Spacer geometry plays an important role in membrane separation processes. In electrodialysis, spacer geometry affects not only the pressure-driven flow but can also possibly influence the local electric-field profile and with that the induced electro-osmotic flow by the spacer.
We previously demonstrated that using polyelectrolyte-coated spacers gave higher ionic currents for the same driving force, underscoring the additional electro-osmotic mixing from using spacers with charged surfaces. In this study, we expand this work to check the effect of electro-osmotic mixing in combination with spacers having different flow attack angles. We have compared, experimentally, the performance of ED using surface-charged spacers with three different flow attack angles. Our results showed that the spacers with 45$\degree$ flow attack angle outperformed the spacers with 30$\degree$ and 90$\degree$ flow attack angle when using uncoated spacers for certain applied voltage (3 to 8V). On the other hand, an improved effect of a charged coating was mostly observed for the spacer with a 45$\degree$ flow attack angle.
ER -