The Transformation of Two-Line Ferrihydrite into Crystalline Products: Effect of pH and Media (Sulfate versus Nitrate)

Zhang, Danni; Wang, Shaofeng; Wang, Ying; Goméz, Mario A.; Duan, Yihang; Jia, Yongfeng

doi:10.1021/acsearthspacechem.8b00001

Cited by 39 publications

(26 citation statements)

References 38 publications

(108 reference statements)

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“…The MS result is consistent with our XRD results (Figure B), which also indicated that the final product in the 5% PHF–Fh system had weaker characteristic Gth reflections. The formation of Hem promoted by PHF may be caused by the enhanced aggregation of Fh particles by PHF, as Hem was formed through the aggregation and dehydration pathway, while Gth may be formed preferentially through the dissolution–recrystallization pathway. , …”

Section: Results and Discussionmentioning

confidence: 99%

Effects of Fullerol and Graphene Oxide on the Phase Transformation of Two-Line Ferrihydrite

Yan

Zhu

Liu

et al. 2020

ACS Earth Space Chem.

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Two-line ferrihydrite (Fh) is an omnipresent iron oxyhydroxide nanomineral with high surface reactivity and weak crystallinity, and its phase transformation in nature has drawn significant concerns. A number of studies have investigated the effects of coexisting natural substances (e.g., ions, organic molecules, and clay minerals) on the phase transformation processes of Fh. This work, for the first time, studied the effects of coexisting carbon nanomaterials (CNM) on the phase transformation of Fh, and CNM with different morphologies, that is, graphene oxide (GO) and fullerol (PHF), were applied. Characterization results from X-ray diffraction, transmission electron microscopy, and Mossbauer spectroscopy showed that the transformed products of Fh are mainly hematite (Hem) with a small amount of goethite (Gth) in the absence/presence of CNM; however, the transformation kinetics, morphologies, and Hem/Gth ratio of the transformed products are distinctly different in each system. In particular, GO decreased the transformation rate of Fh (compared with the Fh system), whereas PHF not only accelerated the transformation rate but also favored the formation of larger Hem particles and higher Hem/Gth ratios in the transformed products. We hypothesized that these results could be attributed to the different behaviors of CNM in affecting the aggregation of Fh as the transformation of Fh into Hem is a solid phase transformation process (via dehydration), which strongly relies on the aggregation of Fh particles. In this term, the samples of CNM−Fh mixtures before transformation were characterized. The results obtained from atomic force microscopy and sedimentation experiments showed that the large lamellar GO could act as a dispersing agent and inhibit the aggregation and contact of Fh particles while the nanogranular PHF functioned as a "bridge" and enhanced the aggregation of Fh particles. This study revealed that the coexisting nanoparticles (e.g., PHF and GO) could exert different influences on the transformation of Fh by influencing its aggregation and dispersion.

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Section: Results and Discussionmentioning

confidence: 99%

Effects of Fullerol and Graphene Oxide on the Phase Transformation of Two-Line Ferrihydrite

Yan

Zhu

Liu

et al. 2020

ACS Earth Space Chem.

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“…Aliquots for aqueous-phase analysis were passed through 0.22 μm filters. The total arsenic and iron in initial ferrihydrite were obtained by the aquaregia digestion method and the solid associative Fe(II) was extracted by 1 M HCl solution [ 36 ]. The pH was measured by a pH meter.…”

Section: Methodsmentioning

confidence: 99%

Effects of Calcium on Arsenate Adsorption and Arsenate/Iron Bioreduction of Ferrihydrite in Stimulated Groundwater

Chen

Xie

Yang

et al. 2022

IJERPH

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The reduction and transformation of arsenic-bearing ferrihydrite by arsenate-iron reducing bacteria is one of the main sources of arsenic enrichment in groundwater. During this process the coexistence cations may have a considerable effect. However, the ionic radius of calcium is larger than that of iron and shows a low affinity for ferrihydrite, and the effect of coexisting calcium on the migration and release of arsenic in arsenic-bearing ferrihydrite remains unclear. This study mainly explored the influence of adsorbed Ca2+ on strain JH012-1-mediated migration and release of arsenate in a simulated groundwater environment, in which 3 mM ferrihydrite and pH 7.5. Ca2+ were pre-absorbed on As(V)-containing ferrihydrite with a As:Fe ratio of 0.2. Solid samples were analyzed by X-ray diffraction (XRD), scanning electron microscopic (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results show that calcium and arsenate can synergistically adsorb on ferrihydrite due to the electrostatic interactions, and the adsorbed Ca2+ mainly exists on the surface through the outer-sphere complex. Adsorbed Ca2+ entering the stimulated groundwater was easily disturbed and led to an extra release of 3.5 mg/L arsenic in the early stage. Moreover, adsorbed Ca2+ inhibited biogenic ferrous ions from accumulating on ferrihydrite. As a result, only 12.30% Fe(II) existed in the solid phase, whereas 29.35% existed without Ca2+ adsorption. Thus, the generation of parasymplesite was inhibited, which is not conducive to the immobilization of arsenic in groundwater.

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“…Removal of the aqueous phase decreases sample mass and prevents the need for frozen storage, and the biochemical profile is preserved through inhibiting microbial degradation. Alternative treatments such as air drying are considered to be more aggressive as they can alter the chemical composition of samples and may inflict significant changes on sediment chemistry, including losses of biomarkers (McClymont et al, 2007) and changes in speciation of heavy metals (Zhang et al, 2001). However, how this process affects the physical properties of samples and their subsequent behaviour towards chemical reagents has not been widely considered.…”

Section: Sediment Freeze-drying As a Limiting Factor On Fe Reductionmentioning

confidence: 99%

Technical note: Uncovering the influence of methodological variations on the extractability of iron-bound organic carbon

et al. 2021

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Abstract. Association of organic carbon (OC) with reactive iron (FeR) represents an important mechanism by which OC is protected against remineralisation in soils and marine sediments. Recent studies indicate that the molecular structure of organic compounds and/or the identity of associated FeR phases exert a control on the ability of an OC–FeR complex to be extracted by the citrate–bicarbonate–dithionite (CBD) method. However, many variations of the CBD extraction are used, and these are often uncalibrated to each other, rendering comparisons of OC–FeR values extracted via the different methods impossible. Here, we created synthetic ferrihydrite samples coprecipitated with simple organic structures and subjected these to modifications of the most common CBD method. We altered some of the method parameters (reagent concentration, time of the extraction and sample preparation methods) and measured FeR recovery to determine which (if any) modifications affected the release of FeR from the synthetic sample. We provide an assessment of the reducing capacity of Na dithionite in the CBD method (the amount of Fe reduced by a fixed amount of dithionite) and find that the concentration of dithionite deployed can limit OC–FeR extractability for sediments with a high FeR content. Additionally, we show that extending the length of any CBD extraction offers no benefit in removing FeR. Moreover, we demonstrate that for synthetic OC–FeR samples dominated by ferrihydrite, freeze-drying samples can significantly reduce OC–FeR extractability; this appears to be less of an issue for natural marine sediments where natural ageing mechanisms may mimic the freeze-drying process for more stable Fe phases. While our study is not an all-inclusive method comparison and is not aimed at delivering the “perfect” extraction setup, our findings provide a collected summary of critical factors which influence the efficiency of the CBD extraction for OC–FeR. As such, we provide a platform from which OC–FeR values obtained under different methods can be interpreted and future studies of sediment carbon cycling can build upon.

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The Transformation of Two-Line Ferrihydrite into Crystalline Products: Effect of pH and Media (Sulfate versus Nitrate)

Cited by 39 publications

References 38 publications

Effects of Fullerol and Graphene Oxide on the Phase Transformation of Two-Line Ferrihydrite

Effects of Fullerol and Graphene Oxide on the Phase Transformation of Two-Line Ferrihydrite

Effects of Calcium on Arsenate Adsorption and Arsenate/Iron Bioreduction of Ferrihydrite in Stimulated Groundwater

Technical note: Uncovering the influence of methodological variations on the extractability of iron-bound organic carbon

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