Degradation of salicylic acid by Fenton and modified Fenton treatment

The degradation of salicylic acid (SA) was carried out utilizing classical Fenton reagents and modified Fenton with ferric iron salt and goethite as source of iron catalyst. The efficiency of the treatments was evaluated on the basis of SA degradation degree, COD and BOD reduction. Due to the tendency of SA to form complexes with ferric iron, decreasing the concentration of catalyst and increasing that of hydrogen peroxide intensified SA degradation by the classical Fenton process. Application of Fe3+/H2O2 led to the same SA degradation degree as classical Fenton process with the following termination, where the entire residual SA is complexed with Fe3+. SA degradation by modified Fenton was intensified with higher goethite concentration and in acidic pH conditions. The addition of UV-irradiation did not improve the action of the Fenton's/modified Fenton's reagent system. Overall COD and BOD removal efficiency comprised nearly 90% under optimal treatment conditions applied.