Maximizing the utilization of photo-generated electrons and holes of g-C3N4 photocatalyst for harmful algae inactivation

Effective contact between photocatalysts and algal cells is important for algae inactivation because of the efficient transfer/utilization of photo-generated charges. Herein, sulfuric acid exfoliated C3N4 (S-CN) is found to be efficient for algae inactivation under visible light irradiation (92% removal rate within 3.5 h). The high performance can be ascribed to the positive surface charge (S-CN can be rapidly adsorbed on the surface of algal cells) and small sized/ultrathin structure (high separation/transfer efficiency of charges). Furthermore, the efficiency can be improved significantly by H2O2 addition (94.3% removal rate within 1.5 h). The addition of H2O2 not only reduce the recombination of photo-induced carriers but also generate more ·OH. Decreased photosynthetic activity, membrane damage and cell rupture occur in the inactivation process. In addition, the organic matters release and leak from algal cells are also partly removed. The present work has great significance in the application of photocatalytic technology for algal remediation.