pH-controlled mechanism of photocatalytic RhB degradation over g-C3N4 under sunlight irradiation

Photocatalysis of dye degradation is one of green and cheap technologies for solving environmental pollution. Whereas it is rarely concerned that the degradation process varied with the change of solution condition, this work studied the influence of hydrion in the solution on the photodegradation process of Rhodamine B (RhB) over g-C3N4. The photocatalytic activity of RhB degradation was enhanced gradually with increased hydrion content in the system. The efficiency for RhB degradation over g-C3N4 in weak acidic system with interference of multiple metal-ions still reached near 95% after 30 min of natural sunlight irradiation. A large amount of oxidation species and the hydroxylation mineralization process were induced by increasing the hydrion concentration. Two degradation processes for deethylation of four ethyl groups and the direct chromophoric degradation were discovered and proved by multifarious intermediates in different systems using the ESR technique, LC/MS and GC/MS analysis. In addition, the photosensitization played a critical role in the RhB degradation. A feasible degradation mechanism was proposed for the RhB degradation based on the experimental results.

Automated summary

The study investigated the impact of hydrogen ion concentration on the photodegradation process of Rhodamine B over g-C3N4, showing that the degradation efficiency remained high in a weakly acidic environment. Analysis revealed different degradation processes and intermediates in various systems, confirming the critical role of photosensitization in RhB degradation.