The temperature also affected the process of silver reduction.
Reaction mixtures incubated at 30, 40 and 50 C showed light
reddish brown color and less pronounced SPR peaks. At higher
incubation temperature (60, 80 and 100 C) dark reddish brown
color and more intense SPR peaks were revealed (Fig. 1e). At
room temperature (30 C) the color change took 10 min to
develop, while by heating the reaction mixtures at 40e100 C
the reduction process was faster and the reddish brown color
was developed within 5 min. The maximum SPR peak intensity
was detected at 100 C. The increase in reaction temperature,
UV spectra show sharp narrow peaks at lower
wavelength region (412 nm at 100 C), which indicate the
formation of smaller nanoparticles, whereas, at lower reaction
temperature, the peaks observed at higher wavelength
regions (440 nm at 30 C) which clearly indicates increase in
silver nanoparticles size. It is a well-known fact that when the
temperature is increased, the reactants are consumed rapidly
leading to the formation of smaller nanoparticles (Park, Joo,
Kwon, Jang, & Hyeon, 2007). Similarly, the size of silver
nanoparticles was decreased with an increase in incubation
temperature when the fungus Trichoderma viride was
employed