Enhanced Dechlorination of 1,2-Dichloroethane by Coupled Nano Iron-Dithionite Treatment

摘要

1,2-dichloroethane (1,2-DCA) is a chlorinated solvent classified as a probable human carcinogen. Due to its extensive industrial applications, widespread contamination and recalcitrance towards abiotic dechlorination, 1,2-DCA remains a challenging compound for the remediation community and one of the great research interests. Batch experiments combining bimetallic or monometallic nZVI (stabilized or non-stabilized) with sodium dithionite were conducted for the degradation of 1,2-DCA. These experiments have yielded up to 92 % degradation of the initial 1,2-DCA concentration over the course of a year. Observed pseudo-first order rate constants (kobs) range from 3.8 x 10-3 to 7.8 x 10-3 day-1. Degradation was also achieved using magnetite and iron sulfide as the metal surface, with kobs values of 6.2 x 10-3 and 4.7 x 10-3 day-1, respectively. Characterization analysis of the nZVI/dithionite nanoparticles shows that zero valent iron as such remains in solution after more than one year of reactivity and that iron sulfide is formed in solution. This novel treatment represents the first nZVI-based formulation to achieve nearly complete degradation of 1,2-DCA.