Dataset Information

Study of Complexes of Tannic Acid with Fe(III) and Fe(II).

ABSTRACT: UV-Vis absorption spectra of tannic acid were gained at pH 1.0?9.0. Due to the pH value dependence of complex, the stoichiometry of tannic acid with iron ions was tested in buffer solution by the mole ratio method. The result suggests that the complex ratio of tannic acid to Fe(III) is 1?:?1 and to Fe(II) 3?:?1 in the carbonate buffer solution, and the complex ratio of iron-tannic complexes is 1?:?1 at pH 2.2. Due to the different color changes of tannic acid with iron ions in the coordination reactions, a tannic acid test paper was designed. The concentrations of Fe(III) more than 5.000?×?10^-6?mol/L and the concentrations of Fe(II) more than 1.000?×?10^-5?mol/L in aqueous solution can be detected by this test paper.

SUBMITTER: Fu Z

PROVIDER: S-EPMC6378047 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Study of Complexes of Tannic Acid with Fe(III) and Fe(II).

Fu Zhaofeng Z Chen Rui R

Journal of analytical methods in chemistry 20190203

UV-Vis absorption spectra of tannic acid were gained at pH 1.0∼9.0. Due to the pH value dependence of complex, the stoichiometry of tannic acid with iron ions was tested in buffer solution by the mole ratio method. The result suggests that the complex ratio of tannic acid to Fe(III) is 1 : 1 and to Fe(II) 3 : 1 in the carbonate buffer solution, and the complex ratio of iron-tannic complexes is 1 : 1 at pH 2.2. Due to the different color changes of tannic acid with iron ions in the coordination r ...[more]

PMID: 30863653

Similar Datasets

Project description:Fe-organic matter (Fe-OM) complexes are abundant in the environment and, due to their mobility, reactivity, and bioavailability, play a significant role in the biogeochemical Fe cycle. In photic zones of aquatic environments, Fe-OM complexes can potentially be reduced and oxidized, and thus cycled, by light-dependent processes, including abiotic photoreduction of Fe(III)-OM complexes and microbial oxidation of Fe(II)-OM complexes, by anoxygenic phototrophic bacteria. This could lead to a cryptic iron cycle in which continuous oxidation and rereduction of Fe could result in a low and steady-state Fe(II) concentration despite rapid Fe turnover. However, the coupling of these processes has never been demonstrated experimentally. In this study, we grew a model anoxygenic phototrophic Fe(II) oxidizer, Rhodobacter ferrooxidans SW2, with either citrate, Fe(II)-citrate, or Fe(III)-citrate. We found that strain SW2 was capable of reoxidizing Fe(II)-citrate produced by photochemical reduction of Fe(III)-citrate, which kept the dissolved Fe(II)-citrate concentration at low (<10 μM) and stable concentrations, with a concomitant increase in cell numbers. Cell suspension incubations with strain SW2 showed that it can also oxidize Fe(II)-EDTA, Fe(II)-humic acid, and Fe(II)-fulvic acid complexes. This work demonstrates the potential for active cryptic Fe cycling in the photic zone of anoxic aquatic environments, despite low measurable Fe(II) concentrations which are controlled by the rate of microbial Fe(II) oxidation and the identity of the Fe-OM complexes.IMPORTANCE Iron cycling, including reduction of Fe(III) and oxidation of Fe(II), involves the formation, transformation, and dissolution of minerals and dissolved iron-organic matter compounds. It has been shown previously that Fe can be cycled so rapidly that no measurable changes in Fe(II) and Fe(III) concentrations occur, leading to a so-called cryptic cycle. Cryptic Fe cycles have been shown to be driven either abiotically by a combination of photochemical reduction of Fe(III)-OM complexes and reoxidation of Fe(II) by O2, or microbially by a combination of Fe(III)-reducing and Fe(II)-oxidizing bacteria. Our study demonstrates a new type of light-driven cryptic Fe cycle that is relevant for the photic zone of aquatic habitats involving abiotic photochemical reduction of Fe(III)-OM complexes and microbial phototrophic Fe(II) oxidation. This new type of cryptic Fe cycle has important implications for biogeochemical cycling of iron, carbon, nutrients, and heavy metals and can also influence the composition and activity of microbial communities.

Dataset Information

Study of Complexes of Tannic Acid with Fe(III) and Fe(II).

Publications

Study of Complexes of Tannic Acid with Fe(III) and Fe(II).

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets