Electrically Pore-Size-Tunable Polypyrrole Membrane for Antifouling and Selective Separation

Antifouling and selectivity are major challenges for membrane separation technology. Herein, a polypyrrole-dodecylbenzene sulfonate (PPy-DBS) membrane with tunable pores is fabricated to alleviate pore blocking and achieve selective separation. The insertion/extraction of ions during the electrical redox process causes the change of PPy-DBS volume, so that the membrane pores can be tuned in situ by applying an external redox potential. The pore size of a fouled membrane is enlarged under an oxidation voltage, then the membrane is backwashed to eliminate foulants in the pores, after which membrane pore size is recovered under a reduction voltage. Thus, membrane fouling can be effectively alleviated by adjusting the membrane pore size combined with cleaning. The specific flux of PPy-DBS membrane increased by 21.91% after applying the voltages and backwashing, and it exhibits great recycling performance. Moreover, the distribution of humic acid macromolecules in the permeate significantly decreased, proving the enhanced sieving effect of smaller membrane pores under negative voltage. This study provides an intelligent strategy for fouling prevention and selective separation in water treatment.