Fabrication of transparent and hazy cellulosic light-management film for enhancing photon utilization in photocatalytic membrane process

Given the high demand of photocatalytic membrane filtration processes on both mass transport and light-utilization, this work introduces a novel transparent and highly porous cellulose film (P-RCF) that can serve as a light management layer to enhance the photon utilization of photocatalytic membrane processes. The built-in micron-sized pores act not only as channels for mass transport (filtration resistance ∼5 × 1010/m) but also as forward scatterers to endow the film with a high transmission haze (∼77%) without impairing its transmittance (∼90%). A g-C3N4 membrane with attached P-RCF (P-RCF@C3N4) exhibited enhanced photocatalytic activity for both tetracycline (TC) oxidation and Cr(VI) reduction. Moreover, by adjusting the incident light angle from 0° to 50°, the observed TC degradation kinetics on P-RCF@C3N4 became more stable than those on the bare g-C3N4 membrane, exhibiting incident-angle-independent properties. This enhanced photocatalytic performance can be attributed to the synergistic effect of refractive-index matching and light scattering within our transparent film, which reduces light reflection and traps the light inside at the photoactive layer, resulting in extended light propagation and utilization. This study provides a novel and versatile strategy for developing light management techniques for advanced photocatalytic membrane systems.