Green synthesis, characterization, photocatalytic, fluorescence and antimicrobial activities of Cochlospermum gossypium capped Ag2S nanoparticles

• Green synthesized stable Ag2S NPs by GK is a low cost, cheap and non-toxic method.
• The Ag2S NPs were spherical in shape with an effective size of 25 nm.
• Photodegradation of FL dye at various temperatures was observed by Ag2S NPs.
• A fluorescence quenching and binding constant of Ag2S NPs by BSA was studied.
• The inhibition zone of bacteria by Ag2S NPs was found to be approximately 40 mm.

The study describes a simple and green method for the synthesis of silver sulfide nanoparticles (Ag2S NPs) using gum kondagogu (Cochlospermum gossypium) (GK). The synthesized NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), fluorescence, UV–vis absorption, zeta potential and thermogravimetric analysis (TGA) techniques. The optical properties and quantum confinement effect of the products were confirmed by means of spectroscopic measurements. The morphologies and sizes were characterized by SEM and TEM. The Ag2S NPs were spherical in shape with an effective diameter size of 25 nm. The photocatalytic property of Ag2S NPs was evaluated by the degradation of fluorescein (FL) dye under solar light. The effect of Ag2SNPs on the photocatalytic degradation of FL dye and influence of other parameters such as Ag2S loading, H2O2, temperature and under solar light irradiation was also evaluated. The degradation reaction follows the pseudo-first order kinetics. The apparent reaction rate was used to calculate the apparent activation energy (Ea = 13.95 kJ/mol) of the degradation process. The activation thermodynamic parameters (ΔG*, ΔH* and ΔS*) were obtained from variable temperature kinetic studies. The interaction between Ag2S NPs and bovine serum albumin (BSA) was studied by using fluorescence spectroscopic measurements. The synthesized Ag2S NPs were showing good antimicrobial activity.

Graphical AbstractGreen synthesized Ag2S NPs using GK under hydrothermal conditions. By using Ag2S NPs, the FL dye is almost completely degraded using H2O2 under solar irradiation at 343 K temperature with in 30 min. The fluorescence quenching of Ag2S NPs was observed with BSA as a quencher and quenching constants are determined by Stern–Volmer equation. Antimicrobial activity of GK capped Ag2S NPs was observed against gram-positive and gram-negative bacteria with high inhibition zone.Figure optionsDownload as PowerPoint slide