Correction: FeS colloids – formation and mobilization pathways in natural waters

Abstract

Correction for ‘FeS colloids – formation and mobilization pathways in natural waters’ by Vincent Noël et al., Environ. Sci.: Nano, 2020, 7, 2102–2116, https://doi.org/10.1039/C9EN01427F.

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The authors regret that they did not make the connection between this work and the work in ref. 41 previously published by the same group of authors clear.

In the Introduction, the section beginning with “The recent study by Kumar…” should have read:

In our previous study⁴¹ we found that the ratio of dissolved sulfide to iron (sulfide/Fe) is a critical variable in the Fh sulfidation reaction, where we only focused on the solid phase transformation. Reductive dissolution of Fh resulted in incremental releases of dissolved Fe(II) up to a sulfide/Fe ratio of 0.5, with Fe(II) concentrations declining sharply above this ratio, suggesting formation and settling of poorly crystalline iron monosulfide (FeS). However, dissolved Fe(II) is not thermodynamically stable in waters at circumneutral pH values and should react with aqueous sulfide, resulting in the formation of aqueous FeS complexes as well as larger colloidal particles.⁴² Aqueous FeS clusters, defined operationally in terms of their voltammetric characteristics, have been previously detected in natural (sub)surface water.^33,42,43 Thus, we posit that aqueous FeS clusters and/or larger colloidal particles are able to resist aggregation that results in precipitation and can potentially sorb nutrients and contaminants and facilitate their transport under conditions outside of the solubility regime of the individual participating ions. Building upon our previous work which focused only on solid phase transformation,⁴¹ in this study, we used selected S/Fe ratios to focus on the characterization of FeS colloids in aqueous phase. We found that the Fh sulfidation reaction indeed generates FeS clusters and larger colloidal particles and determined the conditions required for their stability in aqueous suspensions.

In the section 3.5 TEM characterization of solid fraction, this additional sentence should have been included:

The change in solid solution ratio (200 mg ferrihydrite in 20 mL against 200 mg ferrihydrite in 65 mL) is primarily due to the analysis volume needed in the [present] experiment. Based on the well-supported assumption that the reaction is governed only by S/Fe ratios, we compare results and reinterpret the previous TEM image.

In the 2.1.1 Ferrihydrite synthesis section, this should have read as:

Ferrihydrite was synthesized following the method described in Kumar et al.⁴¹

The Fig. 7 caption should have read:

TEM images of the solid fraction (Fig. 1) from sulfidation of Fh in a 0.1 M NaCl solution after 336 h for sulfide ratio of 0.5 (a) and 2 (b) reinterpreted from Kumar et al.⁴¹ The white circles and lines show the nanoparticles and the orientation of layers, respectively.

In the Discussion section 4.1, the sentences beginning “These results suggest that aqueous…” should have read:

These results suggest that aqueous FeS clusters serve as precursors of larger FeS colloidal particles, which necessitates the following modification to our model proposed earlier⁴¹ for Fh sulfidation at low sulfide/Fe ratios. Fe(II) released from the reductive dissolution of Fh by dissolved sulfide produces aqueous FeS clusters at low sulfide/Fe ratios.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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