Ca-doped g-C3N4 was prepared by two-step calcination for efficient photodegradation of methylene blue

A series of simple and low-cost Ca-doped g-C3N4 (Ca/CN-X) photocatalysts were fabricated through a two-step calcination method for photodegradation of methylene blue (MB) simulated dyeing wastewater. The results showed that the photodegradation efficiency of Ca/CN-15 % on MB removal under visible light was 97.7 %, and the degradation rate constant was 4 times that of CN, showing the best photocatalytic performance. This was attributed to the fact that the doping of Ca expanded the absorption band edge, reduced the band gap, and suppressed the photogenerated electron-hole recombination, thereby increasing its corresponding photocatalytic activity. A possible photodegradation mechanism was explored, and it was found that h+ was the main active species during the process. The above indicated that Ca/CN-X can be regarded as a promising catalyst for dyeing wastewater treatment.