Peroxyl radicals from diketones enhanced the indirect photochemical transformation of carbamazepine: Kinetics, mechanisms, and products

•Diketones could enhance the photoconversion of carbamazepine as well as H2O2.•The promotion effect of diketones was pH-dependent and favorable in acidic solution.•Attack of organic peroxyl radicals was the main mechanism in UV/diketone systems.•Mutagenic acridine was the main cumulative intermediate in the presence of diketones.