Premium
Role of Dissolved Organic Matter in the Release of Chromium from Schwertmannite: Kinetics, Repartition, and Mechanisms
Author(s) -
Xie Yingying,
Lu Guining,
Ye Han,
Yang Chengfang,
Yi Xiaoyun,
Dang Zhi
Publication year - 2017
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.03.0122
Subject(s) - schwertmannite , chemistry , ferrihydrite , dissolved organic carbon , goethite , chromium , jarosite , x ray photoelectron spectroscopy , dissolution , inorganic chemistry , environmental chemistry , adsorption , chemical engineering , organic chemistry , engineering
Dissolved organic matter (DOM) is an important factor influencing mineral biogeochemistry, although the role of labile DOM in the release of chromium (Cr) from schwertmannite, a mineral with high surface area, is unclear. In this study, the interaction of DOM with synthetic CrO 4 2− –schwertmannite was investigated to better understand the potential fate of Cr in high‐DOM environments. Minerals and their products were analyzed using Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy. Experiments were conducted at pH 3.2 or 6.5 for different lengths of time, with a shrinking core model developed to describe kinetic processes. The concentration of total Cr in solution reached a maximum when the pH was 6.5 and the concentration of L‐tryptophan was 5 mM. The newly formed minerals were confirmed to be mixtures involving residual schwertmannite, goethite, ferrihydrite, and jarosite. A possible mechanism is proposed to be a ligand‐controlled binary system, accompanied by possible reduction at acidic pH conditions (3.2), including mass transfer and charge transfer processes. This study gives a new perspective for understanding the reactivity and stability of schwertmannite in the environment; it also provides some predictions on the mobility and fate of Cr. These findings will help design remediation strategies for Cr contamination. Core Ideas The effects of various factors on release of Cr by DOM were considered. A possible mechanism for the release of Cr from schwertmannite was proposed. The time‐dependent product formation has been identified.