g-C3N4–rGO nanocomposite was synthesized by grinding and calcination process.
Introduction of rGO promotes the separation of photo-generated charges.
Photocatalytic ozonation of OA by g-C3N4–rGO is more efficient than g-C3N4.
g-C3N4–rGO shows excellent stability for photocatalytic ozonation of OA.