Aggregation and adsorption of sodium dioctylsulfosuccinate in aqueous ammonium chloride solution: Role of mixed counterions

► The binding of counterions to sodium dioctylsulfosuccinate micelle has been studied. ► Binding of sodium and ammonium mixed counterions is similar to that of sodium ion. ► Synergism in the critical micelle concentration occurs due to mixed counterions. ► An equation for the surface excess in presence of mixed counterions is derived.