Silver nanoparticles (Ag NPs) were synthesized
in situ, using a one-step green methodology with
Camellia
sinensis
(green tea) aqueous extract as reducing agent, and
supported on a carbonaceous material (Ag-CM), originated
from the pyrolysis of sewage sludge. UV–Vis spectroscopy,
X-ray diffraction, scanning electron microscopy,
transmission electron microscopy and Brunauer–Emmet–
Teller were used to characterize the nanocomposite. Ag-
CM composite exhibited very good catalytic activity in the
degradation process of methylene blue (MB) dye in aqueous
solution without using sunlight or UV radiation. Batch
kinetic and isothermal experiments, using 30 mg/L MB
solution, showed that Ag-CM composite removed near to
91 % of MB in 9 h, whereas the carbonaceous material
alone removed only 60 % in 30 h. Experimental data were
adjusted to different kinetic and isotherms models, where
both materials fit the second-order and Langmuir–Freundlich
models, respectively; therefore, a chemisorption
mechanism probably occurs in these heterogeneous
materials.
