Methylene blue purchased from CDH chemicals, India was used for this study. In
order to assess the catalytic activity of synthesized AgNPs, two reactions were carried
out in a 3.5 ml capacity quartz cuvette and absorbance values were monitored
using UV–visible spectrophotometer. In the first reaction, 1 ml of methylene blue
(1
×10−4 M) was mixed with 0.2 ml of aqueous fruit extract and 1.8 ml of water, this
reaction was monitored after 30 min (I). In second reaction, 1 ml of methylene blue
(1
×
10−4 M) was mixed with 0.2 ml extract and 2 ml of synthesized AgNPs and this
reaction was monitored at three different time intervals viz., 30 min, 45 min and
60 min (II). In all the reactions total volume of the mixture was made up to 3 ml. The
values of absorption maxima (max) were compared, with that of methylene blue.
The schematic representations of the two reactions are depicted in Fig. 1.