The objective of this research was to understand the combined effects of pH, ion
types and time on phase transformation of a commercially available granular iron
hydroxide media, Bayoxide E33, exposed to a synthetic groundwater at pH 6 and pH 8
for 90 days in batch experiments, using X-ray diffraction (XRD) technique. No new
iron/arsenic bearing mineral was observed for spent E33 media indicating that arsenic
was not incorporated within the crystalline structure of the media. However, XRD peaks
of spent media at 20 = 21.62º and 36.9º were observed to widen compared to fresh
media. Greater widening of peaks was observed for samples exposed to pH 6 solutions
than that exposed to pH 8 solutions. Observed changes in peak-widths of spent media
suggest the possibility of structural changes in media over time, which may also influence
its arsenic adsorptive capacity over time. These findings are relevant to small utilities that
treat groundwater with high arsenic and ferrous iron concentrations. Concerns appear to
be greater for reduced, alkaline groundwater as the pH 8 sample with ferrous iron present
showed the greatest structural change. Further experiments are underway to collect more
information about changes in degree of crystallinity and arsenic adsorption capacity of
iron oxide media over time, which could be useful in understanding the combined effects
of different environmental factors on its stability and time-dependent arsenic removal
effectiveness. Includes 16 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 790 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 11/01/2008 |
