Effects of Adsorbed Arsenate on the Rate of Transformation of 2-Line Ferrihydrite at pH 10

Abstract

2-Line ferrihydrite, a form of iron in uranium mine tailings, is a dominant adsorbent for elements of concern (EOC), such as arsenic. As ferrihydrite is unstable under oxic conditions and can undergo dissolution and subsequent transformation to hematite and goethite over time, the impact of transformation on the long-term stability of EOC within tailings is of importance from an environmental standpoint. Here, studies were undertaken to assess the rate of 2-line ferrihydrite transformation at varying As/Fe ratios (0.500-0.010) to simulate tailings conditions at the Deilmann Tailings Management Facility of Cameco Corporation, Canada. Kinetics were evaluated under relevant physical (~1 °C) and chemical conditions (pH ~10). As the As/Fe ratio increased from 0.010 to 0.018, the rate of ferrihydrite transformation decreased by 2 orders of magnitude. No transformation of ferrihydrite was observed at higher As/Fe ratios (0.050, 0.100, and 0.500). Arsenic was found to retard ferrihydrite dissolution and transformation as well as goethite formation.

Fullerol modification ferrihydrite for the degradation of acid red 18 under simulated sunlight irradiation

“…1), consistent with previous reports for pure 2-line Fh [38,39], which suggested that the presence of PHF did not significantly affect the structure of Fh. According to the results of element analysis (Table 1), the contents of carbon element for 1.2%PHF/Fh, 2.3%PHF/Fh, 4.7%PHF/Fh, and 9.4%PHF/Fh were 0.81, 1.26, 2.06, and 3.67 wt%, respectively.…”

Aqueous Fe(II)-Induced Phase Transformation of Ferrihydrite Coupled Adsorption/Immobilization of Rare Earth Elements

“…Ferrihydrite was prepared in the laboratory according to previous studies [18,19]. Firstly, 20 g of Fe(NO 3 ) 3 •9H 2 O was dissolved in 250 mL of double distilled de-ionized (DDI) water.…”

Arsenate and phosphate adsorption on ferrihydrite nanoparticles. Synergetic interaction with calcium ions

“…A better understanding of the adsorption of oxyanions on this iron oxide has become increasingly important in recent years (Harrington et al, 2010;Das et al, 2011;Wang et al, 2013;Neupane et al, 2014;Zhu et al, 2014). Retention of oxyanions can be affected by the presence of other ions, which may enhance or suppress the adsorption process.…”