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Bench-scale studies were conducted to evaluate the effects of several processvariables, such as reaction pH, adsorbent dosage, and particle size of the media on thekinetics of adsorption and treatment efficiency of a process for removing arsenic (III)and arsenic (V) from contaminated groundwater by adsorption onto Granular FerricHydroxide (GFHTM). The concentrations of dissolved arsenic in the samples wereanalyzed 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) andarsenic (V), and is effective over a wide pH range. The adsorption of arsenic (III) is lesspH-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 "asreceived" GFH media can be approximated by first-order kinetics. The adsorptioncharacteristics of the media were analyzed and evaluated using the Freundlichadsorption isotherm equation. The regression coefficients demonstrate that theFreundlich model fits both the arsenic (III) and arsenic (V) experimental resultsreasonably well. The rates of adsorption and the treatment efficiency are a function ofreaction pH, media dosage, and particle size. Results of the U.S. Environmental Protection Agency's ToxicCharacteristic Leaching Procedure (TCLP) test showed that the concentrations ofarsenic in the TCLP extracts were less than the regulatory limit of 5 mg/L. GFH mediacan be used to directly treat groundwater or can be added to an existing watertreatment system as a polishing unit without impacting the existing operation. Includes 21 references, tables, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 16File Size: 1 file , 360 KB