Studies of surface plasmon resonance of silver nanoparticles reduced by aqueous extract of shortleaf spikesedge and their catalytic activity.

This study describes the synthesis of silver nanoparticles (AgNPs) using shortleaf spikesedge extract (SSE) to reduce AgNO3. Visual observation, in addition to analyses of UV-vis, EDX, XRD, FTIR, and TEM was employed to monitor the formation of AgNPs. The effects of SSE concentration, AgNO3 concentration, reaction time, pH, and temperature on the synthesis of AgNPs were studied based on the surface plasmon resonance (SPR) band. From the TEM image, highly-scattered AgNPs of quasi-spherical shape with an average particle size of 17.64 nm, were observed. For the catalytic study, the reduction of methylene blue (MB) was evaluated using two systems. A detailed batch study of the removal efficiency (%RE) and kinetics was done at an ambient temperature, various MB initial concentrations, and varying reaction time. Employing the electron relay effect in System 2, the batch study clearly highlighted the significant role of AgNPs in boosting the catalytic activity for MB removal. At 30-100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. The kinetic data best fitted the pseudo-first-order model with a maximum reaction rate of 2.5715 min-1. These findings suggest the promising application of AgNPs in dye wastewater treatment.The SSE-driven AgNPs were prepared using unwanted dried biomass of shortleaf spikesedge extract (SSE) as a reducing as well as stabilizing agent. Employing the electron relay effect, the batch study clearly highlighted the significant role of SSE-driven AgNPs in boosting the catalytic activity for MB removal. At 30-100 mg/L initial concentrations, MB was reduced by 100% in a very short reaction time between 1.5 and 5.0 mins. In this sense, SSE-driven AgNPs acted as an electron relay point that behaves alternatively as acceptor and donor of electrons. The findings revealed the good catalytic performance of SSE-driven AgNPS, proving their viability for dye wastewater treatment.

Methylene blue dye removal on silver nanoparticles reduced by Kyllinga brevifolia.

Silver nanoparticles (AgNPs) were prepared by reacting Kyllinga brevifolia extract (KBE) with AgNO3 aqueous solution at room temperature (22 ± 3 °C). The phytochemical constituents in KBE responsible for the reduction process were identified as carbohydrate, protein, and plant sterols (stigmasterol and campesterol). KBE was also found to function as a capping agent for stabilization of AgNPs. The AgNPs were stable at room temperature and had a quasi-spherical shape with an average particle size 22.3 nm. The use of KBE offers not only eco-friendly and non-pathogenic path for AgNPs formation, it also induced rapid formation of the AgNPs. Methylene blue (MB) removal was then done on the AgNPs in the presence of either KBE or NaBH4. Ninety-three percent removal of MB was achieved with a rate of reaction 0.2663 min-1 in the solution with KBE+AgNPs (pH 2). However, in NaBH4+AgNPs system, 100% MB removal was achieved at pH 8-10. The reaction rate was 2.5715 min-1 indicating a fast removal rate of MB dye. The process of reduction occurs via electron relay effect whereas in KBE+AgNPs system, sedimentation occurred along with the reduction process. Nevertheless, the use of KBE+AgNPs system is preferred as the reducing agent is more benign to the environment.