Biomimetic gill-inspired membranes with direct-through micropores for water remediation by efficiently removing microplastic particles

Microplastic particles (MPs) have been identified as a potentially emerging threat to water environment and human health. It is thus an urgent challenge to develop facile and efficient methods for removing MPs from surface water and even ground water. Herein, we report a series of biomimetic gill-inspired membranes (BGIMs) with oblique and direct-through micropores for the efficient removal of MPs by the cross-flowing filtration of polluted water. These BGIMs were constructed via a bidirectional freezing method of thermally induced phase separation. They show a tunable oblique pore angle of 85° to 25° and an average pore size of 3.5 μm to 10.5 μm. MPs smaller than the pore size can be rejected via a ricocheted away mechanism. BGIMs with an oblique pore angle of 25° and an average pore size of 10.5 μm can remove 97.6% of MPs (700 nm in diameter) from water by cross-flowing on the membrane surface with a rate of 0.43 or 0.51 m/s. This effectual removal efficiency highlights BGIMs as a promising approach for quickly remediating water from the pollution of MPs.