Decomposition of dimethyl phthalate in aqueous solution by UV–LED/TiO2 process under periodic illumination

•Prolonged dark period improved DMP decomposition with higher light intensities.•The existence of more oxygen is useful for replenishing the TiO2 surface.•Photocatalytic decomposition of DMP in acidic solutions were enhanced.•Kinetic model of DMP decomposition by periodic illumination was proposed.•Roughly 50% of electric energy saving was reached for periodic illumination.