S-scheme heterojunction g-C₃N₄/TiO₂ with enhanced photocatalytic activity for degradation of a binary mixture of cationic dyes using solar parabolic trough reactor

Developing photocatalytic systems by larger design to achieve degradation of dye pollutants by using solar light is highly desirable. Present work is devoted to the synthesis of step-scheme (S-scheme) g-C₃N₄/TiO₂ heterojunction which subsequently employed for simultaneous degradation of a binary mixture of Methylene blue (MB) and Rhodamine B (RhB) solution in parabolic trough collectors (PTC) as continuous flow loop photoreactor. The as-prepared g-C₃N₄/TiO₂ was analyzed by various techniques such as FE-SEM, EDS, XRD, FT-IR, BET, elements mapping and DRS. The composite central design (CCD) was applied to express mathematical relationships among variables such as process time, catalyst mass and initial concentrations of MB and RhB in the degradation process. The photocatalytic activity of the as-prepared composite is higher than pure TiO₂ and g-C₃N₄ that is attributed to the positive synergetic effect of S-scheme between g-C₃N₄ and TiO₂ nanostructure. Under solar irradiation in PTC, g-C₃N₄/TiO₂ was able to degrade about 94.92 and 93.07% of binary mixture MB and RhB, respectively.