Synergistic inhibition of green rust crystallization by co-existing arsenic and silica
Research output: Contribution to journal › Journal article › Research › peer-review
Arsenic and silica are known inhibitors of the crystallization of iron minerals from poorly ordered precursor phases. However, little is known about the effects of co-existing As and Si on the crystallization and long-term stability of mixed-valence Fe minerals such as green rust (GR). GR usually forms in anoxic, Fe2+-rich, near-neutral pH environments, where they influence the speciation and mobility of trace elements, nutrients and contaminants. In this work, the Fe2+-induced transformation of As- and/or Si-bearing ferrihydrite (FHY) was monitored at pH 8 ([As]initial = 100 μM, Si/As = 10) over 720 h. Our results showed that in the presence of As(III) + Si or As(V) + Si, GR sulfate (GRSO4) formation from FHY was up to four times slower compared to single species system containing only As(III), As(V) or Si. Co-existing As(III) + Si and As(V) + Si also inhibited GRSO4 transformation to magnetite, contrary to systems with only Si or As(V). Overall, our findings demonstrate the synergistic inhibitory effect of co-existing Si on the crystallization and solid-phase stability of As-bearing GRSO4, establishing an inhibitory effect ladder: As(III) + Si > As(V) + Si > As(III) > Si > As(V). This further highlights the importance of GR in potentially controlling the fate and mobility of As in ferruginous, Si-rich groundwater and sediments such as those in South and Southeast Asia.
Original language | English |
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Journal | Environmental Science. Processes & Impacts |
Volume | 26 |
Issue number | 3 |
Pages (from-to) | 632-643 |
Number of pages | 12 |
ISSN | 2050-7887 |
DOIs | |
Publication status | Published - 2024 |
- Arsenic/chemistry, Silicon Dioxide, Crystallization, Oxidation-Reduction, Ferric Compounds/chemistry, Minerals/chemistry
Research areas
ID: 389362084