhB, can be due to its adsorption on the conductive surface of PE-AgNPs. The results presented in this study give experimental evidence and insights that PE-mediated green synthesized AgNPs can be a promising RhB degrading agent. Besides, the interactions of RhB with PE-AgNPs, can prevent leaching and thus minimize dye toxicity in water.