Influence of pH, iron source, and Fe/ligand ratio on iron speciation in lignosulfonate complexes studied using Mössbauer spectroscopy. Implications on their fertilizer properties

Jaime Carrasco, Krisztina Kovács, Viktória Czech, F. Fodor, Juan J. Lucena, A. Vértes, Lourdes Hernández-Apaolaza

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Iron chlorosis is a very common nutritional disorder in plants that can be treated using iron fertilizers. Synthetic chelates have been used to correct this problem, but nowadays environmental concerns have enforced the search for new, more environmentally friendly ligands, such as lignosulfonates. In this paper, Fe coordination environment and speciation in lignosulfonate (LS) complexes prepared under different experimental conditions were studied by 57Fe Mössbauer spectroscopy in relation to the Fe-complexing capacities, chemical characteristics of the different products, and efficiency to provide iron in agronomic conditions. It has been observed that the complex formation between iron and lignosulfonates involves different coordination sites. When Fe 2+ is used to prepare the iron-LS product, complexes form weak adducts and are sensitive to oxidation, especially at neutral or alkaline pH. However, when Fe 3+ is used to form the complexes, both Fe 2+ and Fe 3+ are found. Reductive sugars, normally present in lignosulfonates, favor a relatively high content of Fe 2+ even in those complexes prepared using Fe 3+. The formation of amorphous ferrihydrite is also possible. With respect to the agronomical relevance of the Fe 2+/Fe 3+ speciation provided by the Mössbauer spectra, it seems that the strong Fe 3+-LS complexes are preferred when they are applied to the leaf, whereas root uptake in hydroponics could be more related with the presence of weak bonding sites.

Original languageEnglish
Pages (from-to)3331-3340
Number of pages10
JournalJournal of Agricultural and Food Chemistry
Volume60
Issue number13
DOIs
Publication statusPublished - Apr 4 2012

Fingerprint

lignosulfonates
Fertilizers
spectroscopy
Spectrum Analysis
Iron
fertilizers
Spectroscopy
iron
Ligands
iron fertilizers
Nutrition Disorders
Hydroponics
Hypochromic Anemia
ferrihydrite
diet-related diseases
chelates
chlorosis
hydroponics
Sugars
ligands

Keywords

  • complexes
  • iron
  • lignosulfonates
  • Mo.ssbauer spectroscopy

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Chemistry(all)

Cite this

Influence of pH, iron source, and Fe/ligand ratio on iron speciation in lignosulfonate complexes studied using Mössbauer spectroscopy. Implications on their fertilizer properties. / Carrasco, Jaime; Kovács, Krisztina; Czech, Viktória; Fodor, F.; Lucena, Juan J.; Vértes, A.; Hernández-Apaolaza, Lourdes.

In: Journal of Agricultural and Food Chemistry, Vol. 60, No. 13, 04.04.2012, p. 3331-3340.

Research output: Contribution to journalArticle

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