Influence of lignosulfonate types and electrolyte concentrations on the adsorption of lignosulfonate onto clay

Abstract

Lignosulfonate has been reckoned as an effective sacrificial agent with the potential to minimize surfactant adsorption onto clay minerals. As such, this paper compares various types of LS at different electrolyte to determine their capability of adsorption onto kaolinite. The adsorption experiment by using depletion method had been conducted to investigate all genres of the LS. The best LS were then furthered investigated in equilibrium and kinetic condition. Adsorption at varying electrolyte values, such as NaCl (3wt%) and CaCl2 (0.5wt%), displayed increment of sodium lignosulfonate (SLS) adsorption onto kaolinite along with escalating electrolyte. Effect of pH showed less effect on the adsorption. Moreover, adsorption isotherm models were taken up to investigate the mechanisms of LS adsorption, which exemplified not only SLS adsorption onto kaolinite was indeed favorable, but the adsorption data also best fitted and described by Freundlich isotherm models. As for kinetics adsorption, pseudo-second order appeared to be the best model that described SLS adsorption onto kaolinite. To conclude, this paper can provide insight benchmark to select the most effective sacrificial agent among the varies LS to minimize surfactant adsorption onto kaolinite.