In order to determine the functional groups on the BPE powder
surface and their possible involvement in the synthesis of silver
nanoparticles, FTIR analysis was carried out as described earlier
[21]. Control samples (BPE powder before reaction with AgNO3)
and the test samples (BPE powder after reaction with the silver
salt) were independently dried and blended with KBr to obtain a
pellet. The FTIR spectra were collected at resolution of 4 cm−1 in
the transmission mode (4000–400cm−1) using a Shimadzu FTIR
spectrophotometer (FTIR 8400).