Differences in solubility parameters and susceptibility to salting-out between softwood and hardwood lignosulfonates

The salting-out of lignosulfonates (LSs) follows the Hofmeister series, but different LSs show different susceptibility to salting-out. By comparing results for a large number of LSs from different plant species, pulping conditions, and post-treatment of the LS, it was found that the salting-out concentration for different LSs is mainly due to differences in the plant species with guaiacyl LS being much more salt-tolerant than guaiacyl-syringyl LS. The pulping conditions have only a minor effect on the salt tolerance of the different LSs. Post-treatment that increases the molecular weight or reduces the sulfonation also reduces the salt tolerance.