Green synthesis of silver nanoparticles using Lathyrus brachypterus extract for efficient catalytic reduction of methylene blue, methyl orange, methyl red and investigation of a kinetic model

Abstract

A facile, green, and an efficient method for the synthesis of AgNPs (silver nanoparticles) using Lathyrus brachypterus var. brachypterus extract is reported. AgNPs was characterized by UV-Vis, XRD, TEM and FTIR. The UV-Vis spectra of the AgNPs revealed a characteristic surface plasmon resonance peak at 452 nm. The synthesized AgNPs reacted as a heterogeneous catalyst for the reduction of dyes (methylene blue, methyl red and methyl orange) both in unary and ternary mixture (TM) with and without NaBH4 (sodium borohydride). The kinetic parameter (k) for the degradation reactions and half-life (t(1/2)) of dyes has been calculated according to Michaelis-Menten kinetics. Green synthesized of AgNPs effectively degraded the dyes at approximately 4-6 min. In addition, oxidation studies of methyl orange with H2O2 (hydrogen peroxide) have been also carried out and it has been reported that AgNPs can be reused as heterogeneous catalysts. The oxidation of MO was monitored with a UV-Vis spectrometer. AgNPs was separated using a filter paper after the oxidation of MO. The separated AgNPs were reused without important loss of its activity with a conversion efficiency of around 98%.