Mechanism of detoxification of aluminum ions by kraft lignin treated with alkaline oxygen

• Published in: Journal of wood science 2003-02, Vol.49 (1), p.93-99
• Main Authors: Saito Katsumata, K. (Tokyo National Univ. of Fine Arts and Music (Japan)), Shintani, H, Meshitsuka, G
• Format: Article
• Language: English
• Subjects: ALUMINIUM; Aluminum; Biological and medical sciences; Biotechnology; BYPRODUCTS; Calcium ions; Cation exchanging; Complex formation; COMPLEXING; Copper; Ferric ions; Fundamental and applied biological sciences. Psychology; Hydroxyl groups; Industrial applications and implications. Economical aspects; Lignin; LIGNINS; NMR; NMR SPECTROSCOPY; Nuclear magnetic resonance; Other applications; Oxygen; POTENTIOMETRY; SOIL CONDITIONERS; Soil conditions; Sulfonic acid; Titration; WASTE UTILIZATION
• ISSN: 1435-0211; 1611-4663
• DOI: 10.1007/s100860300015

Kraft lignins modified by radical sulfonation or alkaline oxygen treatment were rich in acidic groups, such as sulfonic acid, carboxylic acid, and phenolic hydroxyl groups, and were effective as soil-conditioning agents, especially because of their ability to trap aluminum ions eluted from soil under acidic conditions. Formation of complexes between aluminum ions and modified lignins was examined using potentiometric titration and 27Al nuclear magnetic resonance (NMR) spectroscopy. Changes in the titration curve of a modified lignin by the addition of aluminum ions suggest the release of protons after the formation of complexes between them. Disappearance of 27Al-NMR signals assigned to various aluminum ions by the addition of kraft lignin treated with alkaline oxygen was also attributed to the formation of complexes. The relative ease of proton release because of complex formation between a modified lignin and metal ions was as follows: Fe3+ > Al3+ > Cu2+ > Pb2+ > Mn2+ > Ca2+. This indicates that aluminum complexes are quite stable, and the aluminum ion is not exchanged with cations other than Fe3+.