Synergistic inhibition of green rust crystallization by co-existing arsenic and silica
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Synergistic inhibition of green rust crystallization by co-existing arsenic and silica. / Perez, Jeffrey Paulo H; Tobler, Dominique J.; Benning, Liane G.
I: Environmental Science. Processes & Impacts, Bind 26, Nr. 3, 2024, s. 632-643.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Synergistic inhibition of green rust crystallization by co-existing arsenic and silica
AU - Perez, Jeffrey Paulo H
AU - Tobler, Dominique J.
AU - Benning, Liane G.
PY - 2024
Y1 - 2024
N2 - 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.
AB - 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.
KW - Arsenic/chemistry
KW - Silicon Dioxide
KW - Crystallization
KW - Oxidation-Reduction
KW - Ferric Compounds/chemistry
KW - Minerals/chemistry
U2 - 10.1039/d3em00458a
DO - 10.1039/d3em00458a
M3 - Journal article
C2 - 38362760
VL - 26
SP - 632
EP - 643
JO - Environmental Science. Processes & Impacts
JF - Environmental Science. Processes & Impacts
SN - 2050-7887
IS - 3
ER -
ID: 389362084