Shortleaf Spikesedge-Driven Silver Nanoparticles for The Reduction of Methylene Blue Dye

The textile industry is a heavy producer of wastewater, which may result in the discharge of toxic dyes into the environment. Methylene blue (MB) is an example of the most used dye in the textile industry. It is difficult to degrade MB under normal conditions due to its highly stable molecules. Therefore, a catalyst route is desired in MB reduction. The catalyst chosen in this work was silver nanoparticles (AgNPs) synthesised by a biological method utilising shortleaf spikesedge extract (SSE) as a reducing agent. The formations of SSE driven AgNPs were monitored using visual observation (colour), ultraviolet-visible spectroscopy (UV-vis), and transmission electron microscopy (TEM). The different process variables (concentration of AgNO3, concentration of SSE, reaction time, temperature and pH) upon synthesis of SSE driven AgNPs were evaluated based on the absorbance of surface plasmon resonance (SPR) band. The TEM image showed that SSE driven AgNPs are highly dispersed with a quasi-spherical shape and an average particle size of approximately 17.64 nm. For the catalytic study, the reduction of MB was evaluated using two systems. A detailed batch study of the removal efficiency (%RE) and kinetics was done at ambient temperature, various MB initial concentrations, and reaction time. The batch study for System 2 clearly showed that SSE driven AgNPs exhibited 100% reduction of MB at 30–100 mg/L initial concentration (sample coding of MB30, MB50, MB70 and MB100) between 1.5 and 5.0 min reaction time. The kinetic data best fitted a pseudo-first-order kinetic model with the highest reaction rate of 2.5715 min-1. The reduction of MB occurs via the electron relay effect. These findings demonstrate that the SSE driven AgNPs are a promising candidate with potential influence on coloured wastewater.