Kinetic and thermodynamic aspects of adsorption of arsenic onto granular ferric hydroxide (GFH)

• Published in: Water research (Oxford) Vol. 42; no. 13; pp. 3371 - 3378
• Main Authors: Banerjee, Kashi, Amy, Gary L., Prevost, Michele, Nour, Shokoufeh, Jekel, Martin, Gallagher, Paul M., Blumenschein, Charles D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2008; Elsevier Science
• Subjects: adsorbents; Adsorption; Applied sciences; Arsenic; Arsenic - chemistry; Arsenic - isolation & purification; chemical speciation; Exact sciences and technology; Ferric Compounds - chemistry; ferric hydroxide; Granular ferric hydroxide; hydrochemistry; Hydrogen-Ion Concentration; Iron oxide; Kinetics; Other industrial wastes. Sewage sludge; Pollution; reaction kinetics; sorption isotherms; Temperature; Thermodynamics; Wastes; water pollution; water temperature; water treatment; Water treatment and pollution; Iron oxide; Kinetics; Arsenic; Adsorption; Granular ferric hydroxide; Arsenates; Temperature effect; Arsenites; Kinetic model; Iron III; Batchwise; Thermodynamic parameter; Arsenic III
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2008.04.019

Relatively limited information is available regarding the impacts of temperature on the adsorption kinetics and equilibrium capacities of granular ferric hydroxide (GFH) for arsenic (V) and arsenic (III) in an aqueous solution. In general, very little information is available on the kinetics and thermodynamic aspects of adsorption of arsenic compounds onto other iron oxide-based adsorbents as well. In order to gain an understanding of the adsorption process kinetics, a detailed study was conducted in a controlled batch system. The effects of temperature and pH on the adsorption rates of arsenic (V) and arsenic (III) were investigated. Reaction rate constants were calculated at pH levels of 6.5 and 7.5. Rate data are best described by a pseudo first-order kinetic model at each temperature and pH condition studied. At lower pH values, arsenic (V) exhibits greater removal rates than arsenic (III). An increase in temperature increases the overall adsorption reaction rate constant values for both arsenic (V) and arsenic (III). An examination of thermodynamic parameters shows that the adsorption of arsenic (V) as well as arsenic (III) by GFH is an endothermic process and is spontaneous at the specific temperatures investigated.