Fig. 1. (A) Open circuit chronopotentiograms obtained with PDEs of nine samples of Fisher electrolytic (Felc) granular Fe⁰. Samples are identified in Table 1. (B) Typical linear sweep voltammogram for a Felc PDE at 0.1 mV s⁻¹. All results in 0.19 mM borate buffer at pH 8.4.

Fig. 2. (A) Open circuit chronopotentiograms obtained with Felc PDEs with various concentrations of NaCl. Performed with Felc sample A. (B) Typical linear sweep voltammogram for a Felc PDE at 0.1 mV s⁻¹. All results in 0.19 mM borate buffer at pH 8.4.

Fig. 3. (A) Open circuit chronopotentiograms obtained with Felc PDEs with various concentrations of NOM. Performed with Felc sample A. (B) Typical linear sweep voltammogram for a Felc PDE at 0.1 mV s⁻¹. All results in 0.19 mM borate buffer at pH 8.4.

Fig. 4. (A) Open circuit chronopotentiograms obtained with Felc PDEs in borate buffer (0.19 mM, pH 8.4), phosphate buffer (0.19 mM, pH 8.0), and carbonate buffer at 4 pHs. Performed with sample A and C. (B) Typical linear sweep voltammogram for a Felc PDE at 0.1 mV s⁻¹.

Fig. 5. Scanning electron micrographs of Felc Fe⁰ (sample C). (A) The untreated material and (B) after 2 h exposure to DI water. Panel (C) shows partial coverage by precipitates after 2 h exposure to carbonate buffer, and panel (D) shows more complete coverage after 4 h of exposure to carbonate buffer.

Fig. 6. Open circuit chronopotentiograms obtained with Felc PDEs in carbonate buffer at 4 pHs. Two sets of experiments, one performed with Felc sample A and the other with sample C. Same data as in Fig. 4, but rescaled to resolve the effect of pH.

Fig. 7. (A) Open circuit chronopotentiograms obtained with Felc PDEs in carbonate buffer (0.38 mM, pH 5.5). Circles represent times at which a contaminant was added to the system in Agrawal et al. [43]. Performed with sample A. (B) Typical linear sweep voltammogram for a Felc PDE at 0.1 mV s⁻¹.

Fig. 8. Hydrogen concentration measured in headspace of batch reactors containing Felc and carbonate buffer (0.38 mM, pH 5.5). (A) Data for the first 4 h of exposure and (B) data over 32 h.

Dates and treatment information for the iron samples used in this study