Adsorption of methylene blue by silver nanoparticles synthesized from Urena lobata leaf extract: Kinetics and equilibrium analysis

The utilization of green synthesized nanoparticles for the treatment of wastewaters is gaining significance owing to its potential advantages over other techniques. In the present study, silver nanoparticles were synthesized due to catalytic reduction of silver ions by phytochemicals of Urena lobata leaf extract (UL-AgNPs) in 2.5 h. The synthesized UL-AgNPs were characterized by UV–Visible spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier Transformed Infrared Spectroscopy (FT-IR) and X-Ray Diffraction (XRD) analysis. The synthesized UL-AgNPs were spherical, of size 20 nm with SPR peak at 430 nm and crystalline in nature. UL-AgNPs could adsorb 87.47 ± 0.12% of 10 mg/L methylene blue dye with a maximum adsorption capacity of 218.95mg/g. The adsorption process followed pseudo-first-order kinetics ( k 1 = 0.878 h −1 ) and was observed as mono-layer chemisorption as the equilibrium data best fitted Langmuir isotherm ( R 2 = 0.996) with Langmuir constant ( K b ), 0.55 L/mg and R L value, 0.595 indicating the spontaneity of the process. • Silver nanoparticles from Urena lobata leaf extract. • Crystalline in nature, spherical in shape, 20 nm size. • Adsorbed 87.47% of Methylene Blue (10 mg/L) in 4 h. • Adsorption process is monolayer chemisorption and follows pseudo-first-order kinetics.