A model explaining the anomalous enrichment of Pt in phosphatized crusts: The influence of phosphates and organic acids

IF 3.6 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Chemical Geology Pub Date : 2025-02-04 DOI:10.1016/j.chemgeo.2025.122673

Zhengkun Li , Xiaoming Sun , Dengfeng Li , Yongjia Liang

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引用次数: 0

Abstract

Numerous studies have reported a remarkable enrichment of platinum (Pt) in phosphatized ferromanganese crusts, with concentrations several times higher than in non-phosphatized crusts. Understanding the mechanism behind this extraordinary Pt enrichment requires investigating the influence of anoxic water layers, which are rich in various ions, on the accumulation and preservation of Pt in ferromanganese minerals during phosphorization events. This study combines adsorption/desorption experiments, Fourier transform infrared (FTIR) spectrum analysis, transmission electron microscope (TEM) observations, and X-ray absorption fine structure (XAFS) analysis using feroxyhyte (δ-FeOOH) and vernadite (δ-MnO2) as representative ferromanganese minerals in FeMn crusts to examine the fixation and reactivation of Pt during phosphorization events. Our research findings reveal that changes in the ionic composition of water layers during phosphorization events have a significant impact on the adsorption and preservation of Pt by ferromanganese minerals. Fe²⁺, Mn²⁺, and phosphate ions were found to strongly inhibit the adsorption of Pt by feroxyhyte. On the other hand, citric acid enhances Pt adsorption by creating additional adsorption sites at the edges of vernadite through dissolution. Regarding Pt preservation, phosphate ions can lead to a substantial release of Pt adsorbed in feroxyhyte, while only a small amount of Pt in vernadite can be released by phosphate. FTIR analysis indicates that phosphate can reactivate Pt in feroxyhyte by competing for surface hydroxyl groups. XAFS analysis further reveals that phosphate ions weaken the bonding between Pt and vernadite, although not to an extent that causes significant Pt release.

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来源期刊

Chemical Geology 地学-地球化学与地球物理

CiteScore

7.20

自引率

10.30%

发文量

374

审稿时长

3.6 months

期刊介绍： Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry. The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry. Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry. The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.