Heterogeneous photocatalytic removal of the herbicide clopyralid and its comparison with UV/H2O2 and ozone oxidation techniques

► Clopyralid has been detected in water at higher concentrations than 0.1 ug/L. ► Development of novel treatment processes is needed in order to effectively remove this herbicide. ► Three oxidation processes (UV/TiO2, UV/H2O2, O3) have been studied. ► Effects of operating parameters on process performance to remove clopyralid have been studied. ► UV/TiO2 outperformed UV/H2O2 and O3.