Euphorbia geroldii Silver Nanoparticles: Evaluation of Photocatalytic and Catalytic Applications

Industrial waste such as para-nitrophenol (PNP) and azo dyes threaten health and the environment. PNP from pharmaceutical, petroleum, and pesticide industries causes liver, kidney, and nervous system damage even at low concentrations. On the other hand, azo dyes used in food, cosmetics, textiles, and pharmaceuticals enter waterways, harming aquatic ecosystems and producing toxic products. Various conventional degradation methods exist such as hydrogenation and electrochemical techniques; these are costly and energy consuming. However, green synthesis of silver nanoparticles (AgNP) using plant extracts has emerged as a promising alternative due to its simplicity, cost-effectiveness, and environmental compatibility. Despite the growing interest in plant-mediated AgNP synthesis, no comprehensive study has been done using nanoparticles synthesized from Euphorbia geroldii, or multiple parts of euphorbia species. This study assesses green synthesis of AgNPs from different parts of Euphorbia geroldii. In this study, AgNPs were synthesized by reducing silver nitrate using aqueous extracts from Euphorbia geroldii; bark, flower, stem, leaf, and root, which were characterized by UV-Vis spectroscopy, scanning electron microscopy, and zeta potential. Photocatalytic activity of Euphorbia geroldii AgNPs was assessed by methyl orange (MO) degradation under sunlight and catalytic activity of Euphorbia geroldii AgNPs was assessed by reduction of PNP to para-aminophenol, both monitored by UV-Vis spectroscopy. The bark and root formed AgNPs at 90ºC for 60 minutes confirmed by surface plasmon resonance peak at 440 nm. The scanning electron microscopy showed spherical shaped Bark_AgNPs of 30-70 nm with a zeta potential of -23.1 mV. Root_AgNP degraded PNP within 10 minutes showing the highest rate constant (k = 0.153 min^-1). Bark_AgNP showed the highest rate constant (k = 0.1097min^-1) for MO degradation within 15 minutes in the presence of sodium borohydride. These findings conclude that Euphorbia geroldii AgNPs have potential in degradation of environmental pollutants such as PNP and azo dyes.