Laboratory synthesis of goethite and ferrihydrite of controlled particle sizes

Abstract

Iron oxyhydroxides, such as goethite and ferrihydrite, are highly abundant and ubiquitous minerals in geochemical environments. Because of their small particle sizes, their surface reactivity is high towards adsorption of anions and cations of environmental relevance. For this reason these minerals are extensively studied in environmental geochemistry, and also are very important for environmental and industrial applications. In the present work, we report the synthesis and characterization of goethite and ferrihydrite of controlled particle sizes. It has been shown that surface reactivity of these minerals is highly dependent on crystal sizes, even after normalizing by specific surface area. In order to investigate the reasons for this changing reactivity it is necessary to work with reproducible particle sizes of these minerals. We investigated here the experimental conditions to synthesize goethite samples of four different specific surface areas: ca. 40, 60, 80 and 100 m 2 g -1 , through the controlled speed of hydroxide addition during hydrolysis of acid Fe(III) solutions. In the case of 2-line ferrihydrite, samples with two different particle sizes were prepared by changing the aging time under the pH conditions of synthesis (pH = 7.5). The synthesized minerals were identified and characterized by: X-ray diffraction, N 2 adsorption BET specific surface area, transmission electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and maximum Cr(VI) adsorption.Keywords: synthesis, iron oxides, specific surface area, goethite, ferrihydrite, particle size. Resumen

Elemental sulfur reduction in the deep‐sea vent thermophile, Thermovibrio ammonificans

“…Cultures with 160 mg/50 ml ferrihydrite as a sulfide scavenger were also tested. Ferrihydrite was synthesized according to (Villacís-García et al, 2015). Growth curves for both nitrate and sulfur reducing cultures were obtained from direct counts of cells sampled during exponential growth.…”

Microbial Reduction of Metal-Organic Frameworks Enables Synergistic Chromium Removal

“…Although they are morphologically similar, MIL-100 and Fe-BTC vary significantly in accessible surface area. MIL-100 had the largest Langmuir surface area (2188 m 2 g -1 ) followed by Fe-BTC (1512 m 2 -1 ), ferrihydrite (311 m 2 -1 , (24)) and MIL-88A (130 m 2 -1 ) (Table S1). These surface areas closely track our measured Fe(III) reduction rates.…”

“…Ferrihydrite was synthesized by adding 1M NaOH dropwise to FeCl3·6H 2 O (5.4 g, 20.0 mmol) dissolved in 100 mL H 2 O until the pH reached ~7.5. The solid was isolated by centrifugation, washed with water (3x at 25 °C for 10 min), and lyophilized immediately following washing for 48 h(24). Stepanovite was synthesized by stirring red hematite (1.5 g, 9.5 mmol), NaOH (0.38 g, 9.5 mmol), and magnesium oxide (0.38, 9.5 mmol) in 30 mL of 10% w/v oxalic acid solution for 15 h. Single crystals were obtained by filtering and storing the solution at 4 °C for 24 h. Stepanovite powder used for MR-1 reduction was obtained by evaporating the solution after filtration using a rotary evaporator (85 °C, 45 rpm, low vacuum, (13) ).…”

“…(a) The MtrCAB pathway by which S. oneidensis reduces both soluble and insoluble metal species (1) . (b-d) The crystal structure of MIL-100/Fe-BTC (b, (45, 46)), MIL-88A (c, (47) ), and ferrihydrite (d, (24) ). Fe-BTC does not have a known crystal structure (due to its amorphous nature), but it is analogous to MIL-100.…”

Preparation and characterization of synthesized goethite and goethite-date palm seeds charcoal composite

“…Iron oxides are generally known to be responsible for the movement and behaviour of numerous chemical species in soils, rocks and aquatic environments through adsorption processes (Adegoke et al, 2013) and other chemical reactions, particularly onto goethite and ferrihydrite (Villalobos and Antelo, 2011) or through adsorption followed by reduction mechanisms as is the case of susceptible species on magnetite (Villacís-García et al, 2015). Goethite (FeO(OH) or α-FeOOH) named after the German polymath and poet Johann Wolfgang von Goethe (1749Goethe ( -1832.…”