Structural features and Fe(II)-Binding capacities of humic acids from reservoir sediments

Masami Fukushima*, Naotaka Fujisawa, Ken Furubayashi, Hisanori Iwai, Keishi Otsuka, Mitsuo Yamamoto, Takeshi Komai, Yasunari Kawabe, Shigekazu Horiya

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Reservoirs frequently require dredging to remove accumulated sediment. This sediment is currently unused, but represents a possible source of humic acids (HAs) that have potential as iron-binding supplements in fertilizers. In order to evaluate the utility of these materials, we investigated the structural features and Fe(ll)-binding constants or capacities of some HAs obtained from reservoir sediments. The histidine content in the HAs was correlated to the Freundlich binding constant for an Fe(ll)-HA complex, indicating that indole moieties in histidine function as strong binding sites for Fe(ll). The binding capacities (2.2-3.2 mmolg -1) indicated that the HAs have the capacity to be loaded with 12-18% Fe(ll), comparable to the iron content of previously reported Fe fertilizers that employ HAs from other sources (2-17%). The Fe(ll)-binding capacities were positively correlated with the content of phenolic hydroxyl groups. In addition, the positive correlation between Fe(ll)-binding capacity and vanillyl moieties in the HAs indicates that 3,4-dihydroxyben-zene and/or benzoic acid derivatives also serve as Fe(ll) binding sites.

Original languageEnglish
Pages (from-to)452-458
Number of pages7
Issue number6
Publication statusPublished - 2012
Externally publishedYes


  • Binding capacity
  • Humic acid
  • Iron
  • Reservoir
  • Sediment

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)


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