Details

Autor(en) / Beteiligte

• Tang, Hongmei
• Chen, Meiqing
• Wu, Pingxiao
• Li, Yihao
• Wang, Tianming
• Wu, Jiayan
• Sun, Leiye
• Shang, Zhongbo

Titel

The influence of Mn(II) on transformation of Cr-absorbed Schwertmannite: Mineral phase transition and elemental fate

Ist Teil von

• Water research (Oxford), 2024-06, Vol.257, p.121656-121656, Article 121656

Ort / Verlag

England: Elsevier Ltd

Erscheinungsjahr

2024

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •The effect of Mn(II) on Cr-Sch transformation was significantly dependent on pH.•Mn(II) promoted the transformation of Cr-Sch from hematite to goethite at pH 10.0.•Mn(II) was oxidized to Mn(III)/Mn(IV) and uniformly distributed on minerals.•The existence of Mn(II), especially at high concentration, reduced the migration of Cr.•Mn(II) inhibited the release of the outer-sphere coordinated SO42− at pH 7.0. Schwertmannite (Sch) is considered as an effective remover of Chromium (Cr) due to its strong affinity for toxic Cr species. Since the instability of Sch, the environmental fate of Cr deserves attention during the transformation of Sch into a more stable crystalline phase. The ubiquitous manganese(II) (Mn(II)) probably affects the transformation of Sch and thus the environmental fate of Cr. Therefore, this study investigated the impact of Mn(II) on the transformation of Cr-absorbed Sch (Cr-Sch) and the associated behavior of SO42− and Cr. We revealed that the transformation products of Cr-Sch at pH 3.0 and 7.0 were goethite and Sch, respectively. The presence of Mn(II) weakened the crystallinity of the transformation products, and the trend was positively correlated with the concentration of Mn(II). However, Mn(II) changed the transformation products of Cr-Sch from hematite to goethite at pH 10.0. Mn(II) replaced Fe(III) in the mineral structures or formed Mn-O complexes with surface hydroxyl groups (-OH), thereby affecting the transformation pathways of Sch. The presence of Mn(II) enhanced the immobilization of Cr on minerals at pH 3.0 and 7.0. Sch is likely to provide an channel for electron transfer between Mn(II) and Cr(VI), which promotes the reduction of Cr(VI). Meanwhile, Mn(Ⅱ) induced more -OH production on the surface of secondary minerals, which played an important role in increasing the Cr fixation. In addition, part of the Mn(Ⅱ) was oxidized to Mn(Ⅲ)/Mn(Ⅳ) at pH 3.0 and pH 7.0. This study helps to predict the role of Mn(II) in the transformations of Cr-Sch in environments and design remediation strategies for Cr contamination. [Display omitted]