Spectroscopic Manifestation of Interaction of Humic Acids with Ferric Ions in Aqueous Solutions

Khundzhua, Daria; Yuzhakov, V. I.; Korvatovskiy, Boris N.; Paschenko, V.Z.; Kulyabko, L. S.; Kydralieva, Kamila; Patsaeva, Svetlana V.

doi:10.3103/s0027134918060152

Cited by 4 publications

(1 citation statement)

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“…Recent research has shown that humic acids (HA) have a high affinity to Fe 3 O 4 NPs and the sorption of HA on the Fe 3 O 4 NP enhanced the stability of Fe 3 O 4 nanodispersions by preventing their aggregation via electrostatic and steric effects [ 19 , 20 , 21 , 22 , 23 ]. However, weak Coulombic attraction, hydrogen, and hydrophobic (van der Waals, π-π, CH-π) bonds between Fe 3 O 4 and HA [ 24 ] seemed not to protect Fe 3 O 4 NPs from the oxidation in real environmental conditions [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Humic Acids on the Ecotoxicity of Fe3O4 Nanoparticles and Fe-Ions: Impact of Oxidation and Aging

et al. 2020

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The magnetite nanoparticles (MNPs) are increasingly produced and studied for various environmental applications, yet the information on their ecotoxicity is scarce. We evaluated the ecotoxicity of MNPs (~7 nm) before and after the addition of humic acids (HAs). White mustard Sinapis alba and unicellular ciliates Paramecium caudatum were used as test species. The MNPs were modified by HAs and oxidized/aged under mild and harsh conditions. Bare MNPs proved not toxic to plants (96 h EC50 > 3300 mg/L) but the addition of HAs and mild oxidation increased their inhibitory effect, especially after harsh oxidation (96 h EC50 = 330 mg/L). Nevertheless, all these formulations could be ranked as ‘not harmful’ to S. alba (i.e., 96 h EC50 > 100 mg/L). The same tendency was observed for ciliates, but the respective EC50 values ranged from ‘harmful’ (24 h EC50 = 10–100 mg/L) to ‘very toxic’ (24h EC50 < 1 mg/L). The ecotoxicity of Fe-ions with and without the addition of HAs was evaluated in parallel: Fe (II) and Fe (III) ions were toxic to S. alba (96 h EC50 = 35 and 60 mg/L, respectively) and even more toxic to ciliates (24 h EC50 = 1 and 3 mg/L, respectively). Addition of the HAs to Fe-ions yielded the respective complexes not harmful to plants (96h EC50 > 100 mg/L) but toxic to ciliates (24h EC50 = 10–100 mg/L). These findings will be helpful for the understanding of the environmental fate and toxicity of iron-based NPs.

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