Aggregation of kraft lignin derivatives under conditions relevant to the process, part I: phase behaviour
2001 (English)In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, ISSN 0927-7757, Vol. 194, no 03-jan, 85-96 p.Article in journal (Refereed) Published
Aggregation of a commercial, polydisperse softwood kraft lignin (Indulin AT) in diluted aqueous alkaline solutions was investigated experimentally, by means of turbidity measurements. The influence of temperature, salt concentration and pOH and the role of a divalent counterion on the aggregation behaviour were studied. When the temperature was increased, an increased tendency of aggregation in samples containing high concentrations of sodium chloride was found. Phase separation could be detected even at pOH = 2 at 175 degreesC and the effect was pronounced when the concentration of hydroxide ions decreased. The phase transition from soluble to precipitated lignin was found to be irreversible concerning temperature change. Small amounts of calcium ions were seen to induce dramatic effects on the system stability, even at relatively high hydroxide concentrations (pOH 1-2). At a given temperature and pOH, the coagulation was found to appear at a certain critical coagulation concentration (CCC) of the added electrolyte. Furthermore, calculations were carried out to compare with the outcome of the experimental observations. A theoretical model, based on the DLVO theory, was found to predict the kraft lignin solution behaviour well.
Place, publisher, year, edition, pages
2001. Vol. 194, no 03-jan, 85-96 p.
kraft lignin, aggregation, pH, ionic strength, temperature, association, water
IdentifiersURN: urn:nbn:se:kth:diva-21059ISI: 000171824800010OAI: oai:DiVA.org:kth-21059DiVA: diva2:339756
QC 201005252010-08-102010-08-10Bibliographically approved