CNTs/TiO2-loaded carbonized nanofibrous membrane with two-type self-cleaning performance for high efficiency oily wastewater remediation

Fouling of polymeric membranes for oily wastewater has been a major challenge because of the imperfection of regeneration methods. Herein, we designed and fabricated an anti-fouling polyacrylonitrile (CPEN) membrane by assembling the CNTs-COOH and TiO2 via ultrasound, self-assembly, and calcination methods. The bonding structured carbonized membrane demonstrated splendid selective wettability for various oil and water, robust mechanical property (stress load approximate to 7.8 MPa), outstanding thermal stability (400 celcius), and remarkable resistance for acid (1 M HCl)/alkali (1 M NaOH)/salt (3.5% wt NaCl)/solvent (DMF). As a result, relying on the CNTs/TiO2 layer, the surfactant-free and surfactant-stabilized oil-in-water emulsions can achieve an efficient separation (flux can reach 1180 - 3160 L m-2 h-1, R > 99%). Moreover, under photo radiation, the CPEN-CNTs/TiO2 membrane also possessed antifouling and self-cleaning performance, and achieved continuous purification of the dyes/oil emulsions (Roil > 99%, Rdye > 97%). Importantly, under the pyrolysis-induced self-cleaning method, facing the high adhesion crude oil emulsions, the CPEN-CNTs/TiO2 membrane achieved efficient purification and full recovery of the membrane (Rir approximate to 1.1%). We believe that the presented strategy on two-type self-cleaning membrane fabrication has broad prospects in the multifunctional oily wastewater remediation and revivable membrane.

Automated summary

An anti-fouling polymeric membrane (CPEN) was designed and fabricated by assembling CNTs-COOH and TiO2 via ultrasound, self-assembly, and calcination methods. The membrane showed excellent selective wettability, robust mechanical property, outstanding thermal stability, and remarkable resistance to acid, alkali, salt, and solvent. With the addition of CNTs/TiO2 layer, efficient separation of surfactant-free and surfactant-stabilized oil-in-water emulsions was achieved, along with self-cleaning and continuous purification of dyes/oil emulsions.