Mechanism of iron ions sorption by chitosan-genipin films in acidic media


Chitosan-genipin (Ch-Ge) films have been proposed as wine preservative due to their capacity to uptake iron ions. The wine is an aqueous acidic solution of water and ethanol, whose acidity derives from tartaric acid. This acid has been shown to form negatively charged iron-tartrate complexes able to interact with the positively charged amine groups of chitosan, removing the iron ions from solutions. Nevertheless, it is possible that these films can uptake iron ions in the presence of other carboxylic acids. To understand the iron-binding capacity of Ch-Ge films, aqueous solutions of different carboxylic acids were prepared in the presence of iron ions and Ch-Ge films. It was observed that the Ch-Ge films only presented sorption capacity at pH 3.5 in the presence of alpha-hydroxypolycarboxylic acids, through electrostatic interactions. These results allow proposing a broad application of Ch-Ge films to beverages and other liquids containing malic, tartaric or citric acids.




Chemistry; Polymer Science


Rocha, MAM; Ferreira, P; Coimbra, MA; Nunes, C

nossos autores


This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020 & UIDP/50011/2020), QOPNA (UID/QUI/00062/2019) and LAQV-REQUIMTE (UIDB/50006/2020), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. M. Angelica M. Rocha, Claudia Nunes and Paula Ferreira thank FCT for the Doctoral (SFRH/BD/98015/2013) and Post-Doctoral fellowships (SFRH/BPD/100627/2014), and IF grant (IF/00300/2015), respectively. This work was also funded by national funds (OE), through FCT, I.P., within the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the DecreeLaw 57/2016, of August 29, changed by Law 57/2017, of July 19.

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