The detection of new and emerging contaminants in the groundwater may poses a serious threat to water quality. The objective of the study is to investigate the degradation potential of emerging contaminants with zerovalent metals (Zn) and related bimetallic reductants (Pd-Zn and Cu-Zn) at bench-scale for the development of water treatment approaches. The degradation behavior and pathways of emerging organic contaminants, e.g., bromodichloromethane (BDM), chlorodibromomethane (CDM), 1,2-dibromoethane (DBA), 1,3-dichloropropane (DCP), and 1,2,3-trichloropropane (TCP), are being investigated with granular forms of Zn metal (zero valent zinc or Zn) and bimetallic Zn reductants (e.g., Pd-Zn, Cu-Zn) at bench-scale. In specific preparations, bimetallic Pd-Zn and Cu-Zn reductants were freshly synthesized by solution deposition method just prior to use, and the amounts of Pd in Pd-Zn, and Cu in Cu-Zn were 0.02-0.2% and 0.1-2% (w/w), respectively. Batch reactors were set up in anaerobically sealed, 160 mL serum bottles typically with 3 g of metallic granular reductants (20-24 mesh) in aqueous medium with 30 mM TAPSO buffer at pH 7. Reactor headspace was analyzed by gas chromatography (HP 6890) with flame ionization and electron capture detectors.  Preliminary results show that granular Pd-Zn and Cu-Zn can degrade chloroform (CF) quite effectively to methane as reaction byproduct. Pd-Mg and Cu-Mg reductants showed much faster degradation of CF, in comparison to Zn granules. Results also revealed that increase in Pd loading from 0.02 to 0.2% w/w in Pd-Zn did not influence CF degradation rate constant; however, increase in loading of Pd-Zn granules accelerated degradation kinetics, which suggests that surface area of Pd-Mg may play a key role in dechlorination reactions. The results of CF degradation may be useful to better understand the degradation mechanism of BDM and CDM. The degradation behavior of other emerging, halogenated organic contaminants, with Zn, Pd-Zn and Cu-Zn reductants is under investigation.

Degradation potential of emerging contaminants by zerovalent zinc (Zn) and specific bimetallic reductants (Pd-Zn and Cu-Zn) in batch reactors

246th National Meeting (2013)

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