Granular iron hydroxide (GIH) adsorbents are widely used for arsenic removal and have
been reported to operate more than 1.5 years without any regeneration. During this
prolonged operational period the iron hydroxide may shift towards more stable crystalline
forms that have less affinity for arsenate. The objectives of this research work were to
study the effect of extended GIH media storage and shifts in pH on its arsenic removal
effectiveness. Batch adsorption studies were conducted by contacting fresh, six- and
nine-month old granular Bayoxide E33 media (10g/L) with 60,000 µg As (V)/L solution
at pH 4 and pH 7. For 1 day batch equilibrium time, arsenate adsorption capacity was
observed to decrease by 47 % (from 6.0 mg As/g media to 3.2 mg As/g media) and 83 %
(from 6.0 mg As/g media to 1.0 mg As/g media) for nine-month old media in batch
studies, conducted at initial pH 4 and 7, respectively. Further, pH adjustment had little
impact on the arsenate adsorption capacity of the fresh media, but did show some
indications of restoring capacity to the older media. For 15 days equilibrium time, the
arsenate adsorption capacity was increased by 100 % (from 2.7 mg As/g media to 5.4 mg
As/g media) and 27 % (from 2.6 mg As/g media to 3.3 mg As/g media) for six- and nine-month
old media, respectively. The results obtained in this research indicated that the
arsenate adsorption capacity of GIH media may decrease during prolonged media use. In
addition, shifts in pH have the potential to offer a means of prolonging media life by
redeveloping fresh surface sites with high affinity for arsenate. Includes 9 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.2 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 34 |
| Published : | 06/01/2007 |
