Influence of carboxylic group content on the solution behavior of carboxymethylated lignin (CML) in water
2014
Gan, Linhuo | Zhou, Mingsong | Qiu, Xueqing
Carboxymethylated lignin (CML) is well suited as a dispersant or natural adsorbent applied in ceramics, gypsum paste, graphite suspension, and water treatment. In this paper, the effects of COOH content in CML on its behavior in water and the dispersion stability of aqueous graphite suspension has been investigated by means of viscosimetry, surface tension measurement, fluorescence spectrometry, dynamic light scattering (DLS), Turbiscan Lab Expert (TLE) stability analysis, and ζ potential measurement. Viscosimetry clearly revealed the polyelectrolyte effect in diluted aqueous solution of CML. With a higher COOH content of CML, the surface tension of water is reduced. Moreover, the aggregation behavior of CML was strengthened with increasing COOH content, leading to a more compact molecular structure of the aggregates. Based on the results, an aggregation model was proposed to illustrate the variations in the solution behavior of CML with different COOH contents at various concentrations. The dispersion stability of aqueous graphite suspension was improved by adding CML with high COOH content.
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