Zero-valent iron nanoparticles entrapped in SiO2 sol-gel matrices: A catalyst for the reduction of several pollutants

Abstract Zero-valent iron-nanoparticles (ZVI-NPs) entrapped in silica matrices through a sol-gel procedure are investigated as redox catalysts with BH4− (NaBH4) as the reducing agent. The results indicated that the matrix functions as an efficient and multifunctional catalyst for the reduction of halo-acetic acids (HAAs), [BrO3−] and 4-nitrophenol pollutants present in the contaminated water. The present study revealed that the reduction mechanism depends on the nature of the substrate, M0 used and the rate of the reductant addition (batch mode reactor system). The novelty of the present work is double-fold: First, in pointing out that the mechanism of the catalytic de-halogenation reaction depends on the nature of M0-NPs used as a catalyst, probably due to the different over-potential for the HER reaction on each M0-NPs and second, the development of a cost-effective remediation alternative compared to the analogous Au0-NPs or Ag0-NPs catalysts reported in the literature.