Streaming potential across a porous charged membrane in organic-aqueous solutions

Streaming potentials (SPs) across a porous membrane in various organic-aqueous solutions have been studied experimentally. The effects of both the solvent (including its species and weight percentage) and the electrolyte (including its species and concentration) on the SP are presented respectively. The results show that the SP in organic solutions is always less than that in aqueous solutions whatever the bulk solution concentration (C0) is. For ethanol-aqueous solutions with the concentration fixed, the higher the weight percentage of ethanol, the lower the SP. Meanwhile, the SP is higher in an organic solution in which the solvent has a larger relative dielectric constant and vice versa. As for the effect of the electrolyte, it can be found that the SP increases with the electrolyte concentration decrease. The SP in the organic solutions with the same concentration but different electrolytes decreases in the order of LiCl > NaCl > KCl.