| Abstract | The reductive degradation of a chlorinated herbicide by iron powder was investigated at lab scale. The studied substrate was triallate (S-2,3,3-trichloroallyl di-isopropyl thiocarbamate) which contains a trichloroethylene moiety potentially reducible by zero-valent iron. Degradation reactions were carried out in batch, at 25 °C, in the absence of oxygen, by contacting electrolytic iron powder (size range: 20-50 um) with a triallate aqueous solution (2.5 mg l-1). Herbicide decay, corresponding evolutions of TOC, TOX and chloride ion release were regularly monitored throughout the reactions. Furthermore, the main degradation by-products were identified by HPLC/MS. The results showed that, after 5 days, herbicide degradation extent was about 97% and that the reaction proceeded through the formation of a dechlorinated alkyne by-product (S-2-propinyl di-isopropyl thiocarbamate) resulting from the complete dechlorination of triallate. The subsequent reduction of such an alkyne intermediate gave S-allyl di-isopropyl thiocarbamate as main end by-product. The identified y-products suggested that dechlorination took place mainly via reductive b-elimination. However, as traces of dichloroallyl di-isopropyl thiocarbamate were also detected, a role, although minor, was assigned even to hydrogenolysis in the overall dechlorination process. |
| Text | 42234 2004 10.1016/j.chemosphere.2004.06.040 ISI Web of Science WOS 000224879300006 Zero valent iron Reductive dehalogenation Chlorinated pesticides Groundwater remediation CHLORINATED HERBICIDE TRIALLATE DEHALOGENATION BY IRON POWDER VOLPE A., LOPEZ A., MASCOLO G., DETOMASO A. VOLPE A. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5 70123 Bari, Italy LOPEZ A. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5 70123 Bari, Italy MASCOLO G. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5 70123 Bari, Italy DETOMASO A. Consiglio Nazionale delle Ricerche, Istituto di Ricerca Sulle Acque, Sezione di Bari, Via Francesco De Blasio, 5 70123 Bari, Italy The reductive degradation of a chlorinated herbicide by iron powder was investigated at lab scale. The studied substrate was triallate S 2,3,3 trichloroallyl di isopropyl thiocarbamate which contains a trichloroethylene moiety potentially reducible by zero valent iron. Degradation reactions were carried out in batch, at 25 °C, in the absence of oxygen, by contacting electrolytic iron powder size range 20 50 um with a triallate aqueous solution 2.5 mg l 1 . Herbicide decay, corresponding evolutions of TOC, TOX and chloride ion release were regularly monitored throughout the reactions. Furthermore, the main degradation by products were identified by HPLC/MS. The results showed that, after 5 days, herbicide degradation extent was about 97% and that the reaction proceeded through the formation of a dechlorinated alkyne by product S 2 propinyl di isopropyl thiocarbamate resulting from the complete dechlorination of triallate. The subsequent reduction of such an alkyne intermediate gave S allyl di isopropyl thiocarbamate as main end by product. The identified y products suggested that dechlorination took place mainly via reductive b elimination. However, as traces of dichloroallyl di isopropyl thiocarbamate were also detected, a role, although minor, was assigned even to hydrogenolysis in the overall dechlorination process. 57 Chlorinated herbicide Triallate dehalogenation by iron powder Triallate_ZVI_Chemosphere_2004.pdf Articolo in rivista Elsevier 0045 6535 Chemosphere Chemosphere Chemosphere Chemosphere. Chemosphere. Environmental chemistry, Chemosphere. Persistent organic pollutants and dioxins, Chemosphere. Environmental toxicology and risk assessment, Chemosphere. Science for Environmental toxicology, angela.volpe VOLPE ANGELA DETOMASO ANTONIA antonio.lopez LOPEZ ANTONIO giuseppe.mascolo MASCOLO GIUSEPPE |
