Bench-scale studies were conducted to evaluate the effects of several process
variables, such as reaction pH, adsorbent dosage, and particle size of the media on the
kinetics of adsorption and treatment efficiency of a process for removing arsenic (III)
and arsenic (V) from contaminated groundwater by adsorption onto Granular Ferric
Hydroxide (GFHTM). The concentrations of dissolved arsenic in the samples were
analyzed using the Inductively Coupled Plasma - Mass Spectroscopy (ICP-MS)
method, which is capable of detecting arsenic concentrations as low as 1.5 ug/L.
The results reveal that GFH media is capable of removing both arsenic (III) and
arsenic (V), and is effective over a wide pH range. The adsorption of arsenic (III) is less
pH-dependent than that of arsenic (V). Kinetics data indicate that the reaction is fast,
and the rate of adsorption of arsenic (III) and arsenic (V) onto both pulverized and "as
received" GFH media can be approximated by first-order kinetics. The adsorption
characteristics of the media were analyzed and evaluated using the Freundlich
adsorption isotherm equation. The regression coefficients demonstrate that the
Freundlich model fits both the arsenic (III) and arsenic (V) experimental results
reasonably well. The rates of adsorption and the treatment efficiency are a function of
reaction pH, media dosage, and particle size. Results of the U.S. Environmental Protection Agency's Toxic
Characteristic Leaching Procedure (TCLP) test showed that the concentrations of
arsenic in the TCLP extracts were less than the regulatory limit of 5 mg/L. GFH media
can be used to directly treat groundwater or can be added to an existing water
treatment system as a polishing unit without impacting the existing operation. Includes 21 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 360 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 16 |
| Published : | 06/15/2003 |
