Exploring the efficacy of Pongamia pinnata-induced silver nanoflowers for efficient adsorptive degradation of malachite green dye

In this study, silver nanoflowers were synthesized due to catalytic reduction of silver ions by phytochemicals of Pongamia pinnata seed cake extract (PSCAgNPs) in 24 h and subsequently used for removal of malachite green (MLG) dye. PSCAgNPs were characterized by UV–Visible spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X ray spectroscopy (EDAX), Fourier Transformed Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and BET analysis. The synthesized PSCAgNPs were floral in appearance, of size 18.82—23.70 nm with SPR at 430 nm and crystalline in nature. PSCAgNPs adsorbed 90.01 ± 0.17% of 50 mg/L MLG post one factor at a time analysis. Adsorption followed pseudo-second-order kinetics (k₁ = 2.5E-03 g/mg.h), was observed as unilayer chemisorption as the equilibrium data best fitted Langmuir isotherm (Langmuir coefficient = 0.1724 L/mg, R² = 0.9945). Upon interaction of MLG by PSCAgNPs, hydroxylation of MLG leads to formation of MLG carbinol in the first stage of adsorptive degradation, as evident from LCMS chromatograms.