Surface tension of mixed surfactant systems: lignosulfonate and sodium dodecyl sulfate

Abstract.

The association between lignosulfonate (LS) and an anionic surfactant, sodium dodecyl sulfate (SDS) has been investigated by surface tension measurement. Three different LS samples were used in this study. In every case, the critical micelle concentration (CMC) value was close to about 4 mmol/l for mixed systems whereas the CMC value for SDS alone is about 8 mmol/l. Surface tension measurements at different concentrations of LS indicated that LS alone behaves as a polymeric surfactant. In the mixed LS/SDS surfactant system however, it appears that LS behaves primarily as a polyelectrolyte.