Konjac glucomannan reduced-stabilized silver nanoparticles for mono-azo and di-azo contained wastewater treatment

Silver nanoparticles (AgNPs) possess fascinating catalytic, optical, and electrical properties, but their broader application is hindered by their instability and agglomeration tendency. This report presents eco-friendly green synthesis using Konjac glucomannan (KGM) for the synthesis of AgNPs. Here, KGM functions as both reducing and stabilizing agent for AgNPs colloid without the assistance of any toxic reagents. To achieve an optimum synthesis window, reaction parameters such as precursor concentration, media pH, reduction time, and temperature were explored by the factorial design of experiments (FDE). AgNPs synthesized at optimum conditions revealed that the particles are primarily in spherical shapes, smaller in size (14.25 +/- 3.42 nm) with a narrow distribution, highly crystalline (d-spacing = 0.258-0.236 nm), well stabilized (zeta potential = -13.1 mV), and coated by thin KGM-carbohydrate layer. The synthesized AgNPs reveal excellent catalytic performance in the degradation of mono-azo (acid orange 74) and di-azo (naphthol blue-black) dyes. The insights on the reaction kinetics revealed in this study could be extended to the practical application for wastewater treatment.