Superpermeable nanoporous carbon-based catalytic membranes for electro-Fenton driven high-efficiency water treatment

Abstract

Based on the Hagen–Poiseuille equation, theoretical membrane permeability is inversely and directly proportional to its thickness and pore-radius, respectively, indicating that a thin membrane with an effective pore-radius is extremely permeable. However, the trade-off between selectivity and permeability restricts their applications for pressure-driven separation membranes. Hence, balancing the contradiction between the permeability and selectivity of a separation membrane is desired in future applications. Herein, we report a superpermeable nanoporous carbon (PC) membrane which offers a separation layer (∼80 nm) and effective pore radius (∼20 nm) by selectively removing parts of carbon atoms, thus greatly decreasing the transport resistance of water molecules through the membrane. The experimental results have shown a water flux of ∼8000 L m⁻² h⁻¹ bar⁻¹ for the membrane. High selectivity is demonstrated via selective separation of nanoparticles with their narrowly distributed pores. Self-production of H₂O₂ and self-circulation of Fe²⁺/Fe³⁺ was achieved simultaneously on the PC membrane via coupling with electro-Fenton technology, which leads to the in situ production of hydroxyl radicals. The removal efficiencies of organic contaminants (SMX, BPA and phenol) by electro-Fenton driven PC membranes were ∼96.3%, ∼97.4% and 92.1%, respectively. Given their compatible high permeability and high selectivity, our porous PC membranes might provide an alternative as future membranes and motivate the design of innovative membranes.