Desorption of metal ions from kraft pulps. Part 2. Chelation of kraft pulps with different complexing agents and with EDTA in a reducing environment

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Kim Granholm, Leo Harju, Ari Ivaska
Publisher: NORTH CAROLINA STATE UNIV DEPT WOOD & PAPER SCI
Publication year: 2010
Journal: BioResources
Journal acronym: BIORESOURCES
Volume number: 5
Issue number: 1
Start page: 227
End page: 243
Number of pages: 17
ISSN: 1930-2126
eISSN: 1930-2126


Abstract

Desorption of metal ions from oxygen-bleached hardwood and softwood kraft pulps by different chelation treatments were studied. The main focus was on desorption of manganese, iron, and magnesium ions, but also on desorption of some other common metal ions. The metal ion concentrations were determined by the DCP-AES and ICP-MS techniques. Acid treatments with nitric and oxalic acids removed manganese and magnesium very effectively and partially iron as well. Some potential complexing agents such as triethanolamine (TEA), citric acid, oxalic acid, and formic acid were also tested. By using the concept of side reaction coefficients, a comparison of the chelating strengths between different chelating agents can be made. TEA is a strong chelant for iron and did remove part of iron at pH 10. The effect of chemical reduction simultaneously with EDTA was studied by using sodium borohydride, sodium dithionite, and sodium bisulfite as reducing agents. The reducing environment improved desorption of manganese but did not improve removal of iron. The measured redox potentials indicated that the reducing effect with the used agents was not enough to convert iron(III) to iron(II). The effect of the reducing agents was decreased by their decomposition during the chelation experiment.


Keywords

Acid wash, Citric acid, Desorption, EDTA, Kraft pulp, Oxalic acid, Redox potential, TEA

Last updated on 2019-12-11 at 04:42