Adsorption and Desorption Kinetics and Equilibrium of Calcium Lignosulfonate on Dolomite Porous Media

Calcium lignosulfonate (CLS) adsorption and desorption on a porous dolomite rock have been studied. Mnetic results showed that both adsorption and desorption are time-dependent processes, not instant. It has been found that adsorption and desorption have a two-step pattern: a fast adsorption/desorption followed by a slow step. Apparent adsorption and desorption rate constants were calculated by a second-order kinetic model. Desorption is an unequilibrated process under normal injection flow rate, and it is much slower than adsorption. Equilibrium results show that adsorption and desorption of CLS onto dolomite can be well fitted by the Freundlich equation over the experimental CLS concentration range and that increase of CLS concentration increases adsorption density. Increasing temperature slightly decreases CLS equilibrium adsorption. Increase of NaCl and CaCl(2) concentrations in brine increases adsorption density, but CaCl(2) has a much stronger effect than NaCl on the adsorption.