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Keywords:

  • Fe-Ni nanocomposite;
  • basic magenta;
  • bimetallic catalyst;
  • reactive oxygen species (ROS);
  • degradation pathway

The degradation of a basic magenta (BM) from aqueous streams is explored to ascertain the role of dissolve oxygen using Fe-Ni bimetallic nanocomposites as catalyst. XRD analysis of Fe-Ni bimetallic nanocomposites prepared with montmorillonite (MMT) clay suggested its intercalation with Fe-Ni bimetallic nanoparticles whereas TEM images indicated the spherical nature with 20–40 nm. Batch experiments containing 100 mg L−1 dye solution and 1 g L−1 catalyst exhibited complete decolorization of BM within 10 min following first order reaction kinetics. Amongst the nanocomposites, 10% loaded and 50% in situ compositions possess better activity with enhanced degradation capacity below pH 4 because of generation of reactive H• species. LC-MS analysis of decolorized solution revealed the formation of both reductive and oxidative metabolites with prominence of N-demethylated species mainly due to both H ions and •OH radicals. Moreover, when the deaerated solution of BM (N2 purged dye solution) is subjected for catalytic treatment, only 17% decolorization is observed that further vouch for effectiveness of dissolved oxygen on the degradation process. To ascertain this hypothesis, sodium azide, a selective quencher for singlet oxygen, is added to the dye solution and the supernatant thus obtained is subjected for LC-MS analysis. This study clearly establishes the fact that reactive oxygenated species (ROS) indeed influence the course of degradation for organic pollutants and this technology may be regarded as aerobic degradation process mediated by zerovalent metal based nanocomposites as efficient catalyst. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 615–623, 2013