Highly flexible and stable carbon nitride/cellulose acetate porous films with enhanced photocatalytic activity for contaminants removal from wastewater

This study describes the successful fabrication of flexible photocatalytic films to remove contaminants from wastewater, the film is comprising sulfuric acid treated graphitic carbon nitride (SA-g-C3N4) embedded within a porous cellulose network (denoted here as CN/CA films). The SA-g-C3N4 content in the films was varied from 0 to 50 wt.%. The sulfuric acid treatment introduced carboxyl and sulfonyl groups on the surface of g-C3N4, which resulted in strong hydrogen bonding with the hydroxyl groups of cellulose acetate (so strong the partial delimination of the SA-g-C3N4 occurred on CN/CA film formation via solvent casting). The obtained films were around 10 μm in thickness, extremely flexible and durable, with the SA-g-C3N4 uniformly distributed throughout the cellulose acetate network. The CN/CA films showed excellent activities for aqueous dye degradation under direct sunlight, as well as outstanding performance for photocatalytic reduction of Cr (VI). The photocatalytic activity of the CN/CA films at the optimum SA-g-C3N4 content of 50 wt.% was far higher than that of pristine SA-g-C3N4, highlighting a main advantage of the composite film fabrication strategy introduced here. Further, the CN/CA films showed excellent stability and reusability, with no loss in activity seen over 5 cycles of dye degradation.