Kinetic study and DFT calculation on the tetracycline abatement by peracetic acid

Abstract

Water contamination by tetracycline (TC) has emerged as an environmental concern owing to its widespread use and antibiotic resistance. Application of peracetic acid (PAA) in the water and wastewater treatment has recently been proposed and demonstrated to be effective for TC abatement, yet the underlying reaction kinetics between the PAA and TC are not yet clear. To explore the reaction kinetics, the effect of solution pH on TC abatement by PAA is studied and the species-specific rate constants are calculated. The ability to donate and accept electrons for different species of TC and PAA is evaluated via density functional theory (DFT) calculations. The pH-dependent apparent second-order rate constants of TC abatement by PAA exhibits the parabolic shape with the maximum at pH 8.5 (9.75 L mol−1 s−1). This phenomenon is closely related to the speciation of TC and PAA, in which the reaction between PAAH and TTC2− possesses the highest species-specific rate constants according to the kinetic simulation. Further DFT calculations suggest that the HOMO of TTCH+, TTC, TTC−, TTC2− and the LUMO of PAAH and PAA− are –6.40, –6.26, –5.10, –4.94 eV and –0.24, 0.60 eV, respectively. According to the DFT calculations, deprotonation of TC and PAA leads to an increase of the HOMO value of TC and the LUMO value of PAA. Furthermore, the HOMOTC–LUMOPAA values is in good agreement with the trend of species-specific rate constants, which can be used to evaluate the reactivity between PAA and TC with different species. This study provides the kinetic data and theoretical basis for the reaction of PAA and TC, which is critical for the application of PAA in the treatment of water and wastewater.