Influence of oxidation, hydroxymethylation and sulfomethylation on the physicochemical properties of calcium lignosulfonate

The oxidation, hydroxymethylation and sulfomethylation of calcium lignosulfonate (CLS) were carried out in alkaline medium. Different physicochemical properties of the three reaction samples were determined. Results show that all the three treatments increase the adsorption capacity of CLS, and the absorbed amount of CLS on the surface of cement particles is 1.2 times, 6.9 times and 7.5 times, respectively, larger than that of not reacted one after sulfomethylation, hydroxymethylation and oxidation. The influences of three reactions on the surface activity, foaming ability, complexing property and dispersive performance of CLS are different. The first three properties can be strongly improved by hydroxymethylation but the dispersive performance is weakened. Oxidation has an adverse influence compared to hydroxymethylation. Sulfomethylation only enhances the dispersive performance and has little effect on other properties. Results also indicate that the presence of large amounts of hydroxyl group is the main reason that CLS has complexation property. (c) 2007 Elsevier B.V. All rights reserved.