Effect of coating on the environmental applications of zero valent iron nanoparticles: the lindane case

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Commercial stabilized slurry of zero-valent iron nanoparticles (nZVI) as well as laboratory-synthesized polymer–stabilized NZVI nanoparticles were used for lindane (γ-hexachlorocyclohexane) degradation studies in aqueous solution. In the present study, polymer-stabilized iron nanoparticles were stabilized using polyethylene glycol (PEG, Mn ~400 and ~950–1050) and polytetrahydrofuran (PTHF, Mn ~650). To study the effectiveness of the different nanoparticles, a quantitative monitorization of lindane degradation by using solid-phase extraction (SPE) and a qualitative measurement of generated volatile by-products by headspace-solid phase microextraction (HS–SPME) followed by GC/MS were carried out. The obtained data were compared and contrasted with the results obtained in previous work.Results showed that the nanoparticles studied in this work possess superior dechlorination performance compared with previous observations. The freshly prepared Fe0-PEG400, Fe0-PEG1050 and Fe0-PTHF exhibited high reactivity during the dechlorination process of lindane in a very short time. The results obtained with the synthesized nanoparticles were similar to those obtained with commercial nanoparticles. However, in all cases reactivity decreased at reaction's late stage. Degradation of lindane by the studied nanoparticles removed 99.9% of the lindane initial concentration after 72h, except for Fe0-PTHF nanoparticles, for which the reaction stopped after 5min. In all cases, the reaction followed a second order kinetics. Finally, comparing the results from this study with our previous work, where different nature polymers were considered (Fe0-CMC, Fe0-PAA and Fe0-PAP), more gradual degradation profile of lindane was observed for Fe0-PAA and Fe0-CMC. It should be noted that in the present case, the reaction of lindane was speeded up with commercial and Fe0-PEG nanoparticles. Nevertheless, in the later case, the composition of by-products was affected by the presence of partially degraded intermediates. Taking into account the current technologies, the high removal rates obtained and the acceptable degradation times required, the proposed technology is suitable for its aimed purpose.