2. Experimental
2.1. Preparation of nZVI
The synthesis of nZVI was performed using the method of liquidphase
reduction utilizing NaBH4 (Aldrich 4511-2) as the reducing
agent. The applied procedure was reported in detail in our earlier
works [e.g. 4]. In brief, a 17.8 g sample of FeCl2·4H2O (Sigma-Aldrich
22029-9) was dissolved in 50.0 mL solution of absolute ethanol
(Riedel-de Haën 32221) and distilled water (4:1 v/v). An 8.47 g NaBH4
was separately dissolved in 220 mL of distilled water. NaBH4 solution
was then added to a Fe2+ solution drop wise while providing wellstirring
to the reaction mixture. After the addition of all the NaBH4
solution, the mixture was mixed for extra 20 min period. The iron
powder was then separated from the solution by vacuum filtration,
and the filtrate was washed at least three times with 99% absolute
ethanol. The powder was dried in the oven at 75 °C overnight under
atmospheric oxygen.